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Electric Motors
#db200
I've been musing about building a small electric motor from scratch on my Unimat SL.? Just for the fun of it and to learn something new. Seems like a doable project, including using the lathe to assist with the windings. Anyone on the list done anything like this?
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Re: Unimat 3 / PC Cross Slide Backlash from HANDLEWHEEL
So on the SL the cross slide does not have a ¡°nut¡° in it. The Cross light itself is threaded to match the lead screw. So adjusting for wear is hopeless unless one can find a good as new cross slide.? As for your idea to modify the nut, it is valid. The attached photo shows the method to take up the slack in the tag system. ? On Thu, Apr 6, 2023 at 12:17 PM jpow <powster@...> wrote:
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Quinn Golden 603-491-1451 |
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Re: New to this group
#db200
Seems like a common plan. I was buying parts for my recently acquired SL, and suddenly realized I had almost enough parts for a second unit, which I will use as a mill. Adding a DC motor and speed controller, and beginning to think through the process of making the mill both manual and CNC capable.
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Re: Unimat 3 / PC Cross Slide Backlash from HANDLEWHEEL
Thank you everyone for the advice / knowledge sharing! I've realised that for my case, backlash is from both handle assembly (maybe 30% of the backlash) AND cross slide nut (majority of the backlash)? While I accept some backlash will?always be there, I can't help but think of other possible?ways to minimize it. Might this idea be feasible: The cross slide nut is approx 10mm x10mm x 10mm cube.? Is there enough material to modify?the nut into an anti-backlash design, i.e. a) Cut a slit through the nut b) Tap a tiny thread for a screw to finely adjust the size of the slit gap (so as to apply pressure on the threads, minimizing play) Alternatively, replace the entire nut with some anti-backlash design. The only thing is that its going to be a pain to adjust it, as my UNIMAT PC doesn't leave much room to access that nut with the slide assembled fully. @Quinn - One option might be to just replace the cross slide nut, and / or the entire leadscrew, ASSUMING the backlash is due to heavy wear on the threads. - Arceurotrade has a that looks like it could fit with some minor modification. On Thu, Apr 6, 2023 at 11:54?PM Quinn Golden <quinngolden@...> wrote:
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Re: Unimat 3 / PC Cross Slide Backlash from HANDLEWHEEL
Yeah that completely makes sense, I have a Taig CNC machine that uses the same technology as a Unimat, and I program the backlash compensation into it.? When it reads the code it compensates for backlash due to its design. ? ? What were the part numbers of the thrust washers that you settled on ?? I wound up settling on about .0035 backlash on the Y(cross slide) and .0025 on the X.? However in my case I am convinced that the backlash on the cross slide is in the Cross slide itself and not the handle. ? ? I¡¯m not sure buying another used one would make it any better, I might buy another ¡°new old stock¡± if I can find it. ? On Thu, Apr 6, 2023 at 10:18 AM phill05 via <phill05=[email protected]> wrote: On Thu, Apr 6, 2023 at 02:37 PM, Quinn Golden wrote: --
Quinn Golden 603-491-1451 |
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Re: Unimat 3 / PC Cross Slide Backlash from HANDLEWHEEL
On Thu, Apr 6, 2023 at 02:37 PM, Quinn Golden wrote:
you always back off a couple of turns on the handle and then go forward to remove the backlash and make your cut.This is what I was taught to do and have done on all my larger lathes, but on the small SL it was a problem that needed more looking at if I was to use power on the screws, my first thought was I could not get the backlash down to an acceptable level because the cast was a little rough and the aluminium hand wheel was dragging and wearing off creating more backlash, I could have turned some hard plastic washers but having used very small bearings in other work I opted to use the small thrust bearings and I found I could get a really good feel turning by hand and under power it works so well for me. With a wipe of grease on assembly these fit well, feel well and one less thing to worry about when machining. Phill |
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Re: Unimat 3 / PC Cross Slide Backlash from HANDLEWHEEL
When I rebuilt my SL, reducing the backlash as much as possible was a goal. However, there was a point of diminishing return as the hand wheel rubs against a rough uneven casting. With any flex in the screw train that gives a ¡°tight spot¡° as the hand wheel is rotated, exacerbating the problem. I tightened the hand wheel until it touched the casting, put on the nut and then tighten them together by hand, felt it then after a few tries gently tightened the nut. I had hit the ¡°sweet spot¡° that seems to work best. So short of machining that piece of casting behind the hand wheel to make it smoother, one needs to revert to the old primitive machining days of always moving your cutting tool into the work piece. Which is to say, you always back off a couple of turns on the handle and then go forward to remove the backlash and make your cut. ?I think that the casting is a poor enough bearing surface, so even placing thrust washers behind it would not illuminate the ¡°problem¡±. ? That is to see if you consider it a problem, which I really do not. Anything that uses a lead screw into a tapped casting is going to have backlash. It is actually engineered that way.? |
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Re: T-slot adapter screw
12mm. Not 1mm, not 112mm.? William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first.
On Wednesday, April 5, 2023 at 08:41:12 PM CDT, Bill in OKC too via groups.io <wmrmeyers@...> wrote:
We have blueprints for the regular t-nuts, and all you need to get the length of the thread is count the number of threads. That's a 1mm pitch. You get 12 threads? it's 112mm plus 1 or 2 for the chamfer. Ten threads? 10+1 or 2, then add the height of the regular t-nut.? If you use a pair of dividers, you can set them to the corners of the front flat, which is 12mm, IIRC, and then walk the dividers up the photo to measure the height.? There are parts that would be a great deal more difficult to scale from a photo, like the bases for the threading attachment, but this particular part should be dead easy.? Got busy with other stuff, or would have done exactly that for the pile of parts I've been building for mine.? Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first.
On Wednesday, April 5, 2023 at 08:29:07 PM CDT, Charles Kinzer <ckinzer@...> wrote:
This eBay item has two of different lengths.? I don't know what the longer one is all about. And this is one of a different design that looks a little interesting.? Perhaps a stronger scheme. Charles E "Chuck" Kinzer
On Wednesday, April 5, 2023 at 06:14:12 PM PDT, David James via groups.io <davebjames@...> wrote:
Hi all, With a long weekend coming up I need a project. I want to make a T-slot adapter screw. My lathe has not arrived yet so I have no idea of the dimensions of T-slots ect. Does any one possibly have the dimensions of this item like 1. Total length 2. Size of T- nut (base) 3. T-nut shaft diameter 4. Length of T-nut shaft 5. The M12 x 1 thread length, the thread looks like it is about 6-7mm long, counting the threads.
Would be much appreciated if someone could supply these dimensions and it will keep me busy over this long weekend. Thanks |
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Re: T-slot adapter screw
We have blueprints for the regular t-nuts, and all you need to get the length of the thread is count the number of threads. That's a 1mm pitch. You get 12 threads? it's 112mm plus 1 or 2 for the chamfer. Ten threads? 10+1 or 2, then add the height of the regular t-nut.? If you use a pair of dividers, you can set them to the corners of the front flat, which is 12mm, IIRC, and then walk the dividers up the photo to measure the height.? There are parts that would be a great deal more difficult to scale from a photo, like the bases for the threading attachment, but this particular part should be dead easy.? Got busy with other stuff, or would have done exactly that for the pile of parts I've been building for mine.? Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first.
On Wednesday, April 5, 2023 at 08:29:07 PM CDT, Charles Kinzer <ckinzer@...> wrote:
This eBay item has two of different lengths.? I don't know what the longer one is all about. And this is one of a different design that looks a little interesting.? Perhaps a stronger scheme. Charles E "Chuck" Kinzer
On Wednesday, April 5, 2023 at 06:14:12 PM PDT, David James via groups.io <davebjames@...> wrote:
Hi all, With a long weekend coming up I need a project. I want to make a T-slot adapter screw. My lathe has not arrived yet so I have no idea of the dimensions of T-slots ect. Does any one possibly have the dimensions of this item like 1. Total length 2. Size of T- nut (base) 3. T-nut shaft diameter 4. Length of T-nut shaft 5. The M12 x 1 thread length, the thread looks like it is about 6-7mm long, counting the threads.
Would be much appreciated if someone could supply these dimensions and it will keep me busy over this long weekend. Thanks |
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Re: T-slot adapter screw
This eBay item has two of different lengths.? I don't know what the longer one is all about. And this is one of a different design that looks a little interesting.? Perhaps a stronger scheme. Charles E "Chuck" Kinzer
On Wednesday, April 5, 2023 at 06:14:12 PM PDT, David James via groups.io <davebjames@...> wrote:
Hi all, With a long weekend coming up I need a project. I want to make a T-slot adapter screw. My lathe has not arrived yet so I have no idea of the dimensions of T-slots ect. Does any one possibly have the dimensions of this item like 1. Total length 2. Size of T- nut (base) 3. T-nut shaft diameter 4. Length of T-nut shaft 5. The M12 x 1 thread length, the thread looks like it is about 6-7mm long, counting the threads.
Would be much appreciated if someone could supply these dimensions and it will keep me busy over this long weekend. Thanks |
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T-slot adapter screw
Hi all,
With a long weekend coming up I need a project. I want to make a T-slot adapter screw. My lathe has not arrived yet so I have no idea of the dimensions of T-slots ect. Does any one possibly have the dimensions of this item like 1. Total length 2. Size of T- nut (base) 3. T-nut shaft diameter 4. Length of T-nut shaft 5. The M12 x 1 thread length, the thread looks like it is about 6-7mm long, counting the threads. Would be much appreciated if someone could supply these dimensions and it will keep me busy over this long weekend. Thanks |
Steve Johnson
David James
Bill in OKC too
