X axis problems.

[gundog]

It has taken me a while to figure out my problem and I am not sure I have it figured out yet. Randomly since my machine was new it starts making egg shape circles and not cutting accurately.

I first thought my material was moving answer was to build a vacuum table with t slots to hold everything down tight that was not it.

I then noticed when it would start cutting poorly the X axis motor closest to 0, 0 was not holding tight it had a bunch of slop in it. I would turn off the machines control box and re-adjust the rack and pinion fit to that motor. I have done this at least 8 times thinking I was getting play between the pinion and rack. I put on lock washers and lock tite to the bolts it still happened.

I cut a lot of plastic so I thought the plastic swarf was getting between the rollers and the track and causing the slop between the pinion and rack or in the gear and rack itself. I built some wipers that incase the rollers and block the area so the chips can't get to the gear or roller.

The problem still happens. It may go several times with no problem then it shows up again. It dawned on me the last time I adjusted the pinion and rack on that same motor I don't think I am getting slop in the rack and pinion at all. I now think the motor is losing the signal. I am thinking I may have a bad connection to the control for that motor or the motor or board is bad. This is an intermittent problem and it only happens every so often but way to often and has ruined a few parts for me.

When this problem occurs I can move the one end of the car 1/4" - 3/8" by hand while the other end of the car holds tight with the control box on.

When I get time next week I need to trouble shoot this I sure hope it ends up being a bad connection. This has been a very frustrating problem thinking each thing I have done would fix the problem. I have been on the phone with SB at least 3-5 times over the year I have owned this machine and I think we were just looking at the problem wrong.

Mike

[Gary Campbell]

Mike..
Bend an allen wrench into a U on the pinion grub screws?
Gary

[bill_lumley]

Michael , I had a similar problem that was causing me to think my X axis was have a problem in some manner . An observant buddy noticed one of the X-motors was colder than the other but of course there was no indicator telling me this . When I powered down the control box and turned it back on the cold motor would come back up to the same temperature as the working motor . Shopbot support thought one of my Gecko drivers was powering itself off due to heat buildup or something . I had them ship me a new control board and I have not seen the problem in quite some time . Also keep in mind for the PRS with Geckos because their is no real heat sink on them they need to have the control board mounted horizontally so that heat will rise away from the drivers and not build up the same as if the board was mounted vertically .

Hope this makes sense . Now I often touch both motors to make sure they are both working . Gary is right about tightening the screws but that did not solve my problem in the end .

Bill

[gundog]

Gary the pinion screws are not loose I marked them with a pen this is way more slop than that. The pinions were one of the things SB had me check. I think each time I re-tightened the pinion to rack I had it fixed because when it powered back up the slop was gone but now I think it got fixed by powering it on and off. It happened last time after being powered up after cutting some parts but then sitting powered up for an hour or more and not moving until I started to cut some more parts. My machine is a PRS standard 4x8.

Bill I think you may be on the right track with the board. I really don't think I have a bad connection but I plan to check anyway to eliminate that possibility.

Mike

[erik_f]

I had a bad driver. It wasn't all the time and it took me a while to figure out what it was, but you may want to call Gecko also...thats what I did. Gecko told me to wiggle the driver a little while the machine was moving...in the right position the problem would come back.

[gundog]

I have been machining parts again on the SB and the problem popped up again. I thought I had it figured out and added a server cabinet fan to my cabinet that houses the control cabinet and PC. I put a 120mm fan on the back and a vent on the front door. The fan seem to fix it on day one running a couple long cuts a few hours each but today it happened again so I called SB support he told me the control board was overheating that I needed to remove the control box from the cabinet and take the side off and set it on its side. There is no way I can leave the box uncovered in my shop because of the plastic chips would fill it. I run a DC but the plastic still gets past the DC and makes a huge mess.
I have removed the side cover as I was instructed and have the box on its side inside the cabinet with the fan I installed running. I also moved the PC to the other side of the cabinet because there is no longer room for it with the control box on its side. I have been doing air cuts for a few hours to see if the problem will reappear.

I just feel like their control board is a weak link and should be better. I have been in a few CNC shops and I have never seen the control boxes for those machines uncovered to keep them from overheating. I live in the Pacific Northwest where temps right now are in the low 80's what if I still lived in Fresno, Ca where it can run 110 I can't imagine this thing would work at all. The problem is I only use this machine every month or two so I won’t know if it is fixed for a while unless it shows up while I am air cutting right now. This has been a very frustrating problem and this machine has had this problem since day 1 I just kept chasing my tail trying to figure out why. I also figured out it is why my Z depths have been inconsistent.

Here are some pictures of my setup.

Control box in cabinet with lid off you can see the fan in the back.

http://img.photobucket.com/albums/v292/millnut/DSC05584.jpg

This is the cabinet the left side now has the PC and the right side has the control box inside.

IMG]http://img.photobucket.com/albums/v292/millnut/DSC05586.jpg[/IMG]

Any thoughts on this?

Thanks Mike

[Gary Campbell]

Mike...
I am all for getting the paying parts done and then fix the problem. Try a box fan with a furnace filter duct taped to it to keep out chips. Then tape this assembly to the control box for cooling. Make sure the case fans are blowing out.

IT has been 90+ most every day for that last week in our shop. We have been cutting a pile of parts 7+ hrs a day for that week. Stepper motors have been spit sizzle hot, but no problems out of the drivers or the control box. We are running a PRSalpha.
Gary

[beacon14]

If heat is the problem then getting the control box out of the cabinet entirely would be a priority for me. There must be a way to shield it from chips and/or blow it out regularly.

[GlenP]

Hey Micheal, have you done a communication test to see what speed you are communicating at? Also I noticed you are using a dell computer, I had to add a usb card to my computer and also put in a external usb hub which is powered separate from the computer. It took my comms from 72% up to 83%. Also do you have every possible windows update stuff turned off. The pc should be a bare bones operating system to keep comms running smooth. I had a issue once where I could move one side of the gantry 1/4" while powered and I had a loose cable and wire in the connector. When your problem happened again today was it after a long time cutting or has it happened when the control box is cold or just been powered up? If shopbot feels it is overheating and shutting down a drive does the red light stay on when a drive shuts down and if so can you visually see the light off? Last thing and may not be causing your issue but I once tried cutting a file which was saved on a usb flash drive and the machine paused alot and then screwed up the cut as the comms from the flash drive were too slow. Now every file is saved to the hard drive and cut from there, just a thought. Is the slop always in the same motor? I have a PRS standard and seem to get some backlash in my motors but my cuts are good.

[gundog]

I have done a communication test it is 76%. I will check the windows update stuff. When the problem comes up it is always the same motor and yes at least 1/4" movement in that one end. I have looked for a loose connection and did not find one. Today I was doing a repeat drilling path through 1.25" UHMW 24 holes in each part peck drilling with a .190" bit made for plastic from Onsrud. I had 10 parts to do each part took about 10 minutes to do. the first 7 parts were fine. The 8th part I noticed did not drill all the way through just shy by about .075" I wondered what happened so I re-zeroed the bit and the first 2/3 of the holes on that parts were deep enough but then it went shallow again. The last part I just let it drill shallow and drilled them out by hand. I grabbed the end of the gantry and sure enough it was sloppy again. I have had this shallow problem with the Z in the past many times now I think it and the X motor are related. I am not sure about the lights I do know that after powering it down and letting it sit for a few minutes when I powered it back up the slop was gone.

I have been air cutting all afternoon after removing the side cover and have not had the issue again. I am skeptical about having this problem solved because I have thought too many times I had it solved in the past. I think a couple times in the past this has happened with the machine cold when I first powered it up .

Mike

[GlenP]

Are you getting a static charge or spike from your dust collector to the controller? You said you air cut and no problem and a z changing heights sounds like you are have a ground issue. Plastic going through a vacuum pipe has huge static. Are you grounded real well? Comms of 76 % is low and may be causing some issue. On your dell computer is your keyboard or mouse usb? If so put in a usb 2.0 card to get them separated. If it happened when machine first powered up heat is not your issue. If you can move the gantry 1/4" that motor has no power and is not locked in. I had that before so I know the slop you are getting but for me is was a loose connector and the controller. Have you ever lost your home position when your z changes? Get those comms up to the 80% range.

[gundog]

I have everything tied to the system service ground, The table is grounded the back of the control box, the DC hose & the DC all tied to the same ground. My dust collector hose has ground wire molded in and that wire is tied to the ground on both ends. I cannot run a ground through the hose or it will clog the hose plastic is terrible for clinging together and making a huge ball. I even have a ground strap inside the DC collection bag. I have tied all the grounds together from each power source and they are all bounded together to make a common ground. I have done electrical work for 26 years so I know everything is grounded properly.

SB told me as long as I was above 70% on the comm. I was OK.

My key board and mouse are new USB wireless. The problem was there with the old wired mouse & keyboard before I changed them. The problem with this is it comes and goes. Sometimes everything works perfect but too many times it doesn't and I never know when. The material I cut is very expensive so the screwed up parts cost me big $$$.

I was just thinking about it 6 months or so ago I made a .500" UHMW skid plate for a friends motorcycle this was a very short cut and it lost one end of the gantry then and it was the only part cut the problem happened immediately when the machine started and I can remember another time it did it at the beginning of a cut.

Mike

[GlenP]

Hey Michael, Brady Watson had a good post about communication and recommends to be higher than the 70%. When I had 70% I was told it was on the borderline and to try get it higher so I did by adding the usb 2.0 card and also a external powered hub which only cost me $50 for both of them. I am not a electrician but used to wire up control systems for factory automation and was trained to never ground both ends of a device to reduce ground looping. Not saying that grounding at both ends is wrong but just a thought. Was the old mouse a usb or ps2? On Brady's post he stated that the usb mouse steals comm power so to have a seperate card. If it is only one motor can you switch the drives to see if changes to the other motor it may help isolate if it is a drive issue??
I feel for you Micheal as I had numerous small things to iron out on my PRS but it now cuts true. I did disconnect the ground wire from the back of my control box when I was having some z issues and loss of home position and it solved my problem. I do have my table grounded, as well as the ganrty as well. Just makes me wonder when air cutting was fine??

[seana]

Michael,
Sorry if you have said this before but what control board are you running? 4g upgrade or an alpha?
The reason i ask is that i do work for a company that had the 4g upgrade and they were having similar issues.
Pulled a lot of hair out trouble shooting tried every suggestion above and even wore my clean underwear.
found out that one of the x drivers were dropping out and you would have to cycle the control box to get it to come back up.
To rule it the driver i changed the wire i swapped the motor. The owner of the machine sent the board back to shopbot and upgraded the complete machine to an alpha.

Talk to shopbot and see if they can send you a different board and see if that is it.

Again sorry if you have an alpha and none of this applies to you.

Good luck
Sean

[gundog]

My machine is a PRS and only 1 year old so I am not sure what control box that is. It does not surprise me that it air cut ok because the problem is intermittent. My machine came with a USB special device that was supposed to boost the signal.

Mike

[GlenP]

Hey Michael, well my PRS did the loss of one x motor today. I coule move it 1/4" back and forth so I knew it had lost comms or power. Was only cutting a test piece so no loss of expensive material. I noticed the connector on the board for the motor was a little loose so I pushed it back in and recycled power and it is fine. I am wondering if you are getting loose connector on the motor. My understanding from shopbot is that when a motor looses connection at the board even for a moment it will not come back up until a power down and back on to avoid power surge and blowing the board. I am going to look at trying to vip tie mine and hope they don't give a loss of comms again.
When it happened my driver lights were all on (red). I have my controller on its side with a "dirt bag" around it.

[gundog]

Yesterday when I started my machine I had the problem. The machine had only been on less than 5 minutes the computer was not even on yet and the same motor had not locked up. I checked the connections and nothing turn off the machine and back on and the motor was locked. I went ahead and ran the machine and it never dropped out I ran it for about an hour.

This removes many possibilities I think I have a bad board since I have problems with the Z at times as well. I wonder how long my warranty is. The hell of it is this thing has had this problem all along but it has taken a while to narrow it down. My box does not have the lights that some refer to unless you are talking some small led lights inside the box. I have seen pictures of the other boxes with the lights on them. I ordered my machine with an indexer so I got a box with the 5th driver.

Mike

[ecenur]

I was looking into doing something similar, I think I'm going to use a box fan with a furnace filter and have the duct taped to the furnace filter, it seems as if it would work well and seems simple to do.

[gerryv]

These things happen to the very best of products and companies. That said, I worked for a US based company that always kept a couple of extra pumps (a core product) ready to ship to customers whose issues could not be corrected quickly or adequately. We shipped the pumps out, or even had our salesmen deliver them, in advance of the customer shipping their product back to us to test over time in our lab for these intermittent issues. If it was our problem, we paid the shipping. If it was theirs, they paid the shipping. After the fact. A simple document signed up front by fax by both parties took care of that in advance but we never made a big issue of it. Know what? We actually weren't the best but we sure held onto a lot of customers that way and got quite a few new ones too. Maybe a low cost strategy to be considered by a very good company looking to keep or expand it's edge. Just thinking positive.

[Brady Watson]

I doubt that you have a 'bad board', but one of the drivers may be to blame. I would carefully unscrew, remove, reseat and resecure each Gecko drive in the control box - being sure that all terminals are properly tightened. I would also check every motor cable and make sure that it has proper strain relief, is not getting stretched and that there is a good connection.

Also, swap the 5th driver with the X axis channel that you think is at fault.

-B

[gundog]

I doubt that you have a 'bad board', but one of the drivers may be to blame. I would carefully unscrew, remove, reseat and resecure each Gecko drive in the control box - being sure that all terminals are properly tightened. I would also check every motor cable and make sure that it has proper strain relief, is not getting stretched and that there is a good connection.

Also, swap the 5th driver with the X axis channel that you think is at fault.

-B

If you are talking about mine the post is over a year old.

They sent me a new control box and the problem was fixed it has not acted up in the 16 months since getting the new box. I am glad they replaced it and got me going because the first year I owned the machine I wanted to pull my hair out trying to figure out what was happening.

Mike