I was wondering how to remove and attach bolsters for handle fabrication or modification. Keep in mind I'm trying to use readily available tools, so I think forge welding is out of the question.
It depends on the knife and the bolster materials, some are integral to the tang and are forged with the knife as a single piece. If they are brass or nickle silver I would still attempt to leave them on and file/buff out any marring that happened and use a file, if necessary, to provide a true flat edge to mate with the new scales. If they are applied bolsters in that are loose or in bad condition they are often drilled and peened with matching pin stock the heads are filled, sanded and buffed which makes them invisible. They will blend perfectly with the bolster stock.
How would I go about attaching a bolster to a prefab knife?
Here is how I do it. I am assuming that the prefab knife is full tang and already has holes in the bolser area for pins to go through and is already flat.
Make sure both bolsers are flat and clean
super glue on to one side of the handle area
Carefully drill though the predrilled tang holes through the glued on bolster
Superglue the other bolster to the other side and drill through the holes in the opposide bolster and tang.
Remove both bolsters with a sharp smack from a hammer or by putting the bolster in a vise and twisting the knife
Clean up glue from all surfaces, acetone and scraping with a razor both work.
Pin the now removed bolsters together and shape the front and back to ensure they are alligned. Dont worry about the top and bottom at this time, you can grind them down flush with the tang when you shape the handle scales.
Peen the heads one end of each pin so they dome out
Put a drop of epoxy between the bolsters and the tang and insert the pins
Clamp bolsters and peen the other side of the pin head to create a mechanical bond between the bolsters, tang and pins.
Grind off the peen marks and finish sanding and shaping the bolster as necessary.
This is a quick rundown of the steps that I use and leaves out alot of little tips, tricks and methods that each person develops with experiance. If anyone has any input or other ways of doing it, I would also like to hear them.
I do the gross shaping with files so I do it a bit differently. I cut bar stock slightly over sized and flatten the mating surfaces on an engineering plate don't forget to flatten where the bolster meets the scales. Put them together in a padded vise to shape the front making sure they match well, that is followed with thin sanding strips of successive grits to remove file marks. I then use a padded vise grip to hold them evenly together and buff out with emery compound. This gives me a nice transition from bolster to face which can be difficult to clean up later. Then score the inside of the bolster and the tang of the knife staying away from the edge and inside the lines of my marks on the bolsters mating surface. This gives the epoxy someplace to go and increases the mechanical bond of the cured epoxy. I put a drop of epoxy on one of the bolsters and clamp to the tang. I use a bamboo skewer with a shop rag and solvent to clean up any epoxy squeeze out at the front and back where it could interfere with a tight fit to the scales. When the epoxy is cured I drill through the holes in the tang through the first bolster. I then attach the second in the same way making sure they are lined up perfectly and drill back through when set. I then add the pin stock and peen until domed and it has fully expanded into the hole, switching sides every few hammer blows. When all the pins have been peened I file off the heads and shape with the handle.
If you want to add bolsters to a blade that was not pre drilled for them you will need a carbide bit to drill them out first.
A couple things to add to the above:
Rule of thumb is one to 1-1/2 pin diameter out each side, excess length before peining. So, if total thickness of tang and bolsters adds up to 1/2", and you are using 1/16" pin stock, cut your pins 5/8" - 11/16" in length. Less, and the pins won't have enough to form a head before getting too short. More, and they will tend to bend and otherwise fail.
I find it helps to use a light ball pein hammer. I start the peining by very lightly forming a symmetrical head with the ball pein, then gradually upsetting it until the pins won't move anymore, flipping the assembly over as needed. When the pins begin to tighten, I switch to the flat face of the hammer, and hit the pin heads harder, finishing with pretty forceful blows. I feel that this helps the metal upset in thickness into the bolster stock, fitting tighter and greatly lessening the possibility of seeing the pins when ground and polished. Starting lightly with the ball end also helps the pins not to bend before they form a head and tighten up.
After hammering the pins tight/flat, I often go and squeeze the assembly in the post vise, with spacers to avoid the pins and concentrate force on the actual bolsters, to further tighten the bolsters and squeeze out epoxy, and then go back to the anvil for a few more hammer blows on the pin heads.
If you don't want to see the pins when the knife is done, try also not to get any epoxy on the pins when pushing them through. Glue only the bolster/tang joint. If the pin stock seems very surface oxidized, sanding the stock lightly with 600-ish before cutting it may also help to avoid visible pins. And as mentioned above, try when possible to use the same alloy for pins/bolsters. Nickel silvers have differing alloy quantities too, sometimes.
Lastly, I'd start with nickel silver to learn on. It's easier than stainless to work with. Just my $.02.