[BrassBuilder]

I know how frustrating trouble shooting CNC flakiness can be. The mechanical stuff is easy to get your head around, but if it is issues like pulse train stablity or noise interference, you need to be very patient and systematic.

Have you tried running a program for a couple of hours continuously to see if you are missing steps? your want an assymetical program like rapids of an inch at a time in one direction, then a slower feedrate move back to start.

"when I move the ballscrew clockwise and then counterclockwise, the dial indicator will show about .001 to .0015 movement in the same direction before the carriage starts moving the other direction. It happens both ways."

This sounds like your ball nut has play. Mine does too. Not a big deal on a lathe on Z since almost all cutting is in one direction. A second nut in an anti backlash config would help, but on Z this is hardly worth worrying about.

Have you tried installing TurboCNC, or EMC2 and see if you have the same issues. Or run a different computor? TurboCNC and the essential bits of Dos can be loaded on a couple of floppies, so you don't even have to install it.

Well this was interesting to say the least.

First to address a couple of issues that Mark brought up:

During my checks on this (again), I checked the ballscrew to make sure there wasn't any end play...there wasn't. I never got to the point of installing TurboCNC or EMC2 while I messed around with it.

I'm going to get a simple G-code program wrote this week and let the machine run for an hour or so on it and see what happens.

Here are a few of the things that I changed during the last hair pulling exercise:

I added 4 more legs under the bench.

I added some braces to the home made pieces under the carriage and also readjusted the carriage (again). I moved the carriage nearer to the headstock where it is going to spend about 90% of its time anyway. I *think* I might have had the carriage adjusted too tight and was introducing binding during movements. That was, I think, the reason the dial indicator went wacky.

After manually running g-code manually through Mach3, the carriage moves usually within .001 on everything that I throw at it. Once in a while it will be .002 off, but I can live with that. It isn't like I'm making space shuttle parts here....

I'm already looking at some stuff I want to do to it now that it looks like it is going to work. I want to get a better motor and add a spindle speed control. The motor that I have is a cheapy treadmill motor that I got on ebay. Looking at getting a 1 to 1.5hp Leeson or Baldor motor. (Any suggestions?) This treadmill motor just does not seem to run smooth.

Also want to add thread cutting capability. Not sure what I need there, but the spindle speed control is a higher priority.

Still need to get my limit switches mounted and wired. Need to make a cover for my motor belt.

You guys have no idea how grateful I am for all the advice you all have thrown out over the last few months. I would have never stuck it out without all the encouragement!

Thanks much....

Mike :banana:

[RotarySMP]

Cool that it is working for you Mike.

The for threading all you really need is something switching an input pin to the parallel port on/off once per rev. Whether this is an optical gate, a reflective photo sensor, an inductive Prox sensor, a mechanic switch, or a very well trained rat is no big deal to Mach.

The simplest is an optical gate with a toothed disc cutting the beam. Mach can do a multi toothed disc, with one space being 2x wider than the other, for finer speed control.

Spondle speed control is not required for threading. MACH doesn't try to control the spindle to the Zaxis, it controls the axis to follow the speed of the spindle.

I still haven't implemented CNC spindle control. You only really need it with an automated tool changer. As long as you change tools yourself, it is no big deal to switch the spindle off, change the VFD Speed pot to the next tools RPM change tool and then turnback on.

[BrassBuilder]

I still haven't implemented CNC spindle control. You only really need it with an automated tool changer. As long as you change tools yourself, it is no big deal to switch the spindle off, change the VFD Speed pot to the next tools RPM change tool and then turnback on.

OK. Thanks for pointing that out. I never thought of that. I think I'll switch my priorities and go with the threading capability first and then the spindle control. I wanted to add a tachometer to this too and it sounds like the threading conversion is going to head me in that direction anyway.

On the motor that I have now, it has a plastic disk on the back side with a bunch of holes in it. I take it that was for the tachometer on the treadmill?

Mike

[GM1G]

any updates?

been working nightmarish hours havent checked back

yet no new pics!!!!:drowning:

[BrassBuilder]

any updates?

been working nightmarish hours havent checked back

yet no new pics!!!!:drowning:

Been busy finishing up my Masters degree in Information Technology Management. Had to shove three months of homework into two months. Pretty much took all my free time.

I also have an update...but no pics. I don't have any pics to post because I lost the stupid cable for my camera to transfer pics off of it. It does not have a memory card. I've been looking all over for it and can't find it. Might have to look on ebay for one. Should just buy a new camera....

The lathe is workable. I've been trying to learn the lathe portion of DolphinCad/Cam and then getting G-code into Mach3. I've run a couple of practice parts through the lathe. Almost peed myself the first time it ran on its own. The lathe seems to have a higher learning curve than what I went through on the mill. I'm going to sit down and read the Mach3 Lathe manual over the next week or so.

I have my QCTP mounted on the lathe. After using it, I am glad I got it on. I had to make an adapter block...and if I had that stupid cable....I would post pictures.

I picked up a used Baldor 3hp motor that I want to use in place of the cheapy Chinese treadmill 2.5hp motor that I got. The treadmill motor just does not seem to run very smooth. The Baldor, being 1/2hp more is like twice the size and 3 times heavier than the treadmill motor. A very impressive piece of metal.

Still need to mount my limit switches and make a cover for over the pullies and belt.

I was just on CNC4PC.com looking at some parts to put a spindle control on for threading when my phone beeped that I had a new email and saw it was a reply to this thread.
Mike

[BrassBuilder]

Alrighty....got some pics and no....I did not find the cable for my camera. I was up at WalMart and they had a display camera marked down for $49. Seemed like a good deal so I bought it. It is an Olympus X-560WP. It is actually better than what I had that I paid $100 for. Supposed to be weather proof too.

Not sure which order the pics are going to load in, but I guess it will be mostly self explanatory.

1. Here is a comparison of the 2hp Chinese treadmill motor and the 3hp Baldor. Quite the difference, eh? I hope the Baldor is not overkill for the lathe. Is there such a thing as too much power???

2. A couple of pics of the new mount for the QCTP. Works amazingly well plus I got rid of another sliding point.

3. I have the motor mounted, but I need to lengthen the drive belt a few links. I am waiting for the new HP resistor from Solid State Drives to arrive for the KBCC-240D motor controller. The one I had was for the 2HP motor and I forgot I needed to change it out.

4. Someone asked about a picture of the steady rest. Here is what I have. I have no idea if it is the stock one for the lathe.

Still trying to learn how to run this. Friends find it humorous that I built a machine that I don't know how to run.

Yeah...it's hilarious....

Until next time. Same Bat time. Same Bat channel.

Mike

[BrassBuilder]

Got the Baldor motor hooked up and all I can say is WOW!!!!

What a difference!

The lathe runs about 100% smoother. The RPMs seem to be steadier and I ran this past 2000 rpm and it was running great. I could only run the treadmill motor up to about 1800 when it would start vibrating. I think I can run the Baldor even faster, but 2000 rpm is plenty for what I am doing.

I have one concern and I am not sure this is important. When I change the speed of the motor, it takes a few seconds before the motor comes up to speed. It just seems a little slow in speed changes. I've been playing with the settings on the KBCC-225D motor controller and I got it set pretty good now, but I think it could be better. Just not sure what to change.

Maybe changing the gear ratio on the motor and lathe? I have a 3" pulley on the motor running to a 5" pulley on the lathe. I have two smaller pulleys I can go to on the lathe yet.

In the previous pics, I didn't get the tailstock painted yet. Not sure why I thought I needed to point that out. Call me Captain Obvious. It is on the "to do" list.

Mike