More school district surplus sale scores.

bpimm

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Last weekend another local school district had a surplus sale, we went to see what they had, I ended up bringing home a couple finds.

First up is a Hobart commercial oven, they replaced theirs with a bigger unit and I thought this might make a powder coat oven. It is a natural gas oven so I'll need to switch it to propane, the parts are available but more expensive than I thought they would be, about $440.00 to my door and I paid $65.00 for the oven so about $500 for a pretty good size oven. not as good of a deal as I hoped. The new version of this oven sells for about 7K and the refurbished ones are about $2500.00 for the Hobart's.
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Second up is a Powermatic 12" pedestal disk sander for $50.00. It would have been nice if it was 110V single phase but it's 230 3PH so I either need to add a circuit to my RPC to power it or get a small VFD for it. Best would be a 110V 1PH input vfd that gives me 230V 3PH output but so far I haven't found a 110V unit higher than .5 hp. The shop is wired for 110 with a few 220 welder outlets.
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So does anybody know of a 110v in 230v 3ph out 1hp controller?

Or of a way to safely run a NG oven off of Propane other than replacing the gas valve and orifice?
 
Replace the motor with a single phase unit; when going from natural gas, to propane, the orifice size is 11 number drill sizes smaller, you can press a piece of brass into the hole and re drill it; I'd start with a drill 13 or 14 sizes smaller and observe the flame to see if it looks right, you can always drill it larger. The gas valve should work on either gas if it has a high enough pressure rating, you will also have to change the pilot light orifice, unless it has electronic ignition.
 
Sorry, no. It is too dangerous to run a VFD that close to a river. I'll come by and pick up the sander, take it off your hands and solve that problem for you! :). Seriously, nice finds! Suggest you just run a VFD off of a 220V (aka. 230V, 240V) circuit. A 15A, 240V circuit would likely do fine. Your rotary phase converter should work fine too. I think it would be nice to be able to control the speed of the sander using a VFD. Can't help you with the gas question.
 
I had to convert a donated natural gas stove to Propane for a Boy Scout camp I help take care of. If I remember right, we soldered up and re-drilled the orifice's and changed out the regulator. The regulator was not that expensive, we picked it up at the local propane dealer.

Steve
 
Nice finds, but everything I've ever read said don't use any flame around powdercoat. Only electric ovens. I'm not sure if it's the fumes or what but I do know it's dangerous.
 
Replace the motor with a single phase unit; when going from natural gas, to propane, the orifice size is 11 number drill sizes smaller, you can press a piece of brass into the hole and re drill it; I'd start with a drill 13 or 14 sizes smaller and observe the flame to see if it looks right, you can always drill it larger. The gas valve should work on either gas if it has a high enough pressure rating, you will also have to change the pilot light orifice, unless it has electronic ignition.

Replacing the motor was my original plan, I thought I had one sitting on the shelf... They say your memory is the first thing to go and I don't remember what was next on the list... My replacement motor is only 1/3hp not 1. Thats good info on the drill size difference between the gasses. With the Hobart they built the pressure regulator into the gas valve so you have to swap the whole unit. I haven't looked at it yet to see if it could be swapped for a different valve/regulator combo or separate parts. I'll check on the pilot light, Hopefully it's electric ignition.
 
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