View Full Version : Epoxy the bolsters?


JNovak
03-05-2003, 11:10 AM
Well, I'm now a few hours into my very first knife. I've got the blade worked to a beautiful 600 grit finish and the bolsters ground and polished to their proper shape. I did most of my work on a disc sander with the bolsters super-glue together. This works pretty well but occasionally you'll need to re-glue as I'm sure the heat weakens the bond. The polishing and finish work I do by hand. I must say the bolsters are looking really nice-man I do good work! ;) How many of you epoxy the bolsters down before you pin them? I remember reading a 'how-to' recently that suggested you epoxy them to make a water tight seal. Is this neccessary? Thanks again for everyone's help!

John

Ray Rogers
03-05-2003, 12:34 PM
I consider it necessary to put something under the bolsters. Traditionally, this would mean solder. But, lately I have been using JB Weld for bolsters and guards and expoxy for the scales.

Even stainless steel will rust if water stays next to it long enough. No matter how good a it you do it isn't likely to keep moisture out completely if the knife is really used for anything so some kind of moisture barrier is needed. Many of the usual expoxies like Dev Con will soften if left in water long enough so I use the JB Weld on the metal parts and K&G Epoxy (similar to AcraGlas) on the scales.

I'm sure you already know this but I will mention that you should never rely on epoxy alone to secure bolsters or scales. There are a few knives for which this may be sufficient but for most the epoxy cannot provide adequate structural reliability. It is there as a moisture barrier and as a filler for small gaps....

JNovak
03-05-2003, 12:46 PM
Thanks Ray. It seems logical to me as well that there should be something layed down prior to pinning. I just haven't heard many people speak of it here and wasn't quite sure. I wonder if any of these epoxys can handle the heat it'll be subjected to after the bolsters are in place?

whv
03-05-2003, 03:06 PM
john -
i'd follow ray on this one. if you are going to use anything (and many do not) under the bolsters, jb weld would probably be the better choice i think. it is used to repair engine headers, so it should be able to take your finishing heat. then again, you shouldn't be getting to the temp that epoxy would let loose either.
another alternative is to attach with screws so that the knife can be dismantled for cleaning and maintenance.

Ray Rogers
03-05-2003, 03:07 PM
There shouldn't be any heat applied to the knife beyond that provided by a sunny day. Since no solder is used and the blade is already heat treated before the bolster go on, I can't imagine why anyone would heat up a good knife.

P.S.
Never put a good knife is a dishwasher either.....

JNovak
03-05-2003, 03:19 PM
The heat I'm refering to would be from finish grinding the bolsters. It seems to me that a good time to do this would be after they are pinned to the blade giving you something to hold on to. Am I approaching this all wrong?

Ray Rogers
03-05-2003, 06:36 PM
Oh, THAT heat! :D You can keep that heat to a minimum by using a fresh, sharp belt. I've never had any problem with JB Weld or epoxy from that type of heat. If you keep it cool enough that the blade's temper is safe then the rest of it should be OK too.

For what it's worth, I attach a blob of partially shaped steel to a finished (but not sharpened!) blade for a guard or bolsters and glue up and bolt on blocks of wood or Micarta(R) where the handle is supposed to be. The only pre-shaping or pre-finishing I do is on mating surfaces or areas I can't reach after the knife is assembled. Then, when the whole thing hardens into a big mis-shapen blob that vaguely resembles a knife, I start grinding and shaping....

JNovak
03-06-2003, 07:52 AM
Gotcha! I did pick up some JB Weld yesterday and applied it before peening the pins last night. On one side of the blade the pins mushroomed over real nice while the other side it looks as if the pins didn't quite fill the chamfers (in the bolster) 100-percent.
Maybe the pins needed to be a little longer or the chamfers were a little large, I don't know, but we'll see how they clean up. Is there a way to hide a blemish like this if you're left with a slight ring around your pins after grinding they flush?

Gary Mulkey
03-06-2003, 08:44 AM
John,

If you can see a void between the peened pin & the bolster before grinding the pins flush then there is a good chance that it will be more visible afterwards. If it were me, I would carefully drive out the old pins & replace them.

What do you have under the pins when you peen them? I like to have a slight dimple in my anvil (drilled around 1/16" deep) to allow plenty of pin to extend past the bottom of the bolsters in order to have plenty of material to peen on the second side.

Something that I have gone to doing rather than countersinking the pin hole is to drill part way through with a bit around .010-.015 larger than the pin. This gives a strong mechanical bond & is easier to peen without voids.

Gary

Jamey Saunders
03-06-2003, 08:44 AM
Whack them a couple more times with the ball end of the hamer. You'll have to grind the bolsters down a little further, but it sounds like you didn't get your pins swelled up enough. Next time, make them a little longer. The trick is to get them as long as possible without making them so easy to bend with a misplaced hammer blow. Making them stick out of the bolster by a length equal to the diameter of the pin is a good starting point. I like to make them a little longer, but I do bend them on occasion, which will make you learn some new curse words.:D

JNovak
03-06-2003, 09:32 AM
Thanks guys. The pins that were supplied were 3/16 dia. and were probably 1/16-inch longer per side. I layed the assembly on a flat anvil and peened them flipping it over to the other side every couple of blows. The problem I see using a flat surface is eventually when the pin swells and locks everything together it could be hanging out 1/8-inch on one side and nearly flush on the other. It's like you have no control or no idea when the pin will suddenly lock in. That's essentially what happened here I think. I was left with plenty of pin on one side and probably not enough on the other. I'm almost liking Gary's technique of dimpling the anvil and giving the pins somewhere to go on the bottom side. Or maybe I just need some practice.;)

Jamey Saunders
03-06-2003, 09:37 AM
Instead of dimpling the anvil (or whatever you're using), get a fender washer or two and set them on the surface. Then, set your bolster on top of the washers with the pin going through the hole in the washers and peen away. Basically, use the washers to space up the bolsters so the pin will come through far enough and not get pushed back into the bolster when you peen.

Works for me.

JNovak
03-06-2003, 10:33 AM
Yes, great idea Jamey. Now, if I could only turn back time. I'll be grinding them flush today at lunch time so until then my fingers are crossed.

John

John McPherson
03-07-2003, 07:25 PM
Make sure you clean the pins with scotchbrite or fine steel wool just before you use them. Any surface corrosion or dirt will leave a bullseye that will never go away no matter how much you grind.
The hole should be clean and smooth also. Some folks use a 1 or 2 degree tapered reamer to clean up drilled holes before pinning. Industrial supply catalogs will carry them.