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1kg vs. 3kg electromelt

Hello! I’m setting up operations in my studio to do lost wax casting and looking at electromelts to melt my metal (I’m in a basement so torch melting is not an option). I’m wondering if I should go for a 1kg model or pay a little more for a 3kg model? I don’t have any experience casting and I’m having some trouble envisioning the typical metal weights involved, especially when factoring in the extra metal for sprues/buttons etc.

I’m going to be casting mainly silver, but also some bronze and gold, and probably flasks with 1-12 pieces each depending on size etc? I do cast some larger pieces like sterling silver cuff bracelets

Besides the upfront cost (and a slightly higher cost for replacement graphite crucibles) is there a downside to getting a larger electromelt?
Would I see a significant energy difference required to melt the same volume of metal in a 1kg vs 3kg melter?
Would melting smaller volumes in a 3kg melter allow more room for oxygen to contact the metal?

Any suggestions or inputs are appreciated! For reference I’m considering these two electromelts from Rio:

Thanks so much for your help!

Hi Rachel,

I do use an acetylene tank for work in my basement studio, but with several adjustments. The space is built into a hillside so at one end it’s access stairs poured into the building foundation. The other side, the ground level is chest to shoulder high with windows above. Do you have ANY perimeter windows high up in the basement? You could use something along that line to great advantage.

  1. I store my tank right outside a window and have an extra long hose. It’s maybe 4.5 feet from the outside location to the centrifuge location.

  2. i have an adaptable / adjustable ventilation hood that is not all things at once, but adjusts to the ventilation task as needed. The kiln & centrifuge are on two vintage tool stands that were selected for their ergonomic height. I refer to the set up as my “frankenvent” air system.

  3. I built a 3/4 wrap of sheet metal on my 12" tall centrifuge factory housing with wing nuts. It brings the height up an additional foot or so. I can access the centrifuge from the front with a 16" wide opening. It has a cap on top with one of my fans inset.

  4. I use the the same centrifuge station with an insert kiln shelf for soldering, annealing, etc.

  5. I have a taller adjustment, second hood / cap so that my vulcanizer can be used as well.

  6. I have an existing, but unused wall heater, so I use that as the fixed attachment for exhausting fumes out of my studio. I removed the covers and one baffle on the building exterior so that The air would move mite freely. The ventilation hosing is flex aluminum 8" dia from a home improvement store. All the step up and step down pieces are conventional sheet metal connectors from the same source. Add some large hose clamps.

  7. I roll the work stands about two feet to swap out centrifuge for kiln. Then i add one connector to adjust the height. There is a customized sliding track overhead to support the hosing.

  8. the fans are installed inline. One is close to the wall mount heater location. The other is additionally used with the centrifuge, over that combined unit. I move 4.5 times the air volume in an hour. My studio is 850sq feet with 8 foot ceilings. About 40% is dedicated jewelry space with 6 workstations for various tasks. The footprint of that area for the kiln& centrifuge is 10 × 6 with a central walking area to one side. I keep at least 2 foot clearance behind that equipment away from any walls.

  9. I’m not in Ontario, but sunny southern California, I can go barefoot most of the year working(, unless I’m casting). There is a huge water heater in a dedicated closet and I live directly upstairs, so I’m a bit paranoid of blowing up myself and the building I manage, so I designed specific to my spaces issues.

  10. I added a lot of electrical to have 60amps worth of quads where i needed them and a 30amp semi dedicated twisty for the kiln.

If adding a window for both light and air or vent to the basement would help, it really is something to consider. It’s not always WINTER.


Make sure and check the top temp of electromelt capabilities. You may not be able to use it if your casting temperature exceeds top end of electromelt highest temperature.

Also what size of flask will you be casting?

I suggest calling the experts at Rio and tell them what you want to do. They’re very knowledgeable and incredibly helpful. My experience with them has been to help you accomplish your goals and not just make a sale.

Hi Eileen,

Thanks for describing your set-up, it sounds pretty cool! There is one small window up near the ceiling in my work area (ground level to the outside) but its located under a large wooden deck without much clearance for things like gas tanks. Our winters here are long (up to 6 months with snow on the ground) and the freeze-thaw cycles in the winter and high humidity the rest of the year would be rough on an outdoor tank (propane tanks left outside tend to turn into rusty messes), not to mention the hoses, and the under-the-deck location would make regular assessment and maintenance a pain.

I’m already pretty set on casting with a vacuum table and electromelt, I’ll be casting alone, and between that, the difficulty having large gas tanks in the basement, and generally being wary of flinging molten metal around my house (even with additional safety measures) I think it’s the way to go for me.

Thanks again for your suggestions!

Hi Amy,

Both the sizes of electromelts will be able to reach the temperatures I need, I’ll be working with silver (mainly) and some bronze and gold, but no plans for higher temperature alloys like Platinum.

As for flask size my vacuum caster accepts flasks up to 7" high, though I doubt I’ll be producing enough work to regularly cast flasks that large at the beginning, so banking on probably a 3" or 4" high flask.

Thank you for your suggestion to touch base with Rio, I’ve found their tech department very good as well, they can probably help me hash out the pros and cons of each size.

Thanks for your input! :slight_smile:


That deck interference is an issue, I agree. An electro melt sort of scares me a bit, but my kiln doesn’t, go figure. I can just see a California earthquake in the middle of a work day burning a hole thru flooring all the way to China. I’ve seen issues with flying metal in a centrifuge. The reasons are generally “operator error”. I added the taller surround to my centrifuge BEFORE I ever used it. I love my centrifuge compared to vacuum casting because of the better detailing. There’s nothing like flying metal in a secure containment system. But I do have a backup in my vacuum caster.

Eventually, in the next several years, we’re relocating to a colder, damp, but not so snowy environment in the Olympic Peninsula - NoWa when my partner retires. I’m looking at real estate regularly to create a home and suitable work environment. Your solution seeking is valuable to me in reverse.

I hope your studio is a dream to work in. Right now, my studio is an absolute dream, and I have spoiled myself. Autonomy in your own space is such a wonderful creative experience.


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Rachel, I cast bronze and use a custom 3kg electric melter rated to 1250C. My casting sessions require pours of 100 grams up to a kilogram or more.

The bronze alloys I use from Rio are poured at 1020C to1070C. This is very near the maximum rated temperature of 1100C for the Electromelt and similar. This is why I use a furnace rated for a higher maximum temperature.

I think the jewellery casting machines are primarily designed to melt sterling silver or gold. Note that sterling silver casts at 970C and gold is even lower.

I suspect your jewellery electric elements will have a very short life if you melt much bronze in these machines or run near the rated maximum temperature. Heat causes the element resistance to change over time. You should expect your elements to eventually fail.

Ask Rio about the costs for replacement elements or rebuilds of your furnace?

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I have used the 1kg unit in my classroom shop and it works just fine. I’m sure you will receive a variety of opinions and perspectives, but i think the bottom line here is the volume of casting you want to do at one time.

If you are setting up a one person shop, the number of pieces/size of each piece - like cuff bracelets probably won’t be/need to be that many at a time. You are casting them, and you are finishing them. That’s one consideration. Another consideration is the difference in cost.

If you are trying to outfit an entire shop for yourself, is there anything else your heart desires, or you feel is essential for a well equipped shop that $175 could go towards? Over my career as a metal artist I have only asked myself the same question about, oh say, a zillion times. :smile:

And as with your burnout kiln, shop around for a good product at a good price. There are, for example, 5 models of electomelt furnaces available at Contenti ( ranging from $565 - $682 in the furnace capacities you are looking at.

Good luck getting the right furnace for your needs.

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Having both the 1kg and 3kg sizes, I found myself in an unexpected situation.

I feel my hands are too small to operate the 3kg unit while wearing gloves. (I am about 5.5’ tall, riding glove size 7m)

The distance between handle top and knob bottom on the 3 kg is a little over 1/2" (I measured the difference at 0.70") more than it is on the 1kg model, and found this difference too uncomfortable to pour the 3 kg and maintain confidence in being able to control the unit in motion.

I asked a larger person (about 6’4" tall, glove size 2xlw) to pour the 3 kg unit, and they had no trouble at all, they actually prefer using the 3kg vs. the 1kg unit which I am very comfortable using.

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Oh my gosh! I am so sorry! I made the biggest mistake in my reply to the question!

I do not know how to remove my reply, so, here is the mistake I made:

The electromelts I own are the Kerr brand (Electro-melt, with the hyphen) and not the rio brand.

I apologize for my mix up. If there

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