Electronic Lead Screw

ttabbal

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The photos I took are in the thread above. If you click them you should be able to get a larger version.

The encoder mount is simpler than it looks. It's a piece of aluminum block squared off, then drilled to match a right angle bracket I milled some slots in. It's held down to the arm with a pair of T-nuts in the arm slot the same way the stock gears are. The bracket also has holes drilled to mount the encoder on the other side. It's just a piece of angle aluminum.

The servo is on a pair of brackets. The first is a commercial unit that fits the motor. I got lazy and it was something like $5/pair. :) The other is just more angle aluminum with slots. It's mounted to the lathe with some holes I drilled and tapped.

The exact mount locations are determined mostly by the belt length. So I just found a spot that was about right, added a little space for adjustment, and put the holes there, leaving some space in the slots for adjustment.
 

mbonadio

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Hi @ttabbal

I just downloaded the latest version of the ELS and I see that your code was merged into it. What values did you end up using for the following constants?

Thanks
Michael

#define LEADSCREW_TPI 10

// Steps and microsteps
#define STEPPER_MICROSTEPS 3
#define STEPPER_RESOLUTION 800

// Separate step and microstep settings for feed rates. Redefine these if your
// lathe has a separate feed drive train with a different ratio.
#define STEPPER_MICROSTEPS_FEED STEPPER_MICROSTEPS
#define STEPPER_RESOLUTION_FEED STEPPER_RESOLUTION
 

ttabbal

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Those are the settings I'm using, with the change below.

#define STEPPER_RESOLUTION_FEED STEPPER_RESOLUTION * 1.66
 

mbonadio

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Those are the settings I'm using, with the change below.

#define STEPPER_RESOLUTION_FEED STEPPER_RESOLUTION * 1.66

Thanks for the response, will update the source today and check it out. I had some movement last night and it was so exciting, now need to consider the box to contain everything.
 

bcrosby

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I know this is a very old thread, but I'm hoping to revive the conversation. I also have a PM1127-LB and am in the process of installing the Clough42 ELS. I took delivery on my lathe in March of 2020.

I have been researching gear ratios on my lathe and am finding a VERY DIFFERENT reality from some of you. My lead screw is 8 TPI. With the gearbox in position "A", my gear ratios for both the lead screw AND the drive shaft are 1:1. With the gearbox in position "B", my gear ratios for both the leadscrew AND the drive shaft are 1:2. And, with the gearbox in position "C", my gear ratios for both the lead screw AND the drive shaft are 2:1. Does anyone elses experience match mine?

I'm also curious what other's experiences are regarding the sizing of your stepper motor. Has anyone tried a larger stepper motor set up as a direct drive to the gear box input shaft? If so, what did you choose for sizing?

I'm not to the point where I can take pictures, but when I get there, I'll share my experience.

Thanks in advance for anything you can offer . . .
 

GunsOfNavarone

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@bcrosby you can input your lead screw value of 8 tpi into the setup and you would want 1:1 ratio since you are using the Clough ELS. A large stepper motor probably isn't a bad idea from my experience and whatever that stepper is, you can adjust it's steps in the stepper driver setup. I thik his setup is pretty versatile. I also think there is a Clough specific thread you may want to post on as this one is more for the OP's journey to his very different setup. Search for Clough42 and it should be one of the 1st hits.
 

bcrosby

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Thanks much! There appear to be several Clough42 threads, most of them of builds various members have undertaken. I'll peruse a bunch of them and see where they lead me.
 

freethink

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I have been researching gear ratios on my lathe and am finding a VERY DIFFERENT reality from some of you. My lead screw is 8 TPI. With the gearbox in position "A", my gear ratios for both the lead screw AND the drive shaft are 1:1. With the gearbox in position "B", my gear ratios for both the leadscrew AND the drive shaft are 1:2. And, with the gearbox in position "C", my gear ratios for both the lead screw AND the drive shaft are 2:1. Does anyone elses experience match mine?
I'm also in the process of doing the Clough42 ELS upgrade on the PM1127. My lathe was manufactured in 2020, and also has the same gear ratios as you're describing. I think they may have changed gear ratios when they changed the motor drive ratios, but I'm not sure on that. I know the manual they provide doesn't match my machine, so it did change at some point.

I decided to go with the same Nema 23 hybrid servo from Ebay that James uses. For gearing I'm doing a 80T change gear engaged to the 40T spindle gear, coupled with an 80T GT2 gear, and a 40T GT2 gear on the encoder. Lead screw drive will have a 60T HTD 3M gear with a 30T HTD 3M on the servo. Just waiting for all the gears and belts to make their way over from China so I can finish the project. I can update with pictures when I get a little further.
 

RJSakowski

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I know this is a very old thread, but I'm hoping to revive the conversation. I also have a PM1127-LB and am in the process of installing the Clough42 ELS. I took delivery on my lathe in March of 2020.

I have been researching gear ratios on my lathe and am finding a VERY DIFFERENT reality from some of you. My lead screw is 8 TPI. With the gearbox in position "A", my gear ratios for both the lead screw AND the drive shaft are 1:1. With the gearbox in position "B", my gear ratios for both the leadscrew AND the drive shaft are 1:2. And, with the gearbox in position "C", my gear ratios for both the lead screw AND the drive shaft are 2:1. Does anyone elses experience match mine?

I'm also curious what other's experiences are regarding the sizing of your stepper motor. Has anyone tried a larger stepper motor set up as a direct drive to the gear box input shaft? If so, what did you choose for sizing?

I'm not to the point where I can take pictures, but when I get there, I'll share my experience.

Thanks in advance for anything you can offer . . .
I have the same lathe as Clough which has a 12 tpi lead screw. I ran 1:1 pulleys from my 600 oz-in, stepper to the lead screw input shaft which ia essentially the same as direct drive but changed the gear box setting for a 2:1 reduction in speed to obtain more torque. The testing I did resulted in the stepper being able to pull 105 lbs measured at the carriage at 300 rpm and a feed rate of .12 in./rev. or 36 ipm.

With a 50% larger motor and a lower speed range, you may want to opt for a larger stepper to retain full capabilities for power feed. Threading would probably not be an issue and the cuts are usually quite light. The down side is a larger power supply and driver will be required.
 
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