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Rostock Mini Alternative Carriages

Posted by Kurzaa 
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Kurzaa
Rostock Mini Alternative Carriages
May 12, 2015 11:07PM
I was attempting to tighten the belts on my Rostock Mini Pro from 3D Printer Czar tonight when the "loop" connecting the belt to the carriage snapped.

Although I believe I can print a replacement on a Makerbot at the local library, I was hoping for some suggestions for an upgrade, preferably something that will be easier to tighten. I found one or two options on Thingiverse that appear to have teeth on the carriage, which should hopefully be strong then the original "loop", but would appreciate input from others in similar situations or who have already made upgrades to their printers.

Thank you for your advice and assistance.
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sungod3k
Re: Rostock Mini Alternative Carriages
May 13, 2015 12:31AM
Dont do teeth. the belts slips as soon as you tighten it. the cherry pi has a good system but you need slightly more length on the belt.
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dc42
Re: Rostock Mini Alternative Carriages
May 13, 2015 02:44AM
I replaced the carriages on my Kossel by ones with teeth, and they work really well - but the Kossel has a separate belt tensioning mechanism.


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].
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dougal1957
Re: Rostock Mini Alternative Carriages
May 13, 2015 03:01AM
Quote
dc42
I replaced the carriages on my Kossel by ones with teeth, and they work really well - but the Kossel has a separate belt tensioning mechanism.

Dave

Can you possibly post some photo's/details of that tensioning system?

I suspect that T3P3 have done a modification to the original design to incorporate this and would be interested to see it.

The cherry Pi uses elongated slots in the motor mount's to allow for tension adjustment.

I am wondering on the best way to achieve the same using the Alloy corner pieces?

Doug
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dc42
Re: Rostock Mini Alternative Carriages
May 13, 2015 03:41AM
Here are some pics from T3P3's documentation.



You loosen the 3 screws that clamp the top vertices to the uprights, adjust the belt tensioning screws to get the tension you want, then re-tighten the 3 screws.

Edited 1 time(s). Last edit at 05/13/2015 03:43AM by dc42.


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].
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dougal1957
Re: Rostock Mini Alternative Carriages
May 13, 2015 04:05AM
Quote
dc42
Here are some pics from T3P3's documentation.



You loosen the 3 screws that clamp the top vertices to the uprights, adjust the belt tensioning screws to get the tension you want, then re-tighten the 3 screws.

Many thank's for that Dave.

Unfortunately that won't be an option with the Ally bracket's however the Hex cutout that is at the ends of the cross extrusion's goes all the way through the bracket so I reckon we could come up with a bridge to go across the top with 2 screws that will pull the bracket up.

The other option for me would be to allow the tower's to extend under the bottom Bracket be say 75 mm (This would also act as feet) and then just loosen bottom bracket push it down to tension then tighten them up!
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dc42
Re: Rostock Mini Alternative Carriages
May 13, 2015 05:12AM
Quote
dougal1957
The other option for me would be to allow the tower's to extend under the bottom Bracket be say 75 mm (This would also act as feet) and then just loosen bottom bracket push it down to tension then tighten them up!

Couldn't you just loosen the top vertex screws, pull the top frame up to tension the belts and then tighten the screws? It's not as easy as having built-in tensioning screws to get a fine adjustment, but I would have thought no worse than moving the motors in slots.

I may stick to using the printed top vertices for now, or else construct bridges as you suggest.

I notice that the Folger kits use clothes-peg springs on the belts to tension them, so I may try that. Alternatively, some printed parts to clip on to the belts to take up slack.

Edited 1 time(s). Last edit at 05/13/2015 05:14AM by dc42.


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].
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dougal1957
Re: Rostock Mini Alternative Carriages
May 13, 2015 05:26AM
Quote
dc42
Quote
dougal1957
The other option for me would be to allow the tower's to extend under the bottom Bracket be say 75 mm (This would also act as feet) and then just loosen bottom bracket push it down to tension then tighten them up!

Couldn't you just loosen the top vertex screws, pull the top frame up to tension the belts and then tighten the screws? It's not as easy as having built-in tensioning screws to get a fine adjustment, but I would have thought no worse than moving the motors in slots.

I may stick to using the printed top vertices for now, or else construct bridges as you suggest.

I notice that the Folger kits use clothes-peg springs on the belts to tension them, so I may try that. Alternatively, some printed parts to clip on to the belts to take up slack.

I agree about the slots not going that way I think I will use some of the bottom of the vertical towers as feet (allows me to get all electronics under the printer) and just use the slacken push down and tighten although a nice screw adjuster would be nice Will work on that one.

Have order some endless 762 teeth toothed belts for mine (I am prepared to loose a little Z Height for now).

Doug

ps the acc pack arrived yesterday thanks.
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vreihen
Re: Rostock Mini Alternative Carriages
May 13, 2015 11:09AM
Is anyone concerned with the three top corners possibly not being square after using these tensioners?????
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Kurzaa
Re: Rostock Mini Alternative Carriages
May 13, 2015 05:21PM
Thanks for the advice. The Cherry Pi sadly isn't directly compatible with the Rostock Mini carriages, but it did give me a few ideas to investigate after a quick glance. I'll also be wary in regards to the teeth, though I am glad DC42 had success with them.

Please let me know if anyone else has any thoughts on the problem.
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dc42
Re: Rostock Mini Alternative Carriages
May 13, 2015 05:28PM
I just realised that my carriages don't actually have teeth. Instead, they have a peg and a slot so that the belt locks into itself.



Edited 1 time(s). Last edit at 05/13/2015 05:29PM by dc42.


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].
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Kurzaa
Re: Rostock Mini Alternative Carriages
May 13, 2015 05:33PM
Definitely be careful with the teeth then. Thanks for the update.
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dc42
Re: Rostock Mini Alternative Carriages
May 13, 2015 06:53PM
Quote
Kurzaa
Definitely be careful with the teeth then. Thanks for the update.

I don't understand - why should I need to be careful with the teeth? Locking the teeth of 2 parts of a belt together is a standard technique.


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].
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Kurzaa
Re: Rostock Mini Alternative Carriages
May 14, 2015 05:49PM
Sorry, that was a mental note to myself incase I went with a design that used printed teeth. I am happy to see that folding the belt over on itself works so well.
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dc42
Re: Rostock Mini Alternative Carriages
May 14, 2015 06:04PM
My Ormerod uses Y belt clamps with printed teeth, and they work very well.


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].
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Kurzaa
Re: Rostock Mini Alternative Carriages
May 15, 2015 04:04PM
At this point I am considering this design from Thingiverse [www.thingiverse.com], likely the straight version as opposed to the curved one. To close the two ends of the belt, I will use zip ties to form loops on each end, and another to join the belts together. I saw this method at the Midwest RepRap Fest and it seemed to work really well.

Unforunately, the Makerbot at the local library is down for maintenance for a few weeks, at which point I will still need to wait another 3-5 days in the queue. So it looks like I need to modify my existing carriage to get my printer working long enough to print replacements.

Thanks for the feedback everyone.
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dc42
Re: Rostock Mini Alternative Carriages
May 16, 2015 04:23AM
Using zipties to hold the two ends of the belt together when the belt tension is trying to pull them apart is a bad idea. My Mini Kossel was originally built like that, and the zipties slowly slid down the belt. I mostly solved it by using 2 zipties instead of 1, but there was still some slippage. So I strongly recommend using carriages that either have teeth to grip the belt, or a loop and a slot which holds the belt locked to itself.


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].
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Kurzaa
Re: Rostock Mini Alternative Carriages
May 18, 2015 05:39PM
Quote
dc42
Using zipties to hold the two ends of the belt together when the belt tension is trying to pull them apart is a bad idea. My Mini Kossel was originally built like that, and the zipties slowly slid down the belt. I mostly solved it by using 2 zipties instead of 1, but there was still some slippage. So I strongly recommend using carriages that either have teeth to grip the belt, or a loop and a slot which holds the belt locked to itself.

I considered trying to "rivet" the looped ends of the belt, using just a single zip tie then for the belt tension. Also thought about printing a rectangular "ring" to create the loop, though that would likely have slippage as well.

Thanks for the warning. Might just need to figure out my own design using Kossel and Cherry Pi carriages as inspiration.
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boksbox
Re: Rostock Mini Alternative Carriages
May 18, 2015 08:16PM
Quote
vreihen
Is anyone concerned with the three top corners possibly not being square after using these tensioners?????

Exactly my thoughts.

Although I don't have a Rostock but a Kossel Mini, I only used these to fine-tune the square of the frame and made separate adjustable belt tensioners.

By the way, my carriages have toothed belt mounts and they work really well.
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