Tight core fit on 25 tubes

LowRider CNC Troubleshooting
1

Hi, I’m doing a dry fit of LR3 and the core fits extremely tight. I loosed completely nuts for bottom bearings before even could slide core a little bit on the tubes. Also core scratches the braces a little bit.

  • I’m using 25mm tubes (measured outer diameter)
  • Printed 25mm braces (text on the braces “25mm OD”)
  • Printer is squared

Here is the space between bottom bearing and the core - is it ok or there should be no space betwen bearings and nuts/printed part?

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All other bearings have no extra space between them and nuts/printed parts

2

And here is the scratched braces. Should I just slightly sand them or realignment of bearings is required? Or maybe some spacers?

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3

Perhaps you could measure the opening in the braces? And see if your 3d printer isn’t accurate?

4

First tighten the nuts, then see what happens. If it still scratches your printer might be crooked. Ask me how I know. :smile:

1 Like
5

I see the max difference for 0.3mm on the longest side of the brace. And that’s probably because of “elephant foot” on the first layers - but they are not the biggest points of contact. Other dimensions fit 0.15. What the acceptable tolerance?

6

If I tighten them I can’t push the core on tubes at all :sweat_smile: Crooked printer - was it a bad geometry in your case?

7

These are the bolts you need to loosen in order to adjust the tension on the rails, not the ones you have loosened in the picture.

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Loosen these until you have a very loose fit. Then tighten them down 1/4 turn at a time until the tension is set correctly.

Overtightening these bolts has been the cause of many cracked cores.

I tightened mine the absolute minimum amount I could that took the ability to shake the core on the rails out.

You should still be able to turn the bearings by hand.

2 Likes
8

Whoa, thank you, Mike!

Loosening these two solved both tight sliding on the tube and scratching the plastic parts.

Still can’t explain myself why I decided to loose another nuts though :sweat_smile:

9

Eh, I didn’t even see that… Stupid me. :stuck_out_tongue:

1 Like