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  1. #1
    Join Date
    Apr 2006
    Posts
    24

    Practical CNC Failures

    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

  2. #2
    Join Date
    Jul 2005
    Posts
    409
    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

  3. #3
    Join Date
    Apr 2006
    Posts
    24
    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

  4. #4
    Join Date
    Jul 2005
    Posts
    409
    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

  5. #5
    Join Date
    Apr 2006
    Posts
    24

    Practical CNC Failures

    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

  6. #6
    Join Date
    Apr 2007
    Posts
    1

    Smile Help needed on CNC choice

    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

  7. #7
    Join Date
    Apr 2006
    Posts
    24
    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

  8. #8
    Join Date
    Jan 2007
    Posts
    599
    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.

  9. #9
    Join Date
    Jul 2005
    Posts
    2415
    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?

  10. #10
    Join Date
    Jan 2007
    Posts
    599
    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!

  11. #11
    Join Date
    Mar 2007
    Posts
    4

    Which CNC Plasma Tab le

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

  12. #12
    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

  13. #13
    Join Date
    Jan 2007
    Posts
    599
    Quote Originally Posted by roadbyte View Post
    After reading the post which company has good table and support out there without breaking the bank say under $20,000 USD.
    build one yourself

  14. #14
    Join Date
    Mar 2004
    Posts
    93
    I am rebuilding mine now with Tom's new stuff. I am not unhappy with the basic table because I could get good cuts out of it. The Y drive shaft was never straight (cheap) when it was built, so I am upgrading it and the bearings now. I have found every other consumable (bearings, gears, belts, etc.) from other suppliers. I think it is going to run pretty smooth when done. (plasma only) Even using the top rail and plastic type rollers. (Takes crashing really well too)


    I was the first one to run SheetCam on my table and had Tom's THC early on. I am now going to Tom's Nema 23 500 OZ stepper setup because my Practical box stopped working. I am not sure but the Z being tight did not help anything. I have that sliding free now. Mariss warned me a while back about the heat sink deal and I have a feeling that might of raised it's ugly head. My table is a three year old 5X10 version. It's pretty strong with all the extra braces I added and when I get it done I expect it to perform as well as it needs too.

    I am happy that I will never have to email Joe or any of that group again. That right there is worth more then you know. I guess that would put me in the group of happy Practical owners.

  15. #15
    Join Date
    Apr 2007
    Posts
    1

    Stay well away from Practical CNC

    This is the worst company i have ever dealt with.
    I pucrahced and paid in full 7 month's ago and still have not got all the parts in working order.
    I purchaced there top of the range machines and it hasent even ran yet.
    There unbeatable backup is poor to say the least.
    Save yourself the heartake go alsewhere.

  16. #16
    Join Date
    Jun 2007
    Posts
    3

    Practical CNC Problems

    Wish I had found CNCZone before I purchased!!!

    I am new to the CNC world, I do have twenty one years of AutoCad under my belt, a degree in mech. engineering and a degree in optical engineering. I explored and reviewed a lot of information on five or six different routers. Talked to a E-Z Router owner, but was not impressed with the mechincal design of the machine. I spent several hours with a Practical CNC owner & table before I purchased a 5 x 10 Dual Two in March of 2007, recieved late April 2007.

    Did not recieve my tourch adapter or bed, still waiting for those items. No assembly or operating documintation, a video with reference to a machine that did not resemble the machine I recieved. Some vendor documintation with spindel, mistor, wincnc, and bobcad v21.

    After assembling we started with G28, and the "Z" plunged into the bed. Bad encoder, this damaged the "Z" drive nut by pulling the s.h.c.s. thru the plastic flange. Practical responed quickly with a new encoder and we were up and running within days. Cut parts for a day when the "X" took off and slammed into the solid stop of the gantry, bending the "X" drive shaft, bad encoder. This time it took a couple days of leaving messages, our frustration set in, we made a new shaft and wedged a plastic shim under the encoder cat five connection and it worked. We recieved a new encoder and drive shaft in a week or so. After replacing parts we managed about forty hours of machining, when the "Z" plunged into the work piece and the servo controller started smoking. The "Z" servo card blew.

    After leaving messages for several days, Practical responed with a new servo card and stating they have had problems with servo cards. Machine worked well for a few days when the "Z" plunged into work piece. Stripped "Z" nut! It took two weeks to recieve the part and fifteen minutes to replace. The machine worked for three hours when the "Z" plunged into the worked piece. Hit the e-stop in wincnc and turned off the servo controller. Seconds later, turned on the servo controller and "puff", blew all three servo cards.

    After leaving three and four messages a day, five days later, I got through. Sent the controller back, their responce, Practical said the ground shorted due to external power surge or power source. Our machine is isolated from any other equipment or power source. Anyway, to make this long story short, Ive been down four weeks and still waiting for my controller to be returned.

    Do not get me wrong, I like the mechincal design of our machine, but the electronics seem to be weak, my weakness as well. Any advise would be helpful.

    Thanks for me letting vent.

    Best to all!!!!

    CaryK

  17. #17
    Join Date
    Apr 2006
    Posts
    24

    Practical CNC Failures

    Your experience with Practical CNC is roughly similar to my own. My suggestion: get a new controller and the THC-1000 from CandCNC. Run Sheetcam and Mach3. Tom (Torchhead) got my system working and is one of the greatest fellows you'll ever meet; he's honest, helpful and knowledgeable. Anyway, it worked for me. Now my system works like it should.
    Graybeard

  18. #18
    Join Date
    Jul 2005
    Posts
    2415
    Im just telling you that I was lied to by DynaCnc.. I noticed that you did not address that in your response to me. They were sending out a link(and I bet they still do) that showed why there machine was better and showed PracticalCnc using "plastic" parts and such...this was completely false.
    Once again just my experience and opinion.
    Well, here we are again with another liar! He claims his recent PCNC table has plastic parts and bad electronics. We ALL know that's a lie because AB says it is!

    Probably just Dave posting to try and harass poor old PCNC again.....oh, wait....the poster just contacted me and he has a real name, phone number and contact info......

    Tom Caudle
    www.CandCNC.com

  19. #19
    Join Date
    Oct 2004
    Posts
    44

    Plastic ?????? What???? Parts????

    Quote Originally Posted by caryk View Post
    Wish I had found CNCZone before I purchased!!!

    After assembling we started with G28, and the "Z" plunged into the bed. Bad encoder, this damaged the "Z" drive nut by pulling the s.h.c.s. thru the plastic flange. Cut parts for a day when the "X" took off and slammed into the solid stop of the gantry, bending the "X" drive shaft, bad encoder. This time it took a couple days of leaving messages, our frustration set in, we made a new shaft and wedged a plastic shim under the encoder cat five connection and it worked. After replacing parts we managed about forty hours of machining, when the "Z" plunged into the work piece and the servo controller started smoking. The "Z" servo card blew.

    After leaving messages for several days, Practical responed with a new servo card and stating they have had problems with servo cards. Machine worked well for a few days when the "Z" plunged into work piece. Stripped "Z" nut! It took two weeks to recieve the part and fifteen minutes to replace. The machine worked for three hours when the "Z" plunged into the worked piece. Hit the e-stop in wincnc and turned off the servo controller. Seconds later, turned on the servo controller and "puff", blew all three servo cards.

    After leaving three and four messages a day, five days later, I got through. Sent the controller back, their responce, Practical said the ground shorted due to external power surge or power source. Our machine is isolated from any other equipment or power source. Anyway, to make this long story short, Ive been down four weeks and still waiting for my controller to be returned.


    CaryK
    I heard somewhere their response was to put in a bigger fuse.... If the control box fire was not big enough.

    I think IMHO the Z axis plunge is their auto bed material clearing tool. I'm sure you could have solved that with the manual up / down button they have.

    I remember them blaming Geckodrive back then about their controller problems when I was having controller problems... I guess Rutex now has problems with their servo drives.

    Did you say "Plastic Parts". I thought there was a post stating that Dyna was lying about PCNC plastic parts.

    When I owned my PracticalCNC table ( sold it, thank God ), It had PLASTIC PARTS. I guess it depends on which day, which dollar, and which parts they have on the given day in which the moon rises in the SW and follows the rain clouds to the east, depending on the sun on any given day ?????? which parts you get or don't get. But hey, that new table advertisement photo looks great! I just can't figure out why anyone would put that in a regular post instead of the new release products forum.(wrong)

    But just my thoughts....

  20. #20
    Join Date
    Oct 2004
    Posts
    44
    Quote Originally Posted by caryk View Post
    Wish I had found CNCZone before I purchased!!!

    Did not recieve my tourch adapter or bed, still waiting for those items. No assembly or operating documintation, a video with reference to a machine that did not resemble the machine I recieved.

    This time it took a couple days of leaving messages, our frustration set in, we made a new shaft and wedged a plastic shim under the encoder cat five connection and it worked. We recieved a new encoder and drive shaft in a week or so.

    After leaving messages for several days, ..... It took two weeks to recieve the part and fifteen minutes to replace.

    After leaving three and four messages a day, five days later, I got through. Sent the controller back, their responce, Practical said the ground shorted due to external power surge or power source. Our machine is isolated from any other equipment or power source. Anyway, to make this long story short, Ive been down four weeks and still waiting for my controller to be returned.

    CaryK
    Now IMHO thats "Unlimited Tech Support"

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