Phred's Foam adventure

I lost my foam cutting hardware years ago in a Army move. My buddy Jeff Dawson cuts his own cores for all the combat planes he sells. I have helped him a bunch so he will cut just about any wing profile for me.

I want to set my airplane shop up so I can do my own. My original set up was simple but dangerous. A 30" bow of spring tension Ni-chrome wire, connected to the output of a 110 VAC Variac. Worked well but I did not have any safety switches, fuses, or a positive stop on the Variac preventing VAC above 24 ( the starting point of lethal AC voltage).

I have a few items here for a good DC setup at 13.6VDC up to 45 Amp. The original 1997 power supply in the RV is/was old skool transformer iron core heat and humm monster with no real battery management other then constant 13.6Vdc.

I replaced it with a more intelligent 90 Amp version that senses battery bank conditions and adjust from recharge, float, and every 90 day sulfite bust mode.

I ordered a Harbor Freight Router speed control.
I ordered some Iconel and Rene' wire (have Ni-Chrome on hand from Sig)

Fairly simple using the router speed control to adjust the 110 VAC into the Ac to Dc power supply (because it is a dumb supply it will not care) to adjust wire temp. Bows from 20 to 30 inches and small diameter high resistance wire should draw between 3 to 6 amps to get into the 600F range. The PS has 45 Amp max 40 amp continuous spec so it has PLENTY of overhead

A 30" bow is plenty to cut 20-29" wing cores any thickness and width. For the larger wingspans we just use two or more cores.

I cut these last year with Jeff's bow: