The DIY frame jig thread

the vast majority of builders dont weld/braze in the jig. Many would consider it bad practice. By brazing in the jig you can build stresses into the frame. Most people, myself included, tack in the jig then remove it...you have to be in control of the welding process so as not to warp the frame, but you dont have the capacity to build in stresses.

This only goes for tig/fillet brazed frames, IDK about lugs.

Ron cooper mainly used lugged. And I think they sort of hold the angles themselves. Just a bit of cold setting afterwards.
I've also seen a clip of seven cycles tigging up titanium frames that move quite a bit when building. They tack them up and change welding directions as it warps, constantly checking on a separate jig.

Hi bed_bug, sorry for he late response. The kit I bought was exactly what @PhilDAS shared, although you get a print of the jig design as well, should you chose that one.
I got the pieces because they seem to be fairly generic, many (most?) of the jigs use something similar.

I've paused for a bit because of life, and also because of the reasons @wildwest and @Biggles567 and @Rik_Van_Looy outline. I'm going to be building with lugs, and from what I am understanding (please correct me if I am wrong), the jig is not supposed to hold the frame in alignment through the brazing process.

This is a fundamental misunderstanding I had made - I have several jig designs on paper where I was looking to make sure the jig was fairly stiff and unlikely to deform.
I now think that the purpose of the jig is to hold the tubes in place accurately, but without any real strength, because that may lead to twisting/misalignment stresses.

For lugged frames, I am wondering whether I am better with a surface plate, a BB post and then to use the aluminium kit I got just to hold the tubes pretty loosely. That way I can check frame alignment with a dial gauge after each braze.

Did I see someone had bodged a 12mm dummy axle on here somewhere?

I need to mount what is left of a crashed Cotic BFE in my frame jig and don’t fancy paying for a 142x12 dummy axle as I’m unlikely to use it again any time soon. The dropouts and stays are all in one piece so I don’t need to do any brazing around it, it’d just be to hold things in alignment.

Ive seen people make them out of threaded rod, could do that depending on how your jig takes the DA

I did this and it worked okay.

I did have to re-do one dropout on the fork as it just had that slight cross thread feel. I hadn't used the biggest diameter tube that would fit in the axle recess shoulder (I don't know what to call that little lip that the hub sits on while you put the axle in). I did again with a bigger tube and all good. I reckon use the biggest tube you can fit in there for the most rigidity/best chance of square.

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That looks pretty good. Not terribly worried about rigidity and stuff as it’s just to hold the rear triangle in the jig while I track stuff to it so I think a budge like that will be fine.

I was totally unaware of these ideas2cycles jig parts. I was about to spend a load of time lathing stuff up. That's a bargain for what it is. (I'm a rubbish lathe operator). Just ordering now.

interesting jig from PVD
Bit of a long read, basically he just whacked it on a surface plate. Its cool, probably works nicely. Though im not sure how you're meant to get any tacks on the "table" side of the frame when its in the jig. He mightve mentioned it in the words, i skimmed it only.

http://www.peterverdone.com/the-pvd-cyberdyne-system/

Is this only for frame jigs? Anyway, if you're into crafting your own smaller jigs and fixtures too, I just uploaded some 3D- and dxf-files of my fixtures on my web page; kongabicycles.com. They are absolutely free but if you find them useful and would like to pay me something I won't be mad at you. :D

That looks great, do you have photos of the fixtures?

Stem jig.

Brake bridge mitering fixture.

Drill buddies.

Added my frame jig step-file on my website too.

Let's get this thread going again. @Biggles567 you mentioned wanting to use as many off the shelve parts as possible but your angle adjust situation seems quite involved?

Also, a little birdie told me another member wants to be added to the framejig list:

1. Tijmen
   
2. PhilDAS
   
3. Biggles567
   
4. @Brommers
   

Mine is a work in progress. Still making the stand for it.

We were discussing doing a group buy of laser cut plates for pivoting the seattube beam. Max came up with the adjusting mechanism above to avoid it going out of whack when bumped into / leaned on.

I'm thinking taking some inspiration from the simulation world and going for an angular adjustment plate like this.

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I've just lasercut a framejig from 5mm plate. The biggest issue you'll have is validating alignment once it is built. I did it via the long route using angle finders etc. for now. I'm currently figuring out how to make a laser aligner for this purpose.

I used wheels from a 3d printer on eccentric mounting nuts in place of a linear rail system. It holds alignment and has no slop. I'll update with photos of it assembled when I get into the workshop tomorrow eve.

The biggest issue you'll have is validating alignment once it is built

Do you mean the frame or the jig? I'm puzzling over what adjustment I need to build into my jig design to bring everything into alignment before loading the tubes. I suspect that having a fixed feature (probably the bottom of the head tube) and then threaded lateral adjustment for the BB, seat tube top and rear axle will the best way to handle it.

That then got me thinking about making tube blocks for mitring on my lathe, and how I might make and fixture those...

I'm thinking taking some inspiration from the simulation world and going for an angular adjustment plate like this.

That sounds cool

I think trying to build too much adjustment into it is a dangerous game. The jig i have at the moment is the LCFF. Its based around mild steel beams which are not straight. The jig has loads of adjustability so that you can move it, then realign everything.
In theory this is fine, in practice its a pain in the arse, a giant pain in the arse. Every time i want to adjust something, everything goes out, if you want to check how long the chain stays are mid mitring, your gonna have to realign it. Even when you spend 25 mins tapping stuff with a hammer to try and align it, its not always straight anyway. This becomes particularly apparent when working with through axle. Because there is no give in a through axle dropout, you have to be bang on out of the jig. If not the rim will sit off centre at the chain stays. Even when i have aligned it, i dont really trust it to stay straight, The alignment for the lcff is fiddly and annoying and i hate it.

sorry rant over.

as possible but your angle adjust situation seems quite involved?

Yeah not really set on it yet, im still thinking, have ordered some extrusion to have a play with, and see how it feels.

sorry rant over

Don't be! It's all good info.

I want to restrict the adjustment to one degree of freedom at each point so that you can position everything independently. It's all theory at the moment though as I haven't finished designing the jig, let alone built a frame...

Here's the pic I posted in your thread, and it hasn't moved on from there yet.

These 3 plates cad'd up quickly to prove the idea worked. A proper version TBC.

I wanted to use 3d printer wheels to ensure there was no slop in a plate which could both slide and have an angle adjust. usually with 8020 as you loosen a bolt the whole plate will become loose in the slot and weeble wobble about in all planes. the wheels limit the degree of freedom to 1. they're adjustable on eccentric nuts to take up any slop.

Also did a lasercut butt-feeler. For feeling butts

Nice. I've got a DTI set aside for my own butt feeler. Won't be lasercut though - I'll stick to what I know. Bits of leftover random bits of steel and a MIG welder.