Movement of the seattube pillar is intended, and would happen on the top face of the main extrusion. Only the rear axle assembly overlaps the main beam.
Spring loading that cone is genius!!! Definitely going to do that.
My sequence can vary a little but I usually have the seattube and bb attached already at the point I go to set up my fixture.
Oh, right, that makes sense if you’re building on stack/reach. I’ve just been adjusting the HT post until the miters all fit and the angles are right, which is not optimal.
How heavy is 3x3 compared to 1.5x1.5? I carry my jig back and forth between my bike mess & my garage brazing shop, so weight is some consideration, but having something that’s massive enough so that the weight of the frame doesn’t throw the center of gravity off is a big plus.
Before the sputnik I built this based on the Groovey based on the Grove fixtures. I imagine an 8020 version could be done.
I’ve heard that called a “picture frame” style jig. Topical as I’ve been meaning to post my lowbuck angle iron implementation. Recently added the jog of the ST rail to accommodate an offset seat tube.
Headtube axis is fixed, then you set the height of the cones. ST rail is just freely clamped in place at both ends. BB slides along bottom rail, with a screw to clamp in place, rear rail slides horizontally and the dropout slides vertically on the rear rail, with screw clamps to hold position.
I’m with you on the overengineering of a lot of jigs. Effbees are all “want the jig to show my angles,” I’m all “angles aren’t even the driving parameters in the first place, also, learn trig and/or ask your computer to tell you jig settings”
this is the style of jig I used before I got a bringhelli jig.
angle iron and all. It was more ore less sort of accurate
Looks like 3x3 is about 2.5ish times heavier per inch than 1.5x1.5.
Probably depends on how heavy your add ons are but I think you could use the 3x3 and still keep the whole fixture to 50-60lbs.
There are several schools of thought on fixtures for pros and hobby folks. My simplest break down- hobby folks get whatever makes you happy, and for pros get a tool that makes you money.
If I was doing some frames (as in, more than one) and had use for surface plate I’d be tempted to just use 123 blocks and basic measuring over making a dedicated fixture.
Building content:
@Orc did you post a pic of a forc with a front rack that was brazed directly to it?
No; but someone did and there was a discussion about whether that was a terrible idea or not.
Unframebuilding:
One thing to be said for silver brazing is that it’s really easy to melt brazeons and couplers off a frame. Sadly, even though I know how to silver unbraze I don’t know how to silver braze with acetylene, and everything I’ve read says that I should silver braze the (stainless) S&S couplers I just salvaged from a Rodriguez frame.
I also unbrazed some of the low-hanging brazeons so I can reuse them on another frame.
Damn my frame has reclaimed parts? That’s hip
It’s true that you should silver braze stainless always.
Silver is easier to braze. Harder to make fillets. The big difference is you don’t let the metal get to red hot before working with it. You watch the flux and when the flux is all wet and glassy touch some silver to it and see how flowy it is.
Alas no, unless you want me to glue a bottle opener onto it. I will probably use these parts on one or another of my frames (at least the coupled one; those highrise cable stops may be necessary to hoist the brake cable over the coupler wart) but aside from the shifter bosses none of these would really work for your machine.
Why not an internal brake cable with stops mounted on the ingress and egress of the tube? Open it up and use the cable connector?
I thought about it, but that’s fairly fussy compared to popping the coupler locks and folding the frame in half w/o touching the brake cable. The control & lighting wires are easy to do internally because those are compression fittings, but not the brake, and anything I can do to minimize the steps involved in stowing and setting up the machine is good.
Something that I found for silver brazing is to turn off the shop lights and use a flux-flare-cutting filter, then silver brazing temperature is about where it just barely begins to glow. As you feed in the filler it will suck up the heat which looks like a shadow moving behind the dull glow so you can see where it’s flowing to and react as needed.
ETA: these are the filter glasses I use. They’re a pretty good deal, fit over my large eyeglass frames and have adjustable temples. Flip up and lights off for silver, flip down for brass fillets.
That’s a hot tip! I’ve tried silver brazing with shade 3 and it was a disaster, I burned the shit out of the flux. I usually just braze with clear safety glasses which isn’t ideal but with oxy/propane I don’t think is too dangerous.
I’m going to get some of the ones with just the flare cutting lens.
@anon71759125’s frame staggers on towards completion:
A pre-fitting out (it doesn’t have any of the cable stops, shifter bosses, rear rack bosses, or bridges, or quickchainger, or whatever else needs to be glued on) ride to verify that the thing rides steadily and that none of the brazes were so crappily done that they’d pop loose when I looked at them funny.
Nice. I’m pretty sure if you left it like that and put it on the PYB thread, people would lose their gourds.
