Centroid Community CNC Support Forum

ChrisMe wrote: ↑Sun Apr 11, 2021 3:04 pm

swissi wrote: ↑Sun Apr 11, 2021 2:52 pm
Mini Mill!? I only see 2 motors on your BOM. How are you going to move the 3rd axis?

-swissi

That should say mini lathe.

Mini lathe? Explain. WHAT MAKE/MODEL, is it currently a manual lathe, is it a purpose built CNC lathe? Are you converting a manual lathe??
As Swissi is pointing out, throwing ultra precision motors/drives (and the expense) on a manual lathe makes no sense.

You would get MUCH better suggestions if you explain your project, post pictures of it, your tolerance expectations and then we can make better suggestions.

Marty

martyscncgarage wrote: ↑Mon Apr 12, 2021 11:47 am
Mini lathe? Explain. WHAT MAKE/MODEL, is it currently a manual lathe, is it a purpose built CNC lathe? Are you converting a manual lathe??
As Swissi is pointing out, throwing ultra precision motors/drives (and the expense) on a manual lathe makes no sense.

You would get MUCH better suggestions if you explain your project, post pictures of it, your tolerance expectations and then we can make better suggestions.

Marty

Hi Marty

Thanks for the reply. I was really just checking if the motors would work with Centroid Acorn. I was not looking for project suggestions however it is the Sherline chucker lathe which you can find here- https://www.sherline.com/product/chucker-lathe/

For every 300mm (11.8 inch) of travel or 150 rotations of the lead screw the lathe with gain or loses no more that 0.05mm (50 micron or 2 thou). I only need it to travel about 1/5 of an inch for each part.

I'm not running it on the MASSO software because the MASSO software can not reverse the spindle an therefore not blind tap. I'm making small parts with at most 1.5mm (60 thou) of material needing removed so torque is not an issue but accuracy is. The smallest thread I'm hopping to blind tap in the future when I know what I'm doing has a thread of 0.235mm (9.3 thou) or 108.1 TPI.

There will be inaccuracy and defections creeping in with every part of the lathe so to give myself the best shot at achieving this I need the most accurate parts I can get. Do you think this is possible?

For rigid tapping, you're going to need a VFD driven spindle, peferably with a braking resistor and a spindle encoder driven from the spindle at 1:1.

You mentioned your screw accuracy, but no mention of backlash. I'd guess that you would want less than a couple of percent of your finest thread pitch.

ChrisMe wrote: ↑Tue Apr 13, 2021 4:58 am

martyscncgarage wrote: ↑Mon Apr 12, 2021 11:47 am
Mini lathe? Explain. WHAT MAKE/MODEL, is it currently a manual lathe, is it a purpose built CNC lathe? Are you converting a manual lathe??
As Swissi is pointing out, throwing ultra precision motors/drives (and the expense) on a manual lathe makes no sense.

You would get MUCH better suggestions if you explain your project, post pictures of it, your tolerance expectations and then we can make better suggestions.

Marty

Hi Marty

Thanks for the reply. I was really just checking if the motors would work with Centroid Acorn. I was not looking for project suggestions however it is the Sherline chucker lathe which you can find here- https://www.sherline.com/product/chucker-lathe/

For every 300mm (11.8 inch) of travel or 150 rotations of the lead screw the lathe with gain or loses no more that 0.05mm (50 micron or 2 thou). I only need it to travel about 1/5 of an inch for each part.

I'm not running it on the MASSO software because the MASSO software can not reverse the spindle an therefore not blind tap. I'm making small parts with at most 1.5mm (60 thou) of material needing removed so torque is not an issue but accuracy is. The smallest thread I'm hopping to blind tap in the future when I know what I'm doing has a thread of 0.235mm (9.3 thou) or 108.1 TPI.

There will be inaccuracy and defections creeping in with every part of the lathe so to give myself the best shot at achieving this I need the most accurate parts I can get. Do you think this is possible?

See, now you say BLIND tap.....That's a good bit of information.
I see its a small Sherline Chucker...WHAT kind of parts, what kind of material, what size taps do you expect that machine to run.
We are not going to commit to approving your parts list. You did pick out good axis motors. Clearpath SDSK motors.
The spindle motor is DC brush. You need a good DC motor controller, I would give KB Electronics a call and let them know you need a DC motor speed controller with regenerative braking, reversing with an input signal, isolated analog speed control 0-10VDC or 0-5VDC. You will have to provide them the label information off of the motor.

Otherwise, like Tom mentioned a small 3 phase spindle motor and a good VFD with brake will be required. You will also need a good line driver differential encoder belted at 1:1 to the spindle with a timing belt. I'd recommend either purchasing one from Centroid or Automationdirect.com. If you have to hang the pulley off the encoder itself you need a medium to heavy duty encoder. If the pulley can be mounted to a jackshaft with a pair of bearings then you can couple a light duty encoder to it. It must be covered to keep dust and contaminants out.
Go see Franco CNC's videos on YouTube. I believe he fitted up a Sherline chucker lathe.

Centroid Acorn with its TRUE encoder input can accurately rigid tap to depth. The control uses the spindle speed to accurately move the Z axis.
Your challenge will be making sure the machine is fitted up properly with good quality ballscrews, thrust bearings and that you it can handle the parts you expect to run. Must be small parts...small taps....

Lastly and I believe it was mentioned, if you are going with Teknic Clearpath SDSK or SDHP, you should be talking with them. They will help you select the correct parts and size the motors for your machine application. They'll get you closer than a guess.

This is an interesting thread. Chris asked us to check whether he had selected the correct cables from Teknic for the ClearPath drives that he had listed. He had done his homework and had selected the proper cables. I was concerned about his choice of ClearPath servos, not because he was wrong, but because the model number that he listed is not commonly used. On Sunday, he told us that Teknic had recommended those motors.

Most people posting for the first time haven't done as much homework as Chris. I assumed that he would have additional questions as he got further into the project, so I didn't bother him with all the minutia that is normally part of my builds. I doubt that most of that minutia is would be helpful at this point. Probably most of it wouldn't be applicable to his project.

Chris, congratulations on your project. Keep us in the loop as things progress.

Richards wrote: ↑Tue Apr 13, 2021 3:46 pm This is an interesting thread. Chris asked us to check whether he had selected the correct cables from Teknic for the ClearPath drives that he had listed. He had done his homework and had selected the proper cables. I was concerned about his choice of ClearPath servos, not because he was wrong, but because the model number that he listed is not commonly used. On Sunday, he told us that Teknic had recommended those motors.

Most people posting for the first time haven't done as much homework as Chris. I assumed that he would have additional questions as he got further into the project, so I didn't bother him with all the minutia that is normally part of my builds. I doubt that most of that minutia is would be helpful at this point. Probably most of it wouldn't be applicable to his project.

Chris, congratulations on your project. Keep us in the loop as things progress.

Understand Mike.
When I did my build, Teknic assembled the list for me. They insured parts compatibility and sizing before the purchase.
It appears Chris did that and Teknic provided the bill of materials, really there shouldn't have been any second guessing Teknic. They've been really good to work with and the cost of the material is part of their service they provide their customers.

Marty