Problem Hard to explain

[Bert Kemp]

Sometimes when I do a second pass things don't line up . I think the problems in the x axis because it seems to happen more when the laser head runs all the way across the material to complete a circle or something. But its not consistent and the amount its off varies. My belts seem to be tight enough . Sometimes when the x axis makes an abrupt change to one side or the other I hear a thump sound but I only hear that when it makes a quick change from left to right or vice versa. If I draw circle on the left side and one on the far right it just makes a smooth run across the board but its when it jumps back and forth I hear this thump I know I'm not explaining this right but if you have any ideas
Thanks

[Lee DeRaud]

Sounds like it doesn't have enough room out at the edges to ramp the speed up/down. E.g. my ULS needs over an inch on either side when running at 100% speed. Are the acceleration curves tunable on your machine like they are on a CNC router?

(Or I don't understand the question...an example of something that works vs something that doesn't would help.)

[Bert Kemp]

Lee I'm not using the whole length of x Im using maybe half of the 24 inchs I even went from 70mmps to 40mmps and it still did it. it even does it on a 1 pass item if it jumps around see picture Notice LEROY is OK but the x went across table to fill in the O's w and other letters it needed to finish 340146also notice 2 of the leaves are offset too

[Lee DeRaud]

If the X-axis drive doesn't have any lash, I'd still suspect a controller problem, like it's trying to reverse direction too fast and loses track of where it is. Or maybe speeding up too much in the unengraved areas.
Is this machine stepper-motor based or servo?

[Bert Kemp]

If the X-axis drive doesn't have any lash, I'd still suspect a controller problem, like it's trying to reverse direction too fast and loses track of where it is. Or maybe speeding up too much in the unengraved areas.
Is this machine stepper-motor based or servo?
I'm not sure its a Rabbit 6040


Driving system: micro divided stepper

[Bill George]

I would vote for either a belt or bearing issue. If you have already checked the connections on the stepper driver, and controller first that is...

[Lee DeRaud]

I'm not sure its a Rabbit 6040


Driving system: micro divided stepper

Ok, that means it can lose steps if it bangs into the stops on either end. You say you're not using the entire width of the bed, but do the symptoms change if the piece is placed left-edge, center, or right-edge?

[Bert Kemp]

Not sure I'll do some testing tomorrow

[Kev Williams]

My thoughts- you have the same problem I just fixed...twice. First was my NH 3200 cylinder engraver (spindle stepper) and the Triumph (X stepper).

That "thump" you hear is indicative of a stepper motor not knowing what to do. Not knowing what to do can be caused by a variety of things. The controller is one, but I've been finding that if the controller (or data flow) is an issue, usually what will happen is either the machine will suddenly run in one direction towards infinity, or-- the machine will do absolutely nothing at all.

Yours isn't doing that. Now, I did run into a stepper-skip issue that's similar that WAS due to the controller, or rather, a bug in the controller or software. What happened was, I was rastering several small patterns (about 3/8" square) across a 24" wide SS panel, spaced at roughly 4" intervals. Rather than raster a ton of dead space, I made each one a different color. After they were finished, the head was to move back to the left to start rastering a series of 3" long x about .060" thick lines. These too were a different color, but the change to the lines included a higher speed setting. What happened, and I have this on video, is the speed changed in the middle of the dead space move between the last pattern and the first line. It changed on the display too, and when the speed changed, the head movement halted ever so briefly, then resumed at the higher speed. But where it started the line engraving was the wrong place. I found that it would do it every single time I tested it, and would repeat the 'miss' in the exact same place every time. And fwiw, there was no thump. I shot vid to see if Triumph could/would do something about it, but I never pursued it. I've concluded it's a controller or software bug. My fix has been to not mix different colors and speeds in one operation.

But yours is "not consistent", so it's a highly unlikely you're having the same issue--

Back to what may be the problem, a loose or broken stepper motor wire or connector...

My cylinder engraver was giving me fits not long ago, the Z stepper would just run willy-nilly at times rather than move up then down. Willy-nilly is not good because it would go down more than up, and eventually the tool wouldn't raise above what I was engraving- which turned several parts into scrap :( -- The problem turned out to be one of the connector spades in the stepper-side plug was pushed almost out of the plug housing. Since I pushed it back, no issues..

And the Triumph problem turned out to be this:
340147

This the connection point of the X stepper wires- Since the wires that come with the stepper aren't long enough, Triumph (and possibly every other Chinese laser builder) simply added enough wire to reach the X-Y controller boxes. These wires are in the drag chain, and this connection starts rolling up in the chain when the head Y-travel is about 3/5 the way down. That joint simply didn't last thru all the bend/straighten/bend routines. I put 2 and 2 together about my problem when I noticed it was happening worst about 17" down. Upon doing a little playing with the drag chain, I found I could make the machine mess up at will...

Triumph didn't think it was the stepper, but I bought one anyway, and they were right! But they were thankful that I'd found the problem because another customer of theirs was having the same issues and at the time they hadn't found an answer. The pic below is my fix;

340148

I just re-soldered the joint. All it cost was a couple bucks for heatshrink tube! I also re-bent the wiring a bit to hopefully track within the chain better.

It was real simple, the chain (mine anyway) pieces on top just snap in, you can pull them all out of the way with some needlenose pliers within a minute or two, and just pull the wires out. Have a look, if you have soldered up connections like mine in the chain, or somewhere else where they're moving or rubbing, etc., I'll just about bet one of them is broken...

[Bert Kemp]

Wow Kev I guess with some many machines and older ones at that you have probably run into just about every problem any of us can have and mostly likely found a fix for them too. OK so Tomorrow I will check all the wires and connections to the steppers.

Bill I don't think its a belt but the bearing maybe.

Lee I'l still run more tests after I check wires .

thanks guys

[Bill George]

All I know like I said before, on my Chinese machine it was loose connectons. On the ULS the wiring is so well done I don't think connections will ever be an issue. Your belt could have a couple of teeth missing, or it could be a bearing. I have been known to get up in the middle of the night to go check something I just thought of :o

[Bert Kemp]

I'll check the teeth on the belts also


All I know like I said before, on my Chinese machine it was loose connectons. On the ULS the wiring is so well done I don't think connections will ever be an issue. Your belt could have a couple of teeth missing, or it could be a bearing. I have been known to get up in the middle of the night to go check something I just thought of :o

[Kev Williams]

You might give Ray a call and explain you have a stepper 'thumping' and it's losing its place after it does. He should also know if the stepper motors wires have been added to. Not a dig to the Chinese, these guys install the steppers they get from their suppliers with whatever wiring is included, and it's much easier to add wires than to remanufacture a new plug with long enough wires. Keeps the cost down, which is fine with me :) (my new stepper came with the exact same wiring harness that's in my machine)

As for checking the belts, the easiest way is to just move the head and gantry left/right and up/down while it's powered down. If there's any guck or broken teeth, you'll feel it.

I've noted in other posts that the X belt on my LS900 is sadly worn in the first 2-3" from the left home position, and when when pushing the head back & forth with my hands, the slack in that spot is very noticeable, the rest of the travel is smooth...

[Bert Kemp]

If I don't find the problem by Tuesday I'll give him a call:)



You might give Ray a call and explain you have a stepper 'thumping' and it's losing its place after it does. He should also know if the stepper motors wires have been added to. Not a dig to the Chinese, these guys install the steppers they get from their suppliers with whatever wiring is included, and it's much easier to add wires than to remanufacture a new plug with long enough wires. Keeps the cost down, which is fine with me :) (my new stepper came with the exact same wiring harness that's in my machine)

As for checking the belts, the easiest way is to just move the head and gantry left/right and up/down while it's powered down. If there's any guck or broken teeth, you'll feel it.

I've noted in other posts that the X belt on my LS900 is sadly worn in the first 2-3" from the left home position, and when when pushing the head back & forth with my hands, the slack in that spot is very noticeable, the rest of the travel is smooth...

[Bert Kemp]

OK I've check wires and belts didn't find anything that I could see.
BUT with the power off if I run the x axis back and for kinda quick I get a thumping sound and it feels like I hit a bump in the road. and it doesn't do it in the same spot all the time. also if I move it slow it doesn't do it. So when I'm cutting and it finishes a cut on one side and moves real fast to the other side is when this happens.
https://www.youtube.com/watch?v=DSA98vSo0Os

[Bill George]

Bad bearing, rough spot.

[Bert Kemp]

where is the bearing in the stepper motor?


Bad bearing, rough spot.

[Bill George]

Your X stepper motor is at one end, pulley drives the belt that moves the carriage with the mirror and lens. There are wheels that ride on that track, bearings inside those wheels, or should be anyway. Could be a flat spot on a wheel also. Bearings in the pulley at the other end.

[Kev Williams]

As for pushing the head back & forth with the belt & stepper in play, you pretty much just want to go slow and steady. If you move the head quickly the stepper motor can give you the the impression it's 'bumpy'.

You can check both the stepper and the idler belt-cog bearings easy enough. Your belt should be attached to the laser head on one or both sides with a couple of small allen bolts thru a small aluminum bar, or something to that effect. You should be able to just pull 2 screws and let loose the belt to give you access to the gear cogs. Roll the idler cog with your fingers, and see if rolls smoothly, or feels gritty or 'chunky'. Do the same with the stepper motor, just moving it with your thumb or finger, you'll feel the steps, but it should move smoothly with no gritty or catchy spots. Check the gear teeth for guck. While the belt is out of action, move the head back and forth a few times to check the gantry-to-laser head bearings for smoothness.


Another way to test, see if you can loosen the cog pulley from the stepper. Some gears are pressed on, but some like mine use set screws...
340252

If you have set screws, loosen or remove them so the gear will spin freely on the motor shaft. You may have to remove the belt to get to them. If so, then re-attach the belt and run the head back and forth, just fast enough that the gear WILL spin freely on the shaft. This takes the stepper out of the equation and you can check how smoothly the head assembly bearings and idler is working...

[Ivan Pavletic]

Hello

I've had similar problem. When cutting, or drawing lines, lines were drawn very strange.
The problem was belt for Y axis. The belt has built in wire which got loose and wrapped around bearings close to motor so it it made strange nose totally random and it did not sound very nice. Problem is solved by changing the belt :)

[Bert Kemp]

If I ever have a problem with the Y axis I'll remember to check that thanks.


Hello

I've had similar problem. When cutting, or drawing lines, lines were drawn very strange.
The problem was belt for Y axis. The belt has built in wire which got loose and wrapped around bearings close to motor so it it made strange nose totally random and it did not sound very nice. Problem is solved by changing the belt :)

[Bert Kemp]

https://www.youtube.com/watch?v=DSA98vSo0Os

I wish I knew how to make it cut with out jumping all around the place I just cut 2 boxes out and they were perfect but the laser never jumped back and forth it just followed a path around each part of the box nice and smooth no jumping from place to place.
(https://www.youtube.com/watch?v=DSA98vSo0Os)

[Dave Sheldrake]

That clunking is normal if you push the head around, it's trying to tilt and jams the bearings. It can also destroy your drivers as the steppers will work like little generators

[Bert Kemp]

Is it normal when the head moves over and theres a thump and the next cut does not line up. Thats what is happening


That clunking is normal if you push the head around, it's trying to tilt and jams the bearings. It can also destroy your drivers as the steppers will work like little generators

[Dave Sheldrake]

The boxes are likely splines or lines...not poly lines, that will make it jump about

[Dave Sheldrake]

also check what rapid speeds are set to, if they are too high the acceleration will tilt the head and make it clunk

[Kev Williams]

Watch this video, I made this video specifically for Triumph, and this was BEFORE I found the broken wire and I still thought the stepper was bad..

NOTE that the bad action takes place only on lower row of holes-- This fact also hadn't caught my attention at the time. It's the vicinity on the table coordinates where the chain started moving the seamed wires in a tight circle, and the broken wire would lose it's connection OCCASIONALLY.

Also LISTEN to the noise it makes-- it's not just a 'thump' because it's screwing up pretty radically...
https://youtu.be/mODbcMcuIfU

Now for pics--

This is my Y axis drag chain (the side door is open too) -note that I've only put back a few of the upper cover links- That so in case I need to take pics or something... ;)

http://www.engraver1.com/erase2/chain1.jpg


---I can! So I removed more links and pulled the wire out a bit. At first glance, there's no sign of any seamed together wires-

http://www.engraver1.com/erase2/chain2.jpg


Here's they are, up fairly close to the top of the machine-

http://www.engraver1.com/erase2/chain3.jpg


Here I've slewed the gantry down about 12", and notice the pink heat shrink-- the seams are about to curl up the chain...

http://www.engraver1.com/erase2/chain4.jpg


I shooting from inside now-- The seams are now about where the arrow is- When the seams were curled up in the chain is when/where all the bad happened, and the worst of it right about where it is now...

http://www.engraver1.com/erase2/chain6.jpg


--- I'm still thinking your problem is similar, be it bad wire, or a loose wire connection someplace, OR a controller anomoly, rather than a belt or bearing problem...

By doing the test in the video, that's when it came to me that there was a proximity issue going on...

I would suggest a simple test-- draw a 4x4" box, put a 3" high arial "8" inside it, then matrix as many across and down as will fit in your machine- Just use paper, set the machine to cut about 35-40 mm/sec, and as low a power setting as will work. Now vector cut all the 8's and squares, and see if it messes up while cutting any of them...

IF it does, then reset and run another test to see if it messes up in the same general area. If YES, then you may be looking at a wire issue similar to mine, especially if the bad areas are random. From there you can start moving inward with the test engraving to zero in on the proximity..

IF however, it messes up in exactly the same place each time, and maybe repeats the goofy engraving, you may have a controller issue..

ALSO, if the engraving doesn't mess up, but the LOCATION of the engraving changes because of your 'thump', then I would think that also indicates something electronic, because the bad happens ONLY during laser-off dead-space running. That wouldn't matter to a bad wire...

[Dave Sheldrake]

Bearings on the HX machines are rolling endless track Kev, Triumph use cone wheel

[Bert Kemp]

What are rapid speeds and were do i find those settings?


also check what rapid speeds are set to, if they are too high the acceleration will tilt the head and make it clunk

[Rodne Gold]

Try changing your stepper motor drivers around , if it exhibits the same thing on a different axis , you know its the driver , do the same with your stepper motors .. to isolate whether its a driver/stepper problem or something else

[Bill George]

What are rapid speeds and were do i find those settings?

If its been running ok for two years with the factory settings that is not the problem.

Are you 100% sure you have checked all the belt cogs for missing teeth or even a build up of dirt on or something on the belt. Bearings and track wheels checked? Connections?

What does Ray have to say?

[Bert Kemp]

I ran Kev's 8 box test and it seem that the Y axis is also messed up or maybe it was the Y too start with because in my first post the goof was in the big G and the the laser heaD JUMPED ACROSS THE MATERIAL TO DO THE O's any way this is what the test looked like . My cut starts in the lower left and goes up then comes down on the next row where it started to mess up. 340307

[Bert Kemp]

If I run a test box of the entire laser bed its run perfect no thumps no skipping, and no matter where I strt from it runs ok. It just messes up when I have a cut program in. If it was stepper or belts or broken wire wouldn't something happen in test runs?:confused:
https://www.youtube.com/watch?v=6Biwp__KJv8

Also looked at belts I can't see anything wrong with them. The wires in the laser head belt are hard to see but I'd think it would show a problem in the test
(https://www.youtube.com/watch?v=6Biwp__KJv8)

[Bill George]

If I run a test box of the entire laser bed its run perfect no thumps no skipping, and no matter where I strt from it runs ok. It just messes up when I have a cut program in. If it was stepper or belts or broken wire wouldn't something happen in test runs?:confused:
https://www.youtube.com/watch?v=6Biwp__KJv8

Also looked at belts I can't see anything wrong with them. The wires in the laser head belt are hard to see but I'd think it would show a problem in the test
(https://www.youtube.com/watch?v=6Biwp__KJv8)

Yet its random so it would not seem to be a file issue. If you have checked all the belts, bearings and connections wire splices and on the controllers, then I am out of ideas.

[Bert Kemp]

Its not random on the 8 box test it repeats in the same spot. I only ran it one but when you said random I ran it 3 more times and seem to be in the same spot.
I did not let it complete the whole thing tho as when it gets near end it will run agaist back wall so I stopped before it did that any more


Yet its random so it would not seem to be a file issue. If you have checked all the belts, bearings and connections wire splices and on the controllers, then I am out of ideas.

[Bill George]

You know when my GWeike laser started to miss and go wacko I found the wires on the controller so loose I could not believe it even ran as long as it did! Somebody posted in your Thread about the splices he found in the wire bundle. The way I check for loose or broken splices is I pull, really hard. If it comes apart, that was the problem. IF they soldered those connections they can break just about where the solder line ends, where all the flex tends to break the wires.I started out troubleshooting in 1962 for Uncle Sam on air craft electrical from DC-3's to the B-52H, and lots newer. Always learning.

[Bert Kemp]

It seems to be the consensus that my problem is in the wires that run inside the chain belt on the gantry. I'm going to do my best to really check these wires out. It will be difficult as I have big hands and arthritis in my fingers so they don't work the greatest in small areas. :o


You know when my GWeike laser started to miss and go wacko I found the wires on the controller so loose I could not believe it even ran as long as it did! Somebody posted in your Thread about the splices he found in the wire bundle. The way I check for loose or broken splices is I pull, really hard. If it comes apart, that was the problem. IF they soldered those connections they can break just about where the solder line ends, where all the flex tends to break the wires.I started out troubleshooting in 1962 for Uncle Sam on air craft electrical from DC-3's to the B-52H, and lots newer. Always learning.

[Kev Williams]

Very interesting results Bert--
ALL of the engraving is perfect, but almost NONE of it is engraved where it's supposed to be. Mostly in the Y axis, but the X too...

This tells me with, oh, 85% certainty that it's NOT a broken wire or connection issue. If it was, the engraving would be as goofy as the alignment...

Your controller and/or XY drivers are giving the steppers the right "engrave" info, but the wrong "space" info.

In your parameters settings you'll likely find settings for "space speed", "space acc" and "space acc acc".. My Triumph's default values are respectively: 300.00, 2400.00 and 50000.00 -- not exactly sure about the acceleration values, but 'space speed' is the speed the machine moves in the dead space from the end of one engraving to the beginning of the next. It seems that THIS is when your machine is messing up, and that seems (to me) to be a controller issue. Anyway, check your values, and enter new values at exactly HALF the old values-- in my case that would be 150.00, 1200.00, and 25000.00 ... This should cut all of the 'dead space' speeds in half, which should be very noticeable.

Run the test at the new settings... If it still messes up the alignments at half the speed, you can pretty much bet it's a controller or driver (Dave would know better than me!)

[Kev Williams]

Bearings on the HX machines are rolling endless track Kev, Triumph use cone wheel
I was mainly concerned with the belt's idler bearing, and how the gantry feels slewing it back & forth, however it's hung. ;)

[Bert Kemp]

I did call Rabbit and they had me check those settings and they said they were ok.
I stll want to know what that horrible grinding sound is when it makes the jump.
I'm going to make another Vid but will run it with no laser so you can hear the sound back in a few.

new https://www.youtube.com/watch?v=5BjrRYTgYls

[Ray Scott]

Hi Bert,

I just learned about the problem.

If it turns out to be a broken wire... I have some "super-flexible" wire on hand. It is many strands of non-coated copper conductor in a silicon-plastic insulator. It is great for the high movement and flexible areas.

I would spend some more time on the axis.. Check the linear bearing. Use a thin oil lubricant. Belt should not be too tight.

Check the software configuration. The accelerations might need to be tamed down a bit. I would attribute that "thunk" sound to a skip in the stepper motor poles .. Therefore loosing known position. A slower acceleration and slower motion speed will surely help solve the issue.

Remember that there are two sets of accel and run speeds. 1) while cutting 2) while doing space movements... Between cuts.

I will be glad to help more. Feel free to call or email me directly.

[Bert Kemp]

I haven't adjusted belts on the machine at all, I wipe and oil x and y rails once a month give or take and I just gave a wipe and fresh oil today. The vector engrave seems fine except that it jumps and doesn't line up but the the engraving itself is ok meaning a circle is a complete circle and a box is a complete box not broken up squiggly lines Like Kev had on his. So would we agree that we can rule out a broken wire??

[Bert Kemp]

I dropped space acc rate to 800 and then 400 and the problem is still here :confused:


Hi Bert,

I just learned about the problem.

If it turns out to be a broken wire... I have some "super-flexible" wire on hand. It is many strands of non-coated copper conductor in a silicon-plastic insulator. It is great for the high movement and flexible areas.

I would spend some more time on the axis.. Check the linear bearing. Use a thin oil lubricant. Belt should not be too tight.

Check the software configuration. The accelerations might need to be tamed down a bit. I would attribute that "thunk" sound to a skip in the stepper motor poles .. Therefore loosing known position. A slower acceleration and slower motion speed will surely help solve the issue.

Remember that there are two sets of accel and run speeds. 1) while cutting 2) while doing space movements... Between cuts.

I will be glad to help more. Feel free to call or email me directly.

[Dave Sheldrake]

Cut a 50 x 50 square Bert and check the corner angle for 90 degrees...just something I thought of I want to rule out

[Bert Kemp]

50 mm or cm or does it matter


Cut a 50 x 50 square Bert and check the corner angle for 90 degrees...just something I thought of I want to rule out

[Bert Kemp]

I cut a 12 x 12 " sq and all 4 corners are 90°

[Bert Kemp]

I'm still stuck here does anyone else have any ideas whats going on with this laser?:confused:
I think we've eliminated Broken wires, Belts, bearings, stepper motors. What else could cause this. Dave S I ran that sq its 90 degrees on all four corners.

[Bert Kemp]

Thanks Ray Scott from Rabbit Laser:) and everyone else who gave me suggestions on this.
Ray had me slow down my acc rates and the quick speed rate to half of what it was. This fixed my immediate problem.

[Bill George]

Thanks Ray Scott from Rabbit Laser:) and everyone else who gave me suggestions on this.
Ray had me slow down my acc rates and the quick speed rate to half of what it was. This fixed my immediate problem.

Usually when you need to slow down the stepper motors to prevent losing steps especially in your case where it been working fine there are other issues.

[Dave Sheldrake]

Yup slowing it will work as I mentioned before, what it won't do is fix an underlaying problem :(

[Ross Moshinsky]

Take off the stepper motors and check all the set screws.

[Bert Kemp]

I thought we eliminated stepper motor problem because its not random its repeatable on different jobs


Take off the stepper motors and check all the set screws.

[Dave Sheldrake]

Usually jarring is caused the the head being tilted...three possible reasons

Belt tension
Bearings are shot
Acceleration settings are too high

[Bill George]

I thought we eliminated stepper motor problem because its not random its repeatable on different jobs

When your troubleshooting Nothing is eliminated until you find the problem. If a stepper motor is missing steps its because of too much load or friction in the device, motor, stepper driver and power supply issues. Just to mention a few...

Slowing the system down when its been working fine for a couple of years, and its working now is just a symptom of another underlying problem. It would be interesting to find another machine like yours to see if it has problems.

[Bert Kemp]

But if it was a stepper motor problem would this be random and not repeatable .
I ran 3 different jobs a couple times each and the problem happened at thee same spot in each job. I mean I don't know but if a stepper was bad wouldn't it just happen anywhere:confused: anytime