Benbox Laser Machines/CO2 Lasers/3D Printers

General Category => Trouble Shooting => Topic started by: Atlant on November 08, 2016, 10:04:53 AM

Title: Wiggle on X-axis. Please help.
Post by: Atlant on November 08, 2016, 10:04:53 AM
Hello, everyone.
I have a problem with mine 30*40 cm 2500mW laser from Banggood. I assembled it according to instructions - frame is sturdy and square. No problems with software/drivers.
But, when I try to burn something, I cannot get straight lines on X-axis.
Originally I thought that wires were too short and strain from them pulled laser cartridge, causing this "wiggle". So, I extended both wires (motor and laser) by soldering (no connectors were added).
To eliminate any pull-force I installed "wire support" to run wires up from control board and down to cartridge. This did not help.
Then I though that cartridge is unbalanced (I can quite easily wiggle it on rail), so I put some weight on one side thinking that this force will put it to same angle all the time and I will have straight lines. This did not help either..
Lines are wiggle, but parallel to each other, so it's something mechanical. I thought that it could be warped rollers, rotated them separately, but this did not help either.
My last resort will be reassembling laser cartridge and rotating it's rail upside down.
Any other suggestions?

Leo.
Title: Re: Wiggle on X-axis. Please help.
Post by: Agastar on November 08, 2016, 10:32:33 AM
Sounds like the wheels need to be snugged up a bit. There should not be any play when it's tighten up correctly.
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 on November 08, 2016, 11:25:22 AM
This is a common problem/complaint. I believe it is partially due to the axles being 0.5mm undersized for the wheel bearings. Try assembling the top such that the wheels hang down before tightening. Then reverse for bottom. Also make sure that the wheel bearings are oiled and turn easily.
Title: Re: Wiggle on X-axis. Please help.
Post by: Atlant on November 08, 2016, 11:51:56 AM
Agastar, thank you for a suggestion - I will tighten them up tonight and post update.
ggallant571 - sorry, but I did not get it. "Try assembling the top such that the wheels hang down before tightening" - do you mean: assemble top 3 wheels first? Then flip over and add 2 bottom wheels? Or something else?
Wheel bearings are new - received unit just 3 weeks ago, and unit is inside of house without any dust.
Title: Re: Wiggle on X-axis. Please help.
Post by: Agastar on November 08, 2016, 12:20:03 PM
By letting the wheels hang down before tightening them up, this will decrease the gap between the wheels and the aluminum extrusion. For the top wheels, you want the bolt to rest at the bottom of the holes in the clear plastic. For the bottom wheels, you want the bolt to be at the top of the holes. So, you let gravity pull the wheels and bolts down and then tighten them up, flip it over and do the same thing.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 08, 2016, 01:56:35 PM
The holes on my frame were oval, and shortest in the "Z" direction, making it impossible to get the wheels close enough to the profiles to be snug. Two of my wheels were also wobbling regardless of mounting, waiting for replacements.

I used zip ties to force the wheels as close to each other as possible before tightening screws down and sliding the carriage onto the X axis profile. Made it better, but still need to replace wheels.
Title: Re: Wiggle on X-axis. Please help.
Post by: Atlant on November 08, 2016, 04:11:30 PM
Got it! Thanks! Will try later tonight...
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 on November 08, 2016, 05:30:34 PM
I am just starting to get good etches & cuts after 5 months ownership. Dread the need to disassemble the frame to rigidly attach to the safety enclosure. Wonder how we all were duped into purchasing these beasts. Wonder even more why I continue!!! I can't imagine adding belt tensioners and wheel adjusters would add more than $5US to the manufacturing cost.
Title: Re: Wiggle on X-axis. Please help.
Post by: Atlant on November 08, 2016, 07:09:21 PM
Guys, you are the best!
It works beautifully now! Thank you so much!!!!
beikeland - your "life hack" with zip-ties did the trick! Thank you, thank you, thank you!!!!
Title: Re: Wiggle on X-axis. Please help.
Post by: mauvan on November 18, 2016, 04:26:32 AM
same for me tightening helps butr after a while i have same problem again i wonder if it is better to buy bigger wheels ? 1 or 2 mm
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 18, 2016, 06:53:11 AM
Thinner cable ties so they can remain on? Although mine hasn't come loose, get a socket wrench and tighten them down good? Consider changing to a locknut or apply some thread securing?

Anyway, its not easy to find bigger wheels that still fit; as you would only want them wider. Or you will have to make new parts to install new wheels on. My aim is to do the latter, new wheels, new parts that fit the new wheels, and maybe using a chamfer bit in a router to make a V profile to use with the V profile wheels I've bought. I'll do some tests when stuff arrive from China, could easily be next year due to xmas logistics chaos.

Do post here  if you find wheels that are 21.5 and wider than 7mm.
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 on November 18, 2016, 07:22:40 AM
I have been looking into getting/making some eccentric bolts to use on the bottom wheels.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 18, 2016, 09:48:50 AM
Maker slide use these, but it would require changes to the parts
https://www.inventables.com/technologies/eccentric-spacer
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 on November 18, 2016, 01:18:55 PM
I just got an email from openbuilds for a sale on 11/25/2016. They have the eccentic spacers and a variety of wheels.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 22, 2016, 09:41:52 AM
I picked up a bunch of 6mm long eccentric spacers off Ali, and matching plain spacers. As I drew up the model of the machine I realize the spacers should be 10mm for the standard wheels. But I'll be using wider wheels to I hope I can get away with it - worst case scenario, I need to mill a pocket for the excess X axis 20x40 profile, which isn't a big deal as I need to make new Y carriage parts for the smaller and wider wheels anyway.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 22, 2016, 07:33:51 PM
Quick look at the model I threw together shows the default OpenBuilds V wheels being quite a close match for the default benbox wheels, despite being wider.

Almost regretting having already bought the smaller diameter wheels to try and gain some 10mm travel; on the other hand I was prepared to cut new parts anyway. Sadly the package seems stuck for now, probably show up after the xmas madness is over.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 24, 2016, 10:34:50 AM
Got my small openbuilds wheels. Seems to be a better fit in the profile than the default ones, despite the profiles not being V profiles. Was hard to get a picture of the fit, but they ran alot smoother than most of the default wheels.

Some of the default wheels would wobble and fall off the rail, while the openbuilds wheels rolled along the whole slot without any support.

Anyways, pictures and stuff when I get all the wheels and the remaining parts.

Would probably getting the larger size unless you for sure want to cut new plastic parts for the carriages, but the smaller wheel could free up as much as 10mm extra travel length.

Edit: Seeing as pictures wasn't easy, attached a close up of the model
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 on November 24, 2016, 05:33:39 PM
Please measure and post the inside axle diameter. Are you using the original Plexiglas plates?
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 24, 2016, 06:19:48 PM
This drawing seems to be right on the money. So 4.9mm for the inner diameter.
(https://ae01.alicdn.com/kf/HTB1Ag.mNVXXXXX6apXXq6xXFXXXW/223213789/HTB1Ag.mNVXXXXX6apXXq6xXFXXXW.jpg?size=103740&height=800&width=800&hash=9633c87d39d597732b0f3f2ad7ddaa4c)

I measured the bolt to 4.8mm and the inner diamter to 4.92mm. Its not super snug, but a lot better than the original wheels.

No I won't be using the original plexi parts as I ordered the small wheels to recover some travel - but it looks like the bigger wheels could fit the original plexi parts, maybe needing 4 instead of 2 eccentric spacers  (unsure how much adjustment one side will get you).

Given I have 22? T-slots and only need 6 I will try a few methods for sanding/lapping, filing and milling/routing to make a V slot on my 20/20 alu, to get even better support and avoid wear over time. Unsure why there is the little step on these profiles instead of just a small chamfer which would have been a small v-slot.

First up is sandpaper on glass as my 90 chamfer mills are still in transit. But given the small amount of material to remove i think it will work well. And I think I might want to sand/lap after making a deeper V groove on the mill/router anyway.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 26, 2016, 05:43:36 AM
Did a mock fitting with cardboard and a straw today - and its a completely different world!! So much smoother, and thats before I've even looked at grinding down a V slot in the alu profiles.

Will see tomorrow if I can cut some new parts on the CNC or if it will be left alone until I receive a dovetail cutter and some other goodies. But seeing as I would need to machine both normal and the eccentric spacers  think it will have to wait a little.
Title: Re: Wiggle on X-axis. Please help.
Post by: Kunaphil on November 26, 2016, 08:30:51 AM
Beikeland,

So if one was to use the original acrylic carriage plates, which roller would you recommend?

Thanks, 

Phil
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 26, 2016, 08:59:24 AM
(http://www.ol.b8h.com/wp-content/uploads/2013/04/eccentric-spacer3.jpg)

It kinda depends on how these things are intended to be used. I presume the 7.11mm end goes into the wall of the carriage, and there is a need for a concentric shim on the axle between the spacer and the bearing as to only contact the inner race. If so then one would ideally drill up the existing holes to 7.11mm and should be able locate the 7.11mm holes so that you could use either the smaller or larger wheels. But it would seem easier to achieve this with the larger 24-25mm wheels than the 15.5mm ones.

I haven't received those eccentric spacers yet, so I don't know what I'll end up with; although I may be tempted to try machining those spacers from plastic tomorrow if I decide to cut the plates for the carriage anyway.

My only recommendation would be don't use stainless rollers, and only use the rollers with flat middle section for the belt to rest against.
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 on November 26, 2016, 09:21:13 AM
The plastic wheels that came on my GearBest A5 unit measure 21.5mm across. I think this calls for some CAD work.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 26, 2016, 11:22:34 AM
I've drawn up the model having 57mm distance between wheels in the Z direction.

Using that and this model off grabcad https://grabcad.com/library/solid-v-wheel-kit-b-size-1 says the wheels almost fit like a glove. The model in question does measure 23.89mm; given the original wheels has some radial play on the axle and in the hole I think it would be safe to assume that drilling up one or both sides of to accommodate eccentric spaces with give you +/- 0.79mm adjustment or twice that.

My current model is a bit out of whack as I've started adjusting for the smaller wheels, and the hole distances are just below 53mm now. But that goes to show 57mm should be pretty close? no?

Edit: And man I love Fusion 360, change the parametric 2d sketch, the 3d model updates - the wheels are jointed to the holes and fall into their new place, the CAM stuff only need to regenerate toolpaths and post it to try out a new iteration.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 26, 2016, 03:27:29 PM
For the smaller wheels you need to find M5x8mm washers this turns out to be not so easy/cheap. So would probably recommend the larger wheels where you probably can use the eccentric spacers as is, without a washer to prevent contacting both the outer and inner race.

Not sure if I'll try to trim down a reguler M5 washer or drill out an M4, but still time to ponder while the parts make their way here.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 27, 2016, 11:58:14 AM
Forgot the CNC was in dire need of some TLC and squaring up, so only managed to nearly finish up changing the spoilboard and doing a rough cut to level it.

Did make a model of the eccentric spacer if of interest http://a360.co/2gKH3SV and while waiting I cut the final size parts in cardboard + a whole stack of little 5x8mm cardboard shims - hole base seemed to be a perfect fit even without the eccentric spacers. The motion is so much smoother I now feel the tiniest imperfection in profile instead the original wheels binding and catching randomly.

Might order up some of the regular sized wheels just to try as the seller forgot to ship me 12 instead of 10 wheels I don't have enough for all axis anyway. Recovering travel was most important along X anyway.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 30, 2016, 04:13:39 PM
This drawing seems to be right on the money. So 4.9mm for the inner diameter.
(https://ae01.alicdn.com/kf/HTB1Ag.mNVXXXXX6apXXq6xXFXXXW/223213789/HTB1Ag.mNVXXXXX6apXXq6xXFXXXW.jpg?size=103740&height=800&width=800&hash=9633c87d39d597732b0f3f2ad7ddaa4c)

I measured the bolt to 4.8mm and the inner diamter to 4.92mm. Its not super snug, but a lot better than the original wheels.

No I won't be using the original plexi parts as I ordered the small wheels to recover some travel - but it looks like the bigger wheels could fit the original plexi parts, maybe needing 4 instead of 2 eccentric spacers  (unsure how much adjustment one side will get you).

Given I have 22? T-slots and only need 6 I will try a few methods for sanding/lapping, filing and milling/routing to make a V slot on my 20/20 alu, to get even better support and avoid wear over time. Unsure why there is the little step on these profiles instead of just a small chamfer which would have been a small v-slot.

First up is sandpaper on glass as my 90 chamfer mills are still in transit. But given the small amount of material to remove i think it will work well. And I think I might want to sand/lap after making a deeper V groove on the mill/router anyway.
Got one of the chamfer mills today, and did a test cut on one of the 20x20 profiles - worked reasonably well, but can't say I noticed any real difference compared to the original profile. Maybe a larger surface area to contact is better over time, but for now I don't think its worth the effort.
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 on November 30, 2016, 04:31:38 PM
There is something wrong with the picture for wheel 3D0008.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland on November 30, 2016, 04:42:01 PM
Could be, I bought 3D0004 which seems to be spot on, and would only consider 3D0009 as an option for a larger wheel - from what I gather you'd want the flat surface on the weel for the GT2 belt, and not the internal V groove.

But are you saying the picture isn't to scale or that the dimensions doesn't match a physical wheel?
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 on November 30, 2016, 06:07:15 PM
The part descriptor indicates a 15.8mm diameter shaft while the picture show 4.9mm.
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland 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?)
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland 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).
(https://www.dropbox.com/s/kvajf8670eqjyva/2016-12-01%2012.01.15%20%28Large%29.jpg?dl=1)
Was hard to get a good picture of the spacers, but this should provide a rough idea.
(https://www.dropbox.com/s/nk037d3fb47mjm6/2016-12-01%2012_55_34-Autodesk%20Fusion%20360.png?dl=1)

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!
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland 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.

(https://www.dropbox.com/s/uluorqs3ckedm8q/SAVE0008.TIF%20%28Large%29.jpg?dl=1)
Title: Re: Wiggle on X-axis. Please help.
Post by: Uglulyx 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?
Title: Re: Wiggle on X-axis. Please help.
Post by: beikeland 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.
Title: Re: Wiggle on X-axis. Please help.
Post by: Uglulyx 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?
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 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.
Title: Re: Wiggle on X-axis. Please help.
Post by: ROSS 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.
Title: Re: Wiggle on X-axis. Please help.
Post by: Uglulyx 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. :/
Title: Re: Wiggle on X-axis. Please help.
Post by: ggallant571 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.
Title: Re: Wiggle on X-axis. Please help.
Post by: ROSS 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.
Title: Re: Wiggle on X-axis. Please help.
Post by: Uglulyx 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.
Title: Re: Wiggle on X-axis. Please help.
Post by: Colka 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.

(https://www.dropbox.com/s/uluorqs3ckedm8q/SAVE0008.TIF%20%28Large%29.jpg?dl=1)

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.