Print PDF
Favorite
Email
Here's a jig for building bicycle frames. This design is something I've been slowly picking away at for several years. Being both a cheapskate and not having much in the terms of machine tools and/or skills to use them, I've slowly come up with this design.
It's based off the easily available 8020 extrusion, and repurposes a lot of the 8020 small parts. I've tried to make every part requires as little machining as possible. In many cases, I've designed individual parts so that they can be initially made with as little tooling as a drill press, and slowly replaced with nicer machined parts as time/money/tooling allows.
If you want to machine all the parts yourself, you will need a small lathe (a 6" mini lathe is big enough) with a four-jaw chuck and a milling machine (or a milling attachment for the lathe) to make some of the parts. All the machining is simple and would make good practice in a community college machining class, if you don't have the machinery. If you do have to take it to a machine shop, it shouldn't be too expensive.
This Instructable doesn't give exact dimensions or step-by-step instructions. I've left it slightly vague to encourage the builder to customize it. If you want to build BMX frame or XXL 29ers you might want to change the overall dimensions. I've also some included some fancier or alternate parts to consider, if you want to make a nicer jig, practice your machining, or just have an easier time spending money than I do.
In case you're wondering, I don't have plans for sale at the moment. However, if you like the design, you can show your appreciation at my Amazon Wish List. If you get stuck on a part let me know in the comments and I could post more detailed plans. I have some parts drawn in Autocad.
This design and accompanying directions are licensed under the Creative Commons Attribution/Share-alike license. That means you can do anything you want with this design, as long as you give me credit, and allow derivative works to share this license. If you want to machine parts for this design and sell them, go for it. Heck, if you want to build full jigs and sell them, that's fine with me. Just give credit, and maybe buy me a beer if we ever meet. If you do make and sell new and improved parts for this design, I'd love it if you could send me one of your parts too.
It's based off the easily available 8020 extrusion, and repurposes a lot of the 8020 small parts. I've tried to make every part requires as little machining as possible. In many cases, I've designed individual parts so that they can be initially made with as little tooling as a drill press, and slowly replaced with nicer machined parts as time/money/tooling allows.
If you want to machine all the parts yourself, you will need a small lathe (a 6" mini lathe is big enough) with a four-jaw chuck and a milling machine (or a milling attachment for the lathe) to make some of the parts. All the machining is simple and would make good practice in a community college machining class, if you don't have the machinery. If you do have to take it to a machine shop, it shouldn't be too expensive.
This Instructable doesn't give exact dimensions or step-by-step instructions. I've left it slightly vague to encourage the builder to customize it. If you want to build BMX frame or XXL 29ers you might want to change the overall dimensions. I've also some included some fancier or alternate parts to consider, if you want to make a nicer jig, practice your machining, or just have an easier time spending money than I do.
In case you're wondering, I don't have plans for sale at the moment. However, if you like the design, you can show your appreciation at my Amazon Wish List. If you get stuck on a part let me know in the comments and I could post more detailed plans. I have some parts drawn in Autocad.
This design and accompanying directions are licensed under the Creative Commons Attribution/Share-alike license. That means you can do anything you want with this design, as long as you give me credit, and allow derivative works to share this license. If you want to machine parts for this design and sell them, go for it. Heck, if you want to build full jigs and sell them, that's fine with me. Just give credit, and maybe buy me a beer if we ever meet. If you do make and sell new and improved parts for this design, I'd love it if you could send me one of your parts too.
Remove these ads by
Signing UpStep 1The Frame
The frame is built out of 8020 #1530 extrusion. I used the standard 1530 extrusion - there is also a 1530L extrusion that is a little lighter that you could probably use, especially on the adjustable beams that hold the tubes. This would make the jig a little lighter and cheaper
You could probably even build it out of the #1020 extrusion and it would be just fine.
The overall dimensions I used, which should work for most mtbs and large road frames, are 30 inches tall and 51 inches wide. If you want to build 29ers with long-travel forks, you might want to scale everything a couple of inches taller.
At the lower right hand corner the two frame beams are held together with a #4334 Inside Gusset Corner Bracket, so the lower beam is shorter - 48 inches long.
The other three corners are held together using just 16mm M8 buttonhead bolts and 8020 Double T-nuts. The beams are drilled to provide allen wrench access to the bolt heads.
Assembly is easy. Use a T-square to get each join at a 90 degree angle. Tighten it down.
You can order 8020 extrusion and parts from a variety of resellers - see 8020's web site. If you're in the Western US, I highly recommend F & L Industrial Solutions.
We'll look at the rest of the parts in the order they would be adjusted to set the jig up to the right dimensions.
You could probably even build it out of the #1020 extrusion and it would be just fine.
The overall dimensions I used, which should work for most mtbs and large road frames, are 30 inches tall and 51 inches wide. If you want to build 29ers with long-travel forks, you might want to scale everything a couple of inches taller.
At the lower right hand corner the two frame beams are held together with a #4334 Inside Gusset Corner Bracket, so the lower beam is shorter - 48 inches long.
The other three corners are held together using just 16mm M8 buttonhead bolts and 8020 Double T-nuts. The beams are drilled to provide allen wrench access to the bolt heads.
Assembly is easy. Use a T-square to get each join at a 90 degree angle. Tighten it down.
You can order 8020 extrusion and parts from a variety of resellers - see 8020's web site. If you're in the Western US, I highly recommend F & L Industrial Solutions.
We'll look at the rest of the parts in the order they would be adjusted to set the jig up to the right dimensions.
| « Previous Step | Download PDFView All Steps | Next Step » |
great design! I just wanted to ask a question. How long should the button head bolts be? Are they all the same length? Thank you for your time
Chris
So you get the seatpost in place, you get the head tube in place, leaving it a tad loose, and then you cut and grind and machine the top tube until it fits perfect. then slide the head tube over a tad to hold it via friction.
When everything is in place, I guess a few tack welds or a bit of braze would let you take the frame out of the fixture and then weld everything 360.
8020 is awesome! Tinkertoy/Lego/KNEX/Erector for grownups.
will post pictures here when i am done doing it.
once again bravo.
Also if my main jig is level, then I can measure tube angles with a digital angle finder.
on a different note, since i don't have access to a machine shop (or rather, i'm trying to keep things relatively inexpensive), I thought spheres might be just as good as fabricated cones for the seat tube, head tube, and BB brackets. To that end, i thought a few of these might get the job done: http://www.amazon.com/gp/product/B00062YZSA/ref=ox_sc_act_title_1?ie=UTF8&m=ATVPDKIKX0DER
only 8 bucks a pop, free shipping, no fabrication, and they already come with a tapped hole!
Thanks for putting this together, I look forward to putting one together.
On a technical level, as an extrusion the aluminum will distort in more unpredictable ways than mic 6 aluminum tooling plate when it is heated. But if you're that concerned about accuracy., you shouldn't be making this jig.