Holga-rific tilt-shift mechanism
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Well, I tried those files and none of my software liked them. Can you export to SolidWorks, STEP or IGES?
After some poking around with the helical sweeps, I’ve decided to redesign the front two bits so the threads end differently.
One of the things I was going to look closer at was the thread type you chose. I can’t really tell from the images at the Shapeways site but it looks like you are using a type of unifed thread or machine thread with a conical profile. Did you consider Acme threads (or some other trapezoidal form)? Not sure what material you are looking at (maybe plastic?) but sometimes Acme makes for smoother linear motion.
I went with equilateral triangle threads for the filter connection, and I should probably chop the points off and fill the roots of them for the standard profile, but I was lazy when I modeled it. For the focus adjust threads, I went with a square profile, since they can be printed w/o need for a relief on a cutting tool. I suppose that I should switch to a trapezoidal profile just to give more strength to the roots.
Now about clearances. I’ve got zero clearance on all the mating surfaces currently. I hope this gives enough stickiness for the tilt/shift/alignment bits. The material should be elastic enough to withstand stretching the female bits over their corresponding male bits. On the focus threads, I’m a bit more worried. They’ve got more mating surfaces, so should be stickier, hence the possible need for some clearance.
I tried exporting to Solidworks, but that bit isn’t included with the free license. 🙁 Furthermore, I suck at making drawings. I did step up my game and go for the ANSI thread profile for the filter screw 58 x 0.75.
I redesigned the whole thing. This is the most recent rendering. I have not uploaded it yet as I’m still working on removing unneeded volume to reduce the cost. Plus, I picked up some vernier calipers today at Harbor Freight to measure the bayonet flanges on the EF mount.
I added a Canon EF to 58mm female adapter to my models and ordered it. It’s gone to print and should arrive in about two more weeks.
http://shpws.me/gCoJ The purpose of this one is to test the bayonet mount dimensions and screw thread tolerances, and ultimately to allow using extension tubes and macro diopter filters to create a cheap long focal length lens, about 90 to 140mm.
I’ve also created and uploaded a 58mm female to female coupler, in case you’ve already got a 58mm macro reversing ring. Now, only time will tell if they’re any good.
Well, the parts arrived yesterday. I’ve got some dimensional problems. The bayonet angles work fine. The bayonet flanges don’t seem to have enough distance in front of them. Time for the sand paper. The threads work, but they’re really hard to get started. I may need to do some more reading of the Machinery Handbook. Once I get these straightened out, I might design an M42 adapter. How about an FD to EF-M?
My skydrive pics: http://sdrv.ms/QLn8f3 Really huge pics to show surface detail.
So that surface finish looks pretty rough, is that normal for this kind of prototype?
Yeah. They start with a powder and laser sinter to cross-link the polymers. I’d say it’s comparable to 600 grit sand paper, but not so sharp.
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