Self Portrait

Over the years I’ve been asked about my weld sequence.  I’ve been asked it enough times and I’ve written it enough times that I think it’s about time I make it permanent here, in ink, on the 44HQ Blog.  Apologies for the radio silence for some time.  With all that’s been going on, I’ve honestly not been in the mood to do much writing.  Building and riding have been what my focus has been but I think it’s time to start writing again.  I’ve got lots to share and I haven’t not been thinking of writing.  But I digress.  Let’s roll up those sleeves and get into it!

You won’t find much of anything online about this sort of stuff. There’s a lot of ways to weld out a frame but over the years, I’ve arrived at a sequence I can repeat, minimize stacked tolerances, use heat to push/pull the frame into alignment and if there is an issue, troubleshoot. However, there are some concepts that I need to outline immediately. Call these simple points of interest:

– Metal moves towards heat.
– Metal moves when there is a gap. You can use that to your advantage or disadvantage…
– I build in sub-assemblies.
– My Process is reference point driven to avoid stacked tolerances and minimize movement.
– 3 points equal a plane. You’ll notice my tacking sequence establishes a plane between tube junctions.
– I will talk about points around the clock. These are simply to orient you, the reader, around the tube circumference.

Nomenclature: HT: Head Tube / DT: Down Tube / ST: Seat Tube / CS: Chainstay / SS: Seat Stay / BB: Bottom Bracket / DO: Dropout

Editors Note: this is a tacking sequence for Steel. Titanium requires a bit different timing to allow argon to pool and purge the inside of the frame. For steel, I simply set the back purge to 5 SCFH and let it run for 5 minutes and go. It takes surprising little argon to purge a steel frame and reap the benefits of a fully purged steel frame.

1. I build the chainstay sub-assembly first (dropouts, bottom bracket, chainstays). This is referenced off of the drive side of the BB shell, the inner faces of the dropouts and the dimples in the chainstays. Those are the reference points. Any inconsistencies in the stays, asymmetry, you name it have no bearing. Those 3 planes are all vertical, reference each other starting from the dropout and dummy axle interface and as long as those are maintained, anythign can happen between them. Flat mount adds a layer of complexity as those are technically perpendicular to these reference points and unlike ISO or Post Mount, are directly tied to the centerline of the axle and dropout which if you’re building them as separate units vs a complete assembly, can really complicate alignment.

– Tack the dropouts to the chainstays at 12 and 6 o’clock.
– Miter the BB/CS junction
– Now tack BB to the CS/DO assemblies. I start by tacking the two chain stays first towards the center of the frame then outside of the frame. Flip the assembly in the jig and repeat. So there are 4 tacks per chainstay/bottom bracket.

2. Once that is tacked, it’s loaded into my frame jig.

– Load seat tube in place. Tack at 6 o’clock facing you between BB and ST. Rotate and tack at 2 and 10.
– Now wrap from 6 out to 3.
– Wrap from 6 to 9.

3. Load DT into place. Load TT into place (sometimes I actually load the TT and ST in place at once to prevent the ST from pulling forward – depends on the frame size).

– Flip frame vertically. Tack DT to BB at 4 and 7 o’clock (this pulls the DT down and towards the head tube).
– Flip the frame horizontally and pitched forward/down – this allows argon to pool inside the head tube if back purging. Tack DT to HT at 2 and 10 o’clock.
– Tack TT to HT at 2 and 10 o’clock.

4. Flip frame vertically so ST is horizontal (This allows argon to pool inside the seat tube):

– Tack ST / TT at 2 and 10 o’clock.
– Keeping the frame vertical, tack the ST to TT at 6 o’clock.

5. Flip frame upside down so it’s horizontal (Again, this allow argon to pool and collect inside the head tube, DT and TT):

– Tack TT to HT at 6 o’clock.
– Run 4-5 beads across the underside of HT/DT connection at 6 o’clock (This a spot that gets a lot of pull on it when you start welding I’ve found – so I give it some metal!).

6. Flip frame back to right side up and horizontal.

– Run 2-3 beads between ST/DT connection.

See how all the spots in the front triangle are 3 points to equal a plane? See how I tacked the DO’s at 12/6 o’clock? That allows for some movement if I need to make corrections, especially the dropouts. Same with the main tube junctions.

7. Allow the frame to fully cool in the jig. When cool, pull frame out of jig. Make alignment checks. It’s far easier to check for alignment without the seat stays in place. Once you put the seat stays in place, you’re going to be really fighting any kind of correction. I can now use heat to pull the frame and correct it out of the jig if needed. Once I’ve done my checks and moved the frame using additional tacks/beads if needed, I put on the seat stays. Again, any correction needed to the frame must be done BEFORE you tack the seat stays in place. Cold setting will get you in trouble. I only use this as a last resort and it’s typically done when I put the bridges in place as they have a tendency to pull the seat stays together. And finally…

– Tack SS to DO towards the center of the frame, so drive side SS at 9 and Non-drive side at 3 o’clock. (this pulls them towards the center of the frame).
– Tack SS to ST towards center of the frame in same fashion as above.
– Wheel check or wheel check tool to check spacing.
– Now add second tacks to the SS/DO and SS/ST on the outside opposite of the first two pairs of tacks. I typically run a bead down the outsides of the SS/ST junction wrapping it under the seat stay. I’ll completely pass over this when I weld over the frame but it adds a bit more material in that acute area.

Done.