"Gantry Plate" and "Cross-Slide Plate" hole location error


The “Gantry Plate” and “Cross-Slide Plate” holes are incorrectly positioned as shown below:

The width of the track to be passed is 40 mm and 60 mm, and the diameter of the pulley is 24 mm, that is, in practice, the available widths are 36 mm (60-24) and 56 mm (80 -24), simply can not install the track.

Our actual test, the wheel can be inserted into the track about 1mm, so the reserved width of at least 62mm and 82mm.

Thank you very much.

The 60mm and 80mm hole spacing works well; the wheels installed on the plates using that spacing slide on the extrusions smoothly. You can see it action in all of the videos.

The trick is eccentric spacers which are installed in the larger plate holes for the wheels on one side of the extrusion. Details for parts and assembly can be found in the documentation.

Dimensionally, using OpenBuilds extrusions and v-wheels, the wheels fit into the v-slots approximately 1.5mm to 1.75mm, and the eccentric spacers can adjust the spacing 1mm in each direction. So 80mm (hole spacing) + 3mm (2x1.5mm wheel insertion) - 24mm (2x12mm wheel radius) - 60mm (extrusion width) = -1mm + 1mm (eccentric spacers adjustment) = 0mm.

If you can’t get the plates with wheels to slide onto the extrusions while using the eccentric spacers to increase the spacing, the wheels and extrusions you have may not be compatible with the provided hole spacing. You are welcome to change the spacing as you see fit for your specific parts; the models are all available in OnShape.

Oh my God! . .

We bought the wrong model of the track, we did not choose v-slots.

Thank you very much!

@Gabriel I installed my V-Wheels and plates today, they are too tight.
I adjusted the eccentric spacers for maximum distance and even that is very tight.

I will continue and see if the bot can move this amount of torque / fricition, do you
have any other solution if that does not work?

Edit: I fixed it, the tweak is to untighten the “fixed” wheels while the whole system
sits on the tracks (with the gantry installed, otherwise the added weight would make
one to redo later). By then tightening the fixed wheels again, the little tolerance in the
holes is enough to enable adjustment with the eccentric ones. By moving the gantry
for and aft a little, one can see wether the wheels are running correctly or if some of
them don´t make contact.

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For the record I torqued all my wheels to 2NM

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@Klimbim, we had exactly the same problem with the wheels not sliding easily on the track and followed the advice laid out in the edit for your post. Everything looks great now sliding smoothly!

It might be a good idea for those instructions to be added to the official guides on adjusting the eccentric spacers. :slight_smile:

I did so but for whatever reason @roryaronson did not release my edits :wink:

@Klimbim I have incorporated your suggestions into the documentation. Thank you for the contributions!

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@Gabriel: Might be worth writing, that I got best results in loosening the non-eccentric spacers while the whole gantry
was sitting on the wheels… cheers!