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bpimm

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#1
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.
IMG_20181122_084128383.jpg

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.
IMG_20181122_084042405.jpg
IMG_20181122_084109156.jpg

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?
 

benmychree

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#2
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.
 

Reddinr

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#3
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.
 

Bob Korves

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#5
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.
Well, you can use the "220 welder outlets".
 

WyoGreen

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#7
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
 

4ssss

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#8
That oven would make a nice smoker.
 

C-Bag

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#9
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.
 

bpimm

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#10
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.
 

bpimm

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#11
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.
Damn, that's good info, I would have just fired it up not knowing and caused the end of the earth as we know it...;)

110V would allow me to plug it in anywhere in the shop, 220 requires wiring in a circuit for it, I have thought about running a 220 circuit around the shop just for this kind of situation but haven't done it. The RPC would require a 50' run to get to that side of the shop but still doable. With the cost of the 110V VFD, that's off the table, the price on the 220V VFD (thanks Ulma Doctor) I think that's the way to go unless that 1hp motor on my shelf shows it's self.
 

bpimm

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#12
Well, you can use the "220 welder outlets".
I could, they're not where the grinder wants to be, so running a circuit would make more sense in the long run.
Then again nothing in my shop is where it should be...
 

bpimm

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#13
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
Thanks Steve, I still have to tear it apart to see if I can get to the orifice to do that and in Hobart's infinite wisdom they made the regulator integral to the gas valve and expensive. I need to dig into it and see if I can modify or disable the regulator and run an external regulator. Generic parts seem to be very reasonable but the Hobart part is $300.00 for the valve/regulator and $100.00 for the orifice.
 

bpimm

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#14
That oven would make a nice smoker.
It would, or even a nice overflow oven. thought about that yesterday trying to get everything cooked at the same time. even with 2 standard ovens we came up short and dinner was later than we planned.
 

bpimm

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#15
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.
I've read that as well but never found anything solid as for the reasoning, many commercial PC ovens are gas powered and the only talk I've found so far about exploding powder coat it when it's in the dust cloud at application, even then it's mostly theory and no reports of an actual explosion. I'm still reading about it, If it turns out to be true I guess I have a nice big oven. lol
 

C-Bag

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#16
I would guess as long at the heating is done through a heat exchanger I guess there would be no problem. But the powder gives off fumes when it's cooking and its toxic enough for them to say don't ever use the oven again for food. I'm more used to industry underplaying toxicity than over playing. But what would be wrong with taking the guts out of an electric stove and putting it in yours? It would be for easier and cheaper than trying to buy the material to make a powdercoat stove that size.
 

bpimm

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#17
I would guess as long at the heating is done through a heat exchanger I guess there would be no problem. But the powder gives off fumes when it's cooking and its toxic enough for them to say don't ever use the oven again for food. I'm more used to industry underplaying toxicity than over playing. But what would be wrong with taking the guts out of an electric stove and putting it in yours? It would be for easier and cheaper than trying to buy the material to make a powdercoat stove that size.
What I've read so far is that the fumes are toxic but most are not flammable, and I have found both direct fire and heat exchange models of ovens.

The other thing I'm finding is the warnings are coming from guys that are using a toaster oven for small parts. I am still researching so I haven't made any decisions yet, If you have any links to real evidence that would be very helpful. The internet has so much questionable information out there it's hard to decide what's really true.
 

C-Bag

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#18
What I've read so far is that the fumes are toxic but most are not flammable, and I have found both direct fire and heat exchange models of ovens.

The other thing I'm finding is the warnings are coming from guys that are using a toaster oven for small parts. I am still researching so I haven't made any decisions yet, If you have any links to real evidence that would be very helpful. The internet has so much questionable information out there it's hard to decide what's really true.
I agree there is a lot of silly stuff on the net. I got my original info from a DIY book and he specifically pointed out a gas oven is not safe. The big industrial units use heat exchangers and the exhaust doesn't go through the burners and they pick up air outside the shop. But it's kinda common sense that you don't want open flame around any kind of dust, especially this fine. It didn't take much of a google to come up with what happens. This was put on YouTube by a local fire dept. And while I don't foresee blowing the powder directly into the stove the problem is having something fall off the rack in the stove has happened to me. And it's enough of a mess trying to get the part out as it is, but having it on fire too would be a mess too far for me. When you drop an uncured part the dust fall off, nuf said.
 

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#19
I need to find me some of these sales.
 

bpimm

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#20
I agree there is a lot of silly stuff on the net. I got my original info from a DIY book and he specifically pointed out a gas oven is not safe. The big industrial units use heat exchangers and the exhaust doesn't go through the burners and they pick up air outside the shop. But it's kinda common sense that you don't want open flame around any kind of dust, especially this fine. It didn't take much of a google to come up with what happens. This was put on YouTube by a local fire dept. And while I don't foresee blowing the powder directly into the stove the problem is having something fall off the rack in the stove has happened to me. And it's enough of a mess trying to get the part out as it is, but having it on fire too would be a mess too far for me. When you drop an uncured part the dust fall off, nuf said.
I hadn't thought about a part falling in the oven, that's a good point. Whether or not it would reach an explosive mixture or not would be a hard question to answer. at this point I think I will put this oven on hold, maybe sell it on for a profit or keep it to cook with.

The video, to me, is of questionable value as to the oven question because as you said it wouldn't have the powder shot into it, It's more to the point of keeping the powder cleaned up and away from ignition sources, which the oven is one. The same thing can be done with powdered sugar and bakers use gas ovens all the time. Any organic powder can cause the same reaction.

Thanks for the link C-Bag, maybe I can convert it to electric.

Powdered sugar explosion
 

C-Bag

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I hadn't thought about a part falling in the oven, that's a good point. Whether or not it would reach an explosive mixture or not would be a hard question to answer. at this point I think I will put this oven on hold, maybe sell it on for a profit or keep it to cook with.

The video, to me, is of questionable value as to the oven question because as you said it wouldn't have the powder shot into it, It's more to the point of keeping the powder cleaned up and away from ignition sources, which the oven is one. The same thing can be done with powdered sugar and bakers use gas ovens all the time. Any organic powder can cause the same reaction.

Thanks for the link C-Bag, maybe I can convert it to electric.

Powdered sugar explosion
Thanks bpimm. There are so many folks on the net doing stuff that until you get into it a bit you don't get immediately how silly or crazy dangerous it is. When I first started in thinking about doing powdercoat myself I looked and read everything I could find. One vid was this guy just spraying a cloud of powdercoat, no mask, no booth, just a cloud you could barely see him through. On one plane I thought anybody could do this. But then I got there's DIY and just stupid.

I do everything, welding, machining, powdercoating and metal working out of the same two car garage. So when I do powdercoat I roll my oven outside the main door for the fumes and smoke. But also to preheat my pieces out in the sun on top of the oven. So because the Magic Chef oven I use is electric it's easy to move and I have an extension cord on it for 220v. I keep my little DIY powdercoat booth in the middle of the garage out of the sun and hooked up to my shop vac to contain the dust. This keeps the powdercoat from polluting the garage and messing with the other machinery.

I've gotten some crazy deals from school sales too. Not machinery, but office tables etc that I made into work stands for my powdercoat oven, assembly table, my sandblaster cabinet etc. You got some great deals and I hope you get the details worked out to your advantage.
 

bpimm

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#22
Thanks bpimm. There are so many folks on the net doing stuff that until you get into it a bit you don't get immediately how silly or crazy dangerous it is. When I first started in thinking about doing powdercoat myself I looked and read everything I could find. One vid was this guy just spraying a cloud of powdercoat, no mask, no booth, just a cloud you could barely see him through. On one plane I thought anybody could do this. But then I got there's DIY and just stupid.

I do everything, welding, machining, powdercoating and metal working out of the same two car garage. So when I do powdercoat I roll my oven outside the main door for the fumes and smoke. But also to preheat my pieces out in the sun on top of the oven. So because the Magic Chef oven I use is electric it's easy to move and I have an extension cord on it for 220v. I keep my little DIY powdercoat booth in the middle of the garage out of the sun and hooked up to my shop vac to contain the dust. This keeps the powdercoat from polluting the garage and messing with the other machinery.

I've gotten some crazy deals from school sales too. Not machinery, but office tables etc that I made into work stands for my powdercoat oven, assembly table, my sandblaster cabinet etc. You got some great deals and I hope you get the details worked out to your advantage.

There are definitely people doing crazy stuff... That's why I like to ask questions, it can cut down the research time a bunch. When I first started searching DIY powder coat ovens the standard seems to be a propane torpedo heater elbowed into the side of a insulated box. I saw many examples of this idea with praise heaped on them for how good they work... I even found 1 direct heating gas commercial oven available, I should have saved a link.

I think I'll just sell this oven, I only paid $65 for it I should be able to recoup that. I have another Pizza warming oven I bought from the same school district a couple years ago for $20 to convert into a PC oven, it's electric but only goes up to 250* F It's 220V so I'm thinking it may have enough element and I'll just need to change out the controls.

I've had the power coating rig for several years, I went to look at a sandblast cabinet on craigslist and ended up coming home with the SB cabinet a powder coating rig and an older craftsman floor standing drill press. I really don't have the space to set it up right now but that doesn't stop me from spur of the moment purchases for it. lol

My shop is 1200 SF and it has a 3 bedroom apartment over it that were living in until I get the house finished, once I move into the house then I have another 1000 sf to work with, I'm thinking one of the rooms will be a finishing room with a paint/PC booth and an oven vented to the outside.

I have gotten a lot of goodies form the surplus sales over the years, big metal cabinets for storage, tables and carts. Lots of good stuff, the equipment is harder to find but does show up occasionally, there were 3 table saws at this one as well as another disk sander/belt sander combo but it was missing the nose roller assembly for the belt sander portion or I would have grabbed it as well.

Once again thanks for the insights.
Brian
 

C-Bag

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#23
WOW, using one of those kerosene torpedo shop heaters for an oven!?!?!? That is about the dumbest thing I've ever heard as it doesn't take much of a breeze to blow off uncured PC and those things stink so bad I'd rather be cold than have to breathe the stench off them, then add in the PC fumes.........o_O

After doing my own PC now for 8yrs for me it's about the size of the oven. I just bought my old Magic Chef off CL for $25 out of a remodel. It was a semi built in that had 4 electric burners on top. Pulled the top burners and mounted it on the old school table that was heavy duty metal frame that had a shelf under it that was perfect for storing my old ice chest that I keep my 10lbs of powdercoat and other supplies in. Helps regulate the temp and humidity it's exposed to. I do almost exclusively semi gloss black so everything fits in the old ice chest. All the racks, and bread pans store on top of the stove. Because I operate out of 400sqft everything is roll around work stations so the stove is one PC workstation and when not in use is packed up and rolled against the wall far enough back in the garage where the sun doesn't hit it.

Its all about how big of parts you are doing. Everything I do will fit in this old oven. I would love to see live what these ovens you've got look like because the one thing I don't like about my oven is the door. Reaching over the typical fold down door to put in or take out parts is the tricky part. So having side opening doors really appeals if it's deep enough and wide enough inside. Depending on what I'm doing my smaller parts hang off racks that stand in the bottom of the oven. The larger parts I put the wire racks in and put the parts on the bread pans so I can do 4 big parts at a time. Most of my stuff is DIY like my freestanding racks and I've even had to make one wire rack for the oven as I found out the hard way they are NOT standard. Everything is a close fit but it works for me.
 

bpimm

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#24
They we're using the propane torpedoes so they wouldn't have the kerosene stink but still..

The oven I just bought has doors that open to the sides and they're actually tied together, if you open 1 the other door follows it. The rack size is 28"w x 22"d so it's not that much bigger than a standard oven on the inside anyway.
IMG_20181124_101003979.jpg
The pizza warming oven has a single door that opens to the side like a refrigerator. I just dug it out so I could take a pic and my memory failed me again, I thought it was a lot smaller than the one I just bought but it's not... The rack size is about the same you just open the narrow side instead and it's a lot taller so the inside measurements are 22"w x 28"d x 39" tall. Guess I need to test it out and see if it has enough power.
IMG_20181124_101339649.jpg
IMG_20181124_101404059.jpg
 

C-Bag

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#25
Both of those ovens are great. The pizza oven looks like the deal though. You could really load that thing up. There is only two things that would be the concern is there a rack system? And maybe there is some way to put a different thermostat and or heater element. You only need around 400deg for most PC, and some less than that. I've seen pro ovens that look just like that pizza oven.
 

CluelessNewB

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#26
Here are a few single phase 115V input 1hp VFD's, there are others available also:

https://dealerselectric.com/
Teco, L510-101-H1-U
Teco FM50-101-C
Hitachi WJ200-007MF
 

bpimm

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#27
Both of those ovens are great. The pizza oven looks like the deal though. You could really load that thing up. There is only two things that would be the concern is there a rack system? And maybe there is some way to put a different thermostat and or heater element. You only need around 400deg for most PC, and some less than that. I've seen pro ovens that look just like that pizza oven.
Unfortunately no rack system, there are slots in the back wall to hook racks in and some studs in the sides that could be used as well. I need to plug it in and see how hot it will get and see what kind of thermostat I can fit. The thermometer only goes to 280 degrees F so that needs replacement as well. Would be nice to have a window in the door as well.
 

C-Bag

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#28
One of the best investments I made early on was one of those inexpensive infrared temp guns. They are far quicker and accurate than a thermometer. Like $20? Been a while. You can see if there's any cold spots or the difference between the top and bottom, front and back of the oven. Just by pointing and pulling the trigger. Amazing.

To me the glass in the door is not a big deal because you can't really see through the light smoke with the door closed unless you have a really good light inside the oven. I do everything timed so I never check it till I take it out. My system, such as it is, is I'm prepping the next batch as a batch is in the oven. It's like skiing, once I start its constant until I'm done. But I do between 21 to sometimes as many as 65 pieces when I do a run. On my little free standing racks I can hang 7-8 pieces at a time and at 400deg they are done in 14min. By that time I've got another rack full ready and I pull the done ones and put in the next batch. Rinse and repeat.

I'm not sure what I'd do for that pizza oven. I guess a rack unit that would slide in and freestand with a roller rack to move the freestanding racks around to load and unload them. Would be interesting to see what was in there originally.
 

bpimm

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#29
I decided to sell the gas oven and proceed with the electric, I got $400 for the gas one so that worked out good.
I don't plan on doing any production powder coating so it's just going to be parts for my own projects but who knows what may happen down the road.
C-bag, I'd love to see your rack system to get some ideas.
 

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#30
I see there is some disagreement with the type of oven to Safely use for Power Coating.......

FWIW I worked in the automotive paint industry for a few years and I can tell you that ALL of the powder coat ovens I have been in have ALL been Natural GAS. The ovens are heated through a heat exchanger so there is No Open flame in contact with the power coat material. The Main Safety point to be Aware of is that Powder in just about ANY FORM (yes even normal cooking/baking flour) will become highly Flammable if not explosive WHEN it is ATOMIZED AND freely floating in a contained Oxygen Rich environment! The changes for a flash over are very high at that point and Any open flame OR SPARK from an electrical source could produce an explosive result.
 
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