Taper ground saw plate? HOW!!

[Marc Gélinas]

Hi out there in woodworking nirvana, could someone suggest ways of tapering a saw plate. I'm looking at probably making a couple of saws this winter and i'm hoping to find an easy (simple but probably time consuming and back-breaking)way of tapering the plates, short of taking them to the neighbourhood machine shop!
Thanks

[Dave Burnard]

One possible solution is to use a sen (japanese metal cutting/scraping tool - looks a little like a drawknife) to scrape the taper you want. That's what was traditionally used in japan to taper saws. They seem to have caught on with the US knife/sword making community. No machinery required, but you can't just buy one. If you know a knifemaker with a forge you could collaborate and make one.

No back breaking effort required - but you will need to be resourceful. For two saws, probably completely impractical - but who's counting.

[Tim Leo]

Belt sander with aluminum oxide belts?

[Marc Gélinas]

Bothpolishing great ideas, I was thinking along the lines of a diamond polishing wheel like they use for polishing stone. However, for the "sen" could I make one out of O1 tool steel?

[Dave Burnard]

O1 would work fine for a sen, so would 5160 spring steel or 1080-1095. Some of the US knife/sword guys started out with files they had reground and handled - so an old file would work too. Unique to sawmaking is the fact that you'll be scraping your steel (saw blank) after it's been hardened and tempered (I presume - since most makers buy blue tempered spring steel) so you can't temper the sen very much - probably <300F for O1. My sens are a laminated construction so I can get away with even less temper for an even harder cutting edge.

[Marc Gélinas]

About a sen, I haven't been able to find a good image or drawing to go on if I should decide to make one, could someone (Mr. Burnard possibly) post an image, picture or drawing...PLEASE! Oh, and I've got 3/16" X 2" X 36" O1 stock, would that do?

[Mike Wenzloff]

Hi Marc...go here:
http://www.daikudojo.org/ShopTalk/metate_article.htm

The sen are the drawknife looking items part way down the page...Mike

[Dave Burnard]

Thanks, Mike. Also here's my sen page with various photos and sens in use.

Dave's Sen page

Also check out these discussions:

Sen discussion

Knifemakers sen discussion

Swordmakers sen discussion

3/16 x 2 sounds just about perfect. The body should be 4-5 inches long and slightly concave from one edge to the other(you can do that cold in the annealed state or when it's hot) but flat bottomed along an edge. Overall length with handles: about as wide as your shoulders. You can forge out the handles (or just have someone cut out the outline with a bandsaw or plasma torch or water jet - I won't even say "that's cheating" cuz I know how hard it is to forge them out).

Good luck!

[Marc Gélinas]

OK, I think I get the idea. In shape similar to a draw knife with a very high bevel for cutting edge (75-90 degrees). I think I'll give it a try this winter. Keep the information comming, this is great stuff!!

[Dave Burnard]

For a sawmakers sen you grind/file an initial bevel of 45 degrees or so - you can do this before hardening. Then when sharpening you use a bevel angle of around 70 degrees. You need to use a fairly coarse (400 grit or less) stone on the bevel and a medium (800-1200) stone on the back to get it to cut properly. Keep us posted.