Hi,
I have a friend who owns a company where Tungsten Carbide tooling is used manually in a long handle to trim aluminium; brass and steel whilst these are turning at speed and giving an intermittent cut; this cut is punishing to the tool tip and cheap tooling simply isn't up to the job.
During a visit to the works I was shown a TC tip that had failed this having been brazed in-house but a good example of the problem needing to be resolved. My friend had bought 22 high quality tips and asked if I could possibly solve the problem or have suggestions for him which of course I was more than happy to try. As I looked closely at the failed tool in my hand the tip had been thrown; it appeared to me the cause was a dry brazing joint; the guy who had done the brazing was called into the office and I asked him please to take his time and explain exactly his method of brazing the tip. He had followed normal brazing methods but one point really stood out; as the tool reached brazing temperature and the bronze filler started to flow he pressed on the tip with a screwdriver to bring the tip into close proximity with the tool body as the heat was turned off; on the face of it he had done nothing wrong at all.
I returned home with the TC tips and a short length of 3/8" square bright mild steel bar stock to experiment with. I've not done any brazing for about 50 years so here was a nice challenge although once learnt it's not forgotten; I still had a tin of brazing flux.
In the workshop I set about cutting the bar stock into short lengths; I was told it would be OK to simply braze the tip onto the end of the tool but this was the first change I made; I decided to form a recessed "land" for the tip so using hacksaw and engineers files I cut the land giving a snug fit for the tip. A lot of thought was given to the dry joint problem and if I followed the same method previously used my joints too would surely fail? I bought silicon bronze brazing rods but I also wondered if it would be possible to use silicon bronze in shim form? Unfortunately I couldn't find such shim on the web but I did find brass shim so I bought a small sheet of 0.5mm brass sheet to experiment with.
Having gathered everything and bought more bar stock I was ready but the dry joint was troubling me; how could I prevent a dry joint? I dreamt up an answer whilst in bed at about 3am thinking it over; could I gently center pop the land throwing up a circular round burr thereby lifting the tip giving a gap for the filler to flow but not be pressed out.
I was keen to try this out and fired up my big paraffin blowlamp; this proved useless the blowlamp wouldn't heat the tool to cherry red so I then tried my MAPP gas torch; it took a lot of heat but at last the tool was cherry red and the filler flowed. I had set the tool in the vice at an angle giving good secure access; SIF Bronze powder was mixed with a drop of water to form a paste; the paste was brushed onto the land then in turn the brass shim added and this was brushed with paste then the tip was added.
How could the tip be held in position during brazing; I had made a pair of "third hands" to use during TIG welding and one of these proved perfect giving just enough pressure. Care was taken not to linger with the heat once the brass melted and I was delighted when the tool cooled to see it had worked perfectly; I made a first batch of ten using the brass then the second batch I used the bronze filler rod this time dipping the hot end of the filler rod into the powder flux allowing the filler to run into the joint.
I must add that cleanliness is very important; the joint and TC tip needs to be very clean indeed; The tool body was clean after all the filing but the TC tips were very rough indeed; the only way I could clean these was to laboriously rub them on a bench diamond hone with water as lubricant; I rubbed the face to be the joint and also all four sides on each tip bringing them up shiny clean.
TC tips before honing and after honing; cleanliness is so important.
Here an hacksaw has been used to rough out waste for the lands taking a lot of care not to cut too deep.
A land being hand filed; note shoulder protection to run the file true.
The three shallow center pops I dreamt up in action.
0.5mm brass shim added; I even used 240G abrasive paper to scuff the new brass shim.
Tool bodies ready to receive TC tips with the experimental tool in front which was successful.
The brazing set up using the third hand.
Tool production under way.
The bench diamond hone which was slow but did a good job.
Here's an home made high speed diamond hone I made years ago using a cheap woodworking router.
Due to the raging Corona virus I posted the first batch of tooling to my friend and after testing he phoned to say he was delighted with their performance; later I posted the second batch of tooling and I was pleased both batches came up to expectations. My friend has a milling machine for adding lands on further tooling but I'm unable to visit due to the virus. I've requested he buy 50 more TC tips and sufficient bar stock because I'm keen to try something really different as an experiment; not the usual DIY project but something I'm interested in trying.
I like to experiment and at times I'm barking mad but nothing ventured nothing gained.
This is hardly basic DIY but I've now bought a commercial 1,950W microwave transformer but not to make a metal melter from I want to experiment making a brazing machine but I need to tame the power of the transformer to suit my needs; I've wound many transformers over the years so the work isn't new to me but using a transformer for this project is totally new to me.
Just to give an idea of what I'm dreaming up; I can't easily control the transformer output amps unless I add more secondary turns or add a load in series but my idea is to control the supply input volts and have bought a motor speed controller;
https://www.ebay.co.uk/itm/4000W-220V-AC-SCR-Voltage-Regulator-Dimmer-Electric-Motor-Speed-Controller-TE474/143081510744?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
Watts = Amps x Volts; by controlling the input voltage can I control the output amps? As I say I'm barking mad and need to be careful not to encourage others to follow my lead because a project like this at mains electricity supply can and will kill given the slightest chance; my problem is getting decent workshop time due to more pressing jobs around home and gardens.
If I can succeed with the brazing machine then another project involves induction heating; my friend with the business needs to anneal large stainless steel products so I'll look into this; in the meantime I've bought an induction heater to play with just to get the feel of it then I hope to build an induction heater from scratch to give industrial performance but without industrial costs?
https://www.ebay.co.uk/itm/ZVS-Induction-Heating-Board-Module-2500W-Driver-Heater-Tesla-Coil-Dual/193336955666?ssPageName=STRK:MEBIDX:IT&var=493528743914&_trksid=p2057872.m2749.l2649
I hope my ramblings are of interest; I'm never bored.
Kind regards, Colin.
I have a friend who owns a company where Tungsten Carbide tooling is used manually in a long handle to trim aluminium; brass and steel whilst these are turning at speed and giving an intermittent cut; this cut is punishing to the tool tip and cheap tooling simply isn't up to the job.
During a visit to the works I was shown a TC tip that had failed this having been brazed in-house but a good example of the problem needing to be resolved. My friend had bought 22 high quality tips and asked if I could possibly solve the problem or have suggestions for him which of course I was more than happy to try. As I looked closely at the failed tool in my hand the tip had been thrown; it appeared to me the cause was a dry brazing joint; the guy who had done the brazing was called into the office and I asked him please to take his time and explain exactly his method of brazing the tip. He had followed normal brazing methods but one point really stood out; as the tool reached brazing temperature and the bronze filler started to flow he pressed on the tip with a screwdriver to bring the tip into close proximity with the tool body as the heat was turned off; on the face of it he had done nothing wrong at all.
I returned home with the TC tips and a short length of 3/8" square bright mild steel bar stock to experiment with. I've not done any brazing for about 50 years so here was a nice challenge although once learnt it's not forgotten; I still had a tin of brazing flux.
In the workshop I set about cutting the bar stock into short lengths; I was told it would be OK to simply braze the tip onto the end of the tool but this was the first change I made; I decided to form a recessed "land" for the tip so using hacksaw and engineers files I cut the land giving a snug fit for the tip. A lot of thought was given to the dry joint problem and if I followed the same method previously used my joints too would surely fail? I bought silicon bronze brazing rods but I also wondered if it would be possible to use silicon bronze in shim form? Unfortunately I couldn't find such shim on the web but I did find brass shim so I bought a small sheet of 0.5mm brass sheet to experiment with.
Having gathered everything and bought more bar stock I was ready but the dry joint was troubling me; how could I prevent a dry joint? I dreamt up an answer whilst in bed at about 3am thinking it over; could I gently center pop the land throwing up a circular round burr thereby lifting the tip giving a gap for the filler to flow but not be pressed out.
I was keen to try this out and fired up my big paraffin blowlamp; this proved useless the blowlamp wouldn't heat the tool to cherry red so I then tried my MAPP gas torch; it took a lot of heat but at last the tool was cherry red and the filler flowed. I had set the tool in the vice at an angle giving good secure access; SIF Bronze powder was mixed with a drop of water to form a paste; the paste was brushed onto the land then in turn the brass shim added and this was brushed with paste then the tip was added.
How could the tip be held in position during brazing; I had made a pair of "third hands" to use during TIG welding and one of these proved perfect giving just enough pressure. Care was taken not to linger with the heat once the brass melted and I was delighted when the tool cooled to see it had worked perfectly; I made a first batch of ten using the brass then the second batch I used the bronze filler rod this time dipping the hot end of the filler rod into the powder flux allowing the filler to run into the joint.
I must add that cleanliness is very important; the joint and TC tip needs to be very clean indeed; The tool body was clean after all the filing but the TC tips were very rough indeed; the only way I could clean these was to laboriously rub them on a bench diamond hone with water as lubricant; I rubbed the face to be the joint and also all four sides on each tip bringing them up shiny clean.
TC tips before honing and after honing; cleanliness is so important.
Here an hacksaw has been used to rough out waste for the lands taking a lot of care not to cut too deep.
A land being hand filed; note shoulder protection to run the file true.
The three shallow center pops I dreamt up in action.
0.5mm brass shim added; I even used 240G abrasive paper to scuff the new brass shim.
Tool bodies ready to receive TC tips with the experimental tool in front which was successful.
The brazing set up using the third hand.
Tool production under way.
The bench diamond hone which was slow but did a good job.
Here's an home made high speed diamond hone I made years ago using a cheap woodworking router.
Due to the raging Corona virus I posted the first batch of tooling to my friend and after testing he phoned to say he was delighted with their performance; later I posted the second batch of tooling and I was pleased both batches came up to expectations. My friend has a milling machine for adding lands on further tooling but I'm unable to visit due to the virus. I've requested he buy 50 more TC tips and sufficient bar stock because I'm keen to try something really different as an experiment; not the usual DIY project but something I'm interested in trying.
I like to experiment and at times I'm barking mad but nothing ventured nothing gained.
This is hardly basic DIY but I've now bought a commercial 1,950W microwave transformer but not to make a metal melter from I want to experiment making a brazing machine but I need to tame the power of the transformer to suit my needs; I've wound many transformers over the years so the work isn't new to me but using a transformer for this project is totally new to me.
Just to give an idea of what I'm dreaming up; I can't easily control the transformer output amps unless I add more secondary turns or add a load in series but my idea is to control the supply input volts and have bought a motor speed controller;
https://www.ebay.co.uk/itm/4000W-220V-AC-SCR-Voltage-Regulator-Dimmer-Electric-Motor-Speed-Controller-TE474/143081510744?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
Watts = Amps x Volts; by controlling the input voltage can I control the output amps? As I say I'm barking mad and need to be careful not to encourage others to follow my lead because a project like this at mains electricity supply can and will kill given the slightest chance; my problem is getting decent workshop time due to more pressing jobs around home and gardens.
If I can succeed with the brazing machine then another project involves induction heating; my friend with the business needs to anneal large stainless steel products so I'll look into this; in the meantime I've bought an induction heater to play with just to get the feel of it then I hope to build an induction heater from scratch to give industrial performance but without industrial costs?
https://www.ebay.co.uk/itm/ZVS-Induction-Heating-Board-Module-2500W-Driver-Heater-Tesla-Coil-Dual/193336955666?ssPageName=STRK:MEBIDX:IT&var=493528743914&_trksid=p2057872.m2749.l2649
I hope my ramblings are of interest; I'm never bored.
Kind regards, Colin.
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