CNC Build - TEP milling machine conversion

I`ve been wanting a little CNC machine for the last couple of years, not specifically for anything, just to learn more about it really. All the work I currently do on my projects (www.raynerd.co.uk) are on my manual machines.

Despite the constant advice to just go for it and but the bits starting from acratch, I just don`t dare and any machine more complete than this is to expensive, as is buying a bench mill and converting. So this is a cnc build based on confidence and available funds.
I started with a TEP cnc mill which I paid very little for. These are a sturdy machine and quite well made...just a dreadful design and dreadful software which is locked onto the driver hardware!!
I was lucky enough to get hold of the original TEP software from a local chap that has converted one of these (isn`t available from anywhere!!) and it was dreadful. Imagine MSWindows Paint, no numberical input (so no saying I want a 20mm line, 10mm from the origin!!, just simple drag and click stuff!!) Then from that, tell the machine to move.

Here is the machine in its original state:

http://www.raynerd.co.uk/images/tepcnc.jpg

http://www.raynerd.co.uk/images/tepcnc1.jpg

Very very bizzare design and many machine limitations:
Cons:

• In my opinion the x axis should be mounted so the slides are vertical parallel, not horizontal.
• No z axis, it is just a solanoid motor to raise and lower the spindle to a fixed level.
• All hardware is locked so commands can only be sent from the PC interfaced by the TEP software - it won`t talk to Mach or EMC
• Stepper motors are only about 50Ncm
• Both axis are fixed off centre to allow space at the back for the electronics
• Only 12v 5A supply.

Pros:

• I had a working CNC machine as a basis/start.
• If all else failed, I strip it down and the ally plate on it is worth more than the price I`d payed for the machine ! :D

In truth, there is little going for this other than having a solid working basis to start from....

First job was to strip the electronics completely from it. I will be using a TB6560 3 axis driver. I`ve heard nothing but BAD things about these, but I have one anyway and it`ll certainly get me going if I can avoid blowing it up.
I wanted to flip the X axis and although replacing the entire side piece would have been ideal, I couldn`t afford it and had some pieces suitable in stock. I raised the sides and used a plate to join them. It may need some supports bridging the sides later on.
After flipping the X, I could then mount a Z axis. I made the Z axis from a small leadscrew someone kindly gave me and the slides are olite 8mm ID bushes on 8mm silver steel rod slides. The rest is just plate bolted together. There is a problem in that I`ve used a flexible coupling but I haven`t "trapped" the leadscrew. This means that the Z axis compresses on the flexible coupling and moves the relative position of the axis - not good!! This is easy to correct but I haven`t done it yet.
Once i had the X flipped and raised and the Z built, I couldn`t help try it out... it is running of only 12v at the time and the noise from these small motors is horrific, I think the TB6560 is also to blame but since then I`ve jumped upto 24v and the noise is quieter.

http://www.youtube.com/watch?v=vISjt...p;feature=plcp

At this point, the mill went back to its owner while we negotiated price. Other than electronics that we both agreed wouldn`t be needed, it was all replaced to original, thankfully, if he had seen the work I`d put into it I expect the price would have gone up!
Further updates to come: Now running on 24v from two ATX supplies in series, spindle connected, first door sign engraving done...all good fun! Issues: still not sorted the z axis flexible coupling issue. Is the Z axis height too big. Flex is the spindle.

The spindle is taken from Blackburn Marks advice on a brushless DC motor. Using a ER16 chuck with a 8mm shaft and direct replacement adding a bearing house:

camera phone shot.
http://www.raynerd.co.uk/images/brushlessspindle.jpg

Up and running, intial tests:
http://www.youtube.com/watch?v=eZ3BzL82qNg&feature=youtu.be

During the last week I`ve stripped the machine to do some mods and in the last few days got it back together. However, I just can`t get my head around the fact that the movement is well out of sync! Just a simple example, say I draw two ovals concentric to one another, they will end up overlapping and even with little flats on them instead of nice curves!

The wierd thing is, I get the same results on both Mach3 and EMC2... so either I`ve got a setting wrong in the software on both or something is wrong with the TB6560 driver?

I`m sure it was working OK just last week and so after nearly a full day trying to correct it today, any thoughts or suggestions would be helpful...I`m totally out of ideas!

Chris

Chris

Check your wire connections to make sure they are all secure, re-insert all the connections to make sure?

Funny, I just happen to have one of these in front of me and I just happen to come across this thread without searching for it. I cant decide ether to get it working or scrap it for parts, it seems bit of a money pit. Nonetheless I look forward to your progress with this machine.

P.S TB6560; I heard nothing but bad things about these drivers, after wasting money on them I have brought 3 Pololu a4988 with a Arduino CNC shield to use with my TEP unit.

:beer:It's from UK?