Lyman Mould Master XX furnace

[DannyE]

I've had this old furnace (Lyman MM 20lb) for some time that picked it up cheap at a gun show. It was nasty dirty and rusty but disassembly and a steel wool cleaning plus repaint made it like new. I've been trying to date it's year(s) of manufacture. None of my old loading manuals shows this particular model. All I find is the 10lb Lyman 61 furnace with the thermostat on the front. Any info would be appreciated.

[jsizemore]

I had a friend bought out a small ammo manufacturer that retired. In all the stuff was a MMXX furnace and a H&G 8 cavity #68 mold still in the box. I assume they were purchased at the same time. Invoice on the mold was mid-80's. Furnace still works great.

[DannyE]

I had a friend bought out a small ammo manufacturer that retired. In all the stuff was a MMXX furnace and a H&G 8 cavity #68 mold still in the box. I assume they were purchased at the same time. Invoice on the mold was mid-80's. Furnace still works great.

Thanks for the response.

[wv109323]

Is the metal on the outside steel or aluminum? I have one I bought about 1982 that has aluminum sheet metal. The ones with steel were earlier than that.
They are good pots but with mine the electrical points of contact rusted/heated and burnt in two. I finally eliminated the plug-in and thermostat and wired the PID directly to the heating element.

[DannyE]

Is the metal on the outside steel or aluminum? I have one I bought about 1982 that has aluminum sheet metal. The ones with steel were earlier than that.
They are good pots but with mine the electrical points of contact rusted/heated and burnt in two. I finally eliminated the plug-in and thermostat and wired the PID directly to the heating element.

It has the aluminum outside. When I got it there was a round control knob that looked like it was off a kitchen stove. I did a google search trying to find what a correct knob looked like and the all had a pointer knob except for one photo of a beat up pot that had the same knob as was on mine. I found a replacement pointer knob and changed out the round but kept it just in case I can find evidence to verify some of them came with a round knob. I have several old Lyman product catalogs as well as 50s & 60s reloading manuals but none show the furnace I have.

Here's a photo I took before changing the knob.

[jsizemore]

Mine has the "round" knob like your photo.

[DannyE]

Mine has the "round" knob like your photo.

Thank you for that information. So, apparently mine came from the factory with that knob. I need to find an early Lyman product catalog with photos of a MM XX with that knob. BTW, does yours have the bright aluminum housing or flat black like mine? My guess is they were only produced for a short time, first silver color with a pointer knob the flat black with a round knob. I may have that timing backwards so I'll keep researching. Crazy I know!

[georgerkahn]

I bought my first one in 1976! Another was dropped off by UPS-man in 1978; both, brand new purchases. A note is I still love and use both. On both, however, through use the rudimentary bi-metal strip controlled thermostat on both failed. I simply shorted contacts in each thermostat switch and plug the furnace into an in-line PID. This works like a charm! Also, I picked up a handful of free laminate flooring pieces at a local Home Depot and store these adjacent to my Mould Masters. I like to maintain less than 1/2" clearance between bottom spout nozzle and my mould top, so I start my casting session by stacking several of the laminate floor sample pieces under the mould I am about to use. Both the consistency of bullets cast achieved, as well as EASE to the wrists/arms while casting make it more than a worthwhile endeavor. (I have the TWO: One with a softer pistol alloy; the 2nd for harder rifle alloy. Works for me!)
geo

P.S.: Mine have the pointy knob as does yours.

[jsizemore]

Body and control are mill aluminum. Face plate, upper rim along with the lead metering mechanism are all painted black. Like Georgekahn I run the thermostat (?) control wide open and use a PID to control alloy temp. I use mine for my non standard alloys. I use 3 different RCBS Pro-Melts for my standard alloys. All my pots are for casting. They all got paint missing and lead splatter. They look used because they are. They all pour great bullets and are easy to use. They require little maintenance when I feed them clean alloy. Fill it with clean alloy and cast away and have fun.

[DannyE]

In case anyone is interested, I found info in the Lyman Cast Bullet Handbook, 3rd edition, the XX furnace and knob question in my original post was made 1976 through 1984 when a newer version of the twenty pounder was introduced. It first came with the pointed thermostat knob then change to the 'round' type in 1981.