Author Topic: Wiggle on X-axis. Please help.  (Read 1710 times)

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #15 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.

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #16 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
« Last Edit: November 24, 2016, 05:13:54 PM by beikeland »

ggallant571

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Re: Wiggle on X-axis. Please help.
« Reply #17 on: November 24, 2016, 05:33:39 PM »
Please measure and post the inside axle diameter. Are you using the original Plexiglas plates?
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beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #18 on: November 24, 2016, 06:19:48 PM »
This drawing seems to be right on the money. So 4.9mm for the inner diameter.


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.

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #19 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.

Kunaphil

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Re: Wiggle on X-axis. Please help.
« Reply #20 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
Just got my home switches installed!👍

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #21 on: November 26, 2016, 08:59:24 AM »


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.

ggallant571

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Re: Wiggle on X-axis. Please help.
« Reply #22 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.
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beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #23 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.
« Last Edit: November 26, 2016, 12:03:10 PM by beikeland »

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #24 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.

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #25 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.

beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #26 on: November 30, 2016, 04:13:39 PM »
This drawing seems to be right on the money. So 4.9mm for the inner diameter.


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.

ggallant571

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Re: Wiggle on X-axis. Please help.
« Reply #27 on: November 30, 2016, 04:31:38 PM »
There is something wrong with the picture for wheel 3D0008.
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beikeland

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Re: Wiggle on X-axis. Please help.
« Reply #28 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?

ggallant571

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Re: Wiggle on X-axis. Please help.
« Reply #29 on: November 30, 2016, 06:07:15 PM »
The part descriptor indicates a 15.8mm diameter shaft while the picture show 4.9mm.
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