Homemade jig

[hm123]

Hello everyone
I am new in this. Forum
My name is harel I from israel
And for my living I work with a carbon
I decided to build a carbon bike for my self
I build all carbon tube and the chain tube and seat tube
Now I build the jig I've read articles how to build it
I have a few question
How I put all the tube in the same line
How can I know that the head tube and the seat tube are in the same line
Are there any books on the subject or move
Or someone can help me
Thank you

[Andrew R Stewart]

In most jigs the BB shell is held in place with some sort of through rod with cones or pucks contacting the shell's edges. The rest of the main frame tubes are held so that they are in line with the shell. Sometimes held in blocks which split for access, sometimes by Vee block shaped devices (often with a clamp pressing the tube) and sometimes by a cone at the tube's end. The seat tube needs to be held at the correct angle as well. The head tube is held, often like the shell with a through rod and cones at each end. The head tube holding device will need to allow the head angle to be set and the HT to be located at the height and distance from the shell. Many jigs use a back plate and the rods and blocks are mounted to this plate at the correct distance from the plate to maintain all staying in line. The rear frame often has a dummy axle held in line with the main frame with some sort of stand off arm or blocks. The axle needs to be able to be placed at the height and length from the shell.

Your question is almost too big to answer in one reply. If you do some on line reaserch you'll find many photos of different jigs, how they hold tubes, the type of materials used, the amount of pre fabbed VS custom machined parts they use, the skills and tools that a jig maker might need to have to make a jig. Some are more machining focused, others try to use as many off the shelf parts. Some will have a large backing plate that is like a table thet the frame is held off of. Some will be a beam that runs under the frame and have arms extending up to position the tubes. Some will be like a wimdow frame surrounding the frame using members clamped to the surrounding structure that the bike frame parts are clamped to.

You need to do this looking at with as many jigs as you can. In time you'll see similarities and differences bewteen the jigs and their sub assemblies/tube holding clamps. In time you'll get a feel for what your capibilities can produce. And then you'll copy the one that seems best for you.

With metal frames good builders don't trust the jig to hold the St and HT in line, welding/brazing distortions can warp a frame held in any otherwise straight jig. So we depend on a precision surface to be the datum for the frame's line up. We often will spot tack the tube joints in the jig, remove the frame and check/correct then finish off the welding/brazing out of the jig where complete access can be had. How you'll handle the steps in the carbon/gluing process will be your challenge. And how your process/steps effect what you need out of a jig design wise is also your's to find out.

So your question is but the smallest of your steps to discover the world of frame building tooling. Don't expect much specific replies untill you refine and narrow your questions. Andy.