Master Caster thermostat

[Nick Quick]

Well, I just couldn't stop myself when I've seen an used MC for sale and I bought it. The machine works like a charm. I fiddled a bit with adjustments, changing molds etc and it's easy breazy. I'm really happy with the machine overall.
After working few hours with it I observed something weird and I'm not sure what to make of it.
When I started the machine and put the thermostat at 600F the temperature I took with a thermometer showed around 800F. 800F for me means danger so I lower it to 500F where the thermometer showed 700F. Now even if I put the thermostat knob at 450F and I still had reading close to 700F.
Then I stopped casting and spent a bit playing with the thermometer and the thermostat knob.
If I dip the thermometer just a bit (not deep in the alloy) the temperature reading on the thermometer and thermostat is right on the money. 700F or 500F if the thermometer is dipped just a bit then the readings are the same.
Now if I dip the thermometer deep in the alloy the temperature let's say from 450F goes almost to 700F. In a way I get the idea that on the bottom the temperature is higher but the MC is a bottom pour so when I push the lever the alloy will come out from the bottom, so at that huge temperature and not what the thermostat knob shows. Which one should I believe? The thermostat knob or the thermometer.
Can anyone enlighten me as I'm kinda baffled and I have no idea what to do next casting session.
The bullets look good for a brand spanking new mold who's not "broken in" yet but the alloy in the pot looks very fluid, like water and I'm not sure that's normal.
Any suggestion highly appreciated.
Thanx, Nick

[6bg6ga]

I go by the way the bullets look more than I do what is reading on my PID. Don't want them wrinkled or frosty.

[Nick Quick]

I called Magma and they reminded me about the adjustment lil' screw inside the thermostat setscrew. To decrease the temperature it has to be rotate clockwise. So it took me about 40 minutes to adjust the temperature in small increments until the thermometer reading was the same with the thermostat reading.
Now I can totally count on my MC thermostat.

Here is a picture with my new invention to better direct the bullets and the sprue puddle separately in safe and precise place each one.

http://i64.tinypic.com/wthkt1.jpg

[DerekP Houston]

lmao nick that is ingenious and hilarious. Well played sir.

[wv109323]

I am not familiar with the MC either. But the bi-metal thermostat on my Lyman pot was less than precise. First the "switching" of the thermostat relies upon the air temperature around it and not the temperature of the lead. On the Lyman the thermostat is in an area adjacent to the pot itself. Next My thermostat rusted over time making it less accurate all the while. Wire terminations became loose with the heating and cooling cycles. Loose wires cause more heat until they burn apart. Your need to calibrate the thermostat speaks to my experience of these type thermostats.
As to your different temps., was lead added within ten minutes of taking the temperatures? I was amazed as to the length of time it took to get the lead back up to proper temp. After adding lead. I did not discover this until I got a PID controller. I don't think you could have plus or minus 300 degrees in the same pot unless you recently added lead.

[OS OK]

Ingenious idea...but...aren't you a bit embarrassed when the wife comes out catching you casting in your underwear?
On the serious side...make certain that your dial thermometer is calibrated correctly if you are going to use it to calibrate the digital PID. I suppose that end results would justify any setting, correct or not, I just like having the correct values at hand since I've spent my entire working career with multimeters and the like.

[Nick Quick]

All the measurement were done well after the ingots have been in the molten state. It was just out of adjustment for some reason. As soon I removed the thermostat knob and start playing with the adjustment screw inside the thermostat rod, the temperature started to come closer and closer to the thermometer reading. It took me a while to match both temps as I did the adjustments in small increments with long time in between to allow the temp of the pot to decrease and stop at the adjustment level.
Now, when I turn the knob to 650F it is 650F on the nose on the external thermometer on the bottom of the pot right where the pouring spout is. The casting process goes smooth and the alloy flows beautiful into the mold.

After I pull the handle 100 times(200 bullets in the bucket) I stop a bit and collect all the solidified sprue puddles and return them into the pot, then flux, skim and start another uninterrupted 100 string of handle pulling.
I love the machine.

[Nick Quick]

OS OK, I was blessed with a wonderful woman who understands all my passions so nothing about me makes her wonder anymore.

I checked that Rotometals thermometer against another temp measuring device and is reading great. If I would have the slightest doubt I would not touch the machine thermostat adjuster. I do not have a PID yet for the machine. I'm skeptical buying it as per Magma instructions a nut has to be welded on the side of the pot for the temp probe. I don't know any welder I would trust to weld anything on my pot. I'm still debating on the issue as I totally understand the advantages on using a PID controller.

[Lefty bullseye shooter]

I talked to the guy at Magma when I got my Master Caster about the PID. He said without it the Master pot will keep a constant temp +/- 4 degrees. Thats only 8 degrees. I fill my pot to about an inch bellow the top and cast. I put 1.5# ingots on the ledge and place one in every so often and try to keep the level of the pot fairly consistent. 75% of my 194 gr bullets are within 1gr and about 95% within 1.5gr. Works very good for me. Love my master caster.
Scott

[bilco]

I called Magma and they reminded me about the adjustment lil' screw inside the thermostat setscrew. To decrease the temperature it has to be rotate clockwise. So it took me about 40 minutes to adjust the temperature in small increments until the thermometer reading was the same with the thermostat reading.
Now I can totally count on my MC thermostat.

Here is a picture with my new invention to better direct the bullets and the sprue puddle separately in safe and precise place each one.

http://i64.tinypic.com/wthkt1.jpg

Love the ingenuity here.

[AbitNutz]

Huh...guess you lost your pants in that deal...

[Nick Quick]

The poor pants were lost a while back but I didn't threw them away as I always cut pieces of old jeans and make inside pockets for my jeans jackets. This time I found a better use for those ole jeans. The method works like a charm. No more hot sprues everywhere. They all fall almost in the same spot except for the ones who fall on the sides of the machine.
Bottom line it works and every time I cast I use the pants with great results.
I'm not sure Magma would be tempted to "steal" my idea so is not worth it to file for a patent.