Stone Knife Scales

[David G]

While not strictly carving, I had a request to post a brief tutorial I wrote on making stone knife scales. The link posted here is to a tutorial I wrote for fitting stone scales to a Swiss Army Knife, these are cut off the knife and fitted as the last step. The tutorial below is for knife with bolsters, these are finished with the stone fixed to the knife.

 

http://aussiesapphire.com.au/forum/index.php?topic=2152.msg17539#msg17539

 

This is a brief tutorial on how to prepare stone scales for a Buck 501. The comments on my previous tutorial for the Swiss Army Knife about stone selection still hold and is very important, you must select material based on whether the knife is for show or use and the stone must be solid with no cracks, vugs etc. The slab needs to be at least 70mm x 50mm x 4-5mm for the Buck 501. If the stone is patterned sister slabs can look spectacular when the pattern is repeated on each side and along the spine of the knife.

 

There is one major difference in the cutting of stone scales for a knife that does not have bolsters such as a Swiss Army Knife (SAK) (and other multi-blade tools) and ‘standard’ pen knives with bolsters such as the Buck 501. The scales for the SAK’s are cut and finished completely off the knife (in effect they are cut as elongated cabochons) and are glued to the knife as the last step. Whereas the scales for the Buck 501 are preformed then fitted to the knife, and the scales are then brought down flush to the bolsters. The advantage of cutting the scales on the knife is that they look like they are integral to the knife and form a much tighter more streamlined and attractive fit. The disadvantage is that it is awkward and potentially dangerous to hold the knife near the spinning grinding wheels and any touch of metal on the knife accidentally on the wheels will scratch or gouge holes in the bolsters, blade or liners spoiling the look of the finished knife.

 

Safety warning: The blade must be taped whenever the knife is near the grinding/sanding wheels. Unprotected blades and spinning wheels are a recipe of disaster. I use masking tape and put at least 3 layers on it – if the masking tape gets wet be sure to remove it at the end of each working session as the blade will rust if left wet (stainless is rust resistant not rust proof).

 

Step 1 – Preparing the knife.

 

The scales on the knife need to be removed and the knife prepared before the stone scales can be fitted. Be very careful not to scratch or bend the liners or bolsters when removing the existing scales.

 

Blade taped and ready to start.

 

The wooden scales shipped with the Buck 501 are held onto the knife with 2 pins on each side that go through the scales and the liners and are flattened at either end. Thankfully the pin holding the liner lock does not protrude through the scales (like the buck 110 does) and is already peened and flush to the liners. The pins are often quite loose in the liner-holes and a problem is created if they fall out and disappear as this leaves two small holes in the liner where glue can seep through and gum up the folding mechanism. Too avoid this I open the knife, tape the blade and press a small piece of bamboo skewer into the knife between the liners at the point where the two pins are, effectively holding the two sets of pins in place.

I then use an cut-off wheel on the Dremel to cut the tops off the pins on each scale, the scales can then be popped off carefully by pushing a sharp blade between the scale and the liner (be very careful not to damage the liner). Once the scales are off, I use the cut-off wheel to grind the pins down flush with the liners. The bamboo skewers remains in place to hold the pins in place neatly blocking the holes in the liner and ready for later gluing up of the scales.

 

The tops of the pins are carefully ground off to allow the scales to be removed.

 

The central pin holding the liner lock on the 501 is already peened, on other knives this goes through the scale and needs to be cut off and peened (otherwise the knife will fall apart).

 

These holes need to be blocked, otherwise epoxy will gum up the folding mechanism when the scales are glued up. I use the original pins and hold them in place with a bit of bamboo inside the liners.

 

Check the edges where the bolsters meet the scales and file down carefully if they are rough or slightly out of plumb, you want a nice flat face for the stone to butt up against.

 

Step 2 – Marking out the stone.

 

Mark up the scales on the slab of stone using the scales as templates, they can even be taped to the stone using double sided tape, just be sure to block the pin holes with blu-tack to reduce the tendency for the glue on the tape to fail. I then mark on the slab which side will be the top and which end has the blade, this ensures the pattern I want stays on the top and stops two left hand scales being produced. Also the two sides of the knife are not always 100% identical so it is important to fit each scale to the exact side it is going on.

 

 

Step 3 – Cutting out the stone

 

The two scales are cut out on the trim saw.

 

Step 4 – Fitting the scales to the bolsters

 

This is the most critical step in the whole process. The ends of each scale need to be cut and ground to perfectly fit between the bolsters. Note that the bolsters may need a clean up with a file if they are uneven. I cut one end of the scale square and use that as my guide for the other end. Grinding very carefully with a flat lap until the scale fits snugly between the bolsters.

 

Once I am happy with the fit I mark the final shape on the scales and rough grind the scales down to a few mm from the final edge, being careful not to touch the ends.

 

 

 

 

Step 5 – Grinding and polishing the ends

 

This is another important step that needs care. Once the scale is glued to the knife it is impossible to grind and polish the areas where the scale meets each bolster, therefore I grind down very carefully each end to make a pleasing curve to meet the bolster at each end. If the curve is overcut there will be a gap between the bolster and the scale. Once I am happy with the shape I sand and polish each end taking great care not to round off the square end of the scale.

 

Step 6 – Glue up the scales

 

I glue up the scales using epoxy 330 and acetone to clean up any epoxy that is squeezed out. I do one side at a time as the epoxy makes the scales slip about and it is easy for them to move out of position when clamped. The 330 takes about 4 hrs to set and overnight to cure.

 

 

 

 

Step 7 – Grind and polish the scale

 

Grind down the sides of the scale till almost flush with the liners, then bevel and shape in the same way you would for a cab. The tricky bit is manoeuvring the open knife around the grinding and sanding wheels without the wheels touching and metal parts. As with all lapidary patience will be rewarded. Once you are happy with the shape of the scale, sand and polish.

 

Step 8 – Clean up the knife

 

Clean up the bolsters and liners with appropriate metal cutting and polishing compound (I tape up the scales to stop them being dulled). Once finished the folding mechanism needs a good clean out, I use acetone, toothpicks, pins and metal shim to clean all the gunk out of the mechanism so that is opens and closes smoothly. I then apply a light grease to the mechanism.

 

Step 9 – Admire and show off

 

 

 

 

Enjoy,

David

[Dan]

thanks david seems strait enough. only problem is i would make one tonight but i have done no stone carving expierence, dont have the right tools, and i dont have the stone soon and someday though in the mean time do you sell these knives?

[David G]

Hi Dan,

 

yes, having the right kit is a requirements. There are lapidary clubs around you can join where you can access the kit without having to buy it all. They would also have sources of appropriate stone and lots of knowledge (even if they have never done a knife).

 

At present I just make them for friends and family, very much still learning. The link below is to Michael Hoover who makes custom knife scales for a living, I can highly recommend his work both for the quality of the stone used and his amazing craftsmanship. His prices are also very reasonable for the amount of work that goes into each knife.

 

http://redrummdknives.blademakers.com/

 

David

[David G]

Here is one I finished the other day for my physio.

 

 

Original slab, I used Michael Burgess's band saw to cut these out, really quick and reduces grinding by heaps, I gotta get one.

 

 

Fitting the scales up, this I find really tricky very easy to get the wrong angle and over cut, will get it perfect one day.

 

 

The slab edge has a really cool striped pattern on it that would have made awesome scales had the block been orientated that way.

 

 

Glueing everything up:

 

 

Mostly polished, metal yet to clean up.

 

 

For a while there I did not think this stuff would polish, indeed at 50,000 diamond it was still cloudy lacked any sort of polish at all. I finally got a good polish with 100k diamond with leather by hand, I just mix a batch of diamond paste up and watch a movie while working the leather on the stone. The perfect metal polish is still eluding me, I am using Hyfin on a cotton buff. The stainless comes up really well but the nickel silver shows scratches, clouds etc.

 

 

 

 

David