CNC Conversion
Turbo Mini Forums

I'm thinking about converting my mill/lathe to CNC control.

I's a Chester Centurion 500:


(This was when it was new, it's had a bit of use now)

We've more or less got it sussed:
Carriage - 20mm ball screw and NEMA 34 Motor
Cross-slide - 16mm ball screw and NEMA 23 motor
Z- Axis - Nema 23 motor on fine feed.

We shall be using a rotating table and chuck as a 4th axis.

Biggest problem is that we need the machine to make the adapting parts, but obviously the machine will be in bits

Anyone ever tried this or had any experience?

Edited by Paul S on 16th Jun, 2012.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Microw Engineering Ltd - Precision Engineers
52a Tresham Street
Kettering
Northamptonshire
NN16 8RT
Telephone: 01536 519 801
Fax: 01536 519 801

Ask for Allen Rowe he'll be able to help you out with the conversion plates and stuff :) Tell Him Stephen gave you the contact details

I picked up some american magazines called digital machinist Paul, they did a feature on cnc conversion using mach3 in season 2 mags 1-5 i think (have not unpacked them yet) its really good reading also i think theres a site called my cnc or something theres a fair few threads on conversions again good reading.

Looks like good fun.

A chap on 16v mini club is doing something similar

http://www.16vminiclub.com/forums/showthre...4&highlight=cnc

Thanks guys.

I think that we have devised a plan that will allow us to make step upgrades whilst keeping the machine in use. There may be some "hand" fabrication at times but that's no big deal.

First of all, I took the machine to bits to understand how it all worked and sort out the backlash that was getting rather excessive.



Find out how to close up the clearance on the slides, but there is no backlash adjustment on the cross-slide nut :( However that will be replaced with a ballnut.

We'll do it bit by bit, so firstly I'll order the stuff to do the cross-slide.

Edited by Paul S on 16th Jun, 2012.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Backlash is annoying even with elimintators on the machines there is still a small amount of backlash but doult its like the ones we had in college about 6 - 8 mm of moment on the milling machines :(

I should be able to get the backlash down to 0.05mm, that's fine for the sort of stuff that I'll be doing.

I've gone for a 16mm ballscrew on the cross slide (it is 20mm acme leadscrew at the moment). Thinking about using 16mm on the carriage travel as well because it will save a lot of money. It's all to do with whip rather than load. Over just 700mm the 16mm ballscrew should be fine.

But then I'm probably cutting corners :~

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Is there a reason why you couldnt machine a coupling to fit the stepper motors directly to where the handles are currently?

Too much backlash. You need to eliminate backlash if you wish to cut a perfect circle with an end mill.

These ballscrews minimise and can even eliminate backlash. Then you can drive the tables to move the workpiece in a perfect circle.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Ah, of course. Essentially in this case how much you need to the ballscrew before the machine will move in an axis?

After seeing this thread earlier i went and found a copy of Mach3 in the net. Bit naughty, but never mind. It has backlash compensation.

You should near enough be able to zero out backlash. If you decide to use Mach3.

Edited by Sam on 16th Jun, 2012.

A mate of mine is cnc-ing his mini mill. He found a guy in the states that made a conversion kit for his machine.
Had a look at the bits the other eve, looks good and nicely machined.

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

Yeah, some of the popular mills x2, x3, etc all have cnc conversion kits. Lots of manufacturers rebrand these machines and they are easily available in the UK. You can also buy one that's already been converted by Syil although the support isn't great.

We will be using Mach3 and I've got all the electronics side of things sorted.

Fortunately I work in education so have access to CAD/CAM software and should be able to get some heavily discounted :)

Ideal then.

What do you plan on using for converting from model to gcode?

In terms of electronics what do you use to control the spindle?

Ive got my head around axis stepper motors and how they interface with the driver, power supply and break out board. Well the cheap ones im looking at anyway.

All the breakout boards have only had a relay to control the spindle? What about speed and direction?

Edited by Sam on 17th Jun, 2012.

That's a few steps further on. For now we are just going to use manual spindle control. Set the speed with the pulleys, turn it on forward and leave it running :)

For the future we are thinking about using a VSD and toothed belt/single pulleys. Some of the breakout boards have a 0-10v signal for spindle speed and a forward/reverse digital signal.

This is the braekout board we are planning on using:

http://www.cnc4pc.com/Store/osc/product_in...&products_id=46

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

As the old boy says, C11G for the breakout board, kl-5056 for the drivers and nema 23's for the steppers.

Lots of people normally use a 34 on the z axis but as we are only moving the spindle rather than the whole assembly this isn't required.

Model to Gcode I'm currently looking at solidcam but will see if I can trial other products.

good luck with your conversion. i take this sort of thing for granted with where i work. but to have your own small set up at home would be pretty neat.
you'll be able make your own inlet manifold injection bosses. it'll take a few ops but no need for a super m/c to do them on.

one day boost will be mine!

Have a look at MasterCam and EdgeCam. I used EdgeCam at work, didnt take too long to workout how to use it. The tough part was learning the feeds and speeds that you can use on certain cutters and your specific machine.

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

Components for the cross-slide conversion:



Should be able to fit this quite easily. Need to make up some end supports first, make a sleeve for the ball-nut, then take the machine apart to fit the ball nut and all the above.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

All looks pretty fun Paul 0.05mm isn't massive amounts :) not like your working to stupid tolarences

I've made a little progress:



Ball screws on the X & Y axis. Stepper motors on X,Y & Z axis. I'm using double ended motors so that I can still use the lathe/mill in manual mode if I want to just do something simple.

Next step is to wire up all the lectronics.

Edited by Paul S on 25th Aug, 2012.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Looks simple yet complicated.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

first test is going to be very exciting i reckon !

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Emergency stop is on order :)

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."