Fitting Brass Bolsters on Stick Tang Knives....What Am I Doing Wrong Here?

M

mhutch

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Mar 1, 2015
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Hey fellas,
I'm new to knife-making (but not new to screwing around in the garage!) and working on my first Scandinavian stick tang knives. Well, kind of working on them. I'm still on step one...making and fitting brass bolsters. I have some brass bar stock that I've been cutting up, and to start I drill a few tiny holes where the tang will go through, connect the holes with a jeweler's saw, then use needle files to fit. This particular blade does not have a full flat grind so there's a small peak/ridge in the middle of the blade's width as see below.
5156.jpg

Needless to say, filing the hole to fit this contour perfectly is a real chore. On the first bolster that is what I tried to do but the fit didn't turn out as tight as I'd like. I read online that a lot of folks make a bolster with a slightly under-sized hole and then press-fit onto the tang. This sounded like a good bet to me so I tried it this time. The fit on this bolster, shown below, actually turned out a little worse. By hammering the brass bolster onto the tang I believe I stretched or deformed the brass a little bit.
IMG_4138.jpg


Did I use too much force here? Just how meticulous does my tang hole need to be to achieve a tight fit?

Any advice is greatly appreciated

Thanks,
Matt
 
I could be wrong here, but I would have left a ricasso and the tang flat. Then you wouldn't have to contour the bolster to an angle. I'm unfamiliar with a Scandinavian flat tang but most of the images I saw googling it have a flat ricasso.
 
I'd suggest grinding the tang down some more, so it's a taper all the way to the blade in every direction.
If you're handy with soldering you could make that disappear, but it's best to learn how to fit guards well to start
 
getting a good fit is not easy, but it looks like you did pretty well. that would disappear with solder but you hammered on it so it is not flat. i would not try to press fit a guard less than 1/4" thick because it will deform. when you get the guard about 1/8" away from where you want it to be, hold it up to a light and note where where the light shines through the crack, and where it is touching the tang. file only the areas that are touching with a needle file, and repeat until the guard sneaks up the last 1/8" of the tang.
 
When people hear it can take 3-4 hours to get just the guard finished and fitted they just stare at you blankly.

Watch this series
 
Caffrey does great videos. Everyone should take the time to watch all of his. Even if you know how to make knives, you'll still pick up a trick or two
 
Lightly tap around the gaps with a ball peen hammer, refile the slot and make the face of the bolster flush again
 
I cheat. I often make the tang slightly thinner than the blade (not more than maybe 0.5mm for structural reasons). This gives me a little wiggle room and lets me silver braze the guard on without having ugly silver lines visible from the front.
 
I found that in some cases Dremel is excellent for this job . Up to 5mm thickness works fine , especially for thin opening in bolster . Depending on the thickness of tang I use one , two, three cutting discs at once ....Of course depending on the width I use adequate cutting disk Dia. This is bolster for 1.5mm thick tang on kitchen knive .With a file probably would be impossible to do it . . .

tHXeMi0.jpg

NtMjMBR.jpg
 
Assure the tang is tapered away from the blade so there is no binding until the guard seats at the shoulders.

Stupid as it sounds, unless there is absolutely no way you can put the guard on backwards, mark the back side with an arrow pointing to the spine. That way you know what orientation to put the guard while fitting it.

Carefully file the guard and test fit every few strokes - NOTE - You can take a few more strokes to remove more metal if it is still snug, but can't put even one stroke back on if you filed too much.

File the slot at a slight taper, so the back side is wider than the front. This will apply all the snugness in the front, and you can be sure it isn't the back side that is sticking. On a guard or bolster that is over 1/8" thick, route out the backside larger than the blade tang, leaving about 1/16" of the slot to be filed on.

A black Sharpie is your friend. Blacken the inside of the guard slot. Slide on and push tight a time or two and remove. Look inside the slot and see where it is rubbed away .... that is the tight spot.

Learn to soft solder. No matter how good the fit is, there is still a gap and moisture can/will get under the handle. Soldering seals this up and looks professional. JB Weld also works to do the same thing, and is easier to use than solder. A small brass graver made from a 1/4" square brass rod will clean up the joint whatever you use.
In my opinion, you need to learn how to solder and solder all guards/bolsters.
 
Stacy E. Apelt - Bladesmith said:
Assure the tang is tapered away from the blade so there is no binding until the guard seats at the shoulders.

Stupid as it sounds, unless there is absolutely no way you can put the guard on backwards, mark the back side with an arrow pointing to the spine. That way you know what orientation to put the guard while fitting it.

Carefully file the guard and test fit every few strokes - NOTE - You can take a few more strokes to remove more metal if it is still snug, but can't put even one stroke back on if you filed too much.

File the slot at a slight taper, so the back side is wider than the front. This will apply all the snugness in the front, and you can be sure it isn't the back side that is sticking. On a guard or bolster that is over 1/8" thick, route out the backside larger than the blade tang, leaving about 1/16" of the slot to be filed on.

A black Sharpie is your friend. Blacken the inside of the guard slot. Slide on and push tight a time or two and remove. Look inside the slot and see where it is rubbed away .... that is the tight spot.

Learn to soft solder. No matter how good the fit is, there is still a gap and moisture can/will get under the handle. Soldering seals this up and looks professional. JB Weld also works to do the same thing, and is easier to use than solder. A small brass graver made from a 1/4" square brass rod will clean up the joint whatever you use.
In my opinion, you need to learn how to solder and solder all guards/bolsters.
Click to expand...

Well, there's my first mistake. I don't think the tang is tapered actually.

Soldering....didn't think of that one yet. I do know how to solder but I'm certainly an amateur. Never used anything other than the standard lead/tin solder and silver solder a couple times. Is there any solder that will blend well with brass and look inconspicuous? Can I use solder to fix up a poor fit or will it show?
 
Matthew Gregory said:
What John said. The only way to do this well is slowly and patiently.
Click to expand...
Agh, but I hate that way!

In all seriousness the "slow and patient" thing seems to be a theme in a lot of this stuff. I just ordered a small set of diamond-coated needle files in hopes that they'll help me slow down and be a little finer than the standard toothed needle files
 
As long as the gaps aren't massive (and you could probably get away with even a little more than you've got) it isn't really noticable. Especially on mirrored blades. Polish the solder joint with a tiny cratex wheel, and shine it on the buffer. It disappears into the blade.

Soft (low temp) silver solder is ideal, but Moran always used lead plumbing solder.
 
My biggest problem is finding files that are ideal for most of my tang sizes. Needles are too small and flexible. Standards are too wide or thick although I've ordered some 4" ones that I hope are going to be in the sweet spot for me.

So I end up milling mine when I do them.

Another problem I've had, when fitting something I've filed at a taper for a press fit, is keeping the face of the guard perpendicular to the blade. That's really frustrating, filing and fitting, pressing, taking off and filing, over and over and then on the final installation the stupid thing is cocked :mad:

If there's any reason for a knife maker to have a milling machine it's to slot guards imo.
 
Geoff Flato said:
I'd suggest grinding the tang down some more, so it's a taper all the way to the blade in every direction.
Click to expand...
Stacy E. Apelt - Bladesmith said:
Assure the tang is tapered away from the blade so there is no binding until the guard seats at the shoulders.
Click to expand...

I think Geoff and Stacy hit on (what I feel is) and important piece of advice. The tang's taper does not need to be dramatic... but a slight taper really helps ensure a nice gradual fitting process that allows me to keep things tight as I work with the files.

Stacy E. Apelt - Bladesmith said:
File the slot at a slight taper, so the back side is wider than the front. This will apply all the snugness in the front, and you can be sure it isn't the back side that is sticking. On a guard or bolster that is over 1/8" thick, route out the backside larger than the blade tang, leaving about 1/16" of the slot to be filed on.

A black Sharpie is your friend. Blacken the inside of the guard slot. Slide on and push tight a time or two and remove. Look inside the slot and see where it is rubbed away .... that is the tight spot.
Click to expand...

Stacy also gives a couple more good pieces of advice here. On thicker guards, I mill the back side of the slot slightly larger so I don't have to mess with filing the entire thickness to fit tight to the ricasso area. Wheeler provides some good photos and descriptions of this in Post 203 of the Stuck in the Metal WIP. He is working with a parallel ricasso, but the same idea can be applied to non-parallel slots.

I have a huge black Sharpie that I use when fitting all of my guards. Unlike Stacy, I blacken the outside of my tang rather than the inside of the guard. It's just easier for me, and I find that the Sharpie coated tang will leave a visible dark rub mark against the inside of the guard where things are tight.

kuraki said:
My biggest problem is finding files that are ideal for most of my tang sizes. Needles are too small and flexible. Standards are too wide or thick although I've ordered some 4" ones that I hope are going to be in the sweet spot for me.
Click to expand...

I've modified a number of files over time to deal with this... grinding safe edges, and making some of them thinner/narrower.

mhutch said:
In all seriousness the "slow and patient" thing seems to be a theme in a lot of this stuff. I just ordered a small set of diamond-coated needle files in hopes that they'll help me slow down and be a little finer than the standard toothed needle files
Click to expand...

Everybody's processes are a bit different I guess, but I think that you'll be disappointed with the performance of diamond needle files for this type of work. I prefer standard single-cut files just small enough to fit where they need to fit and do what they need to do.

kuraki said:
If there's any reason for a knife maker to have a milling machine it's to slot guards imo.
Click to expand...

:thumbsup: Definitely agree. A milling machine (even a small one) is useful in a million different ways in my knife shop... but guard/fitting work is where it is used most frequetly. Even when fitting to non-parallel tangs/ricassos, the mill is great for getting slots started, and ensuring that they are started straight.

Hengelo_77 said:
Lightly tap around the gaps with a ball peen hammer, refile the slot and make the face of the bolster flush again
Click to expand...

I will sometimes do something similar to what Hengelo is recommending. I will use a peen/punch around the perimeter of the slot when the guard is seated on the blade. This can be helpful for closing minor gaps. as Hengelo mentions, you'll need to re-sand the face to clean up the peen marks.

(Some photos from an old WIP showing Peen marks... and after clean-up. The "Groovy" arrow doesn't pertain to this discussion, but was meant to illustrate a something I do to help in seating the guard into the blade shoulders.)
13334497814_7e90849642_z.jpg
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Good luck Matt.
Erin
 
I've done that as well. I'm really just whining because it's probably the only task I actually loathe in knifemaking.
 
This is one of my least favourite parts of knifemaking, but when you get it right, you know the accomplishment, and when you pick up other knives, you'll see if they were done well or not. It's a sign of quality control to get it right.

On thin knives like kitchen knives, I use a slitting saw matching the thickness of the ricasso. This has saved me a lot of time, and I have way fewer broken small end mills too. :cool:

With practise it gets faster. I have a bunch of Stihl brand chainsaw files (made by Pferd iirc) that I custom shape to the thicknesses I need. For wood bolsters on kitchen knives, lee valley has some great needle rasps that save a ton of time. They're not cheap, but they cut fast, clean, and they don't wear out very fast.

The best WIPs have been by Nick Wheeler, Will Morrison, and I think Karl Anderson has one on using a mill and dual indicator to get a perfect press fit right off the mill. I need to look that up and try it.
 
I've got a few different files around for it, which I use in addition to the mill when required.

A chainsaw raker/depth gauge file with teeth ground off one side, and the sides ground square for starting off. A small (4-6") mill file with all teeth ground off except for one edge is great for lengthening slots. Can grind it thinner or narrower as required. Square files with two sides ground safe can be useful too.

For new files I generally buy grobet, but I'll pick up every decent looking small used file I find, just for grinding into odd shapes. I'd much rather take a 25¢ flea market file to the grinder than a $50 grobet
 
Here's my secret weapon. Carbide coated files. Sharp in both directions. Last forever. I was introduced to them when I worked in an iron foundry, we used them to tweak molds and cores (essentially filing sand). They move metal fast, so for roughing they work well. They're also incredibly handy for tweaking mortised hidden tang holes, since they cut both ways and are much coarser than most files. File whatever you want with them. Steel, brass, G10, carbon fiber, they don't care.

K9hfhYJ.jpg
 
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