# Equipco brakewheels



## Burl (Jan 2, 2008)

I have been experimenting... as many of you know, I have drawn up several styles of brakewheels in Sketchup and now offer them as a 3d printed part through shapeways. The equipco style I found to be impossible to print, due to the thinness of its style. My latest scheme was to etch it in .016" brass:










This is nothing new - I have tried this in the past. I'm happy with the result, but its painfully flat. I had tried stamping with a ball peen hammer before, but found the results unpredictable. But now that 3d printing has been opened up for us, I decided to try 3d printing a stamp. This is stainless steel:










Here's the result of the first stamping:










And here's what it looks like with a stem soldered on:


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## Cougar Rock Rail (Jan 2, 2008)

Hi Burl,

I had no idea what Shapeways or Sketchup was until I read this post--Wow!!!

What a great tool for the hobbyist--and a fantastic job you've done with the handwheel and press. 

Keith


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## SD90WLMT (Feb 16, 2010)

A little more refinement in the model department there Burl, looks great!!

Who is doing the etchings?

Boy - I am going to be .....w..a..y behind the rest of you by the time I get back to building models again....

Thanks for sharing this...
Dirk


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## Burl (Jan 2, 2008)

I did the artwork for the etchings myself, and had them produced through a 3rd party.


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## Garratt (Sep 15, 2012)

They look good but the only problem is that when you have stamped the flat etching the center has rotated slightly which has made the spokes straighten out. This has also made the center ring's curve distort.
There has to be a better way of doing the final shaping. Seems tricky though.

Andrew


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## Totalwrecker (Feb 26, 2009)

ooops


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## Totalwrecker (Feb 26, 2009)

Photo etch
Print, stamp/press etch.
A Boony Doon press might cause less distortion could use nylon dies to prevent damage to printed resist.


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## SD90WLMT (Feb 16, 2010)

Great learning lessons here!!
The original has the correct S curve..
But gets lost during stamping process.
Now one can calculate the difference and add to the S curve..thus making it exagerated in the flat expression, till it gets the final pressed form...
Bringing it back to the correct desired S curve..
Durn neer thar!
Great Burl!!!!!
Dirk


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## Burl (Jan 2, 2008)

I don't know what a Boony Doon press is... maybe someone could explain that to me.

The more I look at the stamping, the more I'm not satisfied with it. Dirk is thinking along the same lines as I was - exaggerate the curve in anticipation of the stamping process.

I'm also not seeing how a nylon die would be any better? There's no damage to the surface of the brass, only distortion in the spindles & inner ring.


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## Garratt (Sep 15, 2012)

The problem is that the spokes need to stretch longer to take on the pressed shape. Rather than keep their designed curl and become stretched and shaped they simply straighten out instead, distorting the work.
It may be possible to make a press that had a coarse thread that rotates as it presses the shape.
You don't actually want the item to rotate but rather to not rotate. If the press was to rotate slightly going with the curl when pressing while giving some slip it may keep enough influence on the pressing to maintain it's curly spokes rather than the item's center rotating back and letting the spokes straighten out which is the actual problem. 
That may not work either but one can only try.
A short square section of tube with a big nut welded over a hole and a large bolt with it's end shaped would make an easy rotational press. A coarse thread would have less friction over the surface of the work for the amount of depth pressed. 

Andrew


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## Burl (Jan 2, 2008)

Interesting idea, though I'm not sure I've got all of it in my head yet... wouldn't the whole brake wheel turn with the rotation of the die?


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## Totalwrecker (Feb 26, 2009)

thee Boony Doon is a hydraulic press. The plates move up and down.
My thinking was the strike of the hammer would erase some resist. Nylon dies can shape the metal with less distortion. Be hard to print in the saucer, flat is a breeze.

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underline added by site...


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## Garratt (Sep 15, 2012)

Only the center of the item is touched by the press at first so that would get the frictional rotation in a rotating press to theoretically stop the center from rotating backwards. May not work though and a rotating press may be problematic because it is dependent on friction and slip which may change as the press becomes worn producing inconsistencies.

There is two things happening. The spokes are straightening rather than stretching and the hub is rotating because it is a shorter path for the spoke. Even if you stopped the hub from rotating the spokes will still straighten out.

For such a small item it would be difficult to stop the inner hub from rotating in relation to the outer rim. It may be simpler to anticipate this distortion in the design. Work out the spoke length on the finished cupped item then make the curl in the spokes to that length on the flat etching. Remember though, the inner ring will need to be designed not as a simple circle because each segment will twist as the center rotates in the press. 
It may take a few designs to perfect. You can use the ones you have now to anticipate how much the inner circle segments twist. Good luck, it will all work out perfect eventually, just depends on how fussy you are.

Andrew


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## Scott (Jan 29, 2008)

Burl, I have had the same problem with some items needing to be minimum of 1mm thick for strength and printabilty. 

However, if you use the move tool you can bow that central portion out to the desired distance. It should still be able to print in metal - they make novelty jewellery with more fineness. 

If you can try that - it may mean one less proccess your manufacturing of the wheel. While also maintaining strength and stabilty.


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## Totalwrecker (Feb 26, 2009)

Burl,
My thought was to shape the disc before the etch. 
Assuming it's a photo etch, for repetition, the key to me is not hurting the printed resist on the metal.
Stamping the thin gives the most always.


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