3d printed winding knob for Bronica ETR/ETRS

mgb74

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Thinking of traveling with my ETRS where space is at a premium. With 2 lenses, WLF, and without speed grip the setup is pretty compact. While I've used it without the grip or crank, a crank winding knob would be nice. But the prices for a used Bronica crank are ridiculous.

So wondering about some of the 3d printed solutions I've seen. I favor compactness over speed of use.
  • This crank is tempting, but not sure how it would stand up to even casual use.
  • This knob is probably closest to what I'm looking for.
Any suggestions from those who might have actually printed one?

TIA.
 

Dan Daniel

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OK, this is a little whacky but it worked really well. A metal cable loop looping connector (not sure of the specific nomenclature). I found that the right size fits the ETR wind knob. The pin goes through one opening. It was even sized so that it would 'lock' into either the folded in or folded out position. And winding was actually very smooth and didn't take a lot of force. I'd suggest going to a hardware store with your camera, finding the right size, and see if it would work for you. I wouldn't use to crank through a wedding but for most day to day use it is compact, cheap, and sturdy. Soften the edges if they bother you.

https://www.walmart.com/ip/3mm-1-8-...m-Sleeves-Clip-Crimping-Loop-100pcs/113233272
 
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mgb74

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@Dan Daniel Ingenious. I have used these to make cables, so might even have a couple laying around.
 

grat

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I printed the crank handle out of PETG, and it's held up quite well. I don't abuse it, but I don't baby it either.
 

4season

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Perhaps I'll try printing that knob at some point, but experience to date with similar objects suggests that it will probably be fine: It's a shape that's well suited to 3D filament printers, and I'd expect ordinary PLA fiber to work well. As for the crank, I don't think I'd want to print that with PLA (hard and somewhat brittle) but I wonder if glass-filled nylon would work.
 

grat

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Only reason not to print with PLA is the relatively low softening temperature. Leave it in your car on a warm summer's day and it'll look like something Dali designed. Glass filled nylon is going to cause a lot of issues-- you need a high bed temperature, and nylon in general is extremely hydrophilic. It's also going to eat your nozzle unless it's hardened steel. PETG takes a little bit to dial in, but once you do, it produces solid, slightly flexible prints that hold up well.

The crank handle is designed to be printed on it's side, so all the layers run the length, giving it strength in the right direction.

I've run through half a dozen rolls of film with mine-- probably printed at 0.2 layer height, although I don't recall.

 
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mgb74

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I had my son print the crank and knob on his low end 3d printer. Using PLA since that's what he had. The crank took a bit of fitting. The knob required some minor cleaning up and to have the hole enlarged a bit.

I think the knob will be robust enough; we'll see about the crank.

 
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