# Dummy axles for dummies and cheapskates



## dr.welby (Jan 6, 2004)

So I've been working a building a mitering fixture for chain and seatstays. I was originally going to use the Anvil dummy axles because any smart cheapskate knows that they are easily worth the $30.

But I'm a lazy cheapskate and to make them work with my limited pile of metal just seemed like a hassle. I wanted to use some leftover 8020 but every design iteration just wasn't working for me. I also have this horrible fantasy of building a snow bike some day and the possibility of wanting to build an offset rear end meant I had to accomodate the remote chance I ever build one. I could just use a scavenged axle, but I want those little D-end tabs that keep the two dropouts aligned to each other.

I noticed that the 1020 extrusion has nice big cavity in the middle with a hole on either side - hmm, if I could run something threaded through the cavity with thread I could just hold it in place with a nut on each side. And that leaves the holes open to clamp the axle assembly to the rest of the jig with a T-nut.

That cavity has just enough room for 3/4" threaded rod. And I love threaded rod. But I don't have any sort of rotary table to duplicate the nice D-ends on the Anvil. But I figured I could just tap it for an M10 bolt and mill the ends to leave a tab sticking up on one side.

Sneak peak:



The question then was how to create the tabs on both ends of the axle aligned. I realized I had the perfect fixturing opportunity - since I'm going to put a nut on each side of the block, I can pin one of them in place with an 1/8" roll pin. I then have reference flats and can flip the piece over when milling the tabs. And I have a way to keep the axle centered when I loosen it to rotate the dropouts to the right angle. If I want to offset the axle later, I can just put a spacer in between the fixed nut and the slot.

Next question was how to keep the axle in the same z-position when it gets flipped. I figured I'd just use the nuts again - I put them in the lathe and made them so the tips of the points were all at the same radius. The bottom tip contacts the bottom of the mill vice, and I can touch off on the top tip and then move the cutter the required amount down to leave a 10mm wide tab.

On my first side the tab came out perfectly. On the other side it was a little off. I'm not sure if that was my mistake or if the threads have enough runout to cancel out the fact that the nuts were turned. The solution would be to turn yourself a little guage out of 1/2" rod that's 10mm on one end and 9.7mm (or whatever your drill size is for the 10mm tap) on the other. Then you can just move the cutter down and touch off on it and then move in and make the cut for the tab.

After I made the two cuts to make the full-width tab, I turned the axle 90 degrees, clamped it between the points and removed the unneeded tab on one side of the bolt hole.

For the 8020 mounting block, it was just a manner of boring a 3/4" hole through, and on one side milling down the edges square a leaving a set of small tabs in the middle that ride in the slot on the 8020.



So I post this for other garage bodger's inspiration, maybe you can see a better way to make something like this...


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## unterhausen (Sep 28, 2008)

For years I just used ... real axles. But I guess real axles are for dummies.


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## j-ro (Feb 21, 2009)

Dr Welby,
I have some anvil dummies, the D tab is nice to 'phase' the DO's, (although its a little loose) with your set up there you could replicate the 'D' with a roll pin or a tiny allen head screw with a 10mm head installed just below the hole for your bolt 
I have a boogered together 80/20 chainstay miter fixture set up on a little benchmaster mill. for the dummy, I used a piece of 1.5x1.5 130mm long ,the existing hole tapped to 5/16" I think and I just used 3/8" shoulder bolts. the two washers on each side space it to 135 for mountain stuff. I cut the axle piece in a chopsaw so it is decently square and paralle which provides a decent sized flat surface to hold the dropoutsl. I had the same desire to have it be as versitile as possible but figured if was to do something with a really wide axle I would just spring for another piece.


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## dr.welby (Jan 6, 2004)

j-ro said:


> Dr Welby,
> with your set up there you could replicate the 'D' with a roll pin or a tiny allen head screw with a 10mm head installed just below the hole for your bolt


I thought about that, but figured I'd never get the screw holes in the right place.



j-ro said:


> Dr Welby,
> I have a boogered together 80/20 chainstay miter fixture set up on a little benchmaster mill.


Cool! What's the source of those little V-blocks?


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## j-ro (Feb 21, 2009)

dr.welby said:


> Cool! What's the source of those little V-blocks?


 I made them myself , they arent the most accurate of v-blocks , I have to shim the left hand one. I plan on making another set one of these days. I'm also planning on putting a centering wheel in the center slot to help with set up. I think Vulture posted a picture of his fixture here somewhere a while back with one in use. He's sharp ,that Vulture


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## j-ro (Feb 21, 2009)

Oh Geez, I did'nt see that you milled the D into the all-thread, sorry about that, 
looks great!


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## dr.welby (Jan 6, 2004)

unterhausen said:


> For years I just used ... real axles. But I guess real axles are for dummies.


Real axles are for realists...


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