Wednesday, July 19, 2006

What's for Dinner?

Or I should say, what's in the oven? :)

It's finally not as hot and humid today so I'm running the heat treat oven. Managed to scramble the last couple of days and got a lot of stuff done. In this load are a couple of Son of PryThings, some Mini Prybaby® XLs, some Prybaby® with spanner XLs, some Imps, a few Micro Bug Out Bars and a few regular Bug Out Bars, some tanto Goblins, the damascus goodies that I wrote about and photographed below and last but not least some wharncliffe Boogers. Not a particularly big load for the kiln but enough to keep me busy afterwards for quite a while.

Heat treat temperature has to go up to 1950F. and be held for approximately 30 minutes, then the pieces are removed and either press quenched between aluminum blocks or set onto thick metal plates (in the case of the Prybaby® pieces) to air quench.

I usually squeeze quite a few packets of tools into the heat treat oven, two pieces per packet. I have had as many as 90 pieces in a single load if they are small and compact. This load has 68 in all and represents more than a week of work to prepare. The packets are made of heavy stainless steel foil that has been folded and creased over a couple of times. The idea is to exclude air but at the same time not so tight as to completely remove the air space around the parts. I have found I get less scale forming if the packets are left a little on the roomy side. This will translate into less work after the heat treat to clean up the little bit of surface scale which inevitably forms to some degree. The commercial guys don't get this problem because they heat treat in a vacuum environment in their special ovens.

Once the heat cycle is complete, the pieces are pulled and they are allowed to cool down to room temperature. At the same time the oven will be cooling down and when it reaches the 650 degree range I will put everything back in for the two tempering cycles. Each cyle is 2 hours and I let the oven cool back down to room temperature in between cycles. I leave everything in the packets for tempering as that covering continues to protect against scale formation.

One exception is the damascus. It has been double wrapped with two pieces of foil, a packet within a packet. This really helps to cut down on scale and I do it on special pieces. After heat treat the packets containing the damascus pieces are put back into a cooler oven for the tempering, usually around 350F. for about an hour. Once completed I can proceed to finish sand and etch the pieces.

The other exception is with the CPM 3V tools, which are the prybars and the Imp knives. They will go through two more cycles at 950F.

After all the heat treat tasks have been completed I can move on to blasting and finishing. Then will come sheaths for the knives and cord wrap for the prytools. The spannerbabies will go back in the oven after blasting for a final heat coloring tempering cycle at the same 600F. temperature for 30 minutes or so. Then they can be tiger striped.

1 comment:

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