Cheap Hand-Cut Rasps

[Jelly]

I was given some truly awful Chinese rifflers about a month ago, worse than useless in fact... So i'm still planning on buying a few nice Italian or French hand cut ones...

But they did present an opportunity to have a crack at making some of my own...

I removed the awful uneven stitching by freehand grinding, annealed them by heating to a bright orange glow with a slightly reducing flame from the oxyacetylene torch on top of some refractory brick and letting them cool naturally with the bricks over 2 hours or so.

Touched up on the power file, and gave them a quick polish, so I could see the impact I made on the surface.

The stitching tool is a ⅜" HSS lathe tool which has been used and sharpened until there was nothing really left of it... ground to a non-regular trigonal pyramid shape (arrived at by trial and error).

I've concluded I should make a new tool that's longer, so I can see what I'm doing, as the tooth spacing is all over the shop; the tooth height is very regular though, which means I've already got a slight improvement over the original stitching.

Also, I now appreciate why Auriou and Lioger charge what they do... I'd say they were cheap, given the difficulty of doing fine stitching.

 

[Biliphuster]

That's impressive and very ambitious. Are you going to harden them back up afterwards?

 

[Jelly]

That's impressive and very ambitious. Are you going to harden them back up afterwards?

Yes, I will probably re-harden using the same hearth set-up to heat treat as last time, when I forged a carving tool... Only now I have access to an IR thermometer so can try to control the temperature better.

Unsure if I'll temper it harder, as it won't be resharpened, unlike a gouge.

 

[matthewwh]

What a great project!

Hopefully this will be useful:

Here's a shot of one of our traditional stitcher's work stations taken from the stitcher's perspective. They sit astride the anvil like a horse, with the blank laid in a lead block that has a horizontal channel and an angled
one that presents the sides. The blank is held onto the lead block with a leather strap, with your foot in the looped end to hold the blank down onto the block. You could always make the block out of scrap wood and use a sawhorse or similar.

The tang is always towards the stitcher, starting at the tang end they work in diagonal rows, each row is started at the farthest point and working back, this way your hands don't impede your view of the work. They use a hammer with a curved handle to avoid wrist strain.

For convex faces (halfround, cabinet, round etc) they work a strip of teeth into the surface then reposition the blank before working another strip, hence the two blurred lines you see on a hand stitched rasp where the fields of teeth meet.

Looking forward to hearing how you get on.

 

[swagman]

Matthew; could you post a couple of photos of that curved handled hammer on its own.

regards Stewie;

 

[Racers]

Have a look here https://www.youtube.com/watch?v=_pzK2Ei19t4

Pete

 

[Jelly]

Thanks Mathew, that's a very interesting missing link between the similar setup I've seen in reference to the file trade (Less heavily curved hammer, more vertical angle of the stitching tool, less issues with visibility) and actually stitching rasps.

I'll let everyone know how it progresses.