Can you clamp to tight for soldering?

blancefitz

Well-Known Member
I tried to silver solder 416 stainless bolsters to 416 liners on a slipjoint (my first try at a folding knife). I cleaned everything up really good and used Stay Brite flux that came with the silver solder and clamped the bolsters to the liners with tiny vise grips and soldered. I saw the solder pulled all the way to other side and there was a nice little line of solder all the way around, so I thought everything was fine. I put both liners together without spring and blade in and began to sand them both down about 1/16" or so to my finished size scribe mark and one of the bolsters came off. The solder had only flowed around the edges. The center where I had it clamped had no solder at all! I looked at and tugged on the others and another one was loose so I had to drill and pin them on and that was no fun at all. In fact it took me almost all day to do! Is it possible that I had them clamped too tight in the center and the solder couldn't get in there? I have no real experience operating a mill or lathe, but I do own a Shoptask Mill/Drill/Lathe combo machine. I am a self taught "farm boy machinist" and can make a pin or simple part for a disc or shredder without putting out an eye, but that is about it! I think liners with integral bolsters would be much better, but with my skill set I am not sure. Any suggestions on how to proceed?
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
it is entirely possible you did clamp it too tight.
Soldering is good skill to master and practice, practice, practice. For me it came down to learning not to burn the flux but still get it hot enough to etch the metal.
Once you get soldering down you might consider using JBweld instead. It's several times easier, cleans up in a snap and does a good job.
 

KCorn

Well-Known Member
Chris Crawford has an awesome tutorial on soldering bolsters on his slip joint DVD. He simply uses the small all metal spring clamps that you can pick up at your local hardware store for a couple of bucks. Just take the rubber end protectors off and clamp the liner and bolster together with just one clamp. Set your spring clamp in your vise at a bit of an angle to where the flux and solder will run downhill a bit into the bolster and heat gently from underneath the liner. Hope that helps!
 

blancefitz

Well-Known Member
I had one of the spring clamps your talking about and removed the end protectors and even ground the jaws down real narrow and re-shaped them a bit. Then for some unknown reason I decided to use the vise grips! I think I will practice a bit more on some scrap and try to break the joints loose and see if the clamp pressure was the culprit. I also like the JB Weld idea. Seems like it would at least give consistent results.
 

cnccutter

Well-Known Member
Tracy,can you talk a little about how your using the JB Weld putting on the boosters? How Are you clamping them? How long file you and start profileing , ect??

Erik
 

blancefitz

Well-Known Member
With solder on both parts how do you accurately place and clamp? Just wipe most of it off so it is an extremely thin film on each? I just found this site a couple of weeks ago and not only am I well on my way to completing my first folder, but I have gotten tips from Bruce Bump and Don Robinson! Life is good. And I mean real good. My wife said tonight, in regards to a KMG grinder, are you just gonna keep looking at that thing or order it. I think she may be getting a grinder for Christmas!
 

KCorn

Well-Known Member
Get the KMG. You will never regret it. It is one solid piece of equipment that will last forever. If you have to leave out any accessories due to cost I would just get the flat platen and the small wheel attachment with a 1/2 or 3/4" wheel. My 10" wheel gets used the least now that I flat grind everything. Just my 10 cents.

Bruce, I have soldered my bolsters just the way I described above after watching Chris Crawford do it that way and I never tinned the pieces first. I have yet to have a problem with my bolsters coming off. Does tinning make the joint stronger? Thanks!
 

Bruce Bump

Forum Owner-Moderator
The KMG is a fine grinder. Take her advice and buy it before she changes her mind.

Tinning both parts and clamping them together before the heat is applied is the best method. The spring clamps will squeeze out any excess solder and air in the joint. If the bolsters are exactly the same size as the liners it very easy to be sure they are aligned. I drill my bolsters and use a pin for alignment. If the pin is coated with graphite from a pencil the pin can be pulled right out.
 

oldknife

Well-Known Member
I use a spring loaded pin to hold things down when soldering, but if you have two mated surfaces and squeeze it tight the solder has no place to get a hold, so like a bolster I take my little air turban and put a trough all the way around it out towards the edge and then cross hatch the rest of it on both pieces then relap them, this gives the solder a place to get a hold, also do the same on the scales for epoxy, takes a little time but works for me. Deane
 

golafson

Member
Get the KMG. You will never regret it. It is one solid piece of equipment that will last forever. If you have to leave out any accessories due to cost I would just get the flat platen and the small wheel attachment with a 1/2 or 3/4" wheel. My 10" wheel gets used the least now that I flat grind everything. Just my 10 cents.

Bruce, I have soldered my bolsters just the way I described above after watching Chris Crawford do it that way and I never tinned the pieces first. I have yet to have a problem with my bolsters coming off. Does tinning make the joint stronger? Thanks!
which Chris Crawford episode was that?
 
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