Brazing Help wityh Lathe

[Andrew R Stewart]

What... yes I have a need to use a torch on a lathe. More to the point the steady rest that came with my new to me 1952 SB 9" C lathe has a broken pivot eye. I'm not sure if it's a cast steel or iron. I've done the initial cleaning and prep for the repair, adding a reinforcement "rib". Next would be a thorough sand blasting of the eye's half of the part before torch work. I use Gasflux B flux and their CO4 brass.

Questions are about the cast nature and if iron or steel do I need greater consideration about heating then usual. Photos attached.

And the 3J collet chuck needs to find a home.

Back story- I have had a toy lathe (Atlas 6" Mk2) new from 1980. It has done a bunch of fun things but the less then robust construction finally got to me. It sold off Craig's list in 36 hours for over 75% of my cost, 40 years ago. AndyIMG_2441.jpgIMG_2443.jpg

[EricKeller]

It doesn't appear that there is anything special about brazing cast iron. I have looked at it because of woodworking tools.

Does that collet chuck thread onto the lathe spindle?

[claritycycler]

Looks like cast to me, but either way its done mostly the same. Put a small bevel on the edges, clean really well, preheat very important for cast(slowly and evenly), use plenty of flux. Not too different than brazing steel bike tubes, but a slow cool down in sand(or other insulator) is recommended. I've probably made 4-5 repairs on cast wood working machines over the years, this worked well for me, they all stayed to together(at least when I still owned them). Google brazing cast, probably find a bunch and more than I know. Given your experience with brazing you shouldn't have any trouble.

regards, Brian Clare

[e-RICHIE]

https://www.velocipedesalon.com/foru...ons-43597.html

[Andrew R Stewart]

Brian- Thanks, pretty much what I thought. I've read of the slow heat cycling and cracking when not followed. Since this cast joining stuff is pretty old there's a lot to read up on that dates from the previous century. I see that the "before me" brazing repair seems to lack a tinning of brass on the fracture face. I'd like to think that it's because of haste or inexperience by the guy who tried to repair this before I got it. I'll post a follow up when done.

Why a steady rest and framebuilding? I've made my own lugs from .058" walled tubes and with to thin down the tube walls before any other work. Will this work? I'll see:) Andy

[Doug Fattic]

Andy, way back in the late 70's I bought a dry flux in a 1 pound can from my LWS that was made specifically for brazing cast iron. I think I still have it but the label has come off so I'm not sure it is what I think it is. I had to braze something cast iron and what I vaguely remember was heating it up very slowly until it got red and it took forever to get up to temperature. You might call GasFlux and ask them for their opinion of filler and flux for cast iron.

[Andrew R Stewart]

So I thought I'd follow up on this thread. I finished the repair of my steady rest. The brazing was a bit challenging. The cast material did react differently then the rolled strip that is the reinforcing rib. I took some care in both prep (sand blasted and thorough cleaning) as well as a lengthy preheat. Still the CO2 filler seemed to not like wetting out on the cast surfaces. But in the end I got reasonable penetration, the rib and the cast are well attached now. The clean up went as after brazing does and I out the parts aside to paint later.

But as it goes then need to use it came before the paint did so yesterday I used it (first time I've used a steady rest) to hold a sleeve for a unicrown fork's steerer. It worked as I think it should and today I brazed the sleeve onto a steerer (which is currently soaking off the flux). Thanks for the help and continuing motivation to try this. Andy