12 mm thru-axle to 9 mm quick release inserts

prusaprinters

<p>NOT FOR 3D PRINTING</p> <p>These are inserts designed to interface with the fork that comes with the Fuji Jari series, allowing you to run quick release wheels in front. The rear already converts between 12 x 142 thru-axle &amp; QR 135 mm. It is a 12 x 100 mm thru-axle (TA) fork, with 1.5 mm thread pitch.</p> <p>The idea is that while the over-locknut dimension (OLD) is 100 mm on 99% of front quick release (QR) wheels, the M9 x 1 mm hub axle itself is nominally 108 mm wide. Standard QR forks have a slot (hence dropout) to allow the hub to slide into position. You can mount a 108 mm hub in your fork by spreading each leg outward a hair over 4 mm on each side.</p> <p>Everything you do is at your own risk. I tested a front QR hub fit on this Fuji<em>carbon</em> fork</p> <p>(spreading it manually &amp; all) without much issue.</p> <p>No idea whether or not this is compatible with similar forks.</p> <p>Turned out on a lathe, then cut the 12 mm hex flats with a mill. I would not recommend this for 3D printing. I've shared the SLDPRT &amp; SLDDRW files for your reference. The drawings have been updated since I last machined the parts.</p> <p>You may need a rear (read: longer) QR skewer since the effective clamping width is going to be much longer.</p> <p>Dimensions in inch/mm since I was working in a machine shop with an imperial DRO.</p> <p>Untested. I am still waiting to cut the M12 x 1.5 threads on the driveside insert.</p> <h3>Design</h3> <p>Bunch of pictures I used for reference are included.</p> <p><a href="https://www.parktool.com/blog/repair-help/basic-thread-concepts#article-section-6">https://www.parktool.com/blog/repair-help/basic-thread-concepts#article-section-6</a> Front QR hub axles are M9 x 1 mm. QR skewers are M5 x 0.8 mm AFAIK. I included a very rough QR skewer &amp; hub axle CAD for reference.</p> <p>Both inserts are drilled out 6 mm deep since the hub axle protrudes nominally 4 mm beyond the OLD.</p> <p>I listed a bunch of imperial drill bits closest to the 5 mm QR skewer &amp; 9 mm QR hub axle close clearance fit - I ended going with #8 &amp; letter T bits respectively with excellent fit results.</p> <p>For reference, a Shimano FH-M615 hub specs about 5.3 mm clearance for the skewer (as opposed to about 5.05 mm with these inserts) - so much larger tolerances are acceptable.</p> <p>I went with 12 mm hex flats since a 12 mm wrench is pretty close to not clearing the fork dropout geometry. I don't have a hex broach for socket options, &amp; milling hex flats is very easy. This may be problematic as there's not much material to sit on the driveside, as you might be able to tell in the photos.</p> <p>Hex flats are 6 mm tall since McMaster tells me thin M12 nuts are 6 mm tall. I reused this dimension arbitrarily for the slip insert.</p> <p>Slip insert (unthreaded non-driveside) has a large-ish chamfer so you can pry it off with a slotted screwdriver should it get stuck for any reason.</p> <p>Untested OD for the M12 x 1.5 thread. I have read that usually the nominal diameter - 0.005" is usually sufficient, or 98%. I will test with the former.</p> <p>I did<em>not</em> end up cutting the thread gutter this time. This would be more helpful if you were to turn the threads on a lathe, but I'm not sure if it's useful for a manual die operation.</p> Category: DIY