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Here is way of way having direct read dials on mini lathe.
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If have a 20 TPI cross feed screw.
One turn is 0.050" some most lathes have a Graduated Dial, 50 Divisions. For direct reading you need a Graduated Dial, 100 Divisions so each 0.001 on the dial takes off on the diameter 0.001. You 100 Divisions from
https://littlemachineshop.com/products/product_view.php?ProductID=6102&category=
The size could a problem it is almost? 2" diameter but easy to read.
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Now if you the metric feed screw and inch reading.
It 1mm or 0.03937" per turn
The best is Graduated Dial, 78 Divisions . Next best you can buy is Graduated Dial, 75 Divisions or each Divisions is 0.00052 or off diameter is only of by 0.00002 " . Diameter is only off by 0.00004"
The size is only larger by 0.078" easy to fit on old Dial.
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https://littlemachineshop.com/products/product_view.php?ProductID=1984&category=
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This what looking and next order I will put cart for upgrade no free shipping I wait for till large order.
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Dave
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Another approach is treating the dial markings as approximations of actual cut depth, since they don't compensate for machine flex, backlash & general entropy of the universe ;-)
These small machines aren't like CNC production machines that are massive to achieve the rigidity necessary for precise carriage movements without operator involvement.
Roy
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I have had to go back forth all life .
Direct read they found machinist make fewer mistakes.?
For high precision turning I use a Starrett dial indicator with ?" shoke and reads to 0.000,1 work great just need to divided by two Never forget .
Dave
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No offense to anyone who's considering this, but? Instead of changing the dial, why not just learn the principles involved in the normal dial. Taking a certain amount off the radius of any cylinder causes the diameter to decrease by twice that amount. That's what you're doing with the cross slide, and it's a simple mathematical principle that's true on the minilathe and will be true on probably any lathe you use for the rest of your life. (And if you're just learning how to use a lathe now, your minilathe may not be the only lathe you ultimately own).
Mike Taglieri?
Here is way of way having direct read dials on mini lathe.
?
If have a 20 TPI cross feed screw.
One turn is 0.050" some most lathes have a Graduated Dial, 50 Divisions. For direct reading you need a Graduated Dial, 100 Divisions so each 0.001 on the dial takes off on the diameter 0.001. You 100 Divisions from
The size could a problem it is almost? 2" diameter but easy to read.
?
Now if you the metric feed screw and inch reading.
It 1mm or 0.03937" per turn
The best is Graduated Dial, 78 Divisions . Next best you can buy is Graduated Dial, 75 Divisions or each Divisions is 0.00052 or off diameter is only of by 0.00002 " . Diameter is only off by 0.00004"
The size is only larger by 0.078" easy to fit on old Dial.
?
?
This what looking and next order I will put cart for upgrade no free shipping I wait for till large order.
?
Dave
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Or maybe you could get really bold, join the rest of the world and stop mucking around by reading the dial as intended.
No offense to anyone who's considering this, but? Instead of changing the dial, why not just learn the principles involved in the normal dial. Taking a certain amount off the radius of any cylinder causes the diameter to decrease by twice that amount. That's what you're doing with the cross slide, and it's a simple mathematical principle that's true on the minilathe and will be true on probably any lathe you use for the rest of your life. (And if you're just learning how to use a lathe now, your minilathe may not be the only lathe you ultimately own).
Mike Taglieri?
Here is way of way having direct read dials on mini lathe.
?
If have a 20 TPI cross feed screw.
One turn is 0.050" some most lathes have a Graduated Dial, 50 Divisions. For direct reading you need a Graduated Dial, 100 Divisions so each 0.001 on the dial takes off on the diameter 0.001. You 100 Divisions from
The size could a problem it is almost? 2" diameter but easy to read.
?
Now if you the metric feed screw and inch reading.
It 1mm or 0.03937" per turn
The best is Graduated Dial, 78 Divisions . Next best you can buy is Graduated Dial, 75 Divisions or each Divisions is 0.00052 or off diameter is only of by 0.00002 " . Diameter is only off by 0.00004"
The size is only larger by 0.078" easy to fit on old Dial.
?
?
This what looking and next order I will put cart for upgrade no free shipping I wait for till large order.
?
Dave
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mario mohl
6:16am? ?
Or maybe you could get really bold, join the rest of the world and stop mucking around by reading the dial as intended.
It is a discussion on standard and direct reading dials,? and how too.? I started out with standard reading dials and new lathe I purchased in 1976 had direct reading . For it was big change for better. They even manufacture DRO for lathes that is direct reading. On huge lathes that is great but do have to worry about skipping from the scales.? I wish the mini lathes would have the? DRO mill into the cross slide so does take-up capacity.? But screw is still more reliable. Dave?
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I for one would be happy to purchase replacement dials that measure the diameter change, rather than the radius.? One less thing to remember as a novice.
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I for one would be happy to purchase replacement dials that measure the diameter change, rather than the radius.? One less thing to remember as a novice.
I like direct dreading / diameter reading dials
What is your cross feed screw TPI or mm?
Can be simple to do?
Dave
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Take a sharpie and cross out the numbers on your dial, then double them and write the new numbers in.
Brian?
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Show quoted text
-------- Original message -------- From: Paul Fox <pgf@...> Date: 1/27/24 1:07 PM (GMT-05:00) To: 7x12MiniLathe@groups.io Subject: Re: [7x12MiniLathe] Direct Reading cross feed dial.
I for one would be happy to purchase replacement dials that measure the diameter change, rather than the radius.? One less thing to remember as a novice.
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Take a sharpie and cross out the numbers on your dial, then double them and write the new numbers in.
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Brian?
Sharpie may last 30 seconds. I like the look of manufacture type dial. My second lathe had most of marks worn off and I used a center punch to fix it look tacky Dave?? Dave?
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If there's a great concern regarding the correct depth of threads there's another way to do it.? The motion of the compound when it's set over to 29.5 degrees can be approximated by two separate motions on Z and Y (the compound and cross slides respectively).? The compound is accurately set to zero degrees, parallel to the bed.? Using this approach, the cross slide is the only thing that determines the depth of the cut so that's why it makes it easier to determine your depth of cut.
A little trigonometry is needed.? Motion at 29.5 degrees simultaneously produces motion on the Z and Y, but that same motion is replicated if you move the compound and cross slide.? The ratio of motions on those axes (Y/Z) is equal to the tangent of 29.5 degrees, which is .566.? In other words, Y/Z = .566.? Let's make Z (the compound) the dependent variable, so Z = Y/.566 = 1.768*Y.? You will get some oddball values you need to set, but calculating this on the fly can be done with a 4-banger calculator or ahead of time by using a spreadsheet.
Using a spreadsheet and making a table of cross slide positions in .005" increments, I got:
Y? ? ? ? ? ? ? ? ? ? ? ? Z(compound)? Rounded to nearest .001"
.005? ? ? ? ? ? ? ? ? ?.009
.010? ? ? ? ? ? ? ? ? ?.018
.015? ? ? ? ? ? ? ? ? ?.027
.020? ? ? ? ? ? ? ? ? ?.034
.025? ? ? ? ? ? ? ? ? ?.044
.030? ? ? ? ? ? ? ? ? ?.053 (1 turn + .003)
.035? ? ? ? ? ? ? ? ? ?.062 ( 1 + .012)
.040? ? ? ? ? ? ? ? ? ?.071 (etc.....? ?)
.045? ? ? ? ? ? ? ? ? ?.080
.050? ? ? ? ? ? ? ? ? ?.088
.055? ? ? ? ? ? ? ? ? ?.097
.060? ? ? ? ? ? ? ? ? ?.106
I did not come up with this scheme, other folks on this forum have mentioned it in previous discussions of single-point threading.
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I find numerous problems with the scheme of moving both handwheels like that for the purpose of making a 29.5 degree vector.? That's all that is happening.? Two vectors at right angles combining to produce a vector at an angle.
First, the standard way doesn't require any trig at all.? You simply view the compound dial as direct reading.? Of course, this is an approximation because the sine of 30 degrees is 0.5 which would relate to exactly a direct reading.? the sine of 29.5 degrees is0.4924 so, technically, there will be an error.? But it is so small that it is typically ignored.? For example, if you had a 0.100 thread depth (pretty big thread in the mini lathe world at least) you get 0.0985" thread depth or a 1.5 thousandths error which is going to be within pretty much anybody's spec for a thread like that.? For typical smaller threads the error is in tenths because the error is about 1.5%.? How much absolute error is that for a 10-32?
Second, the primary purpose of the 29.5 degree compound is to have most of the cutting done on one edge and the other just as a skim cut.? By using the cross slide as part of creating the vector, that goal is substantially degraded as there will be too much cutting on the right edge (for typical right to left threading).? Since the scheme violates the primary goal, anyway, why not just go straight in and be done with it.
Third, you have to accurately set NEW positions on two handwheels.? That certainly increases the exposure for an error and a spoiled part.? Machinists typically don't want to do things a hard way when there is an easier one.
Charles E. "Chuck" Kinzer
On Saturday, January 27, 2024 at 11:17:39 AM PST, davesmith1800 <davesmith1@...> wrote:
Take a sharpie and cross out the numbers on your dial, then double them and write the new numbers in.
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Brian?
Sharpie may last 30 seconds. I like the look of manufacture type dial. My second lathe had most of marks worn off and I used a center punch to fix it look tacky Dave?? Dave?
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Doesn't the acceptable error depend on the length of engagement between the male and female parts?
Ralphie?
On Sat, Jan 27, 2024, 4:14 PM Charles Kinzer < ckinzer@...> wrote:
I find numerous problems with the scheme of moving both handwheels like that for the purpose of making a 29.5 degree vector.? That's all that is happening.? Two vectors at right angles combining to produce a vector at an angle.
First, the standard way doesn't require any trig at all.? You simply view the compound dial as direct reading.? Of course, this is an approximation because the sine of 30 degrees is 0.5 which would relate to exactly a direct reading.? the sine of 29.5 degrees is0.4924 so, technically, there will be an error.? But it is so small that it is typically ignored.? For example, if you had a 0.100 thread depth (pretty big thread in the mini lathe world at least) you get 0.0985" thread depth or a 1.5 thousandths error which is going to be within pretty much anybody's spec for a thread like that.? For typical smaller threads the error is in tenths because the error is about 1.5%.? How much absolute error is that for a 10-32?
Second, the primary purpose of the 29.5 degree compound is to have most of the cutting done on one edge and the other just as a skim cut.? By using the cross slide as part of creating the vector, that goal is substantially degraded as there will be too much cutting on the right edge (for typical right to left threading).? Since the scheme violates the primary goal, anyway, why not just go straight in and be done with it.
Third, you have to accurately set NEW positions on two handwheels.? That certainly increases the exposure for an error and a spoiled part.? Machinists typically don't want to do things a hard way when there is an easier one.
Charles E. "Chuck" Kinzer
On Saturday, January 27, 2024 at 11:17:39 AM PST, davesmith1800 < davesmith1@...> wrote:
Take a sharpie and cross out the numbers on your dial, then double them and write the new numbers in.
?
Brian?
Sharpie may last 30 seconds. I like the look of manufacture type dial. My second lathe had most of marks worn off and I used a center punch to fix it look tacky Dave?? Dave?
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Here is direct reading for a lathes in DRO'S.
To big for mini lathes.
Only for information.?
I found dials are far better as you do not loose capacity with dials.
Dave?
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"I find numerous problems with the scheme of moving both handwheels like that for the purpose of making a 29.5 degree vector."
I could be wrong, but I didn't read it as him DOING it that?way or suggesting that we do it that way.? Rather, he was using vector analysis to CALCULATE how far the tool? move directly into the work when you advance it a certain amount on the diagonal and to work out a table of those values.
Mike Taglieri?
On Sat, Jan 27, 2024, 18:14 Charles Kinzer < ckinzer@...> wrote:
I find numerous problems with the scheme of moving both handwheels like that for the purpose of making a 29.5 degree vector.? That's all that is happening.? Two vectors at right angles combining to produce a vector at an angle.
First, the standard way doesn't require any trig at all.? You simply view the compound dial as direct reading.? Of course, this is an approximation because the sine of 30 degrees is 0.5 which would relate to exactly a direct reading.? the sine of 29.5 degrees is0.4924 so, technically, there will be an error.? But it is so small that it is typically ignored.? For example, if you had a 0.100 thread depth (pretty big thread in the mini lathe world at least) you get 0.0985" thread depth or a 1.5 thousandths error which is going to be within pretty much anybody's spec for a thread like that.? For typical smaller threads the error is in tenths because the error is about 1.5%.? How much absolute error is that for a 10-32?
Second, the primary purpose of the 29.5 degree compound is to have most of the cutting done on one edge and the other just as a skim cut.? By using the cross slide as part of creating the vector, that goal is substantially degraded as there will be too much cutting on the right edge (for typical right to left threading).? Since the scheme violates the primary goal, anyway, why not just go straight in and be done with it.
Third, you have to accurately set NEW positions on two handwheels.? That certainly increases the exposure for an error and a spoiled part.? Machinists typically don't want to do things a hard way when there is an easier one.
Charles E. "Chuck" Kinzer
On Saturday, January 27, 2024 at 11:17:39 AM PST, davesmith1800 < davesmith1@...> wrote:
Take a sharpie and cross out the numbers on your dial, then double them and write the new numbers in.
?
Brian?
Sharpie may last 30 seconds. I like the look of manufacture type dial. My second lathe had most of marks worn off and I used a center punch to fix it look tacky Dave?? Dave?
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I like 90° for picking up threads if need to redo.
Setting for shoulder work.?
Snap ring groves
Cooling fins
Some this could be done with a dial indicator or DRO.?
If compound is set at 29 to 30° it makes harder to setup and have the carriage which not ideal.??
That is why I like direct reading dial on the cross slide only.?
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The first sentence of that post ended with, "...another way to do it."? I see the word "do" there.? And even if it were not, I could certainly respond to the proposed idea whether anybody actually used it or even if just a pipe dream.
Charles E. "Chuck" Kinzer I
On Sunday, January 28, 2024 at 04:07:54 PM PST, davesmith1800 <davesmith1@...> wrote:
I like 90° for picking up threads if need to redo.
Setting for shoulder work.?
Snap ring groves
Cooling fins
Some this could be done with a dial indicator or DRO.?
If compound is set at 29 to 30° it makes harder to setup and have the carriage which not ideal.??
That is why I like direct reading dial on the cross slide only.?
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Charles Kinzer
5:36pm? ?
The first sentence of that post ended with, "...another way to do it." I see the word "do" there. And even if it were not, I could certainly respond to the proposed idea whether anybody actually used it or even if just a pipe dream
They have use Direct Reading cross feed dial since the late 1950's on most lathes.?? I do not know why we see standard read on mini lathes today? Dave?
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"" by Martin Cleeve discusses the compound set over method vs advancing both cross and compound slides.? This book is well worth its modest cost.? Cleeve made his living doing short production runs threading parts for companies.
Cleeve suggests that set over should be 29 degrees rather than 29.5 to ensure that the right flank is shaved with each pass so it does not develop a stairstep roughness due to minor effects.
Cleeve favored keeping the compound at 90 degrees, so he advanced both cross and compound slides.? Rather than using trigonometry he simply advanced the compound half of the amount that he advanced the cross slide - this ensures the right flank is shaved on each pass, similar to a set over of 29 degrees.? This allows using a tool ground for the finest thread, then when depth is reached the compound is advanced to achieve the correct thread root width.? With the set over method the tool point width should be reground to the correct width for each different TPI to achieve the correct root width.
Also, since Cleeve made his living threading, he designed and built a dog clutch for his Myford lathe.
John
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Like said before only selecte number of threads can use a dog clutch. A multiple 1x 2x 3x 4x 5x 6x 7x of the lead screw.?
You can not cut 1.5x , 1.27x and the list goes on.?
Dave?
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davesmith1800
Ralph Lehotsky
GadgetBuilder