Hi,
I have a friend who uses lots of TC tipped tooling for trimming metal spinning. This tooling is secured in a long handle and used manually it being subjected to extreme forces.
Whilst visiting a couple of weeks ago he showed me a tool which had failed after an attempt to braze on a TC (Tungsten Carbide) tip. I closely inspected the failed joint and it looked like a "dry joint" I asked the guy who had done this joint as to his method; he ran through each stage but right at the end he had pressed down on the tip to seat it? Perhaps this excluded the bronze filler?
I came away with 22 TC tips these at 3/8" square x 1/8" thick and a short length of 3/8" square BMS to experiment with.
It's over 50 years since I did this kind of brazing but then I was working in the pit with top class kit like oxy/acetylene. All I have in my workshop is a paraffin blowlamp and a Rothenberger cartridge blow torch.
The tool bodies are 2 1/2" long. I was told it would be OK to simply braze a tip onto the body end but I thought I'd go a bit further. After cutting to length then marking out I cut out each recess by hand using hacksaw and engineers files; I don't have a mill but I do have a lathe; by the time I set the lathe up I could do the job by hand; I was taught to file flat to a thou of an inch as an apprentice so I enjoyed the exercise.
I gave a lot of thought to the actual brazing and not wanting to end up with dry joints I did a bit of online research;
https://vacaero.com/information-res...-joint-strength-vs-joint-clearance-chart.html
As I type the tooling hasn't been tried in anger but in order to prevent a dry joint I came up with the idea of adding three light center pops to each tool "land" this would throw up a low raised circle for the tip to sit on? I also canted the tool body in the vice during brazing to ensure the bronze ran fully into the joint?
I split the tools into two batches; the first batch I used brass shim cut to size. The tool land was fluxed using paste SIF flux mixed by adding powder to a drop of water and stirring; this was brushed on; the brass was cleaned using abrasive paper and a shim square placed on the land then more flux then the TC tip making a sandwich. This worked very well indeed the only snag was keeping the tip fully aligned.
The second batch I added the center pops but used 1/16" Silicon Bronze filler rod the end of the rod heated and dipped into the powder flux. As before I set the job up and for good measure brushed on flux before adding the tip but I found my "third hand" to be extremely useful resting this on the tip. It was very satisfying to heat to cherry red from below and watch as the filler rod melted and ran the joint length; at this point I removed the heat.
The TC tips as supplied had very poor faces so I hand honed each joint face on my Trend diamond bench honing stone; I also honed all four edges of each tip; the tips were left soaking in Acetone overnight and before brazing I vigorously wire brushed the tool body end using a stainless steel wire brush then these in turn were dipped into acetone. Cleanliness is important.
This might seem long winded but I enjoy my workshop time and like to try ideas out; I'm now keen to see how the tooling stands up to use. Time now to get off my backside and wander down to the workshop.
Kind regards, Colin.
Brass shim.
Method using third hand which worked a treat.
A number of finished tools.
Preparing lands by sawing and filing.
Bulk of waste removed using hacksaw; quicker than it looks.
Light center pops.
Hand filing shoulder guide in use.
Tool bodies ready to receive tips.
Before and after honing using the diamond hone; this was the tedious part but well worth it.
These are my own metal spinning tools; the bottom one has an HSS insert for trimming; trimming during metal spinning is highly dangerous; the two top tools are 42" long with 2" dia pitch pine handles; these are small compared to industrial hand spinning tools where 3" dia handles are used with longer lengths; considerable force is required using these tools; I broke a rib and many metal spinners too have broken a rib or two. Metal spinning is a fascinating process.
I have a friend who uses lots of TC tipped tooling for trimming metal spinning. This tooling is secured in a long handle and used manually it being subjected to extreme forces.
Whilst visiting a couple of weeks ago he showed me a tool which had failed after an attempt to braze on a TC (Tungsten Carbide) tip. I closely inspected the failed joint and it looked like a "dry joint" I asked the guy who had done this joint as to his method; he ran through each stage but right at the end he had pressed down on the tip to seat it? Perhaps this excluded the bronze filler?
I came away with 22 TC tips these at 3/8" square x 1/8" thick and a short length of 3/8" square BMS to experiment with.
It's over 50 years since I did this kind of brazing but then I was working in the pit with top class kit like oxy/acetylene. All I have in my workshop is a paraffin blowlamp and a Rothenberger cartridge blow torch.
The tool bodies are 2 1/2" long. I was told it would be OK to simply braze a tip onto the body end but I thought I'd go a bit further. After cutting to length then marking out I cut out each recess by hand using hacksaw and engineers files; I don't have a mill but I do have a lathe; by the time I set the lathe up I could do the job by hand; I was taught to file flat to a thou of an inch as an apprentice so I enjoyed the exercise.
I gave a lot of thought to the actual brazing and not wanting to end up with dry joints I did a bit of online research;
https://vacaero.com/information-res...-joint-strength-vs-joint-clearance-chart.html
As I type the tooling hasn't been tried in anger but in order to prevent a dry joint I came up with the idea of adding three light center pops to each tool "land" this would throw up a low raised circle for the tip to sit on? I also canted the tool body in the vice during brazing to ensure the bronze ran fully into the joint?
I split the tools into two batches; the first batch I used brass shim cut to size. The tool land was fluxed using paste SIF flux mixed by adding powder to a drop of water and stirring; this was brushed on; the brass was cleaned using abrasive paper and a shim square placed on the land then more flux then the TC tip making a sandwich. This worked very well indeed the only snag was keeping the tip fully aligned.
The second batch I added the center pops but used 1/16" Silicon Bronze filler rod the end of the rod heated and dipped into the powder flux. As before I set the job up and for good measure brushed on flux before adding the tip but I found my "third hand" to be extremely useful resting this on the tip. It was very satisfying to heat to cherry red from below and watch as the filler rod melted and ran the joint length; at this point I removed the heat.
The TC tips as supplied had very poor faces so I hand honed each joint face on my Trend diamond bench honing stone; I also honed all four edges of each tip; the tips were left soaking in Acetone overnight and before brazing I vigorously wire brushed the tool body end using a stainless steel wire brush then these in turn were dipped into acetone. Cleanliness is important.
This might seem long winded but I enjoy my workshop time and like to try ideas out; I'm now keen to see how the tooling stands up to use. Time now to get off my backside and wander down to the workshop.
Kind regards, Colin.
Brass shim.
Method using third hand which worked a treat.
A number of finished tools.
Preparing lands by sawing and filing.
Bulk of waste removed using hacksaw; quicker than it looks.
Light center pops.
Hand filing shoulder guide in use.
Tool bodies ready to receive tips.
Before and after honing using the diamond hone; this was the tedious part but well worth it.
These are my own metal spinning tools; the bottom one has an HSS insert for trimming; trimming during metal spinning is highly dangerous; the two top tools are 42" long with 2" dia pitch pine handles; these are small compared to industrial hand spinning tools where 3" dia handles are used with longer lengths; considerable force is required using these tools; I broke a rib and many metal spinners too have broken a rib or two. Metal spinning is a fascinating process.