Troubleshoot my mokume

N

Nathan Gould

Joined
Jul 21, 2008
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Today at college i attempted to make some mokume using brass and copper, i used material about 1.5mm thick and 20 by 50mm. I made torgue plates out of 6mm mild steel and had a layer of stainless between the mokume stack and the mild steel plates.

i cleaned and degreased all of the metal to be welded after i had sanded it to expose new metal, then clamped it up in the torque plates and heated it with a blowtorch until it was a dull red, theni hit it with a hammer until it felt like it had bonded and dunked it in a big tub of collant after a minute or so of letting it cool on the anvil.

When i took the stack out of the torque plates i was pleased that the stainless had done it's job, and the three layers in the middle appeared to have worked though the brass had been reduced to about a 0.25mm layer, i wonder whether this was melted off?

i sawed the stack in half- this was a test piece and it quickly became obvious that it wasn't wleded proper;ly, the pieces delaminated with the pressure from filing.


so- the question is, what did i do wrong? wrong heat, wrong technique, wrong materials?

I was thinking of trying the same thing but using copper wire to holkd the stack together instead of the plates and adding lots of flux to help it along, as i found it difficult to hammer the stack with the bolts in the torx plate.

any helo gratefully recieved


Nathan
 
Whenever I've made it, I've used a forge to heat the stack up. I also didn't hit it, but instead squeezed it down in a vise and let it sit there until cool enough to take apart.
 
thanks scott, so i'm assuming that you didn't have the stack in plates, was it tacked together or held with wire? also did yuou use any flux.

i was thining that the right way to d it would be to use a flypress or a vice, but unfortunately there is neither on the welding department.

thanks for your advice!

Nathan
 
I put an oversized plate on either side with a bolt on each corner and squeeze it down as tight as I possibly can with the bolts. If I had a torch, I would heat the plates up first getting them as hot as I could get them without melting the brass, copper and nickle. This would preheat the center of the stack first.

Yes, I use flux. The same anhydrous borax that I use for damascus. Then into the forge and get it where the material is getting a puddly look. Don't heat it until the borax is like you want it for damascus, or you'll melt the entire stack up. Once up to temperature, take it out and immediately put it into the vise and squeeze it down as hard as you can. It should be welded together at this point.
 
With your method, the metal will oxidize and not fuse properly.
Here is what I do.
I have 1/2" thick torque plates with 3/8" bolts, I use 2X2 sheets (1X2 will work fine,though), stacked anywhere from 1 to 2 inches high. I scrub and clean the metal and wipe it with ethanol just prior to assembling the stack. I bolt it down as tight as I can. I make a bag from HT foil ( you can purchase HT bags ready made), add about 1/2tsp. of powdered charcoal to the bottom of the bag, and seal up the bag real well. I put it in the oven at the prescribed temp for the metals being fused. You need a chart to figure the eutectic point and be about 25-50 degrees below that point.. Too high and you get a melted blob. Heat for about 4-6 hours. Tear open the bag and set on the anvil (hold with tongs). Give it a couple of light blows. Do not smack it hard ! Let it cool until all color is gone and stick in a bucket of water. Remove from the plates, grind the sides smooth, check the sides for splits, and if all is well, forge down to about half the thickness. Anneal and forge ( repeating as necessary) the billet until it is a strip about 3/8" thick. Then use a ball pein hammer to forge it out to about 1/4". Grind the surfaces smooth and the mokume' should be a nice random pattern. You will get a good size bar from this method.
Stacy
 
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