Currently I’ve make some 3D design exploration for custom machined dropouts and IS52/56 head tube for my next own brand steel frame product, my Columbus tubing is ready just missing those parts. Also currently, brazing is my only way
Context why I asking this: There’s lack of CNC vendor and machinist for steels in Indonesia. Even they are exist, their capability only for alloy CNC or and with conventional milling machine, low to average quality, lack of technical and material knowledge, very long query (1-2 months just for 1 steel ZS44/EC44 head tubes), and kind a in pricey spectrum (high MOQ’s).
After doing some research…
I found 3D printing and CNC vendor from China and Taiwan who have that capabilities—long story short—I try their CNC 4130, 1018 steel and 3D printing resin services in very small batch, their quality is very good (precision and finish) for the price. And they have 3D printing for alloy AlSi10Mg, stainless 316L, and Ti TC4 with SLM printing method. Then I wanna try more of their 3D printing services + push my 3D design skills.
So, as the thread title suggest—because they (Chinese vendor) didn’t have 3D printing for steel 4130/1018/similar and I never braze/weld stainless steel before…
Is it possible to braze/weld 316L stainless with steel tubing?
If yes, any tips/prep suggestion for better result, please? filler rod spec? anything to avoid?
@project12 is right, lower persentage might work tho. Get the proper flux, something like Cycle Design Stainless Light Flux. Clean everything really well with sandpaper and acitone, including the rod. Try to have good heat control when brazing, silver flows a lot when it gets too hot.
Stainless is a poor conductor of heat so you end up putting a bunch of heat in to get it to work and then you go over board with it. Takes a bit more practice to get consistently good at it. If you want to braze use 56% silver and good overlap with a slip joint…or just TIG it.
You will want to use one of the silver fillers 35-48% for fillet joints and then 56% for lugs/lap joints. You will need the appropriate flux as well. Cycle Design has what you need.
I find using a softer flame makes it less likely to overheat a spot and burn the flux. As Devlin said, Stainless doesn’t conduct heat like 4130. Once you burn the flux, you stop, find a way to clean it back to bare metal and then start over with new flux etc. The silver won’t flow where the flux has been burned. The common tendency, when you see the filler not flowing into a gap, is to add more heat to make it flow. At that point, you’re already over the edge and you’re going to have to start over. Use a lot of flux and low temp soft flame.
Does anyone have any experience using G-72 rod to braze stainless to 4130? I’m doing some practice joints now and not having a lot of success getting the g-72 to wet out onto the stainless and then it just gets burned up real quick.
For reference, am using Type B flux, G-72 filler rod, an in-line gas fluxer, and practicing with a piece of 304/304L .083" thick tubing to scrap pieces of .025" wall tubing. My plan is (was) to braze .035" wall stays to paragon 17/4 sliding dropouts. I figured if I can figure it out on these thicker/thinner tubes, I shouldn’t have any problems with the main dropouts and stays I plan to use. On my second attempt I was able to get a solid joint, although it 's not the prettiest and still ended up overheating the flux in a lot of places in an attempt to get the filler to flow anywhere. I also undercut both tubes quite a bit in order to smooth out the edges just to see what it would take.