Locking belt to carriage

Hi all,

The instructions for the Fisher state:

"Engage the ends of the belt and pull them up through the slot in the carriage. This will require a reasonable amount of force, and lock the belt into the carriage. Do not tension the belt yet; you will need to release the top of the side panels to fit the top plate, later. Anytime you remove the side panels, release the tension in the belt first, or the idler bracket will be pulled downwards."

I am really struggling to get both ends of the belt through the slot of the carriage, it's extremely tight. Anybody managed this? Any tips? Or has anyone come up with a better solution?

I had completely the opposite problem where teh hole was slightly too large. I ended up inserting a small wedge up the hole to jam the belt it.
Perhaps you could just carefully cut or file the hole larger?

I assume you've noticed that the hole is tapered - the belt end should be pushed up from the underside.

Quote
sneaky_print
"Engage the ends of the belt and pull them up through the slot in the carriage. This will require a reasonable amount of force, and lock the belt into the carriage.

That sounds to me awfully similar to how the Ormerod 1 Y belt was supposed to lock.

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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].

sneaky_print, bluesign2k is quite right. Push the end of the belt from the top down through the carriage, engage the two ends of the belt together under the carriage, then push the carriage down over the join. The carriage slot tapers from underneath. The end of the belt should be pulled back through the carriage, as it's engaged with the end already coming through the carriage. If it is loose, you can shim behind the belt to make it tight, but I haven't seen any that are loose yet.

Quote
dc42
That sounds to me awfully similar to how the Ormerod 1 Y belt was supposed to lock.

It's much tighter. And as you tension the belt, it gets even tighter. There's also a lot less mass pulling on it. We did learn some lessons...

Ian
RepRapPro tech support

I also found the belt lock to be too loose. I could make the teeth slip by tensioning the belt. Certainly couldn't make the belts 'twang' like the Ormerod.
I have reprinted the carriages and they are now very tight.
Regards
John

Hi John

Thanks for the feedback. Sorry you got a kit where they were not tight. I'll look into why this may be the case.
For anyone else with this issue, you should be able to shim the belt; a small piece of folded up paper between the back of the belt and the printed part should work perfectly well.

Ian
RepRapPro tech support

Thanks for the replies. Yes I realise the slot is tapered. I still haven't managed it, got my misses trying now hopefully she can manage where I have failed.

She's only gone and done it.

Hi Ian,
I've just printed the parts for my second Fisher on the first Fisher (both Betas). using slic3r 1.2.9 with the configs and the beta parts off your website. The carriage comes out too big for the belts and the bearings, even if I print the carriages at 95% scale (however I don't want to scale it down as there will be problems fitting on the rods)

The best way I've found so far is to have some tape or paper between the belts as the belt squishes and grips against the pastic better than paper does.
David

Hi David

Check the size of the stl parts. The rod spacing has changed for Fisher 1 by 3mm (though 3mm LESS than Fisher beta), and I'm not sure we've posted the updated version for Fisher beta yet. Try printing a known-size object, eg a 20mm x 20mm x 20mm cube, and see what size it comes out. Have you changed any of the calibration settings? If so, what? Also make sure that there is no backlash in any part (motor pulley, belts, carriage, rods, effector) or the calibration will be incorrect.

Ian
RepRapPro tech support

I had to use a pair of plyers to pull the end of the belt up through the slot. but it did work in the end.

"Check the size of the stl parts. The rod spacing has changed for Fisher 1 by 3mm (though 3mm LESS than Fisher beta), and I'm not sure we've posted the updated version for Fisher beta yet. Try printing a known-size object, eg a 20mm x 20mm x 20mm cube, and see what size it comes out. Have you changed any of the calibration settings? If so, what? Also make sure that there is no backlash in any part (motor pulley, belts, carriage, rods, effector) or the calibration will be incorrect."

Everything is tightened up so minimal backlash as far as I can tell, printed objects are the correct height but the XY is uniformly too large by about 1mm in a 30mm object. The printer parts are all the beta set of correct dimensions and there are no v1 parts. No calibration settings have been changed, I just run the G32 levelling process until the reported error converges.

Is there any guidance on how to calibrate the XY axes?