Re: securing new ratchet block
Yes, please send a pic if you do not mind, Mark.
Thanks!
Brian
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Re: securing new ratchet block
Thanks so much for the quick and helpful answers. I have not purchased the ratchet block yet but was thinking about the H2135 57 mm ratchet block from Harken. Thoughts on that?
Many thanks!
Brian
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Re: securing new ratchet block
Hi Brian We'd suggest getting the block first then going to the hardware store to find the right size fasteners. Make sure to get good stainless, marine grade preferred. Machine screw, washer and nylon stop nut. Assuming you are attaching the block to the cockpit lip we like to get fasteners that are not too short and not too long. Too short and it is hard to get the nut started on the screw back in its blind spot. Too long and you need a deep socket to hold the nut as it threads over 10 miles of screw. 1/2 inch extra thread is about right.? Get a pencil and mark the spot for the fastener holes. Don't go too far forward or you drill into the internal hull or forward cockpit bulkhead. Too far aft and there is no clearance for the nut.? Some folks like to add a thin metal or plastic backer plate underneath the lip. Not needed but helpful. The manufacturer does not add anything other than washers.?  Fire away with questions. Our question is which block are you installing? -- Cheers Clark and Skipper Our blog Our book?
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Re: securing new ratchet block
Hi Brian, ? I took an original, pretty nice, 1984 AMF Alcourt boat and put all the racing equipment on it. I used a Harken eye strap and Harken ratchet block. You need to through bolt it on the deck just above where the current brass mainsheet hook is. Instead of washers I used a second eye strap underneath the deck and use that to secure the forward end of the hiking strap. ? I'm just about to do the same thing to my practice boat which is now sitting on the beach at Lake Onalaska in La Crosse (part of the Upper Mississippi River system). I've only sailed it one time and I have to say it was fun using the hook since I haven't done that in a Fish since I got my first one in the 1960s. At the beginning, for racing, that was all that was legal (along with the Manella mainsheet). Then they approved just a single brand/model, center, mainsheet cleat that worked very poorly. A few years later they open that up for all options. ? If you would like, I'd be happy to send you a photo. ? Best regards, ? Mark ? Sunfish 7500 La Crosse Sailing Club La Crosse, Wisconsin ? 
? Mark A. Kastel Kastel@... 608-625-2042 ?
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From: [email protected] < [email protected]> On Behalf Of Brian Rood Sent: Friday, May 22, 2020 6:32 AM To: [email protected]Subject: [SunfishSailor] securing new ratchet block ? Hi folks,
How do you fasten a new ratchet block to the Sunfish deck? Does one drill pilot holes first and then fasten? I am also having difficulty finding exactly what screws or other fasteners that should be used in this application. I have a 73 that is still in excellent condition and would rather not make a mistake here.
Many thanks!
Brian
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Re: securing new ratchet block
Brian,
I cut out a block of wooden decking board as a backing plate, clamped it in place and drilled thru holes for a #8 or #10 SS machine screw.? Mount ratchet block and secure with screws ?washers and nyloc nuts.? I mounted a cam cleat instead
of a ratchet but the procedure should be the same for both.? Select the proper screws (oval head, countersink, etc) depending on requirements.
?
Mr Mike
?
Sent from for Windows 10
?
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From: Brian Rood
Sent: Friday, May 22, 2020 7:32 AM
To: [email protected]
Subject: [SunfishSailor] securing new ratchet block
?
Hi folks,
How do you fasten a new ratchet block to the Sunfish deck? Does one drill pilot holes first and then fasten? I am also having difficulty finding exactly what screws or other fasteners that should be used in this application. I have a 73 that is still in excellent
condition and would rather not make a mistake here.
Many thanks!
Brian
|
securing new ratchet block
Hi folks,
How do you fasten a new ratchet block to the Sunfish deck? Does one drill pilot holes first and then fasten? I am also having difficulty finding exactly what screws or other fasteners that should be used in this application. I have a 73 that is still in excellent condition and would rather not make a mistake here.
Many thanks!
Brian
|
Re: Questions From The First-Time Sailor
Ah — cut with the blade notching into a sacrificial fence! ?Simple but a new one on me. ?So your cutoff is on the same side as the fence. ?That lets you cut way down on irregularities due to any curvature of the pole, because your fence is right at the corner you’re cutting off. ?And takes way less math.
But I’d certainly stand aside, and maybe also have a gloved helper pull the cutout on through once its end reached the blade and got severed. ?Or at least have an outfeed support that kept the cutout from prying its tail end up against the blade. ?A lot of the happen-before-you-know-it accidents occur when the support of the workpiece or tool suddenly changes — the moment when the cutoff becomes severed, the moment when a drill breaks through the far side, etc.
Yes, the cutout is small but has no less length, so it’s got no less mass per unit of end area than the main workpiece does — it could spear you with about as much frontal pressure as a bigger stick of the same length. ?That stick that took out Hank’s tempered-glass window was less than a 1x1, and less than a foot long.
Crispin
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I counted sheep last night too (well sitting at the dining table) and came up with a couple of constants to use to cut the 12 faced blank.? The lateral distance from the fence to the blade is about .211 times the side of the square and the vertical distance from the table to where the blade intersects the fence is .366 times the side of the square.? Of course you only need one of those if you've got your blade at 30 degrees and the lateral one is most practical.? I usually measure as close as I can and then do a few test cuts, just barely touching the sample wood to the spinning blade.? However, this does use what you probably consider the more dangerous fence/blade configuration, but I have found (so far) that if the blade is embedded into the sacrificial fence, the cutoff is less likely to ride up and kick out.? ?And the relatively small piece of cutoff doesn't pose as much of a danger as when the blade could get hold of the whole blank.? In theory.? But I always stand to the side, out of the line of fire, at any angle of the blade.
I'll try to draw it up and show the equations later but it's simple enough.??
Very good on the 38 degree trick.? I'll go through it and see if I can follow, but will need to draw that too.? I suppose the possibilities for this trick are endless.? Perhaps not practical but endless just the same.
Thanks!, James On Thu, May 21, 2020 at 9:28 AM crispin_m_miller < crispinmm@...> wrote: Back to you, James,
Of course, once you’ve got the fence-distance formula of ?"1+ (sqrt3)/3 ) r” ?i.e. 1.577 r , then if you know “r" (half the width of your blank), you can also just do the multiplication and set the fence.? Depending on your particular fence and your particular tilt-reading scale, I 诲辞苍’迟 know which approach would be more accurate. ?
But if you set the fence by measuring tape, you have to deal with a tilted blade, and if you set it by a built-in scale, you need the blade tilt motion to be centered exactly at the table surface.? So the lay-against-the-blade trick does bypass both of those uncertainties, and also the measuring and multiplication tasks.? You do need a blade with teeth enough that a number of them (of the relevant tooth-set direction) fall within the face of the blank, for the blank to rest against the blade accurately.
cm
On May 21, 2020, at 8:33 AM, crispin_m_miller via ??< crispinmm@...> wrote: (Then remember to reset your blade to 30deg to make your actual cuts…) On May 21, 2020, at 8:28 AM, crispin_m_miller via ??< crispinmm@...> wrote: Good morning, James —? On May 20, 2020, at 10:16 PM, crispin_m_miller via ??< crispinmm@...> wrote: Next assignment: what is a similar trick to cut a dodecagon?
Octagons not good enough?? Oy.? Not this week, I’m supposed to be loading a truck with our belongings and they’re not even all boxed yet.? Misjudged how soon my big strong son would be done with his (now online) schoolwork and could help me.
There does have to be some theoretical plane of the blade that would let you use the same trick — i.e., tilt up the corner of the stick to define the desired fence distance. ?(And then having set the fence, reset the blade to 30 degrees off vertical and make your cuts.)
OK, used this question as my substitute for counting sheep last night and saw a simpler way to frame it. Woke up now and punched it in.
Can look for a time on the road to prepare an intelligible sketch, but I get that the initial blade tilt for setting the fence should be practically 38 degrees — if I have it right, the trig is
angle = arccos ( ( 1+ (sqrt 3)/3 ) / 2) = 37.94 deg
constructed by (looking at the square blank endwise)
Call the half-dimension of the square “r” (since it will be the radius of your finished cylinder.)
You want to end up with 12 flats, each of them square to the radius at one of the 12 hours of the clock (and at distance r from the middle)
Assuming your blade tilts to the left (otherwise, once you’ve drawn this, hold it in a mirror):
Your desired initial cut will form the 8:00 flat, so it will be be 30deg off vertical, crossing the 8:00 o’clock radius at a distance of r from the center
(This makes it hit the left side of the square at 8:30 but that was a distraction, no help in the trig)
More usefully, it hits the bottom at 7:00 forming a 120deg corner there between the flats of 6:00 and 8:00 because you won’t have cut the flat for 7:00 yet
Draw a radial line to that 7:00 corner: from center of the square to 7 o’clock on the bottom side of the square
Your desired 8:00-flat cut is a line from there upward to left at 30deg off vertical, so the fence distance starts from that 7:00 point and reaches to the lower right corner (at 4:30 so to speak)
Distance from 7:00 to 6:00 measured along the bottom side is r tan 30deg = ((sqrt3)/3) r
Distance from 6:00 to the 4:30 corner is r
so distance from 7:00 to 4:30 corner is r(1+ (sqrt3)/3 ) ?(or r(1+ tan30deg)
Your initial (fence-setting) blade tilt needs to cock the bottom of the stick upward so that with its width of 2 r as hypotenuse, it spans a horizontal distance equal to the fence setting.? Whatever that tilt is from horizontal, the blade needs to be set at that angle from vertical.
So you want a tilt of arccos ( r(1+ (sqrt3)/3 ) / 2r ) and the r’s cancel and I get 37.94 degrees.
Please retrace my steps and see if I’m awake yet.
BTW I would have to think more whether this non-45 scheme will tolerate radiused corners the way I mentioned that the octagon trick would (I suspect not) -- so at least for now I’d do this one using sharp square-cut corners.
OK, gotta cook brek, wave it under the kid’s nose to wake him up, and we gotta carry boxes
Be careful with your saw
Crispin
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Re: Questions From The First-Time Sailor
I counted sheep last night too (well sitting at the dining table) and came up with a couple of constants to use to cut the 12 faced blank.? The lateral distance from the fence to the blade is about .211 times the side of the square and the vertical distance from the table to where the blade intersects the fence is .366 times the side of the square.? Of course you only need one of those if you've got your blade at 30 degrees and the lateral one is most practical.? I usually measure as close as I can and then do a few test cuts, just barely touching the sample wood to the spinning blade.? However, this does use what you probably consider the more dangerous fence/blade configuration, but I have found (so far) that if the blade is embedded into the sacrificial fence, the cutoff is less likely to ride up and kick out.? ?And the relatively small piece of cutoff doesn't pose as much of a danger as when the blade could get hold of the whole blank.? In theory.? But I always stand to the side, out of the line of fire, at any angle of the blade.
I'll try to draw it up and show the equations later but it's simple enough.??
Very good on the 38 degree trick.? I'll go through it and see if I can follow, but will need to draw that too.? I suppose the possibilities for this trick are endless.? Perhaps not practical but endless just the same.
Thanks!, James
On Thu, May 21, 2020 at 9:28 AM crispin_m_miller < crispinmm@...> wrote: Back to you, James,
Of course, once you’ve got the fence-distance formula of ?"1+ (sqrt3)/3 ) r” ?i.e. 1.577 r , then if you know “r" (half the width of your blank), you can also just do the multiplication and set the fence.? Depending on your particular fence and your particular tilt-reading scale, I 诲辞苍’迟 know which approach would be more accurate. ?
But if you set the fence by measuring tape, you have to deal with a tilted blade, and if you set it by a built-in scale, you need the blade tilt motion to be centered exactly at the table surface.? So the lay-against-the-blade trick does bypass both of those uncertainties, and also the measuring and multiplication tasks.? You do need a blade with teeth enough that a number of them (of the relevant tooth-set direction) fall within the face of the blank, for the blank to rest against the blade accurately.
cm
On May 21, 2020, at 8:33 AM, crispin_m_miller via < crispinmm@...> wrote: (Then remember to reset your blade to 30deg to make your actual cuts…) On May 21, 2020, at 8:28 AM, crispin_m_miller via ??< crispinmm@...> wrote: Good morning, James —? On May 20, 2020, at 10:16 PM, crispin_m_miller via ??< crispinmm@...> wrote: Next assignment: what is a similar trick to cut a dodecagon?
Octagons not good enough?? Oy.? Not this week, I’m supposed to be loading a truck with our belongings and they’re not even all boxed yet.? Misjudged how soon my big strong son would be done with his (now online) schoolwork and could help me.
There does have to be some theoretical plane of the blade that would let you use the same trick — i.e., tilt up the corner of the stick to define the desired fence distance. ?(And then having set the fence, reset the blade to 30 degrees off vertical and make your cuts.)
OK, used this question as my substitute for counting sheep last night and saw a simpler way to frame it. Woke up now and punched it in.
Can look for a time on the road to prepare an intelligible sketch, but I get that the initial blade tilt for setting the fence should be practically 38 degrees — if I have it right, the trig is
angle = arccos ( ( 1+ (sqrt 3)/3 ) / 2) = 37.94 deg
constructed by (looking at the square blank endwise)
Call the half-dimension of the square “r” (since it will be the radius of your finished cylinder.)
You want to end up with 12 flats, each of them square to the radius at one of the 12 hours of the clock (and at distance r from the middle)
Assuming your blade tilts to the left (otherwise, once you’ve drawn this, hold it in a mirror):
Your desired initial cut will form the 8:00 flat, so it will be be 30deg off vertical, crossing the 8:00 o’clock radius at a distance of r from the center
(This makes it hit the left side of the square at 8:30 but that was a distraction, no help in the trig)
More usefully, it hits the bottom at 7:00 forming a 120deg corner there between the flats of 6:00 and 8:00 because you won’t have cut the flat for 7:00 yet
Draw a radial line to that 7:00 corner: from center of the square to 7 o’clock on the bottom side of the square
Your desired 8:00-flat cut is a line from there upward to left at 30deg off vertical, so the fence distance starts from that 7:00 point and reaches to the lower right corner (at 4:30 so to speak)
Distance from 7:00 to 6:00 measured along the bottom side is r tan 30deg = ((sqrt3)/3) r
Distance from 6:00 to the 4:30 corner is r
so distance from 7:00 to 4:30 corner is r(1+ (sqrt3)/3 ) ?(or r(1+ tan30deg)
Your initial (fence-setting) blade tilt needs to cock the bottom of the stick upward so that with its width of 2 r as hypotenuse, it spans a horizontal distance equal to the fence setting.? Whatever that tilt is from horizontal, the blade needs to be set at that angle from vertical.
So you want a tilt of arccos ( r(1+ (sqrt3)/3 ) / 2r ) and the r’s cancel and I get 37.94 degrees.
Please retrace my steps and see if I’m awake yet.
BTW I would have to think more whether this non-45 scheme will tolerate radiused corners the way I mentioned that the octagon trick would (I suspect not) -- so at least for now I’d do this one using sharp square-cut corners.
OK, gotta cook brek, wave it under the kid’s nose to wake him up, and we gotta carry boxes
Be careful with your saw
Crispin
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Jim,
If you been sailing Sunfishes for almost 60 years you must be close to me in age.? I appreciate your sense of humor with this turtling.? I think I have mine fixed now where it won’t turtle.? I like to keep mine up right.? In the summer
there a lot of power boats zooming the ICW, so I like my sail on top where they can see me.? Sometimes I have to tack across the ICW and these boats are going fast and many cut right in front of me or right behind.? And a lot of them are drinking beer and
have the stereo blasting and aren’t paying attention.? In the winter, without the boat traffic, I 诲辞苍’迟 want to go in the cold water, even with my drysuit.??? So I avoid capsizing and am likely a bit on the conservative side but I still ?love it nonetheless.
?
My Force 5 will likely get the Clorox bottle on the top of the mast.? The sail is sleeved and there is no good way to install a permanent float.? The capsize rate on the F5 is about three times the Sunfish.? And with that high aspect ratio
sail it is much more difficult to right especially when the mast gets some water in it and the sail is under water.
?
Mr Mike
?
Sent from for Windows 10
?
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From: James Sherwood
Sent: Wednesday, May 20, 2020 4:08 PM
To: [email protected]
Cc: James M. Sherwood
Subject: Re: [SunfishSailor] sunfish floatation
?
Hello, I have been sailing Sunfishes for almost 60 years. Have capsized and turned turtle?innumerable times. That is all part of the fun. So long as all parts and spars are securely attached to to hull, there should not be a problem. I
have capsized and righted many times without getting so my as my foot wet. I have?never done anything to prevent turning?turtle, but it seems to me that just tying a bunch of milk jugs to the top of the yard would work very well. It would be simple and free
and quick and easy and quite effective. Certainly worth a try. Personally, I think that turning turtle can be fun, especially?when you right it and it comes back up with lots of mud on the spars and sail and it drips all over you. Then you just capsize again
and it washes off. Thank, Jim?
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Re: Questions From The First-Time Sailor
Ahh, ok, understood, thanks! On Thursday, May 21, 2020 09:55:17 AM crispin_m_miller wrote: To make the CUTS, you most assuredly would have the blade at one of those
angles.
The funny 38-degree setting is for a trick that uses the tilted square
blank as a spacer to set the fence. ----->< other good stuff snipped ><-----
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Re: Questions From The First-Time Sailor
Back to you, James,
Of course, once you’ve got the fence-distance formula of ?"1+ (sqrt3)/3 ) r” ?i.e. 1.577 r , then if you know “r" (half the width of your blank), you can also just do the multiplication and set the fence. ?Depending on your particular fence and your particular tilt-reading scale, I 诲辞苍’迟 know which approach would be more accurate. ?
But if you set the fence by measuring tape, you have to deal with a tilted blade, and if you set it by a built-in scale, you need the blade tilt motion to be centered exactly at the table surface. ?So the lay-against-the-blade trick does bypass both of those uncertainties, and also the measuring and multiplication tasks. ?You do need a blade with teeth enough that a number of them (of the relevant tooth-set direction) fall within the face of the blank, for the blank to rest against the blade accurately.
cm
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On May 21, 2020, at 8:33 AM, crispin_m_miller via < crispinmm@...> wrote: (Then remember to reset your blade to 30deg to make your actual cuts…) On May 21, 2020, at 8:28 AM, crispin_m_miller via ??< crispinmm@...> wrote: Good morning, James —? On May 20, 2020, at 10:16 PM, crispin_m_miller via ??< crispinmm@...> wrote: Next assignment: what is a similar trick to cut a dodecagon?
Octagons not good enough? ?Oy. ?Not this week, I’m supposed to be loading a truck with our belongings and they’re not even all boxed yet. ?Misjudged how soon my big strong son would be done with his (now online) schoolwork and could help me.
There does have to be some theoretical plane of the blade that would let you use the same trick — i.e., tilt up the corner of the stick to define the desired fence distance. ?(And then having set the fence, reset the blade to 30 degrees off vertical and make your cuts.)
OK, used this question as my substitute for counting sheep last night and saw a simpler way to frame it. Woke up now and punched it in.
Can look for a time on the road to prepare an intelligible sketch, but I get that the initial blade tilt for setting the fence should be practically 38 degrees — if I have it right, the trig is
angle = arccos ( ( 1+ (sqrt 3)/3 ) / 2) = 37.94 deg
constructed by (looking at the square blank endwise)
Call the half-dimension of the square “r” (since it will be the radius of your finished cylinder.)
You want to end up with 12 flats, each of them square to the radius at one of the 12 hours of the clock (and at distance r from the middle)
Assuming your blade tilts to the left (otherwise, once you’ve drawn this, hold it in a mirror):
Your desired initial cut will form the 8:00 flat, so it will be be 30deg off vertical, crossing the 8:00 o’clock radius at a distance of r from the center
(This makes it hit the left side of the square at 8:30 but that was a distraction, no help in the trig)
More usefully, it hits the bottom at 7:00 forming a 120deg corner there between the flats of 6:00 and 8:00 because you won’t have cut the flat for 7:00 yet
Draw a radial line to that 7:00 corner: from center of the square to 7 o’clock on the bottom side of the square
Your desired 8:00-flat cut is a line from there upward to left at 30deg off vertical, so the fence distance starts from that 7:00 point and reaches to the lower right corner (at 4:30 so to speak)
Distance from 7:00 to 6:00 measured along the bottom side is r tan 30deg = ((sqrt3)/3) r
Distance from 6:00 to the 4:30 corner is r
so distance from 7:00 to 4:30 corner is r(1+ (sqrt3)/3 ) ?(or r(1+ tan30deg)
Your initial (fence-setting) blade tilt needs to cock the bottom of the stick upward so that with its width of 2 r as hypotenuse, it spans a horizontal distance equal to the fence setting. ?Whatever that tilt is from horizontal, the blade needs to be set at that angle from vertical.
So you want a tilt of arccos ( r(1+ (sqrt3)/3 ) / 2r ) and the r’s cancel and I get 37.94 degrees.
Please retrace my steps and see if I’m awake yet.
BTW I would have to think more whether this non-45 scheme will tolerate radiused corners the way I mentioned that the octagon trick would (I suspect not) -- so at least for now I’d do this one using sharp square-cut corners.
OK, gotta cook brek, wave it under the kid’s nose to wake him up, and we gotta carry boxes
Be careful with your saw
Crispin
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Re: Questions From The First-Time Sailor
On May 21, 2020, at 9:55 AM, crispin_m_miller via < crispinmm@...> wrote: The funny 38-degree setting is for a trick that uses the tilted square blank?as a spacer to set the fence
This stunt was originally described in my email of 6:18 PM (EDT) yesterday, about laying one flat of the square blank against a 45-degree blade (not turned on) in order to space the fence for an octagon.
Then James asked me to get cute and calculate a blade tilt to do that for 12 sides instead.
cm
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Re: Questions From The First-Time Sailor
On May 21, 2020, at 8:55 AM, Randy Kramer < rhkramer@...> wrote: I'm having trouble understanding why the fence would be set at anything?
other than 30 degrees or 60 degrees.
Hi, Randy,
To make the CUTS, you most assuredly would have the blade at one of those angles.
The funny 38-degree setting is for a trick that uses the tilted square blank as a spacer to set the fence.
Once you’ve got the fence in place, then before you make any cuts, you reset the blade to 30 degrees (measured from vertical).
I 诲辞苍’迟 know how radial-arm saws have their tilt scale arranged, but table saws customarily measure in degrees from vertical. ?This means they call a standard 90-degree cut a setting of zero. ?This caused a problem one time when I sent a shop a drawing for segments of a hexagon frame, and dimensioned the miter angle on my drawing by its actual physical shape of 60 degrees, and the shop guy used the number instead of using his head, ?and jumped through hoops because 60 was beyond the angle scale on his saw — he actually built a sled jig to hold my boards up on end so he could cut them as if he had set the saw?to 60 degrees. ?Never mind that the 30-degree chisel angle he sawed my boards to looked nothing like the drawing.
About safety, I think most rotary saws probably stop at 45 from square, because the farther you go from a square cut, the more you risk having the cutting force of the blade shove the work sideways on the table, and then things would get ugly for both safety and work quality.
(But the 38-degree angle was not about safety. ?All that stuff about kickback was a separate discussion.)
So what I’d guess would be best is to set your blade at only 30 degrees from vertical (no matter what the scale calls that), and cut 10:00 and 2:00,? roll the stick a quarter turn to place 3:00 up, and cut 1:00 and 5:00, roll again (6:00 up) and cut 4:00 and 8:00,? roll again (9:00 up) and cut 7:00 and 11:00.
Since the original faces all survive at 3:00, 6:00, 9:00, and 12:00, you 诲辞苍’迟 have to reset the fence, you’ll still have one or another of those faces to run along the fence.
Only thing about the sequence I gave above is that to cut each of those pairs of faces (for example 10:00 and then 2:00), you have to turn your blank end-for-end, so it may be easier to?
cut 10:00, roll 90, cut 1:00, roll 90, cut 4:00, roll 90, cut 7:00 —? then turn end-for-end just once, and do the same routine to cut 2:00, 11:00, 8:00, and 5:00.
I bet James is right that it’s a good idea to mark your four original faces before you start removing corners, so you 诲辞苍’迟 get lost.
best,? Crispin
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Re: Questions From The First-Time Sailor
On May 20, 2020, at 10:16 PM, crispin_m_miller via groups.io <crispinmm@...> wrote: Next assignment: what is a similar trick to cut a dodecagon?
Hmm, I have a radial arm saw (and no table saw), so everything looks like a ??? ;-) But, I'm having trouble understanding why the fence would be set at anything other than 30 degrees or 60 degrees. Ignoring safety considerations, which I would not, and would have to think about, I'd set my radial arm saw so the blade is at a 30 degree angle to the table (if I can do that, maybe I'm limited to 45 degrees in which case I'd set it to 60 degrees). Then I'd set the distance from the fence to the blade such that I could cut what I'll call the faces for 5 and 7 oclock with one of the square faces (the bottom one) on the bottom, then turn the piece 180 degees (so the top is on the bottom) and cut the 1 and 11 oclock faces. (Those should all be cuttable with the fence at the same horizontal distance.) Then I'd turn the piece 90 degrees and work on cutting the 3 and 8 oxclock faces, and then turn 180 degrees and cut the 2 and 10 oclock pieces . I have to think about it, but I may have to move the fence for these last 4 cuts (or not). Not sure what I'm missing. (Well, I am not thinking about safety.)
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Re: Questions From The First-Time Sailor
(Then remember to reset your blade to 30deg to make your actual cuts…)
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On May 21, 2020, at 8:28 AM, crispin_m_miller via < crispinmm@...> wrote: Good morning, James —? On May 20, 2020, at 10:16 PM, crispin_m_miller via < crispinmm@...> wrote: Next assignment: what is a similar trick to cut a dodecagon?
Octagons not good enough? ?Oy. ?Not this week, I’m supposed to be loading a truck with our belongings and they’re not even all boxed yet. ?Misjudged how soon my big strong son would be done with his (now online) schoolwork and could help me.
There does have to be some theoretical plane of the blade that would let you use the same trick — i.e., tilt up the corner of the stick to define the desired fence distance. ?(And then having set the fence, reset the blade to 30 degrees off vertical and make your cuts.)
OK, used this question as my substitute for counting sheep last night and saw a simpler way to frame it. Woke up now and punched it in.
Can look for a time on the road to prepare an intelligible sketch, but I get that the initial blade tilt for setting the fence should be practically 38 degrees — if I have it right, the trig is
angle = arccos ( ( 1+ (sqrt 3)/3 ) / 2) = 37.94 deg
constructed by (looking at the square blank endwise)
Call the half-dimension of the square “r” (since it will be the radius of your finished cylinder.)
You want to end up with 12 flats, each of them square to the radius at one of the 12 hours of the clock (and at distance r from the middle)
Assuming your blade tilts to the left (otherwise, once you’ve drawn this, hold it in a mirror):
Your desired initial cut will form the 8:00 flat, so it will be be 30deg off vertical, crossing the 8:00 o’clock radius at a distance of r from the center
(This makes it hit the left side of the square at 8:30 but that was a distraction, no help in the trig)
More usefully, it hits the bottom at 7:00 forming a 120deg corner there between the flats of 6:00 and 8:00 because you won’t have cut the flat for 7:00 yet
Draw a radial line to that 7:00 corner: from center of the square to 7 o’clock on the bottom side of the square
Your desired 8:00-flat cut is a line from there upward to left at 30deg off vertical, so the fence distance starts from that 7:00 point and reaches to the lower right corner (at 4:30 so to speak)
Distance from 7:00 to 6:00 measured along the bottom side is r tan 30deg = ((sqrt3)/3) r
Distance from 6:00 to the 4:30 corner is r
so distance from 7:00 to 4:30 corner is r(1+ (sqrt3)/3 ) ?(or r(1+ tan30deg)
Your initial (fence-setting) blade tilt needs to cock the bottom of the stick upward so that with its width of 2 r as hypotenuse, it spans a horizontal distance equal to the fence setting. ?Whatever that tilt is from horizontal, the blade needs to be set at that angle from vertical.
So you want a tilt of arccos ( r(1+ (sqrt3)/3 ) / 2r ) and the r’s cancel and I get 37.94 degrees.
Please retrace my steps and see if I’m awake yet.
BTW I would have to think more whether this non-45 scheme will tolerate radiused corners the way I mentioned that the octagon trick would (I suspect not) -- so at least for now I’d do this one using sharp square-cut corners.
OK, gotta cook brek, wave it under the kid’s nose to wake him up, and we gotta carry boxes
Be careful with your saw
Crispin
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Re: Questions From The First-Time Sailor
Good morning, James —? On May 20, 2020, at 10:16 PM, crispin_m_miller via < crispinmm@...> wrote: Next assignment: what is a similar trick to cut a dodecagon?
Octagons not good enough? ?Oy. ?Not this week, I’m supposed to be loading a truck with our belongings and they’re not even all boxed yet. ?Misjudged how soon my big strong son would be done with his (now online) schoolwork and could help me.
There does have to be some theoretical plane of the blade that would let you use the same trick — i.e., tilt up the corner of the stick to define the desired fence distance. ?(And then having set the fence, reset the blade to 30 degrees off vertical and make your cuts.)
OK, used this question as my substitute for counting sheep last night and saw a simpler way to frame it. Woke up now and punched it in.
Can look for a time on the road to prepare an intelligible sketch, but I get that the initial blade tilt for setting the fence should be practically 38 degrees — if I have it right, the trig is
angle = arccos ( ( 1+ (sqrt 3)/3 ) / 2) = 37.94 deg
constructed by (looking at the square blank endwise)
Call the half-dimension of the square “r” (since it will be the radius of your finished cylinder.)
You want to end up with 12 flats, each of them square to the radius at one of the 12 hours of the clock (and at distance r from the middle)
Assuming your blade tilts to the left (otherwise, once you’ve drawn this, hold it in a mirror):
Your desired initial cut will form the 8:00 flat, so it will be be 30deg off vertical, crossing the 8:00 o’clock radius at a distance of r from the center
(This makes it hit the left side of the square at 8:30 but that was a distraction, no help in the trig)
More usefully, it hits the bottom at 7:00 forming a 120deg corner there between the flats of 6:00 and 8:00 because you won’t have cut the flat for 7:00 yet
Draw a radial line to that 7:00 corner: from center of the square to 7 o’clock on the bottom side of the square
Your desired 8:00-flat cut is a line from there upward to left at 30deg off vertical, so the fence distance starts from that 7:00 point and reaches to the lower right corner (at 4:30 so to speak)
Distance from 7:00 to 6:00 measured along the bottom side is r tan 30deg = ((sqrt3)/3) r
Distance from 6:00 to the 4:30 corner is r
so distance from 7:00 to 4:30 corner is r(1+ (sqrt3)/3 ) ?(or r(1+ tan30deg)
Your initial (fence-setting) blade tilt needs to cock the bottom of the stick upward so that with its width of 2 r as hypotenuse, it spans a horizontal distance equal to the fence setting. ?Whatever that tilt is from horizontal, the blade needs to be set at that angle from vertical.
So you want a tilt of arccos ( r(1+ (sqrt3)/3 ) / 2r ) and the r’s cancel and I get 37.94 degrees.
Please retrace my steps and see if I’m awake yet.
BTW I would have to think more whether this non-45 scheme will tolerate radiused corners the way I mentioned that the octagon trick would (I suspect not) -- so at least for now I’d do this one using sharp square-cut corners.
OK, gotta cook brek, wave it under the kid’s nose to wake him up, and we gotta carry boxes
Be careful with your saw
Crispin
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Re: Questions From The First-Time Sailor
And re the hazard of a kickback from a table saw — in case this spares anyone an accident — I have a friend who supplied a vivid description, nine years ago, to another group:
All my woodworking mentors have urged me always to use a splitter on a table saw and never never never to stand directly behind the workpiece being fed into the blade, because sometimes the saw will grab a slice of wood and zip it back to, and occasionally through, the operator.
As one vividly put it, "A kickback can punch right through your bellybutton and, if you're squared up, right through your spine." I had regarded this as well-intentioned hyperbole.
A splitter is a vertical fin of thin metal directly behind the sawblade that prevents either the workpiece or the offcut being sawn from it from curving back into the sawblade (which rotates toward the sawyer) and kicking back toward the operator.
I seldom use my splitter because it's cumbersome and sometimes snags the workpiece. But however, mindful of my bellybutton and spine, I never stand directly behind the sawblade. Wherefore I am able to address y'all tonight.
This morning, whilst engaged on a secret project related to the upcoming relaunch of [a friend’s 63' motorsailer being renovated], ?I needed to cut a little piece of ash into a littler piece of ash. As woodworking skills go, I am classed as what one of my mentors called "sawdusters," guys who cut and cut and cut again, finally cut too small, and start over. I was starting over. I was using my left hand to press against the cutoff (left) side of the workpiece to keep it from chattering as I fed it through the saw with my right hand.
Suddenly there was a zing, and the cutoff disappeared. My left middle finger, formerly pressed against the cutoff, now pressed itself against the sawblade. The damage was much less than I deserved, being bandaid manageable. But since I take a baby aspirin daily to thin the blood trickling through my aged arteries, I bled like a stuck pig, and it took rather a while to get all a-tanto.
It was only when I returned to the shop that I noticed the shattered window. The offcut -- a piece of ash 6 1/8" x 3/4" x 5/8" -- and weighing no more than an ounce or two, had shot 30 feet across the shop and through a 4' x 6' window. The tempered glass had done its duty, crumbling into forty-leven million pieces, of which over the course of several hours I managed to sweep up forty-ten. What blew out onto the ground I may leave to the archaeologists.
An afternoon of phoning round established that tempered glass of such dimensions is no longer standard but that for somewhat less than a million bucks I could have a sheet custom-made, perhaps in time for Christmas.
Later in the day, back on the secret project, I managed to remove the fingerprints from two of my fingers with my belt sander. Still, life is good. All my fingers -- not to mention both thumbs -- still belong to me, and the majority of them are operable. Life is good enough.
So then I replied, at too much length to paste in here, about the importance of foreseeing the nature of such accidents, because the only way to avoid them is beforehand — that is, once the machine gets hold of something, that bite enables it to get an exponentially stronger bite very quickly, so that once these accidents are underway, they’re over before you know what’s hitting you. ?Ducking or dodging is not an option.
He responded with:
My most recent woodworking mentor used to have a pronounced hitch in his gitalong. When he got ready to use a machine he would stand there, cock his head, and pause with his hand on the power switch. Sometimes the pause was quite extended. Finally I asked him wassup. He held up his left hand, which had a fat shiny scar straight across the palm. "I try to always stop to think about all the ways a machine can hurt me," he said. "If I forget, my palm tingles to remind me."
I retrieved my rogue cutoff from among the window shards on the ground and have suspended it above the table saw so that it taps me lightly on the noggin when I square up to the machine.
(“Squaring up” being what the previous mentor had said would put you in the line of fire, a few paragraphs above.)
Crispin
===================
On May 20, 2020, at 10:16 PM, crispin_m_miller via < crispinmm@...> wrote: Re shifting the fence — I’m glad you’ve mentioned that because 诲辞苍’迟 have a way here to send a sketch, and I neglected to emphasize that if you do what I’m attempting to describe (as I think you’re describing too), you are slicing off a LOWER edge of your square pole. ?(With your pole sitting in a lopsided vee between fence and blade.)
I hope so because I?诲辞苍’迟?think you want to set up the fence and blade to slice off an?upper?edge. Some experts might possibly know of exceptions, but i 诲辞苍’迟 think you ever want to trap a workpiece under a sloping blade, between the blade and the fence, because if the stick ever goes out of line and the blade gets too good a hold of it, that will set up a classic kickback event. ?Such as have been known to impale people. Next assignment: what is a similar trick to cut a dodecagon?
Octagons not good enough? ?Oy. ?Not this week, I’m supposed to be loading a truck with our belongings and they’re not even all boxed yet. ?Misjudged how soon my big strong son would be done with his (now online) schoolwork and could help me.
There does have to be some theoretical plane of the blade that would let you use the same trick — i.e., tilt up the corner of the stick to define the desired fence distance. ?(And then having set the fence, reset the blade to 30 degrees off vertical and make your cuts.) ?What’s less clear to me is whether that desired initial blade plane is within the 45-degree range the blade can actually go to. ?I did sketch at it for a little while (can you tell I’m avoiding something?) but I didn’t see a clear way to define the angle without plowing into equations with a calculator. ?Many angles in the sketch are 30’s and 60’s, but then the angle of the desired edge below the middle of the side is 15, and that makes the angle I want to find look messy. ? When I allow myself to come back to it, I think I’ll punt the math and draw it up in Onshape, and just let the software tell me what the angle is. ?(Do you know about Onshape? It’s a cloud-based full-blown 3D solid-modeling CAD app by the same guy who launched Solidworks. ?if you’re willing for your work to be accessible to others, the subscription is free.) ?(But then there’s also FreeCad, which lives on your own machine and is as private as you like, but it’s less debugged because it’s designed and coded entirely by volunteers. ?So it’s still beta, but very impressive that it even works.)
Disclaimer: ?the octagon trick is not my discovery, I only verified it (so as to believe it). ?I thought it was pretty slick too. ?I was told it by my friend Dennis Goodrum — a guy who pulled off transferring into MIT at 38 from a Wisconsin junior college and was formerly a carpenter — so this is presumably carpenter lore, from such guys as know what all the engravings on a rafter square are about.
At the time, by the way, I was doing a research project on how MIT kids who are such whippersnappers on paper can very often be so clueless in the shop. ?(I suspect it’s just because being rewarded for bookwormery means you may not be very motivated to get your nose out of your books. ?But it was interesting to find an inverse correlation between the mechanical comprehension I was assessing and the MIT GPAs of those same students.) ?
Dennis signed up for one of my research interviews. ?I had two topics, one on structure and one on power transmission (ways to gear down a wimpy motor), and I normally interviewed each volunteer on either one or the other. ?Dennis blew away the first topic in half the normal time, so I also gave him the other one, and he did the same on that one too.
More next week some time, if you haven’t done the trig yourself by then —
Crispin
——————————— Crispin,
I did a quick mock-up of your 45 octagon trick and can see it ought to work.? Pretty slick.? I didn't go through with making the cut which would have required shifting my unifence from left to right. ?? Next assignment: what is a similar trick to cut a dodecagon?? It's been awhile since I've done it but I suppose I figure out the fence distance with a little bit of trig.? It's a simpler process of getting?to round when I start with a 12 sided blank.? The saw is set at 30 degrees and the four corners are cut off.? Then the blank is flipped around and four more cuts are made.? It does take some care to make sure you keep the work flat?down on the table, and it's helpful to make some marks so you don't get lost, but I find it worth the extra effort.
James Lovegren
|
Re: Questions From The First-Time Sailor
Re shifting the fence — I’m glad you’ve mentioned that because 诲辞苍’迟 have a way here to send a sketch, and I neglected to emphasize that if you do what I’m attempting to describe (as I think you’re describing too), you are slicing off a LOWER edge of your square pole. ?(With your pole sitting in a lopsided vee between fence and blade.)
I hope so because I 诲辞苍’迟 think you want to set up the fence and blade to slice off an upper edge. Some experts might possibly know of exceptions, but i 诲辞苍’迟 think you ever want to trap a workpiece under a sloping blade, between the blade and the fence, because if the stick ever goes out of line and the blade gets too good a hold of it, that will set up a classic kickback event. ?Such as have been known to impale people. Next assignment: what is a similar trick to cut a dodecagon?
Octagons not good enough? ?Oy. ?Not this week, I’m supposed to be loading a truck with our belongings and they’re not even all boxed yet. ?Misjudged how soon my big strong son would be done with his (now online) schoolwork and could help me.
There does have to be some theoretical plane of the blade that would let you use the same trick — i.e., tilt up the corner of the stick to define the desired fence distance. ?(And then having set the fence, reset the blade to 30 degrees off vertical and make your cuts.) ?What’s less clear to me is whether that desired initial blade plane is within the 45-degree range the blade can actually go to. ?I did sketch at it for a little while (can you tell I’m avoiding something?) but I didn’t see a clear way to define the angle without plowing into equations with a calculator. ?Many angles in the sketch are 30’s and 60’s, but then the angle of the desired edge below the middle of the side is 15, and that makes the angle I want to find look messy. ? When I allow myself to come back to it, I think I’ll punt the math and draw it up in Onshape, and just let the software tell me what the angle is. ?(Do you know about Onshape? It’s a cloud-based full-blown 3D solid-modeling CAD app by the same guy who launched Solidworks. ?if you’re willing for your work to be accessible to others, the subscription is free.) ?(But then there’s also FreeCad, which lives on your own machine and is as private as you like, but it’s less debugged because it’s designed and coded entirely by volunteers. ?So it’s still beta, but very impressive that it even works.)
Disclaimer: ?the octagon trick is not my discovery, I only verified it (so as to believe it). ?I thought it was pretty slick too. ?I was told it by my friend Dennis Goodrum — a guy who pulled off transferring into MIT at 38 from a Wisconsin junior college and was formerly a carpenter — so this is presumably carpenter lore, from such guys as know what all the engravings on a rafter square are about.
At the time, by the way, I was doing a research project on how MIT kids who are such whippersnappers on paper can very often be so clueless in the shop. ?(I suspect it’s just because being rewarded for bookwormery means you may not be very motivated to get your nose out of your books. ?But it was interesting to find an inverse correlation between the mechanical comprehension I was assessing and the MIT GPAs of those same students.) ?
Dennis signed up for one of my research interviews. ?I had two topics, one on structure and one on power transmission (ways to gear down a wimpy motor), and I normally interviewed each volunteer on either one or the other. ?Dennis blew away the first topic in half the normal time, so I also gave him the other one, and he did the same on that one too.
More next week some time, if you haven’t done the trig yourself by then —
Crispin
——————————— Crispin,
I did a quick mock-up of your 45 octagon trick and can see it ought to work.? Pretty slick.? I didn't go through with making the cut which would have required shifting my unifence from left to right. ?? Next assignment: what is a similar trick to cut a dodecagon?? It's been awhile since I've done it but I suppose I figure out the fence distance with a little bit of trig.? It's a simpler process of getting?to round when I start with a 12 sided blank.? The saw is set at 30 degrees and the four corners are cut off.? Then the blank is flipped around and four more cuts are made.? It does take some care to make sure you keep the work flat?down on the table, and it's helpful to make some marks so you don't get lost, but I find it worth the extra effort.
James Lovegren
|
Re: Questions From The First-Time Sailor
We had some kayaker friends in the seventies who once came upon the floating debris field of a yacht capsize in Great Egg Harbor, NJ. ?
The yachters had abandoned the scene, so our friends picked and chose what they could stack on their kayaks. ?One thing was about a 12”-screen Panasonic B&W TV. (TV’s being built of CRT’s in those days, it floated very well.)
Since it had spent time in sea water, they brought it home and threw it in the swimming pool overnight to rinse out. ?Then let it dry a few days. ?It was fine, except the paper speaker cone had deformed, so no sound. ?They named it Moses.
Eventually it was handed down through a string of friends to me. ?I opened it up and soldered some wires to the speaker terminals and installed a phone jack in the housing so I could plug in an external speaker.
That was my TV for about ten years.
cm
———————
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Our friend capsized while out sailing and listening to tunes on his waterproof bluetooth speaker. He sailed around gathering stuff in 20+ knot winds and choppy waves, figured the speaker was gone but at one point he heard the bluetooth connecting and sailed that direction. Found the speaker!
Air Force Colonel, Flight Surgeon. I think he gets just as big of a kick out of the Sunfish as he does the warbirds.
--
Cheers
Clark and Skipper
Our blog
Our book?
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Re: Questions From The First-Time Sailor
Our friend capsized while out sailing and listening to tunes on his waterproof bluetooth speaker. He sailed around gathering stuff in 20+ knot winds and choppy waves, figured the speaker was gone but at one point he heard the bluetooth connecting and sailed that direction. Found the speaker!
Air Force Colonel, Flight Surgeon. I think he gets just as big of a kick out of the Sunfish as he does the warbirds.
--
Cheers
Clark and Skipper
Our blog
Our book?
|
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