Re: Mini lathe motor temperature
I am looking for temperature be for smoke.?
I can only go by what in print.
I hope motor stays cool.
The? ambient used is either 40°C or 45°C? plus 60°C for motor.?
It all for longer life.?
Dave?
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On Sun, May 5, 2024 at 01:18 PM, Tony Smith wrote:
Those are not operating temperatures, they are MAXIMUM temperatures.? You want to be as far away from them as possible.
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If your casing is 80 degrees then your armature is far hotter than that.
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You can run your motor for 20,000 hour OR at 105°C, you cannot do both.? Read the spec sheet, it will derate the motor life based on temperature.
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For example run capacitors are rated at about 80 degrees, but again that’s the MAXIMIUM, you will kill your motor very quickly doing that.? For electronics the rule is for every 10 degrees Celsius rise the life expectancy halves.? Conversely dropping 10 degrees doubles the life span.
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Generally anything above 50 degrees makes a lot of people unhappy, 80 degrees would make them very unhappy.
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Tony
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Here is max temperature from Baldor to last 20,000 hours.
Remember this a Chinese motor could be a little less.
Most motors under 100 hp use class A
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Re: Mini lathe motor temperature
Here's a pic of the motor that goes on my mini lathe.? Looks like
it's rated class E, which is 120 C per a wikipedia article.?
Stan
On 5/5/24 14:48, davesmith1800 wrote:
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Here is max temperature from Baldor to last 20,000 hours.
Remember this a Chinese motor could be a little less.
Most motors under 100 hp use class A
Temperature (°C)
Maximum Winding
Temperature (Tmax)(°C)
A 105
B 130
F? 155
H 180
?
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You're drilling lots of these holes, so it would waste too much time to use a spotting drill, mill flats on the rod, and so on. Instead I would use a guide block, but different than the one in your picture. You say everything is locked to the table, but I see your hand holding the rod. I suggest drilling and tapping your guide so a setscrew? (maybe one on each side) could hold the rod in place.? Also, I would make the guide of steel and MUCH taller. There should be? by 5-10 mm of metal supporting the drill bit before it reaches the rod. If the drill is supported like?that, it should easily make the holes.
Mike Taglieri?
Thanks boys, you have given me some new idea. ? I am lazy, so I will first shorten a drillbit to minimum so it will not be so flexible. Only 3 mm visible length. I have a good mill. The rod is cheap hard metal, however, everything is locked very well to table . The drill is new and of good quality. Regrinding a 1 mm drill is difficult. Litlebit wrong grinding, and the drill will jump around. ? If this not work well, I will make a punch and hammer a mark for the drill. Maybe I have a 1 mm center drill?? The brass bit will keep the rod in correct position. ? Milling first a flat is also possible. Take some extra time, however, maybe it will take away a bit of the rod strength? See you next week. ? /johannes Mexico ? ?
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Re: Mini lathe motor temperature
Those are not operating temperatures, they are MAXIMUM temperatures.? You want to be as far away from them as possible. ? If your casing is 80 degrees then your armature is far hotter than that. ? You can run your motor for 20,000 hour OR at 105°C, you cannot do both.? Read the spec sheet, it will derate the motor life based on temperature. ? For example run capacitors are rated at about 80 degrees, but again that’s the MAXIMIUM, you will kill your motor very quickly doing that.? For electronics the rule is for every 10 degrees Celsius rise the life expectancy halves.? Conversely dropping 10 degrees doubles the life span. ? Generally anything above 50 degrees makes a lot of people unhappy, 80 degrees would make them very unhappy. ? Tony ? ? ?
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From: [email protected] <[email protected]> On Behalf Of davesmith1800 via groups.io
Sent: Monday, 6 May 2024 5:48 AM
To: [email protected]
Subject: Re: [7x12MiniLathe] Mini lathe motor temperature? Here is max temperature from Baldor to last 20,000 hours.
Remember this a Chinese motor could be a little less.
Most motors under 100 hp use class A
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The idea of a spotting drill is they have an angle slightly bigger than your drill, so 120 or 140 degree is typical.? This means the drill starts off nice and centred as opposed to what happens with something like a centre punch. ? But yeah, they’re not really all that good at drilling holes.? Terrible chip clearance and all that. ? You can get 90 degree ones for countersinking screw heads, they do a better jo than a countersink drill because you can match them to the screw head diameter and recess them a bit.? You don’t get that little gap that the countersink bit gives you. ? Tony ? ?
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From: [email protected] <[email protected]> On Behalf Of Johannes via groups.io
Sent: Monday, 6 May 2024 4:58 AM
To: [email protected]
Subject: Re: [7x12MiniLathe] Drill a Hole? ? Thanks Tony I learned a new word to day: spotting drill I had one in my box, always wounder how it looks so “funny” . It was also not good to drill a 10 mm hole with. To morrow I will check my center drills , maybe I will find one packed in a oily paper, packed in a red box. /johannes Mexico ? ? ? Use a spotting drill to make a pilot hole.? They're roughly the same thing as a centre drill except wider tip angle (centre drill is 60 degree). ? Then again a centre drill would probably work just fine given you're only drilling 1mm holes. ? ?
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Re: Mini lathe motor temperature
Here is max temperature from Baldor to last 20,000 hours. Remember this a Chinese motor could be a little less. Most motors under 100 hp use class A
Temperature (°C)
Maximum Winding
Temperature (Tmax)(°C)
A 105
B 130
F? 155
H 180
?
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Re: Mini lathe motor temperature
The 105° is class A motor Insulation witch most motor use.?
The temperature drops as pass to outside casing.?
After that I use 176°F [ 80°C] for outside case? max temperature just to be on safe side.?
Note Most could burn your had around 140°F to 145°F
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On Sun, May 5, 2024 at 10:38 AM, Tony Smith wrote:
Well it shouldn’t, but I’m not the one trying to measure it.? I don’t know what Dave thinks he’s measuring, but that 105°C he’s set as his upper limit (over boiling water temperature, by the way) is the point where the enamel on the armature coils starts failing.
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The case temperature is going to be a lot lower.? As said, if you can’t touch it it’s way too hot.
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Tony
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Why should a minilathe motor be getting extremely hot in the first place? Mine never does. These machines aren't made for heavy use and cuts should be light. On the rare occasions that I've taken heavy cuts, I use a spindle crank.
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105°C sounds rather suspiciously (or perhaps not that suspiciously) like the lower temperature limit on most magnet wire used in motor coils.
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Gets hot, the enamel melts and the coil shorts out.? If you’ve spent enough time around motors or transformers you know the smell.? That 105°C is basically the maximum temperature for the motor coils, if you let it get anywhere near that you’re asking for trouble.?
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You can get magnet wire with better heat rating, up to about 250°C, but you don’t see that much.? That’s what the class of a motor means, better insulation.? Thoe old rule of if it’s too hot to touch, it’s too hot is well worth following.
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The other reason for keeping the heat down is the magnets.? Won’t bother the typical old-school mini-lathe motors, but newer motors (eg brushless) with neodymium magnets need to be kept cool as they start losing magnetism at around 80°C.
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Tony
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After researching of motors are 221°F [105°C] after that the life is shortened.?
The outside temperature is about? 60°F to 70°F? [15 to 20°C ] less the coil temperature.? So if outside is could be wend the coil is? 221°F [105°C] the outside is between? 151°F and 161°F [85 an 90°C].
On my gauge I set the red mark at 80°C and 105°C.?
If I see gets never red it time to let motor cool down and gives little to finish the cut.?
The Capillary is attached by HVAC Aluminum tape , max temperature is 145 °C at this point the motor is toast?
Dave?
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? Thanks Tony I learned a new word to day: spotting drill I had one in my box, always wounder how it looks so “funny” . It was also not good to drill a 10 mm hole with. To morrow I will check my center drills , maybe I will find one packed in a oily paper, packed in a red box. /johannes Mexico ? ?
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From: Tony SmithSent: s?ndag 5. mai 2024 10:33 To: [email protected]Subject: Re: [7x12MiniLathe] Drill a Hole ? Use a spotting drill to make a pilot hole.? They're roughly the same thing as a centre drill except wider tip angle (centre drill is 60 degree). ? Then again a centre drill would probably work just fine given you're only drilling 1mm holes. ? ?
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Re: Mini lathe motor temperature
Well it shouldn’t, but I’m not the one trying to measure it.? I don’t know what Dave thinks he’s measuring, but that 105°C he’s set as his upper limit (over boiling water temperature, by the way) is the point where the enamel on the armature coils starts failing. ? The case temperature is going to be a lot lower.? As said, if you can’t touch it it’s way too hot. ? Tony ? ? ?
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From: [email protected] <[email protected]> On Behalf Of Miket_NYC via groups.io
Sent: Friday, 3 May 2024 5:27 PM
To: [email protected]
Subject: Re: [7x12MiniLathe] Mini lathe motor temperature? Why should a minilathe motor be getting extremely hot in the first place? Mine never does. These machines aren't made for heavy use and cuts should be light. On the rare occasions that I've taken heavy cuts, I use a spindle crank. ? 105°C sounds rather suspiciously (or perhaps not that suspiciously) like the lower temperature limit on most magnet wire used in motor coils. ? Gets hot, the enamel melts and the coil shorts out.? If you’ve spent enough time around motors or transformers you know the smell.? That 105°C is basically the maximum temperature for the motor coils, if you let it get anywhere near that you’re asking for trouble.? ? You can get magnet wire with better heat rating, up to about 250°C, but you don’t see that much.? That’s what the class of a motor means, better insulation.? Thoe old rule of if it’s too hot to touch, it’s too hot is well worth following. ? The other reason for keeping the heat down is the magnets.? Won’t bother the typical old-school mini-lathe motors, but newer motors (eg brushless) with neodymium magnets need to be kept cool as they start losing magnetism at around 80°C. ? Tony ? ? ? After researching of motors are 221°F [105°C] after that the life is shortened.?
The outside temperature is about? 60°F to 70°F? [15 to 20°C ] less the coil temperature.? So if outside is could be wend the coil is? 221°F [105°C] the outside is between? 151°F and 161°F [85 an 90°C].
On my gauge I set the red mark at 80°C and 105°C.?
If I see gets never red it time to let motor cool down and gives little to finish the cut.?
The Capillary is attached by HVAC Aluminum tape , max temperature is 145 °C at this point the motor is toast?
Dave?
Attachments:
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Use a spotting drill to make a pilot hole. They're roughly the same thing
as a centre drill except wider tip angle (centre drill is 60 degree).
Then again a centre drill would probably work just fine given you're only
drilling 1mm holes.
You might also consider bits used for drilling circuit boards (PCBs).
Normally those are carbide, but you can get HSS ones. They have a 3mm shank
and the fluted part will be 5-10mm, so stiffer than a typical drill.
The carbide versions need high speed (above 20k) and are very brittle, but
could work. Not in your drill press though, you need something like those
air die grinders for that.
Possible that mounting the carbide drill in the lathe and the steel bar on
the tool post might work. I've put my die grinder on the tool post and used
it to drill holes and grind stuff.
Tony
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-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of
Johannes via groups.io
Sent: Sunday, 5 May 2024 12:59 PM
To: [email protected]
Subject: [7x12MiniLathe] Drill a Hole
Maybe this is wrong group, however, a lot of clever members:
I have to make a lot of 1 mm holes in 2 mm steel rods. I have made a guide, and as you see, a lot of testing guide hole to compensate for different drilling twisting forces.
My questions:
1) what is the best start method to make a start mark?
2) when I am drilling:
a) constant soft pressure?
b) pumping up/down to release spoon
(My steel are only making dust)
Johannes Lavoll.
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If drilling "a lot" of holes, milling a flat on the rod is not practical.
A grooved block with a guide hole will be far more practical
Thanks boys, you have given me some new idea. ? I am lazy, so I will first shorten a drillbit to minimum so it will not be so flexible. Only 3 mm visible length. I have a good mill. The rod is cheap hard metal, however, everything is locked very well to table . The drill is new and of good quality. Regrinding a 1 mm drill is difficult. Litlebit wrong grinding, and the drill will jump around. ? If this not work well, I will make a punch and hammer a mark for the drill. Maybe I have a 1 mm center drill?? The brass bit will keep the rod in correct position. ? Milling first a flat is also possible. Take some extra time, however, maybe it will take away a bit of the rod strength? See you next week. ? /johannes Mexico ? ?
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Yea - I modified? it so it has very little drag.? It works well.?? I bought a mag DRO for it but I'm waiting to do the 16" bed mod to put it on.
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On 5/4/2024 8:26 PM, Mark Kimball via groups.io wrote: On Sat, May 4, 2024 at 05:44 PM, WAM wrote:
That's how I did it:
toggle quoted message Show quoted text ( #quoted-237560421 ) Aha!? I thought I had seen something similar but couldn't remember where.
I like your swarf shield, that's something that still needs to be done.? The portion behind my bracket is easy but the front part is a different story.? I want something like a shield rather than a brush or felt pad since I went to a lot of trouble to reduce the friction as much as possible.
What type/brand of DRO did you use?? I'm assuming its frictional drag is low enough to not cause a problem like mine.
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You might try pushing the bit further into the chuck as a way to shorten the bit even though it will be on the flutes some. Paul M
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Thanks boys, you have given me some new idea. ? I am lazy, so I will first shorten a drillbit to minimum so it will not be so flexible. Only 3 mm visible length. I have a good mill. The rod is cheap hard metal, however, everything is locked very well to table . The drill is new and of good quality. Regrinding a 1 mm drill is difficult. Litlebit wrong grinding, and the drill will jump around. ? If this not work well, I will make a punch and hammer a mark for the drill. Maybe I have a 1 mm center drill? ?The brass bit will keep the rod in correct position. ? Milling first a flat is also possible. Take some extra time, however, maybe it will take away a bit of the rod strength? See you next week. ? /johannes Mexico ? ?
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Standard drill bits are springy and will bend, this is why they wonder around. ?Start the hole with a “center drill” these is very short and stubby drills that are only used to make a “V” shape indent. ? Then you come back with the standard bit.
If you are unable to mill a flat spot then the usual procedure is to place a punch on the guide hole and make a dent. ?Punches come ig different dimeters like drilled and look a little ?like a drill with no flutes but only a sharp point. ?Hit it with a hammer andmake a divot. ?then center drill and then final drill. ? Just remembered, the punch is called a “transfer punch”. ?You can make one from drill rod if you have the means to case harden it.
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On May 4, 2024, at 9:29?PM, Gerald Feldman via groups.io <gfeldman2904@...> wrote:
All of Mark’s comments are valid (especially milling a flat spot to keep the drill from trying to wander when it starts to cut).? Because of its small diameter, you will want the drill to be spinning at quite a high RPM and your drill may currently be spinning too slowly.? You also will want to consider using a good quality cobalt drill as they will stay sharp for a longer period.? It would help us to know what kind of steel you are trying to drill.? ? Jerry F. ??? ? ? Hi johannes,
Check if your drill works OK on ordinary flat material.? Maybe it's dull.
Check if your rod is rotating while you are trying to drill it.? The drill may be creating forces that want to cause the rod to spin as it's being drilled.??
It appears you have had some problems with your fixture so maybe it's not quite right yet.
Drills don't like starting on round stock, they tend to wander.? If you can, try milling a small flat on the rod before you drill a hole there.? Using a small? spotting drill to get your hole started may also work.? ?In the case of milling a flat on the rod, that option likely depends on what your requirements are.? Getting a hole-to-hole seal:? bad idea.? A center-cutting end mill with the right diameter also might work:? or starting with a smaller one and finishing with a drill the right diameter would.?
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All of Mark’s comments are valid (especially milling a flat spot to keep the drill from trying to wander when it starts to cut).? Because of its small diameter, you will want the drill to be spinning at quite a high RPM and your drill may currently be spinning too slowly.? You also will want to consider using a good quality cobalt drill as they will stay sharp for a longer period.? It would help us to know what kind of steel you are trying to drill. ? Jerry F. ??? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Mark Kimball
Sent: Saturday, May 04, 2024 8:37 PM
To: [email protected]
Subject: Re: [7x12MiniLathe] Drill a Hole? Hi johannes,
Check if your drill works OK on ordinary flat material.? Maybe it's dull.
Check if your rod is rotating while you are trying to drill it.? The drill may be creating forces that want to cause the rod to spin as it's being drilled.?
It appears you have had some problems with your fixture so maybe it's not quite right yet.
Drills don't like starting on round stock, they tend to wander.? If you can, try milling a small flat on the rod before you drill a hole there.? Using a small? spotting drill to get your hole started may also work.? ?In the case of milling a flat on the rod, that option likely depends on what your requirements are.? Getting a hole-to-hole seal:? bad idea.? A center-cutting end mill with the right diameter also might work:? or starting with a smaller one and finishing with a drill the right diameter would.
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Hi johannes,
Check if your drill works OK on ordinary flat material.? Maybe it's dull.
Check if your rod is rotating while you are trying to drill it.? The drill may be creating forces that want to cause the rod to spin as it's being drilled.?
It appears you have had some problems with your fixture so maybe it's not quite right yet.
Drills don't like starting on round stock, they tend to wander.? If you can, try milling a small flat on the rod before you drill a hole there.? Using a small? spotting drill to get your hole started may also work.? ?In the case of milling a flat on the rod, that option likely depends on what your requirements are.? Getting a hole-to-hole seal:? bad idea.? A center-cutting end mill with the right diameter also might work:? or starting with a smaller one and finishing with a drill the right diameter would.
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Maybe this is wrong group, however, a lot of clever members:
I have to make a lot of 1 mm holes in 2 mm steel rods. I have made a guide, and as you see, a lot of testing guide hole to compensate for different drilling twisting forces.
My questions:
1) what is the best start method to make a start mark?
2) when I am drilling:
a) constant soft pressure?
b) pumping up/down to release spoon
(My steel are only making dust)
Johannes Lavoll.
|
On Sat, May 4, 2024 at 05:44 PM, WAM wrote:
That's how I did it:
toggle quoted message Show quoted text
Aha!? I thought I had seen something similar but couldn't remember where. I like your swarf shield, that's something that still needs to be done.? The portion behind my bracket is easy but the front part is a different story.? I want something like a shield rather than a brush or felt pad since I went to a lot of trouble to reduce the friction as much as possible. What type/brand of DRO did you use?? I'm assuming its frictional drag is low enough to not cause a problem like mine.
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Very elegant solutions gentleman!
Ryan
On May 4, 2024 at 5:44?PM -0400, WAM <ajawam2@...>, wrote:
That's how I did it:
https://www.ajawamnet.com/ajawam3/swarf/DSCN2848.JPG
https://www.ajawamnet.com/ajawam3/swarf/lathetopassylg.gif
On 5/4/2024 4:30 PM, Mark Kimball via groups.io wrote:
Some time back I started working on a DRO scheme for my lathe cross slide.? There's not a lot of room on top so many of the approaches I saw had one disadvantage or another.? As a result I came up with a scheme to put the DRO underneath the lathe and used a "C" shaped piece to transfer the cross slide motion beneath the lathe.? I had an iGaging DRO for the purpose because I bought two when I was working on my Z axis DRO setup, so I already had what I needed.? Or so I thought.
Unfortunately, the iGaging design uses a sliding contact with a fairly strong spring, which required a fair amount of force to overcome.? DRO mounting schemes that put the mounting system inline with the sensor aren't affected by this, but my C shaped piece would deflect under the force enough to cause about a .005" error.? I tried several ways to stiffen up the system but that was about the best I could manage.
So I decided to modify my DRO to reduce the amount of force needed to move the rule through the sensor.? This involved making a replacement base out of aluminum and replacing the sliding contact with bearings.? I used aluminum because the rule MUST be connected to the sensor's internal ground in order to work correctly.
My first iteration used flanged bearings because the rule needed to be constrained on two of its axes, but the flanges rubbed on the rule too much, which caused erratic variations in the force needed to slide the rule back and forth.? So I replaced the flanged bearings with conventional ones -- but then had to add bearings to the bottom and top assemblies to constrain the rule on its vertical axis.
At this point I debated on whether it really was worthwhile to continue my attempt to use an iGaging DRO, but since I already had a fair amount of time invested in this thing I forged on.? This is known as the "sunk cost" syndrome, and I admit to falling victim to it.
So after buying more bearings and? spending more machining time on the base (and 3D printing a cover, also with bearing pockets) I got this:
The top photo shows the scale, sensor, aluminum base and printed cover.? The side bearings are 3x10mm and the top/bottom are 3x6.
And here are photos of the mounting scheme:
I used a "T" extrusion in an attempt to stiffen up my "C" assembly but it didn't improve things much.? The 3D printed stuff was done with an older Ender 3 I bought from a friend.? This is the first project I've used it for.? The pieces were designed using openSCAD.? Not shown:? all the pieces that had something wrong with them :).
The scale passes through a slot I milled in the vertical piece.
At first the (re) assembled DRO had a terrible EMI problem.? I added some shielding on the back of the sensor board, which helped a teensy bit.? It turns out that the main problem was the spacing between the bottom of the sensor board and scale.? I had used some 3mm brass washers to make sure the board didn't rub against the scale, but that turned out to be a mistake.? I removed them and suddenly the noise problem disappeared.? The board still isn't rubbing so that was a solution without a problem.? I was sure that the DRO would misbehave once it was installed and the motor controller was turned on, but so far so good.
I checked the DRO vs the dial and they are very close.? That was a big unknown, since I wasn't sure if the spacing between the scale and sensor board would affect the readings.
Lipstick on a pig?? Well, probably.? If I had known what I was going to encounter along the way I think I would have just bit the bullet and found myself a DRO that would work right out of the box....
Attachments:
Base cover sensor.JPG: /g/7x12MiniLathe/attachment/119497/0
Scale.JPG: /g/7x12MiniLathe/attachment/119497/1
Mounting assembly front.JPG: /g/7x12MiniLathe/attachment/119497/2
Mounting assembly rear view.JPG: /g/7x12MiniLathe/attachment/119497/3
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davesmith1800
Johannes
