Having trouble soldering bolsters

B

Brian.Evans

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Aug 20, 2011
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I am having trouble tinning my bolsters. I think maybe I can't get them hot enough. I can get the liners to tin, and they end up shiny solder on them like they should. But on the bolsters, I can get the solder to melt, but it is dull gray and of course isn't sticking to the bolsters. It seems like I can't get the bolsters hot enough. Does that seem like an accurate assessment, or am I missing something here? I'm using a propane torch, if that makes any difference. This is on a slipjoint by the way.
 
A propane torch has many times the BTU output needed to solder on bolsters. That is not the problem

Clean, clean, clean...that is a must. Any surface dirt on it will stop the solder form flowing.
DO NOT OVERHEAT...that is a must. The metal only needs to get to about 400F to flow the solder
Do Not apply too much flux....that is a must. It will burn and make the solder not flow.
Scraping the solder around on the surface with a steel pick can help. This creates fresh surfaces for the solder to grab and start flowing. Rub the pick around and the solder usually will follow it. This works well for getting the seam to fill a spot on a guard that the solder is not flowing along.


What is the metal, and what solder are you using? ....many stainless steel won't solder without a special solder and flux.
 
What are the materials? and what are the solder and flux you are using?

My first thought is that it sounds like you may be trying to solder stainless bolsters to brass liners? I think this needs a more aggressive flux to deal with the oxide layer on the stainless, and usually needs a Silver-bearing solder. I'm sure someone who actually knows what they are doing will chime in though; it's a long time since I did any stainless soldering and I'm in the UK so any materials supplier advice I could offer would be near-useless.
 
Brass to stainless needs a silver solder. On bicycle frames we can use nickel silver, but it requires heating above the temperature of the brass. It might be appropriate for stainless to steel prior to heat treat though. Make sure you have the right flux, and the metals are freshly cleaned. Fluxes come in many different compositions and temperature ranges.
 
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It's not stainless. It will be nickel silver to nickel silver. The solder is from usaknifemaker. I think I had several issues.

Not clean enough
Forgot the flux
Didn't try to push the solder around with a pick
Using the wrong tip on my torch. The flame didn't look right, but I ignored it last night. I switched out the tips and the flame cone looked perfect. I think I had a plugged office in that other tip.

I will run to the store today and get silver solder flux. I was practicing on scraps, so no harm done. I was just at the part of the process that I was tinning the parts before clamping them together. My dry fit-up was as close to perfect as I could get. Lapped them flat on sandpaper on G10.
 
I was taught by a maker who is known for his fillets o solder, and as everyone has stressed cleanliness is key! I use radnor stay clean flux, and solder from usa knifemakers, my pre solder cleaning process is methodical, and I do a fresh light sanding of areas to be solder, even if the fit up is good. If the parts to be soldered have sat, light sand em again, next for me is a wipe down with acetone, then a hot wash with some dawn soap and water! But all of this is worthless with no flux though!:D
Greg
 
The most important part is Don't Over Heat.Use a soft flame and heat alittle and back off then heat alittle more till it melts.That was the hardest part of soldering for me,I was way overheating.

Stan
 
S.R. Johnson shows how to do the soldering with a heat gun. It works great. If you can find a copy of his video it is worth it many times over.
 
I just wanted to update the thread. I got my liquid flux in a few days ago. This morning I finally had a chance to try the new process. The flux makes the difference!! I have one bolster where there is no seam, and one where there is just a touch of a seam on the underneath side. I think my bolster n that side wasn't quite flat enough. All in all, I'm pretty impressed with it. I will be doing this again I think.
 
Good deal.

My friend has always had a fit soldering guards and but caps. I finally gave him a cheap HF heat gun. He makes perfect solders now.
 
It's about heat control. Both pieces to be soldered must reach the flow point temperature of the solder for the solder to flow. Like said before, cleanliness is also absolutely essential for a good solder joint. If you are using lead based solder and you see the flux turn black...stop and re-clean everything and start over. The flux is burnt and the solder won't flow. ...Teddy
 
Something that I have found that helps greatly during soldering is using a charcoal block, soldering pad, or firebrick to place the work on.
You don't want to solder on a heat-absorbing surface.
 
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