Toothed Iron Making Experiment

[rxh]

I have been playing at toothed iron making using this rather Heath Robinson apparatus. I used cable ties to attach a Dremel tool to a piece of MDF held in a vice. A cut-off disc was fitted to the Dremel. I was able to swing the table of my drill press near to the vice and use its cross vice to hold the iron and provide X Y motion for the cutting operation. Z motion was achieved using the table raising handle. I am happy to report that the process works. Grooves are cut rather than slots.

I used ¾” wide irons for test purposes but the method should work for any width.
The irons were made from O1 gauge plate and were heat treated ground and sharpened in the usual way after the teeth were cut.

 

[Mike.S]

I have been playing at toothed iron making .....Grooves are cut rather than slots.

?? Not sure if I'm misunderstanding you but the final picture shows slots cut all the way through the iron, rather than grooves.

Here's a pic of a toothing iron from a plane I recently sold (click on it for larger version):

Picture's not clear but, iirc, the grooves are cut about half depth - thus are supported on both sides, so each 'tooth' is less likely to be bent/broken off.

That aside, I applaud your ingenuity =D>

 

[D_W]

I agree with the above comment on depth.

Are you intending to use something that will mitigate tearout, or do you want to make a scraping plane like most of those irons came in?

 

[rxh]

Thanks Mike. The grooves are cut about half the depth of the iron - the photo is just misleading. The pics below show it better (taken after the grooves were cut but before heat treating etc.).

D_W: Yes, I intend to use for planing difficult grain (mainly lutherie) rather than for preparing a ground for veneering.

 

[AndyT]

That's an ingenious experiment but I wonder how effective it will be. You'll end up with a series of very narrow blades, each with a flat (but narrow) cutting edge. A conventional toothed iron works as a series of narrow blades, each with a pointed edge.

I wonder if you could achieve this by tilting your cutting disk so it's at 60° to the surface of the steel, rather than 90° and spacing the cuts closer together?

(I've no confirmation of this, but looking closely at a toothed iron, I reckon that they must have been made in much the same way as hand cut files, by hitting a chisel into the iron to make a closely spaced series of dents and ridges, before hardening.)

 

[profchris]

I have a modern toothed iron from Veritas which has square section grooves - works fine.

I also have a woodie scraper plane with narrower V grooves, which also works fine. It works the surface down a bit slower than the Veritas iron I think, but it's hard to compare because the Veritas is for their apron block plane so is smaller, and of course the angle is very different.

I'd always thought the shallow V blades were for veneer toothing, but I don't know why I thought that, could be quite wrong.

However, I can say that square section grooves work fine for gnarly grain.

 

[bugbear]

Here's how the old blades were made;

post281125.html?hilit=%20toothing%20diagram#p281125

BugBear

 

[rxh]

Andy & Chris - thanks for your replies. I have several violin planes with square cut grooves in their irons. They work very well so I aimed to put similar shaped grooves in the irons I have made. I have only tried planing fairly "mild" wood so far but I intend to try violin back maple, which should be suitably demanding. If the result is not satisfactory I'll try and get the grooves closer together.

BugBear - thanks for the link. That thread dates from "before my time" and it was very interesting to read. I saw that at least one other person has had the idea of using a Dremel tool for doing the grooving.

 

[Keith 66]

I just found a toothed iron while sorting my late fathers workshop. It was made by Aaron Hildick (diamond) mark warranted cast steel, fine teeth 26 to the inch, never really knew what it was for but having read about them i think i will hang onto it!

 

[MIGNAL]

Sometime last year I made a toothed blade from an old single woodie iron. I cut the grooves with a saw file. It completely mashed the saw file but I managed to get across the full width of the blade. Amazingly it works, in fact I prefer it to the Kunz toothed blade that I have!

 

[rxh]

Keith, yes, I'd hang onto that iron if I were you.

I tried my iron on an offcut of violin back maple and it worked well.

 

[condeesteso]

Resourceful as ever Richard. I suppose if you wanted the pointed teeth you could easily use a different profile cutter in the Dremel.

 

[bugbear]

Keith, yes, I'd hang onto that iron if I were you.

I tried my iron on an offcut of violin back maple and it worked well.

Looks like you tried the blade in an "old" plane... :lol: :lol: :lol:

BugBear

 

[bugbear]

Thanks Mike. The grooves are cut about half the depth of the iron - the photo is just misleading.

So save work (and heat), the teeth surely only need to be as deep as the thickest shaving you intend to take.

BugBear

 

[rxh]

Resourceful as ever Richard. I suppose if you wanted the pointed teeth you could easily use a different profile cutter in

Thanks Douglas. The cut-off discs seem to be available only in "flat edged" form and they wear away quite quickly during this process. To get a V-shaped groove I think that the iron would need to be inclined first one way then the other.

Looks like you tried the blade in an "old" plane...

Yes, I'm not sure if the Saxons had discovered toothed irons

So save work (and heat), the teeth surely only need to be as deep as the thickest shaving you intend to take.

That's an interesting point - I think you may well be right. I'll put shallower grooves in the next one I make and put it to the test.