Threaded rod too small

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morrildl
Posts: 2
Joined: Mon Jan 21, 2013 8:21 pm

Threaded rod too small

Post by morrildl » Mon Jan 21, 2013 8:28 pm

I ordered an Inventables kit and received it last week; this weekend I assembled it, mostly.

Long story short, the Z-axis threaded rod is essentially not usable, as far as I can tell. My calipers tell me that the coupler is indeed almost exactly 8.0mm; but the threaded rod is only ~7.75m - 7.8mm at the outside of the threads. Tightening the set screws on the coupler obviously makes it smaller, but not enough smaller. The rod just spins inside the coupler.

I tried electrical tape per a tip on the wiki, which does hold for a little while. But eventually the torque vs. the threads shreds the tape and I'm back to square one. I'm not really interested in grinding down the threads because it's pretty obvious that that isn't going to help -- knocking another mm off the diameter isn't going to make it easier to grip.

Everything else seems to be working; X and Y seem to be doing their thing, and for the brief intervals where I can get Z working with a Sharpie, it seems to draw pretty well. So this appears to be my last hurdle.

Anyone have any suggestions?

cvoinescu
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Re: Threaded rod too small

Post by cvoinescu » Mon Jan 21, 2013 8:52 pm

Adhesive aluminum tape is much better than electrical tape. If you don't have any handy, and don't want to buy a whole roll just for this, try a strip of aluminum kitchen foil, tightly wound. Other people have suggested plumber's PTFE tape, but I disagree. Other metal tapes are also good -- you may have copper tape which is sold as a slug and snail repellent for gardening, or for shielding electronic circuits.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

morrildl
Posts: 2
Joined: Mon Jan 21, 2013 8:21 pm

Re: Threaded rod too small

Post by morrildl » Tue Jan 22, 2013 1:21 am

Thank you! Metal tape is an excellent suggestion. I'll see if I can make it over to the hardware store to see what they have.

I also contacted Inventables and they are sending me a replacement rod; but who knows whether it will actually be a different SKU or the same part I already have.
cvoinescu wrote:Adhesive aluminum tape is much better than electrical tape. If you don't have any handy, and don't want to buy a whole roll just for this, try a strip of aluminum kitchen foil, tightly wound. Other people have suggested plumber's PTFE tape, but I disagree. Other metal tapes are also good -- you may have copper tape which is sold as a slug and snail repellent for gardening, or for shielding electronic circuits.

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