Kossel mini carriage roller problem.

Hi all,

I am currently in process of building a kossel mini printer with 2020 v-slot extrusions. I am using all injection molded parts for the corners, carriages etc ordered from aliexpress. Presently, I find an issue while assembling the roller carriages which I am unable to figure how to fix it. The problem is, while attaching the roller bearings to the carriage assembly, I find that there is tilt when the carriage is mounted on the extrusion, specifically on the carriage side which has single roller. Caliper reading indicates the rollers and the carriage screw mounts takes M5 in my case. I tried few ways to find a way to reduce tilts like adding washers, but none seems to work out .

The attached image would give a better idea of the problem I face. Has anyone been using injection molded parts in their setup facing any such problems with it? I am all out of ideas to fix it, it would be very helpful is anyone can assist me to fix it.

Cheers,
Arvind.

IMO the first thing to do is get rid of those shower door rollers and use Delrin V-rollers instead. But you may have difficulty finding rollers that need the axle spacing of your existing carriages.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The spacing of the wheels is to small.

The delrin V rollers might work since there have a smaller diameter then the white roller wheels you have now.

But in a nut shell your have to get a print of a different carriage that has a bigger wheel spacing or smaller diameter wheels.

Definitely use delrin v rollers, those rollers are not going to work on that profile.

Hi all,

Thanks for your suggestions/opinions.

> IMO the first thing to do is get rid of those shower door rollers and use Delrin V-rollers instead. But you may have difficulty finding rollers that need the axle spacing of your existing carriages.

> The spacing of the wheels is to small.
> The delrin V rollers might work since there have a smaller diameter then the white roller wheels you have now.
> But in a nut shell your have to get a print of a different carriage that has a bigger wheel spacing or smaller diameter wheels.

> Definitely use delrin v rollers, those rollers are not going to work on that profile.

Yea, right from the time I am trying to assemble the carriages, I strongly started feeling that the entire carriage structure is a bit smaller in dimension to be used with the extrusions. I borrowed these rollers from a friend of mine who happen to use the same set of molded parts and the white rollers on his kossel mini (2020) setup and he has no such tilting problems (don't have a photo at the moment of his working setup atm) which makes me think whether I am missing something here. I would have happily went for Delrins as this was my first choice to be used, but these rollers are pretty difficult to get it locally and very very pricey to source it to where I live .
Is there any other type of rollers which could work with v-slots? Has anyone experimenting with such roller implementations?

As a last resort I will be printing new carriages.

Cheers,
Arvind.

You can try an lossen the tension bolt on the side.
Also i check the pics again. And there shouldnt be a nut on that right wheel.
All 3 should be carriage, wheel, nut.
You have on the right side carriage, nut wheel ,nut.

Those shower door rollers come in different diameters. ( from 19 to 25mm IIRC )
Try to find smaller ones than you currently have.
I had bad luck with 19mm rollers. They were advertised as 6mm wide, but were only 5.4mm. They got pressed in the slot.
-Olaf

Hi @xile6,

>You can try an lossen the tension bolt on the side.
> Also i check the pics again. And there shouldnt be a nut on that right wheel.
> All 3 should be carriage, wheel, nut.
> You have on the right side carriage, nut wheel ,nut.

The earlier pics were set of few iterations I tried to level the tilts. I also had tried "carriage->wheel->nut" assembly which yields a same result (pics attached). It was the first thing I did when the problem was discovered. In the pictures, looking closely, when the carriage is attached to the extrusion, the lower right half (the U-shaped end) actually raises up a bit which seems to add the tilt. There are actually no tensioner action added to the whole assembly (which itself it pretty tight to roll on the rails), The screw on the right is just a dummy, actually the tensioner side hole too, is pretty loose to fit M3s properly and there are no bolts or thread taps inside it to tighten it (but they carriage has a slot hole to insert a M3 nut for the tensioner bolt which is not added at the moment) .

Cheers,
Arvind.

Hi @Olaf,

> Try to find smaller ones than you currently have.

I have been roaming around the city for past couple of hours to find anything suitable for rolling over the extrusion which I can use. I try checking this option too.. The problem, even these set of rollers are hard to get in local hardware stores. Will try out my luck tomorrow.

Cheers,
Arvind.

Quote
tuxhead
Hi @xile6,

>You can try an lossen the tension bolt on the side.
> Also i check the pics again. And there shouldnt be a nut on that right wheel.
> All 3 should be carriage, wheel, nut.
> You have on the right side carriage, nut wheel ,nut.

The earlier pics were set of few iterations I tried to level the tilts. I also had tried "carriage->wheel->nut" assembly which yields a same result (pics attached). It was the first thing I did when the problem was discovered. In the pictures, looking closely, when the carriage is attached to the extrusion, the lower right half (the U-shaped end) actually raises up a bit which seems to add the tilt. There are actually no tensioner action added to the whole assembly (which itself it pretty tight to roll on the rails), The screw on the right is just a dummy, actually the tensioner side hole too, is pretty loose to fit M3s properly and there are no bolts or thread taps inside it to tighten it (but they carriage has a slot hole to insert a M3 nut for the tensioner bolt which is not added at the moment) .

Cheers,
Arvind.

Removing that m3 bolt will make it a little better, but the carriage is still to small for thise wheels.

You can get some others printed out.
Thingivers will have a ton of them to choice from.

Quote
tuxhead
Hi @xile6,

>You can try an lossen the tension bolt on the side.
> Also i check the pics again. And there shouldnt be a nut on that right wheel.
> All 3 should be carriage, wheel, nut.
> You have on the right side carriage, nut wheel ,nut.

The earlier pics were set of few iterations I tried to level the tilts. I also had tried "carriage->wheel->nut" assembly which yields a same result (pics attached). It was the first thing I did when the problem was discovered. In the pictures, looking closely, when the carriage is attached to the extrusion, the lower right half (the U-shaped end) actually raises up a bit which seems to add the tilt. There are actually no tensioner action added to the whole assembly (which itself it pretty tight to roll on the rails), The screw on the right is just a dummy, actually the tensioner side hole too, is pretty loose to fit M3s properly and there are no bolts or thread taps inside it to tighten it (but they carriage has a slot hole to insert a M3 nut for the tensioner bolt which is not added at the moment) .

Cheers,
Arvind.

Your 2020 extrusion look to be approx. 6.4mm centre space width so work with roller of 7mm thickness. For the adjusting tension function requires M3 screw and two M3 nuts. Some pictures of the built up units here

Hi,

> Your 2020 extrusion look to be approx. 6.4mm centre space width so work with roller of 7mm thickness. For the adjusting tension function requires M3 screw and two M3 nuts. Some pictures of the built up units

@win3d , good point, after visiting the link posted, I tried measuring the spacing and roller width, which unfortunately seems to match up the dimensions. Caliper reading indicates the center spacing of extrusion is around 6.24mm while the roller thickness appears to be 7mm approx. (images attached)

Quote
tuxhead
Hi,

> Your 2020 extrusion look to be approx. 6.4mm centre space width so work with roller of 7mm thickness. For the adjusting tension function requires M3 screw and two M3 nuts. Some pictures of the built up units

@win3d , good point, after visiting the link posted, I tried measuring the spacing and roller width, which unfortunately seems to match up the dimensions. Caliper reading indicates the center spacing of extrusion is around 6.24mm while the roller thickness appears to be 7mm approx. (images attached)

I'm using diameter 21.5mm rollers could it be your rollers are larger diameter?

Hi,

> I'm using diameter 21.5mm rollers could it be your rollers are larger diameter?

The rollers I have seems have a diameter of 23mm (aprox 23.24mm). This could be the the cause of all the tilts and tightness. If the roller needs to changed to something smaller, what size or diameter should I go for ?(obviously smaller , but) any specific suggestions to start with?

Like dc42 and the others suggested, The delrin v-rollers appears to be small and perfect fit in my case. Searching around in my place, I was able to find few stores who does have those 623 bearings:
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[www.think3dprint3d.com]
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But no one sells or makes those delrin outer shells to fit it. I am still in search of those complete set of rollers. If not those V-rollers, will these type of rollers work with the setup (may be I could find some dealers for it here as this design appears more commonly used)?
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[www.servocity.com]
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Cheers,
Arvind,

Also the rollers I have takes M5 screws to fit in properly. Is it a right one so far anyone uses in their setups?

Cheers,
Arvind.

Quote
tuxhead
Also the rollers I have takes M5 screws to fit in properly. Is it a right one so far anyone uses in their setups?

Cheers,
Arvind.

I'm using the same carriages as yours, the diameter 21.5mm rollers work good too. Finding no discernible print quality difference with my rollers and hiwin clone linear rails.

> I'm using the same carriages as yours, the diameter 21.5mm rollers work good too. Finding no discernible print quality difference with my rollers and hiwin clone linear rails.

Hmm, I am currently searching smaller diameter rollers to test whether it works in my case too. All other options (delrin v-roller, LM guides etc) seems out of reach (too pricey) for me.

Cheers,
Arvind.

Hi all,

After a long wait, based on your suggestion I was able to fix the problem by replacing the shower door rollers with delrin mini-v-wheel kit I bought it from [www.aliexpress.com]. In this in process, I replaced the molded carriages with printed one as the rollers were bit smaller to run with it and constantly rattled sideways while moving over the extrusion. I used this [www.thingiverse.com] carriage design which perfectly matches the mini v wheel rollers and sliding is buttery smooth with no more tilts.

Thank you all for sharing your suggestions/opinion which helped alot to fix it.

Cheers,
Arvind