Practical CNC Failures

[Graybeard]

Hi All,
This is just a quick warning for newbies who might be considering purchase of a Practical CNC. In a word, "Don't."
I made the mistake of buying one and in five months it never worked right. I spent hundreds of dollars shipping parts to Practical for repair/replacement. I had a controller burn out, three motor failures, and four driver failures and a bent X axis shaft. Their expensive torch control system never did work right and slammed my new torch through a sheet of steel doing considerable damage.
I replaced the Practical CNC torch height control system (which didn't work) with the MP-1000 THC system from CandCNC (which works great). Practical CNC then used that as an excuse for denying warranty service on the controller. Please note that the controller and torch height control are separate things.
Anyway, in desperation, I finally bought a prototype controller from Tom Caudle at CandCNC. Now everthing is working great. Tom gives fantastic service and his advice is a tremendous help. Need help? Ask Tom on this site or on the CandCNC Yahoo group.
I use Corel Draw and ProgeCAD Lt (ProgeCAD Lt is free) for my design work, SheetCAM for layout and to generate GCode, Mach3 as the controller software, PSC-650 power supply and controller, and the MP-1000 THC system. Now I have a system that works pretty damned well. And Tom has become a friend. I wish that all businesses were run by his principles.
I hope this helps some people to avoid the mistakes I made by choosing Practical CNC.
Paul "Graybeard" Paine

[cut more]

Graybeard,
How long ago did you buy your Practical machine? I bought mine a little over a year ago. Now they are using linear rails on all axis(not on mine though!) Did you get the servo or stepper control?
I also question whether it was a mistake to buy practical but I am making parts with it as a router & a Plasma.
I would recommend anyone who does buy a practical to not buy the practical THC. Although mine does work, you have to baby sit and raise the torch between cuts.
I have the stepper drive and have not had any problemswith them.
My .02
Cutmore

[Graybeard]

Hi Cutmore,
I got my machine about six months ago. It has the linear rails and servos. It was definitely a mistake to buy from Practical. About the only thing good about it is that I've learned more about CNC tables than I ever wanted to know. The education may be a good thing though since my neighbor wants me to build him a table that works better than the commercial unit he bought for $75,000. We are working on the design right now. We are planning on using the controller and THC system from CandCNC.
Graybeard

[cut more]

Graybeard,
Thanks for the info,I too learned a lot about cnc that I did not know before, like what not to buy! I run a Motionmaster router at work, it has a Fagor control and is great to work with. If pix of their design would help let me know. Who made the one your neighbor bought?
Cutmore

[Graybeard]

Cutmore,
I think we have the essentials pretty well worked out. We are planning to go as simple as we can on the new machine. My neighbor runs a steel fab shop building natural gas compressors, pressure tanks, and components for oil rigs - on-shore and off-shore. Also does sand blasting and industrial painting. The plasma table he uses now is from Retro-Tech and it works pretty well. It has an 8' x 12' table and he uses it to cut parts up to about 5/8". It can do plasma cutting and oxy/acetylene cutting. He farms out heavier work to a local company and light work to me. The new machine we are planning will also be 8' x 12' and should do material up to about 1.25". The Retro-Tech has nearly paid for itself in the first year by savings on parts cutting. We are hoping a new machine would result in even more savings. By the way, he is accepting requests for quotes if anyone needs big fab work done.
Graybeard

[TurboRambler]

Hey folks I am new to CNC machines so be gentle.

I would like to get a turn key system to do router and plasma work. I was looking at practical but now you guys are scaring me. Who makes a table and controller that someone uses today that they would recomend? Am I going to have to buy the pieces from seperate vendors to get a good machine? If yes then I may see if someone can guide me to the best places to get the parts.

Thanks!
Turbo

[Graybeard]

Hi Turbo,
If I could afford to do it over again, I would build my own machine in the form of the EZ-Router, using CandCNC controller and torch height control, with good steppers. I'd rely on Tom Caudle (Torchhead) for advice and Mariss at Gecko. run with SheetCAM and Mach3.
Graybeard

[xjdubber]

you know its funny, i have a practical cnc that has been running for about 6 years now. Its been abused but still works good. I guess is all in what you expect to get out the money that you put into it i guess.

[Torchhead]

Not all Pintos burned up. Not all Practical's are junk....just some of them. PCNC has had a rollercoaster history of quality control problems, electronics that are marginal and customer service that reads like a horror story.

Example:

Customer: "My table came in and when I turned it on the Z slammed into the grid and blew the 10A fuse on the back. What should I do?"

PCNC "Support Engineer" (his reference not ours): "Ahhh...put in a bigger fuse. Those drives can handle 20A's"

The results from that advice was that Fire shot out of the back of the unit.

If you got a good one then you caught them during an up time. 6 years? You must have one of the first ones they made that uses Flashcut and Gecko's....wait, I don't think Gecko's were around at that point. Better worry because Joe quit using Geckos because they were "defective" In fact he didn't pay for the last 35 pieces he used and refused to return them because they were "evidence". He has a lot of "evidence" from other vendors too since they never got paid for their goods.

I have a mailbox full of PCNC stories. All true and all from their customers or vendors. Want to trade a few?

[xjdubber]

yep it uses geckos and flashcut, I know the stories about PCNC. Ive read joe's blurbs on the internet. I guess i should be just happy that mine works just fine!

[roadbyte]

After reading the post which company has good table and support out there without breaking the bank say under $20,000 USD.

[Mariss Freimanis]

Be sure your drives are adequately heatsunk. I heard stories the drives were run without any heatsinking at all. Touch the drives after the machine has been on for about an hour. If they are uncomfortably hot to the touch then it's also uncomfortably hot for the electronics.

Mariss