Rasp Tomahawk Problem

[BrittS]

I was messing around yesterday and thought it’d be fun to try a wrapped eye tomahawk. I thought I had it welded up but when I drifted it the weld popped the entire length and only left the very edge welded (I think). I set the weld using a 2ish pound hammer and then really hit it with a 4 pound drill hammer. The top was welded but I barely got the bottom to weld. My question is what did I do wrong with the weld as to have it pop the entire length? Sorry for the blurry picture of the edge itself. 

[JHCC]

The three keys to solid-state welding success are heat, cleanliness, and pressure. With forge welding, pressure isn't really an issue, and you can set and refine a weld with a comparatively small hammer. (When I made my first wrapped-eye hatchet, IFI member Latticino let me use his Magic Welding Hammer, which is barely over a pound.) If your workpiece isn't hot enough, you're less likely to get a weld, but if it's not clean enough, you're REALLY not going to get a weld.

You don't say how you prepped your workpiece, how you heated it, or whether or not you used flux. Can you fill us in on those details?

[BrittS]

I wire brushed it before bending it over, closed it up, and then put a bead of the iron mountain black flux on the top and bottom. I was using an old coal forge and heated it up to a yellow to white heat. I was trying to weld the edge first and it got thin and I burned it lightly a couple of times. 

[Latticino]

Also recommend that you rethink the final shaping of the eye after the weld is complete.  You are really using a mandrel to shape it (most hammer blows should be with the mandrel inserted and the "side" of the eye on the anvil face with hammer blows from above) and should not be doing any major drifting to increase the opening size.  For the inevitable first shaping of the somewhat wonky forge weld I suggest you trap the welded section in your post vise securely when you first seat the mandrel.

Also, always weld from the front of the eye towards the bit.  The front of the eye is the critical location and most difficult to get cleanly welded.  Of course I always weld a HC bit into my hawks, so I do that side afterwards.  Still, as John mentioned, keeping the stock fairly thick while welding (light hammer) seems to help as well.  Even with your coal forge you can oxidize the surfaces, making for a difficult weld.  Make sure you are in the reducing zone of the fireball.

[JHCC]

The surfaces may have scaled up between the wire brushing and the fluxing. Flux isn't glue, but you do want it to coat the weld surfaces sufficiently to dissolve the scale and prevent further oxidation, especially if you're having trouble keeping the workpiece in a reducing flame.

[Jason L]

I'm not sure how you insert air into your forge but when I was first trying to forge weld I was cranking the blower as fast as I could to get it up to heat not realizing that I was making sure there was causing the steel to scale more. Since I slowed to a crawl with my blower and let it take it's time coming up to heat I have no problems. I can even forge weld with no flux at all fairly reliably on small basket twists. Oxygen may keep you alive but it kills your welds. I always take my time and go as slowly as possible until the steel comes out. That's when I test my speed

[BrittS]

It’s a factory bottom blast champion forge and I probably wasn’t ready for a project like this but I was able to get consistent faggot welds on a piece of bar stock and thought that maybe I would try it. Thanks everyone for the advice. 

[Irondragon Forge ClayWorks]

The problem with forge welding a rasp is by the time it's hot enough through & through it's at the burn point.

 

I can't control the wind, all I can do is adjust my sails. ~ Semper Paratus

[Frosty]

Don't forge the folded section of bit down thin before you weld them. Only forge the inside edge of the bit down thin-ish to prevent a cold shut when welded. Shine the smooth components up and flux before you close the joint on the bit. That way the flux will be there when you start heating it to prevent oxygen contact. 

Works for me.

Frosty The Lucky.