Need Advice on Finishing

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Ken Cox

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Over two years ago I started to make an 18" short-sword/heavy-dagger out of BG-42 using only hand tools.
Barry and Philip Jones gave me endless help, as did others.
Many thanks.

I have now arrived at stage of polishing with 1200 grit silicon carbide paper.
The blade presently looks better than I ever hoped it would.
I intend to go on to 2000 grit.

Several tasks presently face me and I would like some advice.

First, I have made some carbon fiber scales which I intend to pin to the handle with 1/16" pins and glue with Brownell's AcraGlas.
The tang will extend beyond the scales, and so I intend to 99% finish the scales prior to attaching them to the handle, rather than trying to work on the scales after I have attached them.

I have noticed that the carbon fiber has some minor surface voids.
These voids have so far disappeared as I have removed material, but if I reveal some new voids I assume I will need to fill the surface of the finished and polished carbon fiber with something.
And if the carbon fiber finishes up with no voids, I might still want to treat the surface with something.
I don't know.
Any suggestions?

Regarding the pins, I entend to leave them just a little long so I can peen them lightly and then sand them flush.
How high above the scales should I leave the pins?
One diameter, 1/16"?

Also, I don't have any power tools and so I have so far shaped the scales by hand.
It does not makes sense to finish the scales any more smoothly than the grit of sandpaper I will use to sand the pins flush.
At what grit should I stop in anticipation of using the same grit to sand the pins flush?

Regarding the use of AcraGlas, the blade and tang now have a mirror finish.
Some advisors have told me I will need to rough up the surface of the steel under the scales with 220 grit in order to get good adhesion with AcraGlas.
After so much polishing, the vain part of me resists the idea of roughing up something I have polished into mirror smoothness.
Given the use of pins, do I really need to depend on adhesion between the underside of the scales and the steel, or will the AcraGlas in the pin holes suffice?
I kinda already know the answer, but I would like to hear any comments.

Finally, advisors have told me I can use vinegar and/or acetone to clean up any AcraGlas that extrudes out from underneath the scales during the assembly process.
Further suggestions or comments?

I can now see the end of this project, the light at the end of the tunnel, and I can hardly wait to share the pictures with the folks who have helped me so much, especially Thomas Haslinger and the Jones Brothers.

Many, many thanks to all.
 
Ken, is the tang going to extend all around, or just the pommel area(rear)? If all the way around, you might want to rethink that. It is very uncomfortable to hold/use a handle like that. Of course, if you are after some specific type of look/vision, I certainly understand.
Either way, make sure the front part of the scales are polished, or finished to your liking, no good way to do them after assembly. You can rough up the surface with one of those vibra tek tools, the type you use to mark your possesions. You should also have a corresponding roughness to the inside of the scales. I like to dimple them slightly also, with a 1/8" drill bit, to provide extra area for the epoxy to grab.
On the pins, I wouldn't recommend peening them, acraglas on the pins will hold them fine, just finish down flush. I don't know the existing finish of the scales, so that is hard for me to comment on. If I was doing this by hand, I would flush the pins with 80 grit, jump to 220, then 400, 600, etc. Make sure to back the paper with something like a heavy piece of leather etc., so you don't dish out the handle around the pins.
Give the handle enough time so that the epoxy is stiff, but not completely cured(able to be dented with a fingernail), then go at the residue with cotton swabs and Acetone. That will keep it from undercutting the scales. You can, of course, wipe off major excess' right after you clamp the scales, that will leave you less to clean up after partial setup.
No doubt I have missed some things here. If you have more questions, just ask away.

Edited to add; Use a #52 drill bit on the tang and scales, that will leave just enough room for the epoxy on the pins, and compensate for the material shrinking back as you withdraw the bit. Pins are usually a tad bit oversized too.
 
I like to 'rough up' the pins in the center also. What I actually do is "ring" them a couple places with side cutters.
I'm not really recomending this for anyone else but I peen the pins before finishing. I think it helps to fill any gap around the holes in the scales.
My 2 cents, Lynn
 
The tang will extend all the way around.
Gene Osborn made a 13.5" prototype of this blade for me which appeared in the October 2000 Knives Illustrated, and he left the tang exposed all the way around.
With 1/4" thick steel and a rounded edged, the tang has not made itself felt.
And, as Mike correctly intuited, it does have something to do with specific look.

I have presently used 100 grit paper to shape the scales, and so I will follow Mike's advice and not finish the top surfaces of the scales any smoother until after I have sanded the pins flush.
However, I will finish the edges, as Mike suggests, since I will not have access to them after attaching the scales to the tang.

I assume from Mike's advice regarding dimpling the underside of the scales that he thinks I should also rough up the steel under the scales.

I like Lynn's idea of ringing the pins, and I will do that.

Mike and Lynn have the same difference in opinion regarding peening the pins that I have so far encountered elsewhere.
For example, Thomas Haslinger recommends I do not peen the pins and Gene Osborn says to peen them, and I respect both of these makers enormously.

I'd like to know more about peening the pins, like when in the process to do it if I decide to do it, and why not to do it.
I bought this special itty-bitty little ball peen hammer for $14 (I think they saw me coming) just to peen the pins.
I don't need to use it just 'cause I have it. :)
 
Good advice so far
I generally peen pins, but for the size your using I don't think it would make a big difference. They're so small it would be difficult to get the end to expand rather than bend over. Acraglass is tough stuff, and lots of folks have quit peening pins so that should be fine.
As far as roughing things up for the glue, I don't think you need to go to too much trouble. Its a very important step, but you have to bee sure to keep the mating surfaces flat. I've found that having the surfaces clean is much more important than how rough they are. I would scuff sand both surfaces with 80 grit or lower sandpaper, and DO NOT TOUCH IT with your bare hands again. Any oil or dirt on the surface will lower the strength of the bond.
Mikes idea with dimpling with a drill bit will help, but be sure that they are minor dimples. Large globs of epoxy tend to set up slowly, or even remain somewhat gooey. You want a lot of surface to bond to but you do not want a large pocket of epoxy under the slabs.
When the epoxy is setting up, you'll want something to pull everything together. I like the little spring loaded hand clamps. I put 4 or 5 on a knife as its drying. If you don't have, them there are other options since your using pins. The pins will index everything and keep it lined up. So you could put zip ties around the handle about an inch apart, or sandwhich all together under books or something heavy. You don't need to squish it too tight, but just enough pressure to keep everything pulled together.

I wouldn't sand the scales beyond 220 before attaching them. You'll probably want 80-100 grit paper with some sort of block to get the pins flush, and plan on being messy with the epoxy ;) After the initial shaping and the heavy scratches are removed it really isn't that much work with the finer grits. Be sure to do the front end/edge of the scales before hand as you can't do that without messing up the finish of the blade after attaching.
Get yourself a roll of masking tape too. It will be really handy for covering up areas that are already done (like the blade) while you do the next steps.
 
Peening pins has it's place. For example, metal bolsters where the pins are the only thing holding them on. You need to severely peen the pins to get the proper pin upset, so that when finished down, the pins are invisible in the bolsters.
Peening pins in soft handle material can very easily lead to cracking/splitting the scale. If nothing else, it leaves less room in an already tight area for epoxy to do it's intended purpose, which is to hold the pins together with the scales. I have found it a totally unnecessary step, one that can lead to the aforementioned problems.
Acraglass has tremendous holding strength, as do most epoxys used in knifemaking. Peening was for a time before them.
If the tang is to be exposed, then Ken is wise to finish all sides first. ;)
 
Oops looks like we were typin at the same time.

In regards to peening. 2 things are important. Don't try to do too much, and make sure you have releived a small ( SMALL) area around the head of the pin for it to expand. If you peen it all above the surface of the scale, you will sand the expanded part off getting it flush. I like to use a drill bit bigger than the hole for the pin, and BY hand push it against the hole and give it a twist or two.
I peen pins right after the epoxy has set, not at full strength but when it is firm. With 1/16" pins a pair of side cutters will be a big help. You can clip them off close the scale and then square the end up with a sanding block or file.
Leave them long while the epoxy is setting, you can take care of the length issues after the glue is set. Should they happen to shift and one side is too short, you can use a soldering iron to heat the pin (and only the pin don't touch the scale) and the epoxy will release it so you can slide it through the hole one way or another. In this case, I wouldn't do that though. I would just sand that particular pin flush and move on to the next.
The pins should be almost flush with the surface especially pins that size. Maybe leave them sticking out about 1/32" on each side. Let the weight of the hammer do the work, and flip the peice repeatedly as you work. You'll need a vise or peice of scrap steel to put the back of the pin against while you work on it. This gets tricky on curved surfaces.
Hope that helps, sorry I got to rambling and couldn't keep stuff organized better
 
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