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greenail

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I'm wondering what is state of the art for electronic lead screws these days and if anyone has advise based on implementing on on an import lathe?
 

JimDawson

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The options are almost endless. What exactly are you looking to do?
 

greenail

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The options are almost endless. What exactly are you looking to do?
I'm wondering what hardware software combination to use. the original ELS project seems a bit long in the tooth. There are 3 or 4 on github and a Russian lead screw design.

I "need" a 1/2"-12 left hand thread. My lathe has no reverse so i'm thinking it would be just about as hard to do the electronic lead screw as it would be to add the reverse. I'd also need to make a thread dial. Changing the gear on that thing set is no picnic either.
 

markba633csi

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You can cut a left handed thread by simply reversing the carriage travel- and you would need the gearing to cut 12 tpi
mark
 
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JimDawson

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It is really a very short distance from ELS to full on CNC and the CNC may actually be easier and cheaper to accomplish due to the availability of various kits. The total cost could run from <$500 to as much as you want to spend.

If you want to keep full manual capability then it gets a bit more complicated, but not a show stopper. The only addition required is backlash control on the carriage, and a couple of relays or switches to disconnect the stepper motors from the drives. I was going to do this to my lathe but then I bought a CNC lathe and dropped that project.
 

greenail

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Jim, do you ever find yourself wanting to have a manual lathe again? I suppose the only thing stopping me is that having to do CAM for everything is a barrier to getting stuff done sometimes. I have a cnc mill and a manual mill. I kinda don't want to convert the manual mill since it is convenient and quicker for many things.
 

JimDawson

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I still have my manual lathe, I didn't sell it when I bought the CNC. I would really miss it if I didn't have it. They are really 2 completely different machines with different purposes. I have thought about adding CNC capability to the manual lathe, but keeping full manual operation with an instant change over. I have all of the parts on the shelf to do it, but really have not had a need to do it.

My knee mill is almost instantly convertible between full manual, 2, 3, or 4 axis CNC. Many times I use a combination of operating modes on a single job.
 
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Dabbler

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There's a nice ELS from Germany that they call an Electronic Lead Screw - Stefan Gotteseinter did a review of it on his youtube channel. They will have a complete English manual available early this year. It leaves manual operation untouched and is DIY for the home machinist.
 

greenail

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My divorce got in the way of my attempt to implement an ELS but I recently saw a deal on mini lathe and ended up starting a CNC conversion with centroid which cut it's first chips last night!

I've watched clough42's videos. I wish he had picked a more common and cheaper controller. An esp32 is around $4 and an stm32 is about $1.5. Both should be able to do the work. The nice thing about the esp32 is that it has 2 cores and you can have one core handle monitoring the button inputs and the display while the other stays focused on spindle sync. I also wonder if he is going to power the cross slide or if he is just going to leave it setup to sync the screw. Adding cross slide feeding and feeding back to the start position saves a ton of cranking.

My attempts used an esp32 which has plenty of processing power to synch the spindle. I also attempted to set my implementation up to allow you to cut both ways but the backlash in my lead screw made this not possible. I may dig back into it at some point but now that I have centroid to learn it may be a while.

If you implement an ELS you are really about 5 steps away from a full CNC implementation. The thing that pushed me towards ELS was keeping manual control. The ideal world has the full CNC conversion but allows for a really good manual control scheme. I was thinking that some force feedback control wheels would be a very nice way to manually drive a converted lathe and maybe is a better project overall to work on. I wish grbl's jog interface didn't suck so much, there are a few forks that implement spindle sync and bart dring's esp32 port is very nice.
 

kb58

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I've watched clough42's videos. I wish he had picked a more common and cheaper controller. An esp32 is around $4 and an stm32 is about $1.5.
The controller board is maybe another $20, roughly 15% of the total. Does that make it a no-go?
 
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greenail

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answer a: I have a few spares of the other MCU's so it would be easy to test if he chose something I already had on hand.

answer b: I think you could get away with a non-hybrid stepper at a much cheaper cost. the hybrid will give a much better torque curve and that really helps if you are trying to thread at a high speed.

answer c: at $250 you are pretty close to a centroid or linux cnc setup. The utility of a full CNC lathe setup is questionable for the hobbyist.

answer d: I think engineering the costs down as low as possible would make it more approachable to small lathe owners and the more prevalent the MCU is the more people could contribute. I also think a fully canned threading cycle like the Russian ELS has would be fairly easy to do and would be worth the effort.

All in all I wish the CNC community was a bit more open source oriented in general. RepRap did a ton for 3d printing and I think there is still tons of room for the CNC hobbyist community.
 

ttabbal

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I'm actually waiting for parts to give it a go on my PM1127. I ordered a larger stepper, not the hybrid. He mentioned testing both successfully, and I don't need the higher speeds. I suspect the stepper is overkill, but it wasn't that much more expensive than the smaller ones. I ordered a couple of belt and gear options, and the lathe has a gearbox for rough adjustment.

While I have ESPs and other micros around, the cost of the MCU wasn't an issue. I know that it works and it looks like it has plenty of headroom. The MCU has a free IDE that is cross platform. Not quite as easy to pick up as Arduino, but it doesn't look difficult to work with.

I know it's not much further to go full CNC, but I've been wanting to do at least the feeds this way for a while, and threading needs almost the same setup. That's enough for me, having a lathe has taught me that I always want a manual lathe around. CNC might be interesting on a second lathe in the future if I use my CNC router enough.
 
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