Stainless Tab Dropout Advice

[cblandford]

Hi All -

Working on a Rohloff frame, and I'd like to use the purpose-built Paragon Rocker rear dropout. Tab-style stainless.

I'm comfortable brazing 4130 with brass - and I'm comfortable sweating silver - but I haven't yet brazed a stainless dropout. I know this has been covered, but I was hoping for some targeted feedback.

Here's what I'm working with:

Oxygen/Acetylene (~7psi/6psi), Smith 203 Tip
Reducing flame (tiny hint of a rumble... ~1" in cone size.)
CycleDesign Stainless Light Flux
CycleDesign FilletPro Filler
Tab and slot both cut to 10mm, for 20mm overlap

Here's my first practice attempt:

I followed my usual brass-brazing process. First, tacked the "ears" and sweat the slots:




Quick(!) photo, then, filled it up.




I completely guessed on filler amount and just went for two good gulps down on each side (which felt unforced), and then capped off the top.

When I sliced it open, I got sweat to the bottom of the tab, but only a full plug to about the bottom of the slot, if that. This is the bottom ~2-3mm of the tab.



Questions:

1. Any advice on flame size/type? I found the fill portion here challenging - do you sharpen up your flame at all once everything is evenly sweat to target the heat more easily as with brass?
2. How much filler do you expect to stick in a stainless tab dropout? Is the goal a full plug all the way to the bottom of the tab as with brass?
3. Any other feedback based on photos would be great.

Thanks in advance, as always. Once advised, I'll give it another shot!

-Chris

-
Chris Blandford
blandford.chris@gmail.com

[Eric Estlund]

1. Flame size and shape will depend quite a bit on how you move your torch. Play around as you are until you are comfortable.
2. When in doubt, more is better. Try uncoiling a section of equivalent volume to what you would use with brass, then add a bit more.
3. It's tricky to build below the drop out as too much heat will just blob the silver down, and too cold will stop it part way. Keep playing until you get a sense for how much is going in and can predict your results.

[cblandford]

1. Flame size and shape will depend quite a bit on how you move your torch.

Eric - Thank you very much. As a quick follow up before I keep playing... Is there anything inherently wrong with using a neutral (or at least more neutral) flame for this type of silver joint?

-Chris

-
Chris Blandford
blandford.chris@gmail.com

[Eric Estlund]

Not in my experience.

[cblandford]

Practiced a bit more:





I switched to a Smith 201 tip and used a small, neutral flame. Felt much more natural - like brass but requiring my moving more quickly. That is encouraging. Eric - thank you for your tips on the flame front. I'm also finding that consistently moving drippy flux from the stay back up to the dropout mouth during the process kept things from burning away so quickly.

Upon inspection, I feel much better. I don't have a full plug, but there's at least a little fillet on all sides of the tab, down 20mm to the very bottom.

I'll cut a couple more practice pieces, and then have a go at the Rockers. Thank you again for your advice. Let me know if anything looks concerning.

-Chris

-
Chris Blandford
blandford.chris@gmail.com

[steve garro]

IMG_3443.JPGIMG_6323.JPG

Feed in around 16" of 1/16th rod = same as a bronze joint.

I've done hundreds of these.

I use 45% or 50N interchangeably and a custom personal mix of type H and type U fluxes from gas flux.

You need a tight fit

Feed filler down the tube as well as on the plates.

Spearpoint your stays before you feed filler as it will allows you access to farther down the tab and require you to file less silver off.

Ron Sutphin once told me to look at the shiny dust between your feet as lost profits.

- Garro.

[cblandford]

Thank you Steve - that’s a great help.

One further question: in comparing your photos to the Rockers I have on hand, I’m curious... did you tab the dropout at all? Or just slot?

And, fortunately (or unfortunately, perhaps), my shiny dust will merely represent wasted purchase. Can’t lose profits from a hobby! (I will shape the stays, though... Thanks!)

PS. Ron taught the 2nd UBI course I took... and still uses that line.

-Chris

-
Chris Blandford
Blandford.chris@gmail.com

[steve garro]

IMG_3244.jpgIMG_3247.jpgIMG_3253.jpg

Thank you Steve - that’s a great help.

One further question: in comparing your photos to the Rockers I have on hand, I’m curious... did you tab the dropout at all? Or just slot?



PS. Ron taught the 2nd UBI course I took... and still uses that line.

-Chris


Chris Blandford
Blandford.chris@gmail.com

- No, I do not modify the tab beyond knocking back the little ramps a bit so I can get at least 13mm and better 15mm of slot depth.

They were made for more of a cap design, IMO.

Ron fuckign rocks - I love talking to that guy,

My class over 15 years ago was Ron And Mike DeSalvo teaching.

- Garro.

[cblandford]

- No, I do not modify the tab beyond knocking back the little ramps a bit so I can get at least 13mm and better 15mm of slot depth.

They were made for more of a cap design, IMO.

- Garro.

That's awesome. I've wondered how those were done.
Thanks for sharing - I will report back with my results.

-Chris

-
Chris Blandford
blandford.chris@gmail.com

[cblandford]

Got these done this afternoon:






Steve - I did not disregard your advice on slot-only. But, I had already cut the tabs before you chimed in so I just went with them. I did, however, deepen my slots and knock back those little ramps to increase my total overlap to 16mm. I will remember that for next time, though... I now see that there there are a lot of dropout designs where a tab would be awkward. Good to know either way works.

Shoved 16"+ of filler into each of these. Little drippy, but I think they'll clean up.

Thank you both again. Your willingness to share your acquired knowledge is very much appreciated.

-Chris

[steve garro]

Got these done this afternoon:


-Chris

Looks good !!!!

offsetting the slot to one side will also allow the L insert to travel through it's entire swing without hitting the stay
- Garro.

[cblandford]

Looks good !!!!

offsetting the slot to one side will also allow the L insert to travel through it's entire swing without hitting the stay
- Garro.

Thanks!

That makes a lot of sense. I hadn't even considered it, which shows you how much I know... When/if there's a next time, I'll definitely keep that in mind.

-Chris