Missing steps frustration

[Eppert]

I have a PRS standard 96x48 and am having the same issues as many have had. turning up the speed a little and losing steps (stutter). 4 years ago when I purchased my shopbot this was an issue and I finally came to the conclusion that it just wouldn't do it. I came to the forum for another reason / advise and came across many others with the same issue and this sparked my intrest back up. After spending the last 3 weeks reading posts and trying every trick from every post I have read on here to try and eliminate the problem and increase my jog speed "nothing" :mad:

tested connection speed = 86%
Dedicated computer = check
followed all the grounding guides = check
checked for squareness and Resistance = check
Checked wire connections for any corrosion / loose = check
Inspected gears and rails for wear = check (nothing visibly wrong at all)
tried with and without dust collector = check
tried with spindle on / off = check
tested using different software programs to write the SB files = check
increased humidity to 50% = check
max jog speed = 4 IPS

I am extremely close to being able to afford the major upgrade to new stepper motors and drivers but, I need a little push in production speed / time in order to achieve this. Any other advice that anyone has other than what I have already tried? Anything over 4 (on jog speed) and I get my hiccup (in different locations not in the same spot on the machine , x or y)

[ken_rychlik]

If your motors are adjusted to tight it would cause this.
I would loosen the motors all the way and roll it around by hand checking for smoothness.
Mine used to jog at 8 without trouble before I upgraded it to alpha, but when it had adjustment issues, it would not.

[danhamm]

I would also check the voltages to see if they have changed from original,
I would drop the motors and run them up individually..I would also suspect one driver getting weak, by check motors individually you would see which one..

[Eppert]

I will try both approaches this weekend when I have an extra second. Thanks

[Brady Watson]

Troy - where are you in Indiana?

-B

[Eppert]

Elkhart, IN (Almost to the Indiana, Michigan border)

[Eppert]

Update;
I dropped the motors and ran it at 8.5 IPS without any issues. This leads me to believe I am running the motors too tight. I will "snug" them up a little less this time and try again tonight.

[Brady Watson]

It isn't really possible to set the motors (aside from the Z axis) too tight on a PRS. You can only push them up so far & that's it. On a PRT, that's a different story, as they are spring loaded.

For the heck of it, ditch the USB hub, plug the Bot directly into your PC and see what you communication rate is. I bet you have a hub that is on it's way out.

-B

PS - I was in Indy last week...thought you might be close enough to drive to.

.

[Eppert]

It's a little bit of a hike from Indy ~3hrs.

With the x motors dropped I ran a program 10 times in a row with the jog speed @ 8.5 IPS and had 0 missed steps. I mounted them back up (just a hair less than last time) and began running with a speed of 6 IPS. I haven't had any issues with missing a step but, I do have a bit more chatter than before. While cutting out the wood products that I was cutting that wasn't a big deal but, when I switch over to Acrylic this weekend I will need to help that out a little bit.

I will try bypassing the powered hub tonight and let you know of the results.

Thanks,
Troy

[Brady Watson]

Troy,
You really don't want to run the motors loose on a PRS. Push them all the way up & forget about it. They are not going to be too tight. If you run them loose, you are going to chew up both your racks and your pinions. This is not good & will kill your cut quality and the racks which are harder to replace than pinions.

It sounds to me like you have some sort of communication or interference problem. First, eliminate or replace the USB hub. Second, make sure that if you are running dust collection that you have a bare copper wire going THROUGH the collection tube all the way to the dust collector. Poke it out both ends, tying one end to clip on dust foot & the other end to a known good electrical ground. This will wick up all the static electricity (very high voltage) that could be knocking out USB communications (that run at a low 5 volts).

-B

[russ]

Troy,

This is an interesting read from Jimmy in NC. I believe he hits the nail on the head! http://www.talkshopbot.com/forum/showthread.php?t=12954&highlight=G203 or get you a multimeter and call Gecko tech support you can have yourself a real informative afternoon. In the end my bet is that you need to replace your drivers.

[michael_schwartz]

I started having similar issues recently but I attribute them my control PC. When I checked last night com rates were at about 54%. In my situation there is an obvious reason for this. Even at that it will jog at 6 IPS. 8 was causing definite loss of steps. I think that the poor com rates combined with some sort of other hiccup end up causing my problem since I may cut just fine for an hour and a half until I see loss of steps. Things may go wrong 5 minutes into the next file.

This is while running off USB 1.0 since either my USB 2.0 card, or PCI card slot went bad . Long story short my p4 dell optiplex is going in the garbage. I also suspect this pc may be infested with viruses from my thumb drive.

I ordered an off lease Lenovo think center last night that has a 1.8ghz core 2 duo, 1gb of ram, XP Pro, USB 2.0 and much better specs overall for $150.00 I wanted to build something from scratch but it would have cost me upwards of $350 to match this with no OS.

I am also going to take a bit of time to make sure that XP is set up in a bare bones configuration.

[Brady Watson]

...my p4 dell optiplex is going in the garbage.

I am also going to take a bit of time to make sure that XP is set up in a bare bones configuration.

Well you're off to a good start in getting your computer optimized for CNC! Dell makes the worst USB hardware of any computer I've seen connected to a ShopBot.

Don't rule out Windows7. It's stable and will do whatever XP Pro will do. If you like the Classic view of WinXP, download the free 'Windows Shell' on the net. I've used it for years since I hate 7's interface.

-B

[michael_schwartz]

I have windows 7 installed on my desktop that I use for design work. This is a core 2 quad system I built about 3 years ago around an asus mobo, and corsair power supply. It has been rock solid to say the least. When it comes time to upgrade my design system I will use it to run the bot.

The PC I ordered has an XP Pro license so I am going to use that for now.

I would have preferred to build something, because then I can make sure that it has quality components. At that point I will just build a new design PC, based on an i7, and run the bot with my current one.

I will never buy another dell again. Between the optiplex, and an inspiron laptop I had that only lasted 6 months I have learned my lesson.

Of course I an writing this on my unibody macbook pro but I will leave my mac tendencies out of this discussion.

[russ]

Michael,
Money well spent!!!! That being said you’re still going to have a four cylinder engine with a slipping fifth gear. My PC has everything that you have listed, even connected to my laptop with 4gs of ram same problem.

[Brady Watson]

Building your own PC is best. You know EXACTLY what hardware is in it & you know just where to get a replacement without any 'proprietary' agg...

-B

[michael_schwartz]

Michael,
Money well spent!!!! That being said you’re still going to have a four cylinder engine with a slipping fifth gear. My PC has everything that you have listed, even connected to my laptop with 4gs of ram same problem.

Up until this round of USB problems began I had been getting along just fine for about 2 years so if I can get back to where I was I will be happy. I had occasional com errors but never while cutting under normal circumstances.

I used to run 3-6 hour long files all the time with no lost steps, and I would cut as high as 4-5 IPS. I never did push my jog speeds too far beyond 6. I even cut a number of projects successfully after my USB 2.0 card failed, running of 1.1 before I started having trouble.

The dell isn't worth the bother to troubleshoot or repair. I am optimistic that my problem is just a computer/software issue. At least I hope thats all it is.
My standard was built in november 2009, and it is the newer version with the third set of legs, and the new control box. That is with the Oriental Motor drivers.

I will report back after I try the new computer, and "barebones XP configuration". I will also explore how far I can push jog speeds as well. I usually run on the safe side because I don't need to run for 8 hours each and every day. When I can get to the point some day where jog speeds are a serious bottle neck to productivity I will be very happy, and at that point upgrading to an alpha would be a no brainer.

[Eppert]

It is supposed to be a slow weekend for me coming up. (time to do some experimenting :D ) I will try everything that is suggested in all of the comments that I have received. Thank you to all that have replied.

Update to be posted soon (hopefully all good news)

Troy

[michael_schwartz]

I setup the Lenovo PC yesterday and hooked it up to the Bot this morning. I then went through and cleaned all the old dirt and grease out of the racks, pinion gears, v bearings, and rails and re-lubed everything. I kind of felt like I was working on my truck for 4 hours. I also tightened the bolts for the feet which eliminated a lot of vibration.

I also installed the latest control software, and firmware. I setup a powered USB 2.0 hub in-between the PC and bot, rather than the unpowered one supplied with the machine.

The results are com rates above 80%. I was able to jog at 8IPS with no problem, and ran at 12 with no apparent loss of steps, over 3-4 end to end jogs with a dial indicator setup to check.

As a comparison when I was having problems one of the X motors would stall followed by a com error. I would then have to restart the PC. This was guaranteed to happen with jog speeds around 8IPS.

Now I can push it until I loose steps with no loss of com. This brings me to believe that loss of steps followed by a com error is most likely a usb, or software performance issue.

There were also a couple other problems I had had that are now resolved. Before I could never switch between move/preview mode without loosing com. Now that works juts fine. The control software feels much more responsive, and stable as well.

I went with the "blackviper" barebones XP configuration, but I had to turn a couple of services back on to get things to work correctly. XP is also noticeably faster after doing this. I suspect there is allot of **** built into windows that can cause USB hiccups. I spent an hour disabling stuff so I hope it is actually causing an improvement.

I wouldn't be surprised if my old control PC was infected with viruses, and male-ware from my thumb drive. I had allot of problems with that sort of stuff on my design PC before I nuked it and went from xp to 7. I suspect this sort of thing could cause problems as well.

I will try cutting something tomorrow.

[kevin]

Micheal I belevie your right I don.t think you can run a shopbot properly with out a clean computer

Another tip I put scila bags from electronics in my control box .Before I was getting mystery sounds from the motor .It seemed to be a moister problem .I did it almost a year ago and not one sound

I.am also 200 ft from the ocean

[michael_schwartz]

I am regaining confidence. I have logged about 4-5 hours now with no problems. I was jogging at 8IPS last night. between the new computer, and maintenance, the bot feels like new machine.

[Eppert]

Well I got busy enough I haven't had a chance to do a lot of testing or have discussions about it :/ I have done everything that is suggested now and appear to be out of the woods with having problems. I am still too chicken to do the jog speed at 8IPS but, I have had it at 6 for a week now without any issues. I did pull the wire back out of the dust pipe though. I was having too many issues with dust and the strings from the plywood getting caught up on it.

I'm inches away from ordering the upgrade and, this has helped me a lot to get to that point. Thanks to all for the ideas and help

Troy

[cowboy1296]

The last three projects have either been messed up by erratic z issues or destroyed. I have to get this figured out. I just wasted about 150 dollars worth of black walnut.

Last night i did a profile cut out while watching the control panel closely. The tool path was set up to cut .1. but as I was reading the values on the screen, a .1 tool path registered a .097 on the control panel. each time it lowered a .1 it would again loose .03. by the time I know it was cutting more then 1.8 inches deep it was reading 1.73. but the cuts were smooth. the feet rate was 1.5 and rpm set at 10000. this is just one of the issues. in some of my profile and pocket cuts the z just drops down very deep, much below the assisgned tool path depth. while doing a pocket cut which had a max dept of .5 the z just dropped down to about .8 from when it should have been around .2. i am not sure if this is a software problem or mechanical. i will try and remove the z motor to check everything today, any ideas. thanks

[srwtlc]

Rick,

Is it possible that you have the wrong unit values for the Z axis? Do the other axes maintain position?

When this happens, does it return to the same height that it started at when finished? Meaning that if you started out at say 1" above the material or table, when you're finished and tell it to go to 1" again, is that where it goes to (verifying no lost steps)?

[cowboy1296]

to be honest with you i do not know but will pay attention. i have been to interested in my project being destroyed to notice. i guess to insure that the wrong z values are not logged i can just reset my defaults by running UR? I will do some inspecting, cleaning, testing and watching later this afternoon.

[cowboy1296]

as far as i can tell the x and y are fine. also the sudden plunge into the wood is spuratic.

[cowboy1296]

as it turns out the settings were still on the table from last night. assuming my board did not turn on me. the control panel still shows the z at 1. i turned the router on and moved the z to 0. its hard to judge but it drilled a hole in the board about .05 deep.

[cowboy1296]

Every day it seems as if it is an education. the cost of this one was one large and thick black walnut plank.

I reset the default settings. Did a profile cut, pocket cut, and vcarve in a junk piece of cherry. does not get much harder then that. all readings and cuttings went great.

i did clean the gear on the z motor but i don't think that was the problem.

last week when i was setting up my c3 in shop bot set up i changed the value of my z on that page, instead of VL. Now yall tell me if that was my screw up. after reseting defaults i did not mess with the z, and for now all is good.

thanks Scott for rescuing me again.