Problem with diameter of idler (20T W10 B5)

first I want to introduce myself because this is the first topic I create in this Forum.

I am DJ living in the North of Germany and I am using the MPCNC since 7 - 8 month. I have modified a lot of things because I want to use the mpcnc for aluminium and carbon. I realized a couple of parts in Alu - even with AW 7075 - aircraft aloy). Not easy but possible.
Therefore I have built the MPCNC on a Alu-tFrame 30x30 with a Alu-bed etc. etc. A couple of parts for it I have designed and also placed on Thingiverse.

I am now in the upgrade process of the MPCNC to Primo because I was even thinking about designing an own CNC with stronger Z-part of the MPCNC. Now that I have seen the Primo I will try it.

Currently I am printing all the necessary parts but I will directly modify the Primo in using my Aluminium Frames.
For the prints I used all my remain material of the last month. Printer is a PRUSA i3 MK3S.

I have used PETG (blue metallic), PLA (blue, black and silver), ASA (orange) and for the core I will use CPE (needs to be printed next week).
In the foto you can also see my legs for the TFrame 30x30, that I have modified (here in PETG, ASA and PLA)
My slogan: COLOUR YOUR WORLD :rofl:

So that was my introduction, hope that’s OK :sunglasses:

Now to my question:
I printed the Trucks (here in ASA-orange) and tried to install the idler. In the built description it is mentioned to use T20 W10 B5 idler but these parts can’t be installed.

They don’t fit because the diameter of the standard T20W10 idler is 18mm and in that Truck only diameters of 13 or 14 mm fit.
Currently I am trying to sand the edge (see picture below) but that’s really a … work.

How did you realize that? What parts are you using?
Any ideas are really appreciated

Best Regards from Germany

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Current status of my prints of the MPCNC Primo

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Test of sanding the edge

You need idlers without teeth, like those:

Hey Philipp,

wow, that was really fast! I was thinking about ordering these idlers but the dimensions are identical. They also have a diameter of 18mm, doesn’t matter if with or without teeth.
Sure that they will fit?

These are the ones I ordered and they fit. Check out Schneewittchen in the forums. :stuck_out_tongue:

/edit: Maybe your print is off and a little too small? Or you printed the J version? :smiley:

OK, ordered!!

I basically live here. :stuck_out_tongue:


Seems so :rofl:
I do not believe that my print is too small. All the screws fit very well without any additional final works. I will try the idlers you’ve mentioned above.

What is the J version? I downloaded the files from Thingiverse some days ago and started printing directly.


Is the problem really the diameter or is it the axial length? 18mm diameter seems about right. What is the length of your pulley?

Hey Jamie, length is 14mm (± 0,05).
As mentioned above, I ordered the idler without teeth and will test it out.

It does not matter, since the pulleys etc. stay the same. Was a bad joke. -_-

If the idlers don’t work, you can find me in Oldenburg to beat me up. :wink:

Will test the ordered idlers and give you a feedback. otherwise Oldenburg is not that “far” :stuck_out_tongue_winking_eye:

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So? :smiley:

Still waiting for the ordered idler. Hope they will arrive in the next days because I would like to upgrade my CNC at the weekend.
Currently I am printing the last part: Core (21 hour job with CPE)

Open issues: I need to design some new “cable chain trays” for my Alu-TFrame construction. First tests are “running”. :crazy_face:

I pass Oldenburg very often traveling to the coast (Nordsee).