Hey, whatever happened to the talked about group buy thing if we collectively decided on a forum sub $1000 jig design? Are we still doing that? If not, any way we can get a group buy together for like some Paragon cones or subassembly plates or something… and then everybody does there own preferred jig design?
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I apologize for the lack of updates on this project. The NMW business has really taken off, so I’ve been strapped for free time to drive these projects. Thankfully other members (IE. @dogtag) are helping to keep the project going. I will have more time to revisit this fixture project in the fall with fresh eyes and new knowledge from the frame building “industry”.
This question has given me the chance to reflect on this fixture project:
Thanks to all the posts from the community, I have a better feel for how hobbyists build bikes, the target tolerances, and the tools they have access to. I have recently experimented with .25thk bent sheet metal parts from Send Cut Send, and have been very impressed with the stiffness and accuracy:
At the moment, I think the final form of this entry-level fixture is an MDF style with .25"thk steel bent sheet metal risers. Geometry would be set by manual drafting or by printing out a 1:1 drawing. In addition to the fixture, I would design a tool to both check alignment and calibrate the centerline of the risers. Finally, a separate CS sub assembly fixture (also on an MDF board) would be really nice to have for accuracy.
This has been in my head for a while, I just haven’t had the time to design and test it! My schedule free’s up after August, so hopefully I can get hacking on this again in the fall.
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Hey everyone, this is my first post.
Thank you @Daniel_Y for starting the forum and this thread, it is very informative and inspirational.
I have a couple of (maybe very basic) questions concerning the indexing of the moving parts on the aluminium extrusion…
A 10 mm key in a 10,2 mm slot is too sloppy, right?
How do you deal with the potential “inaccuracy“ of the extrusions slot?
First buy the extrusion and then machine/print the keys to fit the slot perfectly?
Between Bosch, item and Misumi, is there an brand that is more precise when it comes to this?
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@Benjamin How conveniently, I just made some! I made some pins to locate the plates on the 8020 rail by turning them on my lathe to the dimensions of the 8020 rail gap and the 6mm hole in the plates for the Open Source Bike Fixture.
I bought extrusion from 8020.net and it seems very consistent. Also, I noticed that even though my tolerance was all over the place for each plastic pin, varying from 8.10 to 8.25mm diameter, the acetyl plastic deforms easily enough with minimal pushing. The slightly larger pins made the plates really snug on the 8020 extrusion
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1.) Depends on the length of the key really… if ist’s short and you’re trying to make something that has the correct angle or perpendicular, then 0.2 can result in quite a lot of angular sloppiness
2.) I made the keys as long as possible and also built in a bit of adjustability if they were too snug or loose
3.) I used ITEM and also those 0.2mm are taken from their spec sheet. This is just a tolerance though, most profiles end up being a lot closer to spec than this. I don’t know if other manufacturers claim to be more accurate but I doubt that. The extrusion process is what it is, if you like to achieve tighter tolerances, you could try and mill out the slots to 11mm maybe?
Thank you @Dogtag and @Luniz82 for your response!
I don’t have a lathe or mill, and have to depend on a milling service. I think I will first buy the extrusion and check if the slots are close enough and if buying dowel pins or key stock makes sense.
I have a little Prusa printer and could print well fitting keys in PLA or PETG. @Daniel_Y I saw in an earlier post that you did that. Do you think they would hold up long term?
@Luniz would you mind telling me where you bought the key stock for your fixture?
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I think the plastic key would be fine. The issue I ran into was slot is 8mm wide but the 8020 nuts were only really available in 6mm. That does not leave enough material to be strong enough. Alternatively, I think you could laser-cut brass keys, and just sand them down till the correct fit.
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I just ordered the ideas2cycles kit, and the seller mentioned that they’re moving and are looking to clear out their stock. Knocked 20 euros off the price.
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The Keystock I used was from Fixmetall-Shop: – Fixmetall Online Shop in Germany. It’s called “Keilstahl” in German
@Luniz82 Thank you for the Link!
@Daniel_Y Thanks for the suggestion!
I started drawing up a budget fixture, which I would love to get some feedback on at some point (not an engineer 
).
I will hopefully make enough progress in the next month to be able to post something here.
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Are these MIC-6 aluminum plates? How thick did you go?
rattleCAD provides settings for different types of frame jigs:
rattleCAD 4.0 - Bicycle FrameBuilding CAD - Main Design Principle - Geometry
for any idea to improve rattleCAD I am very grateful. In any case: please do not hesitate and just contact me
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I have been using RattleCAD for years. Awesome program! Thanks Manfred!
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3D model of the rattleCAD frame jig:
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Hey Dogtag! Do you have any photos and updates with your jig build? Curious how the dummy axle is fixtured.
Hey there!
I haven’t solved that quite yet, but I 3d printed a block that holds the average Paragon dummy axle and bolted it to one of the plates. I had to set the project aside for the summer, but I hope to get back to it now that the weather is cooler. 
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Maybe it is just where I am (Calgary AB, Canada) but extrusion is SO EXPENSIVE.
Just wondering if anyone has used 30x60 sized aluminum extrusion for their frame fixtures? I imagine this size would be fine for forks, stems, etc but worried it might not be stiff enough for an entire frame.
The local 3d printing shop has smaller 20 series 20x100 and 20x80 but when I look at my 3d printers, I’m not sure I’d trust that size to hold up a bike frame.
I do have a crazy idea of using a steel beam back bone of some kind and somehow bolting on some 40x40 extrusion (fairly inexpensive at the 3d printer shop).
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The backbone of my fixture is 40x120 extrusion and I recon that is too flexy so I would be hesitant to go any smaller. I was thinking I might get a plate laser cut to bolt to the back of the extrusion to stiffen it up but I use the rear slots for full squish shock points and whatnot. I think I will get a 120x120 backbone at some point. If you have a look at @SoyWater 's yt channel you can see he put an mdf backer on his to stiffen it up.
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Could you like to the YT channel? I tried to search for it but just come up with soy drinks 
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lols probably should have been more specific eh!
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