Seax inspired friction folder.

[tomsm44]

I got this one rough ground this week.  I posted pictures of a straight razor I started last year that would have been my first folder, but I never finished it.  I only do flat grinding, and I didn't really like how the flat grind turned out for a razor.  Anyway, I saw a piece is scrap 1084 laying on my work bench a few days back and got a wild hair to try again.  I'm going with more of a working blade design this time.  Not sure why I thought of a seax, just kinda popped in my head.  Not positive on the handle design yet.  The sketch is mainly just to work out the mechanics and nail down the hinge pin location on the blade.  Do you guys think a 3/32" SS pin will be sufficient for the hinge, or do I need a 1/8" one?  Also, with what I'm thinking for now, the small pins will be 1/16" SS attaching the scales to either SS or copper liners.  The three in the end will extend all the way through a 1/8" spacer.  The third small pin from the left (the one that's smudged) would extend all the way through and act as a stop for the blade in both the open and closed positions.  Once again, would a 1/16" pin be sufficient for that purpose, or should I use a larger pin in that position?  Just trying to think everything through so I can get it right on the first try.  Anyway, here's what little I have so far.

 

[D.Ellis]

Matt.
You want the stop pin to be closer to the pivot pin.......and if you use that one to stop the blade in the closed position, it's going to be riding on the sharpened edge.
Take some stiff paper/cardboard(cereal box or similar) and a thumbtack for your pivot and make a working model......ideally, you should have done that before the blade was profiled, but you can design around it most likely.
I will try and design a quick model with a similar blade shape and post it here to show you how to make one of those work.

I would use 1/8' pins for the pivot and stop pins personally.

As the governator would say......I'll be back!   :D  

Darcy

[tomsm44]

Thanks Darcy.  I actually started grinding the blade thinking of a small hidden tang, but decided halfway in that there wouldn't be enough tang to be strong enough.  That's part of the reason for the poor planning.  That's my excuse at least.  Anyway, I did what you said and I can make a few small tweaks to the profile and make it work.  I thinned the back piece a little, and you can see the pencil line where I would need to reshape the back of the choil (I guess it's called a choil on a folder?).  See if it looks better now.  1/8" SS hinge and stop pins through SS bolsters, then I'll probably do the 1/16" SS to attach the scales like I mentioned before.

 

[tomsm44]

I think this should work now.  I definitely should have waited to start my flat grinds until after I nailed down the profile and pin locations.  My plunge is a little further back than I'd prefer now that the profile has been fine tuned.  It'll be ok for a knock around utility blade though.  I also shortened the little back piece a little (can somebody please tell me what that thing is called so I can at least sound like I know what I'm doing).    I may simplify this one from my original plans and just do wood scales with no bolsters or liners.  If it works out, I may take what I learned here and do a second one with my original plans.  We'll see.  

 

 

[KSCATTRAPR]

Very cool, I can't wait to see the finished product.

[tomsm44]

And now getting the handle profile figured out with a scrap piece of poplar.  Not sure yet what I'll use for the handle.  One more quick question though.  As I said in my last post, I was thinking about just doing a wood handle without bolsters or liners, but looking at it now, that's not a lot of meat around the hinge pin to just be wood.  Do you guys agree that at least liners would be a good idea for added strength?  

 
 

[bjansen]

Nice work Matt. I've never done one before' but I would agree that liners are needed.

[D.Ellis]

Good work Matt.    
Yes, I would do liners, also, when you peen the pin, it helps with strength to have some sort of washer under the peened heads of the pin, that helps reinforce the pivot.
like this one.
 
 

Anyway, I did this up real fast but it looks like you have it figured out anyway.

The pivot pin should be lower than center of the handle as shown by the blue lines.
The important lines are shown in red.....kick at the tang is thick enough for strength, enough meat near the pivot.
Green dot is your stop pin.


 

Adjust the tang around the pivot to clear your stop pin (Red arrow) and in the full closed position to stop the blade in the position you want it to sit(green arrow)

 

Full closed position, showing where to lay out back spacer.

 

When you peen the pin, put a shim of brass in between the blade tang and liners on both sides......aluminum can will work too. Peen the pin equally on both sides a little at a time until the blade gets snug, then remove the shims, and peen a tiny bit more until you have the amount of friction you want in the blade pivot.
Put a drop of oil in the pivot hole before you peen it.

I like your design.    

Darcy

[tomsm44]

Thanks again Darcy.  I wouldn't have made it this far without your help.  Or at least I would have ended up with a crappier knife.  I'm going to look and see if I can find any small washers for the pins to go through.  Anyway, here's the last on this one for now.  I dug through my wood pile and found an old piece of padauk that'll work for this one.  I cut and rough shaped the scales, laid out the back spacer shape, and drilled my pin holes.  Still have to cut out my liners and spacer and get it all fit up and shaped just right.  But first, I need to HT the blade and do a little hand sanding.