Missing comm

[cowboy1296]

I maybe premature with this question. But the last 3-d plaques that i did I went though hours of cutting, as many as 16 per plaque with no problems. During the cut out of both plaques i got a missing comm error. Time wise this is the shortest tool path. Any one ever experience this.

Of course i did a c-3 and i was back in the game.

[Chuck Keysor]

I have had com errors, some of which have happened near the end of some very long cuts. And the only way I knew how to get back to where I was, was to run the entire file all over again, very time wasting. (Once I had a com error, and I found some command somewhere that said resume at last line,,,,,,, something like that,,,,,,,, and it didn't work, or do what I thought, and it ruined my piece as it started cutting in the wrong place. That is why I just start all over. And I have also taken to breaking my projects into smaller parts, so if I start all over, I am not loosing hours........) Chuck

[tlempicke]

I have kind of discovered something, and it may be pure bunk, but it is working for me.
When I first start the machine I do a c5 to warm up my spindle.
Afterward the machine seems to get cranky. Nothing specific, it just does not respond quite like it should.
So after I do a C5 now I shut down SB3 and re-start it.
I haven't had a comm error in months now!

[cowboy1296]

I have a router but have considered the restart as well. The first of the two plaques i had two comm errors (at different lines) during the profile cut out. But only 1 on the second. Its just funny that i can do hours of cutting with no issues and then bamm.

[Gary Campbell]

Is there a chance that after a number of "hours" that your computer is set to shut down hard drives, USB or some other function that is crucial to CNC operation?

[cowboy1296]

I dont think so. The computer does not shut down. Just a missing comm. Now if i am missing your point tell me how to check it.

[Gary Campbell]

The majority of those settings are in the Power section of the control panel. There are numerous settings, sometimes one gets overlooked.

[srwtlc]

This one in particular can be an issue and it can get re-enabled with a Windows Update (I've seen it happen).


http://www.talkshopbot.com/forum/attachment.php?attachmentid=29099&stc=1

[cowboy1296]

thanks i will double check everything.

[Chuck Keysor]

I'm with Cowboy, "Its just funny that i can do hours of cutting with no issues and then bamm." is my experience as well. I know early on someone suggested I needed to check my sleep mode settings, and I was not set to shut down. But to make sure I hadn't missed anything, I left my computer on for a couple of days, and it never turned off, or tried to do any updates. It just sat there........

It has been suggested to me a couple of times, once very recently, that I should try installing a powered hub between my Bot and PC. I have never done that as that just seemed too improbable. But I have made every grounding change anyone has recommended.

The one thing I have meant to do, and not gotten around to, is to replace the PC that runs my Bot. I am still using the XP machine that came with my Bot when I bought it.

So I have watched with interest for the dedicated control computer that Shopbot may be bringing out that would as I understood/recall, would eliminate the continual data exchange/handshaking between the PC and the Bot. Maybe that was just a dream that I had..........

Chuck

[tri4sale]

I'm with Cowboy, "Its just funny that i can do hours of cutting with no issues and then bamm." is my experience as well. I know early on someone suggested I needed to check my sleep mode settings, and I was not set to shut down. But to make sure I hadn't missed anything, I left my computer on for a couple of days, and it never turned off, or tried to do any updates. It just sat there........


Some of the backend items that power down you'd never notice. If you've got sleep turned off and screen blanking turned off, you'd never notice some of the other things that could be causing issue, like USB mentioned above, Hard Drives powering down, PCI express, CPU, etc.

[Gary Campbell]

Chuck...
When you say: "It has been suggested to me a couple of times, once very recently, that I should try installing a powered hub between my Bot and PC. I have never done that as that just seemed too improbable."

What if it NOT improbable, but has been recommended because it works?

[tri4sale]

Chuck...
When you say: "It has been suggested to me a couple of times, once very recently, that I should try installing a powered hub between my Bot and PC. I have never done that as that just seemed too improbable."

What if it NOT improbable, but has been recommended because it works?

And it's a dirt cheap method to see if it helps, a lot cheaper than ruining one piece of nice wood.

[guitarwes]

Chuck...
When you say: "It has been suggested to me a couple of times, once very recently, that I should try installing a powered hub between my Bot and PC. I have never done that as that just seemed too improbable."

What if it NOT improbable, but has been recommended because it works?


Can anyone point me in the direction of this powered hub mentioned here so I can buy one?

[srwtlc]

If you are running SB3 version 3.8.XX, it will likely not improve transfer efficiency, as 3.8.XX generally works best without the hub. If you are running version 3.6.XX, it can definitely improve it. If you run SpeedTest.exe before and after installing a hub, you can verify any gains in transfer efficiency %.

Most any decent quality powered USB hub will do. You may have even received a non-powered 4 port hub with your machine.

[cowboy1296]

Scott mine was on enable and i changed it to disabled. Just what does this command do. FYI i am still running 3.6. My control computer is not hooked up to the internet so i dont get windows updates. I am running barebones, i dont think anything could turn back on by itself with everything else shut down. But anyhow I may have been premature with my question. I will be cutting in the near future and will give you an update.

[Chuck Keysor]

I borrowed a powered USB hub. Before installing it, I ran the transmission efficiency test and found I was running at 81.9%. When I connected the USB hub, I found that it didn't work, in that SB3 could not find the port that communicates with my PRT alpha.

Now, upon reading Scott's newest post, should I just upgrade to the newest version of SB3 and not use a powered USB hub (since it will degrade transmission efficiency)? Or will the problem I have with Com Errors transcend the degradation of my USB communications efficiency? Or should I just leave my SB3 at its current version (3.6.0.38)? and install a powered USB hub?

Thanks, Chuck

[srwtlc]

USB Selective Suspend (https://www.google.com/search?q=usb+selective+suspend&ie=utf-8&oe=utf-8). Not sure how SB3 and the drivers handle it, but it's possible that older versions may not handle it as well.

One thing we should differentiate on here is, are we talking actual comm errors or the dreaded erroneous limit hit warning which can sometimes be followed with a comm error I guess. Something I've started doing when running a long 3D file, is to turn off limits with VN and #1 off.

Chuck, your rate without a hub is good. Anything over 70 is acceptable. To get the hub to work, you would need to make sure that SB3 has found it on the new port and the speedtest app can also scan for a tool. Could be something with the hub or just a matter of getting the PC to 'recognize' it. Never-the-less, 81.9 is real good and I wouldn't bother with a hub then. It's likely that your issue it something else that is interrupting in the way of PC activity or static (heading into that season again, watch this issue become more frequent on the forum again). At the least, I'd update to the last 3.6 version of 3.6.46 as your version is quite old and there was likely many fixes since then.

Your control card is likely too old to run 3.8.XX.

[Chuck Keysor]

Thanks Scott. I'll contact Shopbot tech support to see if my machine will support an upgrade to SB3.8.XX, and I will proceed accordingly. Thanks again, Chuck

[cowboy1296]

Well i need to insure that there not some kind of bone headed operator error before I scream for help. Right now i am betting on mistake on my end but will let you know if i keep having problems.

[cowboy1296]

When I first started this I thought I knew a lot about computers, WRONG. What I knew about was the internet. Using black vipers suggestions I went back and checked "programs and features" and found some stuff on that should have been off. I corrected that and am currently doing about a 10 hour cut. I will post the results. I am running windows 8.1 on my control computer. But on black vipers site I could not find the bare bones settings. Am I missing something or should it be there?

[Gary Campbell]

Don't forget that it is now static season. Static caused by dust collectors and shop vacs will also cause a comm error.

[cowboy1296]

Turns out it was not my fix. I had a missing comm during roughing. I never downloaded 3.8. Have all of the issues with it been resolved? My speed is 76% so i am good there

[nat_wheatley]

+1 on the static. Last week had my first 2 comm errors , since replacing my control computer 6 months ago. Turns out the ground wire in my dust hose had broken loose (who knows when). So far no issues since fixing the wire...

[cowboy1296]

thanks i will take a look as soon as the roughing has finished.

[Mayo]

I noticed an interesting thing today which may be related to some of these missing com situations.
When getting ready to do a Z Zero routine, I always first manually touch the aluminum contact plate to the bit to make sure there is electrical contact.
Well surprise surprise today there wasn't! It did make contact and light up the #1 switch light when I touched the Y gantry rail though.
So that told me that the V rollers on the Y carriage were not contacting the rails. There was an accumulation of PVC dust on them and when I cleaned it off, I could then get electrical contact through the bit.

So is it possible that the reason some of you get comm errors after long cuts, is because dust has built up and insulated part of your machine which should normally be dissipating static charges as they happen - and the charge goes somewhere and back feeds through the motors?
I don't know if that's even possible but not having any electronics engineering background, it makes sense to me!

So, periodically blow off anything sticking on the roller bearings.

[cowboy1296]

My dust collector runs through a trash can. The connecting ground wire also runs through the can and is exposed inside of the can. I have noticed in the past as like yesterday that large amount of large shavings had collected on the wire. I did clean that off before i started my finishing tool path. Can that create a problem?

One hour into a roughing cut i had a comm error. I checked all of my ground wire connections and moved them to insure they were in tact. The i did a 10 hr finishing tool path without a hitch.

Also whats a roller bearing? FYI i have a shopbot buddy.

[Chuck Keysor]

Hello Mayo. That was interesting that you were able to build up enough foam dust between your rails and the V-roller bearings to insulate the Y-car from the main table chassis.

When I first had Com Errors, someone asked me if I had a ground wire running from my spindle to the main frame of my table. It turns out that I did not have such a wire. I immediately added a ground wire connected right to the top of my spindle, which then goes through the y-car's E-chain, then through the X E-chain, then to the table frame. This change, while logical, was not sufficient by itself to cure my Com Errors.

However, the "rise times" of ESD discharges can be so fast (nano-seconds), that they are inherently high-speed in nature, where the equivalent series inductance of my long ground wire is effectively an open circuit in the eyes of an ESD pulse. That renders my long ground wire as useless against fast surges. While I am a degreed Electrical Engineer, ESD was not my bag. We had people at work who had expertise in ESD, and would spend weeks zapping systems, looking for problems, and then attempting to remediate them. Much of their work was trial and error, with very sophisticated equipment. Since our company was closed more than 10 years ago, I don't have any access to the experts or their equipment..........

But while not a scientific observation, I feel that I have com errors as much in the summer in my damp/moldy basement in the summer cutting wood as I have in the winter. And I don't have a dust collection system. So I continue to read the Com Error posts and hope one day I'll hit the jackpot. Hey, even the Cubs won the world series last night, so anything can happen! Maybe next year I'll get lucky........ Chuck

[bleeth]

"What's a roller bearing": http://www.ebay.com/itm/like/361466657283?lpid=82&chn=ps&ul_noapp=true

How I grounded my bot: I started with a ground wire bolted to the z plate. Made sure the paint was removed where the wire was. Ran it to the end of the gantry and also bolted it there. Ran another wire from one of the legs on one side to one of the legs on the other side and then to the first wire. Ganged them with a third wire that went to a grounded surface mount receptacle box on the wall. #12 Solid core wire. My dust collector was a double bag with a long section of pvc between the black flex on both sides (bot and DC were pretty far from each other) Never added a ground. Never had static issues, summer or "winter" but once. Discovered one of the wire connections had broken at the bolt. Note when I changed from the gecko computer case controller to the aluminum box RBK I mounted it on the wall, not the Bot.

[cowboy1296]

Since cleaning the ground wire that was in my dust collecting trash can and checking for tightness of all wire nuts that connect the grounding wire, i have not had an issue. I have done one 10 hr finishing tool path, one 1 hour roughing tool path and one 4 hour finishing and no problems. So with fingers crossed i am hoping that the issue was resolved.

[cowboy1296]

Over the years i have read much about grounding issues but have not suffered any. Until now i ran a grounded dust collecting hose from my kent shoe to the dust collection trash can and through it to the dust collecting bag. A ground wire was run from this hose to the actual motor of the dust collector and that was it. After experiencing another issue yesterday, i ran a ground wire from the dust collection motor back to the bot. I then did 12 hrs of cutting with no issues. Not ready to declare victory just yet since i have been know to snatch defeat from the jaws of victory before.

[cowboy1296]

Just an update and hopefully my last post on this. I used a volt ohm meter to check the resistance been the buddy and the dust collector. As you can imagine it was a solid "open". Now here is where some will laugh at me. I had to do some long cutting and was not in the mood to go to town. So i used an old coat hanger that had no coating on it to connect the 2. I did 20 hrs of cutting with out a hitch. Now i have a legit ground wire between the both and have done another 13 hrs without a hitch. Its dry here in Colorado right now, although i dont see sparks flying the static electricity may have been the problem. So for now problem solved.

[jerry_stanek]

Static can be a problem even on heavy iron. Our Beisse broke a ground wire at the swivel ball in the dust hose and caused all kinds of shut downs and missed steps.