Full tang bolster assembly

maxcutter03

Well-Known Member
Two piece bolster assembly on full tang knives the way I was taught and the way that I do it.

I start by prepping my blade. I do tapered tangs so you will get to see how I do that. Most of these pictures are recent but I will have to dip into some of my older stash to present some things. Some of these pictures will be very large as I didn’t have a chance to shrink them down.

When I get my blade back from heat treat (HT) I will finish my hollow grind to my desired finish……usually mirror finish.

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Using my flat platen on my KMG I taper my tang. Notice the tape on the hollow grind.....Tape is out friend to ward off scratches on our finish.

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With my horizontal mount 9” disk I make sure the tang is as flat as I can get it. Then I will lap it on my surface plate and bring the ricaso area to a polish.

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Now I will mark the area where the bolster will rest with a sharpie and measure how long to cut the stock.

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Once I cut them out and get them flat on my 9” wheel. Just a quick explanation on how I get my stuff flat. I have a toggle light switch on my flat grinder motor which works like a foot switch. I set the piece to be ground on the disk, then, with my hip I turn on the grinder. This will assure I am flat on the disk and no oh @@#$ grinds.
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When the pieces are flat to my liking I drill my holes for my pins. No they are not glued together. They are flat enough that a drop of water will stick them together.
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I am working with tapered tangs so I have to have something to hold the knife’s center line horizontal. Thus this clamp that I had made my a machinist.
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One at a time I get the bolster aligned to the blade and get my holes done. I use 3/32” pin stock and drill with a #41 drill bit. This makes for a really tight hole. I don’t taper my holes. With the proper crush from a press or preening, the pin will expand all the way to the tang. Due to a small case of dumb a$$, I had to grind and drill one off. I cut the pin stock .250 or ¼” longer than the total measurement of the thickness of the bolster material and the tang.
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Now that the holes are drilled I can get on to shaping the leading edge of the bolster and setting my dove tails. Putting the pins into the holes I mock attach the bolsters to the blade and mark the shape of the bolster’s leading edge. I take it to the grinder and shape it and take it to polished finish. Because once it is on………..This is where my moment of short term dumb a$$came into play.…..you can’t work it to a finish without messing up the blade.
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In this picture I am grinding the dove tails into the bolster using my flat platen….I have since bought me a vertical grinder with a rest that can be set at an angle. This makes for a better fit and ease of dove tailing.
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You will have to mock fit the bolsters together to make sure your tails are even. Grind as necessary to make sure that you don’t have offset tails. Now we are ready to attach.
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With my press….well before the press I peened with a hammer….I compress the pins evenly into place, making them seem to weld themselves into place.
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Then I grind the bolster to get it ready for finish.
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Then I take it over to my band saw and cut off the excess and then grind the rest off with my grinder.
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I clamp the knife back into the clamp and attach my handle material. I grind my tails into my wood, then glue them into place one at a time. Drilling the holes for my bolts after each gluing.
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Once the glue is set and the holes are drilled and the bolts glued and tight, its time to start shaping. I bring everything to a shiny finish.
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Hope this was able to help someone.
 
that's a great wip, i've been wanting to do some bolsters, what type of steel do you use for the bolsters and pins ? oh and thats a fine looking knife you got there..

thanks jim
 
that's a great wip, i've been wanting to do some bolsters, what type of steel do you use for the bolsters and pins ? oh and thats a fine looking knife you got there..

thanks jim

Jim

I use 416 SS X 1/4" and 3/16" steel and also 416 3/32 rod for my pins. Using the same steel and rod from the same supplier will make for more invisible pins. If you can get the same run of pis and stock from the same company, you will get better results.
 
That's exactly how I do it. Exactly, except that you do it a little better! Two things I'd add:

1) with a tapered tang the angle is so small that while it is preferable to drill the bolsters like you did it isn't imperative. They can be drilled on a flat surface and everything will come out ok, especially if you chamfer the holes in the tang.

2) This is more of a question: You did a phenomenal job on shaping and keeping the bolster material even with the handle material. Since the wood is so much softer than metal I find this difficult to do, especially on my mega fast Craftsman 2x42. As a result I have taken to using a coarse half round mill ******* file for this final shaping. What do you do to get such great results on a grinder?
 
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That's exactly how I do it. Exactly. Two things I'd add:

1) with a tapered tang the angle is so small that while it is preferable to drill the bolsters like you did it isn't imperative. They can be drilled on a flat surface and everything will come out ok, especially if you chamfer the holes in the tang.

2) This is more of a question: You did a phenomenal job on shaping and keeping the bolster material even with the handle material. Since the wood is so much softer than metal I find this difficult to do, especially on my mega fast Craftsman 2x42. As a result I have taken to using a coarse mill ******* file for this final shaping. What do you do to get such great results on a grinder?


I do some filing with a round file. Then I take the platen off my square wheel and go into slack belt. If you split a belt down to about 1/2" you can carefully conture the finger choil then back to a full belt and blend the wood to the metal.

*******KEY #1******** use a sharp belt!!!!!!!
*******KEY #2******** take your time!!!!!
 
Excellent idea on using the same supplier for stock. I'll keep that in mind.
Good tutorial and beautiful work and knife.

Thanks.
 
Really great post. May I ask you at what angle you grind the bolsters at their mating surface with the handle material? And do you grind all four parts at the same time so you don't need to readjust the platen? Also, who is you material supplier? Thank you very much, Sir.
 
Excellent tutorial, Marvin. It was great to meet you and your wife at Blade and hope to see you again one day soon.
 
Nicely done tutorial.

Pretty much the way I do it. Only thing different is I put a _very_ thin coat of JB weld down before I put on the bolsters to serve as a seal against moisture. Almost all of it gets squeezed out.
 
great tutorial. Did you grind your dovetails for bolster and wood with the grinder set the same and just flip them to mate to make the proper complimentary angle?

I have a hard time getting that right with my grinder, even though it seems like I should be able to do it.

Question - I have a high torque mini mill, and I have been using it to flaten handle and bolster material. Couldn't I set my bolster material at an angle on blocks in the mill vise and cut the dovetail angles that way? I have the added issue that my tangs start to taper from the back of the bolster, which means that the handle dovetail has to be about a degree different from the bolster dovetail so the handle material sits flush.

Hope my question makes sense - use the mill with material set on angle blocks and held in vise to cut dovetails, then use same angle setup plus about another degree to make accommodation for change in knife shape between bolster and handle material?

thanks for this, it has gotten me inspired to finish two of the knives on my bench.

kc
 
Thanks Max. great post. It is always helpful to see how others do it. After viewing this I am gonna change my bolster procedure a bit..looks like your way is easier.

Kevin
 
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