Author Topic: Wiggle on X-axis. Please help.  (Read 2174 times)

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #30 on: November 30, 2016, 06:35:07 PM »
Ah, well I wouldn't trust one more than the other.

Although I'd guess one of them has mixed up the plastic wheel without two bearings sandwhiching a 4.9mm ID shim and one with bearings and shim. There is a 4.9mm ID shim in the middle of each wheel to give it a snug fit on the M5 bolt it seems.

In any case I'd look for wheels with bearings and shim, and also with a flat middle section for the GT2 belt. (Unless you're just putting new plastic on worn out old wheels?)

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #31 on: December 01, 2016, 04:01:55 AM »
Finally got the spacers and new X carriage bits cut (stock is HDPE chopping board from ikea).

Was hard to get a good picture of the spacers, but this should provide a rough idea.


They ended up way too accurate and a little tight so assembly was a pain. Gonna cut new X carriage parts at least, they were worst, maybe I forgot to update the CAM from 1/8" cutter to 3mm cutter after I broke the 1/8" (RIP!).

Anyways, it works beautifully with the V groove wheels on the non-modified non-V profiles. No wobble or wiggle, super smooth, and ridiclouslly easy to adjust the pre loading by turning the nut part of the eccentric spacer. Ended up re-using the cardboard spacers I cut the other day as I didn't have 5x8x1 shims/washers, but even between the springiness of the cardboard and the softness of the HDPE there was a lot less play, virually zero while maintaining a smooth linear motion.

Looking forward to testing with the laser soon!

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #32 on: December 01, 2016, 03:27:19 PM »
After adding the motor and belt I could still feel a slight binding at some point along my X axis, so it needs further investegating - but results are much improved. 10x10mm grid on scrap cardboard.


Uglulyx

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Re: Wiggle on X-axis. Please help.
« Reply #33 on: December 23, 2016, 07:22:34 PM »
I'm having the same issue with my laser. Did the zip tie trick not work out?

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #34 on: December 24, 2016, 02:12:17 AM »
For me the oval holes (being shorter in Z direction) and lacking tension, which the zip-ties helped with, was only half the problem; the some of wheels were out of balance and
wobbled when rolling, causing the z axis carriage to tilt and the beam to wander.

Its easiest to see if you sight down the length of the 2020 profiles and slide the carriage back and forth keeping your view point steady; or even better affixing a (action)camera to the axis.

Uglulyx

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Re: Wiggle on X-axis. Please help.
« Reply #35 on: December 27, 2016, 03:09:33 PM »
Tried to zip ties. No luck. Seems like one or more of my wheel is not actually round.

Not sure how to fix that really. I guess I might have to check the wheels by feel and make sure only the good ones are on the X-axis.

You made some replacements for your's right?

ggallant571

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Re: Wiggle on X-axis. Please help.
« Reply #36 on: December 27, 2016, 07:43:53 PM »
Some things to consider:
  1. Lubricate the bearing with a light oil.Spin by hand till working effortlessly.
  2. Check that you have the correct spacers. Most kits have two lengths.
  3. Set the current limits on the stepper drivers.
  4. Proper belt tension.
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ROSS

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Re: Wiggle on X-axis. Please help.
« Reply #37 on: December 28, 2016, 12:36:07 AM »
I have mentioned before..you could try ball (bearing) races.  Just need to search for the right size.  They are perfectly round.
« Last Edit: December 28, 2016, 12:37:36 AM by ROSS »
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Lasers are wonderful machines..not ONLY  can they cut a finger off BUT  they can also cauterise it at the same time.....

SAFETY -  IS NO ACCIDENT

Uglulyx

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Re: Wiggle on X-axis. Please help.
« Reply #38 on: December 28, 2016, 05:56:18 AM »
I have mentioned before..you could try ball (bearing) races.  Just need to search for the right size.  They are perfectly round.

Hmm... that would probably work. I actually to go to a bear supply place for something unrelated today, maybe they can get me some. What size do you think I need?

Should I just get them the same size as the wheels, or should I get them sized to run inside the track?

Some things to consider:
  1. Lubricate the bearing with a light oil.Spin by hand till working effortlessly.
  2. Check that you have the correct spacers. Most kits have two lengths.
  3. Set the current limits on the stepper drivers.
  4. Proper belt tension.

1.Will do.
2. Pretty sure, but I'll double check.
3.What exactly do you mean by current limits?
4.What is considered the correct tension? I have my quite snug.

EDIT:

ROSS, what do you think of these bearings?

https://www.bearingscanada.com/PU5X27X6-2RS-Polyurethane-Rubber-5x27x6-p/pu5x27x6-2rs.htm

They should be the correct size to ride IN the track.(I may have to elongate the screw holes to allow some adjustment. I think I'd only do these on the top though since they would interfere with the belt.

the same place also has these ones.

https://www.bearingscanada.com/5mm-Bore-Bearing-with-18-5mm-Plastic-Tire-p/5mm-with-18-5mm-plastic-tire.htm

Which are the same as the ones that come with the kit. Just not sure if I'd get better quality out of them. :/
« Last Edit: December 28, 2016, 04:07:09 PM by Uglulyx »

ggallant571

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Re: Wiggle on X-axis. Please help.
« Reply #39 on: December 28, 2016, 08:57:52 PM »
There is a trim pot on the A4988 stepper motor driver boards that limits the current going to the motors. They are usually NOT calibrated prior to shipping. There are online how-to documents detailing the process.  Setting the value too low will result in missed steps and too high with overheating. If you have 2 motors on the Y-Axis you will need twice the current on the associated driver vs the X-Axis.
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ROSS

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Re: Wiggle on X-axis. Please help.
« Reply #40 on: December 29, 2016, 12:22:07 AM »
As regards the bearings its a choice the individual has to make.  However..I think all other possibilities should be checked before swopping the bearings.  There are quite a few checks recommended on the forum to make sure the machine operates smoothly.  Make sure the voltage to the steppers is correct  for a starter.
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Lasers are wonderful machines..not ONLY  can they cut a finger off BUT  they can also cauterise it at the same time.....

SAFETY -  IS NO ACCIDENT

Uglulyx

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Re: Wiggle on X-axis. Please help.
« Reply #41 on: December 29, 2016, 03:45:27 AM »
Ok I'll have to look into that.

But I'm still pretty certain the issue is with the wheels, even moving it by hand you can pretty clearly see the wobble.

Colka

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Re: Wiggle on X-axis. Please help.
« Reply #42 on: January 06, 2017, 11:45:51 AM »
After adding the motor and belt I could still feel a slight binding at some point along my X axis, so it needs further investigating - but results are much improved. 10x10mm grid on scrap cardboard.



I had a similar issue on my x-axis. I found the cap head bolts holding the laser head on were not countersunk and were tending to catch on the rail and causing it to either snag and lose position or wobble and have uneven lines, I removed it and drilled the slots slightly deeper to pull the head away. works like a charm now.