Frame building fixtures.

APL

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Aug 6, 2018
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Thought I'd open up a thread on fixtures of various types and designs, frames, forks, whatever. Pictures, links, parts,
anything fixture. Just to get this stuff in one place so people can get ideas on the good, the bad, and the ugly.

It seems that there is no such thing as a perfect fixture, they all have some good and bad points, and there are some
differences between brazing, welding, and bonding. Also, home building, and production fixtures.

Show us what you have, or have seen. :)

(it's always a good idea to keep pictures down to 150 kb or so, or they might not load, or disappear in the near future)
 
I'll kick it off with this three part link, while I dig around for photos of some others that I have seen, or used.

https://www.mtbr.com/threads/a-small-contribution-about-frame-jigs.890411/

https://fernandoj.wordpress.com/2013/12/31/bicycle-frame-jigs-23/

https://fernandoj.wordpress.com/2014/02/14/bicycle-frame-jigs-34/
 
The problem with most diamond frames, is that they are a road bike design first, and make a poor conversion to e-bike.
No place for batteries, direct drive only, and the dropouts aren't made for big motors, nor are they made for the extra
weight and speed.

Same goes for many of these fixtures,.. road bikes. If were going to make electric bikes, then dang it,.. we need e-bike
frames! And so, we need e-bike compatible fixtures as well.
 
I have copied this style of bean fixture made of cold rolled steel.

https://www.instagram.com/p/BZmynChHBbI/?igshid=j2atdytk9qjs

https://www.instagram.com/p/BGNGTMnwBjp/?igshid=12734dqb4n59q

https://www.instagram.com/p/BOlz-S0gB6M/?igshid=1klwqqsxlq0lr

I don't seem to have a good pic of my own with a frame in the jig but this is an older frame posing in progress.
https://www.instagram.com/p/Bkgcw-mhdRq/?igshid=920r60cl0ik4

The cold rolled steel is good because it's close enough dimensional that you can register off the jig and use pieces of cold rolled to set spacing in the jig. It's also much cheaper and the usual 80/20.

I also like doing my frames with the head tube rotated to 90 degrees. All locations can be measured and set in X, Y coordinates from my CAD model.

I need to make a rear end specific jig for my full suspension bikes, I have built several in position in the jig and getting all the pivots and shock mounts to line up is a pain.

Something like this but from cold rolled.

https://www.instagram.com/p/B_CzP_hlzhK/?igshid=cnngzdf549ld
 
Thanks for this thread. However...the images are not all accessible***, and won't be there any longer than the external site hosting them happens to have them around. If you attach them directly to your post using the attachments tab, they will then be visible to anyone that can see the thread itself, *and* they will stay with the thread regardless of what happens to the rest of the intarwebs. ;)

***all I can see for linked instagram images is a white page with a camera icon in the middle.... :(



When i make the new trike, maybe I should build a fixture (or set of) for building the frame. Previously my fixtures tended toward stacks of bricks holding things up or spacing them apart, tack welding, then ensuring it all fit "close enough", and welding it good and solid. ;)

While the resulting frames do work, they aren't exactly "square" or straight. :oops:

For instance, on SB Cruiser, when I built the cargo / seat box, and the back end cargo area, I had to individually clamp each board in place, cutting it as I went, gluing down and then adding the next, and the next.... Would've been much more convenient if I could have built panels that just bolted in place, knowing it was already all square and the same on each side, etc. :lol:


Building a jig for something like Cloudwalker (nee' CrazyBike2) may be rather complex. It has square and round tubing, and some "complex" angles (no curves though).

Most of SB Cruiser (and probably it's successor, whatever that ends up as) is just square or rectangular sections, mostly 90 degree connections, just about all square tubing.
 
I could see the instagram photos, but I couldn't copy one, and I worry about copyrights, so we'll have to find one like it.
A very nice fixture though, and looks like it will work very well. I think about making one similar to that often, and I like
the easily obtainable square tubing aspect of it.

We call this the bean fixture,.. a friend of mine from Masi/America at the helm, it's a modified table fixture with cut-
outs for accessibility.

Masi 'bean' table fixture..jpg

And this is Tim Issac's rotating fixture, that I've had a chance to use for a while. You can spin it around to help with
brazing. Interesting, and works well, but I didn't like the bottom bracket holder all that much, so I would just tack it, and
take it out to braze it later. It also has a built in fork jig. (picture shows it upside down)

Tim Issac rotating fixture..jpg

Nothing wrong with building like that amberwolf, for some frames you have to do it that way. It doesn't pay to make a
fixture thats 'too' complicated for one off projects, especially trikes and such, which tend to be wide and spacial. And if
your welding then you only need the moment to get the 'tack', and then the fixture can be dismantled.
 
Interesting thread.

Calfee Designs sales a line of DIY Bamboo Bicycle Frames. Among other things that they have is a "jig kit" that is basically some fixtures that the end user attaches to piece of plywood or other sheet material. The following URL is for their intro "introduction" video that includes a segment showing the setup of the jig.

https://calfeedesign.com/introduction-video/

Bike Jig.png
 
Thats awesome LewTwo, lots of ideas there. Those guys that are bonding frames have it made! Glue it together and watch
it dry. :wink:

Man, I didn't know that bamboo was that thick!
 
After just free-styling it on my ebike builds for the past 12 years, I'm gonna build a jig...

Something easy like this one https://www.youtube.com/watch?v=0NdjDi95NFA
but long enough and with 4"x 4" uprights so I can do the wheel holding like this guy does https://www.youtube.com/watch?v=I8qUFJlgul8 4" spacing between the horizontal rails is so I can fit moto rims too, and I'll just maintain the 4" width and have plenty of wood spacer pairs to be able to center all size rims. I'll stick with the 4", so all of my fixtures to the jig will keep their center.

I'm tired of worrying until the end whether wheels will perfectly align, and now that I'm doing some mid-drives too I need to get drive and wheel sprockets or pulleys aligned on the same plane too. With all the time I could spend fiddling with adjustments at the end and clamping and supporting and balancing stuff on a table, I think the frame jig will save enough time to pay for itself on the first build.
 
I think your right, the horizontal 4x4 rails as a base, and able to insert wheels is a grate idea. Gives you a nice base for
all the other add on's, and can be more universal. Being able to put the wheels in while your building is a super good idea,
like you say, wheels, chainline, and length is questionable until the thing is built, and then you have to go backwards to
correct it. I like the second video,.. lots of great ideas. :thumb:
 
APL said:
I think your right, the horizontal 4x4 rails as a base, and able to insert wheels is a grate idea. Gives you a nice base for
all the other add on's, and can be more universal. Being able to put the wheels in while your building is a super good idea,
like you say, wheels, chainline, and length is questionable until the thing is built, and then you have to go backwards to
correct it. I like the second video,.. lots of great ideas. :thumb:

Yeah, the old guy in the 2nd vid had good ideas, which is where I got the tire clamping idea, but I don't want to lose centering of any fixtures, so I came up with the fixed 4" spacing between the bottom rails and I'll just have different thicknesses of wood and plywood to be able to wedge tires tightly and centered. Just being certain that my wheels will be true and on the same plane at the end will be worth building the jig. I've hated that uncertainty before and during assembly. Sure I can always fix issues, but they are time consuming. Plus with a frame that fits batteries in the way it's often hard to tell if the wheels are true until getting out on the road and following someone else riding the bike to get a good look. Starting with the wheels perfectly true and the exact wheelbase I want will be such a nice change.
 
I have a fixture, but I think people that don't have one might consider following Paul Brodie's minimalist approach. Although he does tend to run to the lathe or mill when he needs something. https://www.youtube.com/c/paulbrodie/videos
 
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