RCBS Pro Melt Temp Fluctuations

[mktacop]

I recently purchased an RCBS Pro Melt and am wondering about the temperature fluctuations. I know it has a thermostat built in, but is there any way to fine-tune its temperature response?

I was casting yesterday with the pot set at about 700 degrees. My digital thermometer was showing temps as high as 740, then dropping down to about 650 before climbing back up to 740. It repeated this cycle the whole time.

If there is no way to fine-tune the thermostat, can it be bypassed so that the Pro Melt could be PID controlled?

[Alan in Vermont]

Mine has close to those same wild swings in temp. Can't say that I care for it much(the 'stat, not the pot, which I really like otherwise).

Using it with a PID controller should be as simple as setting the onboard control to the highest setting and plugging the pot into the PID. A PID is on my wish list, all I need is the $$$.

[ph4570]

I just got a new one set up. Its temp setting is not close to my PID box temp measurement. I have not cast with it yet. I got it set up with PID probe and filled with lead just last night. When I cast with it I will max out its temp control and just use the PID. So the apparent poor temp control will not bother me.

When I was assembling the pour handle an obvious enhancement came to mind. I installed a compression spring on the pour adjustment bolt shaft. The spring applys pressure holding the pour handle down more than just the weight of the handle. I do not know if the unit would otherwise have a drip issue but the handle's feel when pouring is much nicer with the spring installed. Perhaps later I'll post a picture of the installation.

[mktacop]

I just got a new one set up. Its temp setting is not close to my PID box temp measurement. I have not cast with it yet. I got it set up with PID probe and filled with lead just last night. When I cast with it I will max out its temp control and just use the PID. So the apparent poor temp control will not bother me.

When I was assembling the pour handle an obvious enhancement came to mind. I installed a compression spring on the pour adjustment bolt shaft. The spring applys pressure holding the pour handle down more than just the weight of the handle. I do not know if the unit would otherwise have a drip issue but the handle's feel when pouring is much nicer with the spring installed. Perhaps later I'll post a picture of the installation.

Please do. I may copy your spring idea. I love the pot, just not the wide temp swings. I already have a PID I was using with my old drippy Lee pot, so I will probably just try it with the RCBS set to max and see how it works.

[ph4570]

I just got a new one set up. Its temp setting is not close to my PID box temp measurement. I have not cast with it yet. I got it set up with PID probe and filled with lead just last night. When I cast with it I will max out its temp control and just use the PID. So the apparent poor temp control will not bother me.

When I was assembling the pour handle an obvious enhancement came to mind. I installed a compression spring on the pour adjustment bolt shaft. The spring applys pressure holding the pour handle down more than just the weight of the handle. I do not know if the unit would otherwise have a drip issue but the handle's feel when pouring is much nicer with the spring installed. Perhaps later I'll post a picture of the installation.


The spring notion:
http://castboolits.gunloads.com/imagehosting/thum_88054fff189b93b7b.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=5862)

PID probe mount:
http://castboolits.gunloads.com/imagehosting/thum_88054fff18ad88b2c.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=5863)

Mr. PID
http://castboolits.gunloads.com/imagehosting/thum_88054fff18c1bca47.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=5864)

[mktacop]

Very Nice!

Set my RCBS up with my PID tonight. Turned the RCBS dial up to max and plugged in to PID. Temp was holding +/- 2 degrees from where I had it set. I REALLY like the RCBS Pro Melt now!

[OuchHot!]

My pro melt also shows sizeable fluctuations in temp. It is certainly better than my Lee 20# pot but I run both on PID now. I like the spring loading on the arm! My pro melt does drool a little, I'll give that spring a whirl.

[Lee W]

Here is a post I did in 2007 about the RCBS thermostat.

http://castboolits.gunloads.com/showpost.php?p=435537&postcount=8

I went to PID control pretty quickly after starting this hobby.

[ph4570]

I did some casting last night with and without the spring pictured in my post #5. While there was no dripping without the spring (did not expect it with a new machine) the handle operation feel is much better with the spring. Also I suspect the spring will help discourage any inclination of the beast to develop the drips.

I cranked the thermostat all the way up on the Pro-Melt and let the PID do its thing. I had been using the PID on a Lee 20#er for a few years. Not sure what I will do with the lee. Maybe seal off its bottom pour and use it for ladle pour. I have a couple of molds that seem to prefer ladle pour.

[wymanwinn]

Very Nice!

Set my RCBS up with my PID tonight. Turned the RCBS dial up to max and plugged in to PID. Temp was holding +/- 2 degrees from where I had it set. I REALLY like the RCBS Pro Melt now!

OK Buddy.....parts list....gotta stay with ya on the mods...LOL

wyman

[mktacop]

OK Buddy.....parts list....gotta stay with ya on the mods...LOL

wyman

email coming to you. :)

[Lance Boyle]

I like the spring idea, probably completely unnecessary but gives a better more positive feel.

Only thing I wonder is if the heat will cause the spring to fade in short time. When I get my own spring, I'll find that out!

[gandydancer]

The spring notion:
http://castboolits.gunloads.com/imagehosting/thum_88054fff189b93b7b.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=5862)

PID probe mount:
http://castboolits.gunloads.com/imagehosting/thum_88054fff18ad88b2c.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=5863)

Mr. PID
http://castboolits.gunloads.com/imagehosting/thum_88054fff18c1bca47.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=5864)
where does one get a PID? and a spring kit??

[dromia]

Frozone does PID kits, just ordered mine.

http://castboolits.gunloads.com/showthread.php?t=155381

Springs I've got from any DIY/hardware shop.

[ph4570]

where does one get a PID? and a spring kit??

You local hardware store should have a selection of springs.

[Silver Hand]

I recently purchased an RCBS Pro Melt and am wondering about the temperature fluctuations. I know it has a thermostat built in, but is there any way to fine-tune its temperature response?

I was casting yesterday with the pot set at about 700 degrees. My digital thermometer was showing temps as high as 740, then dropping down to about 650 before climbing back up to 740. It repeated this cycle the whole time.

If there is no way to fine-tune the thermostat, can it be bypassed so that the Pro Melt could be PID controlled?

It is normal for heating elements to work this way when governed by a thermostat.
The closer the tolerances the higher the cost.
My guess is that it is piratical for casting lead.
I never notice swings using my old Lyman mould master 1,000 watt or my Mold master 850 watt.
Might be my thermometer has smaller numbers.

[OuchHot!]

I have had a good pyrometer (thermometer) for a long time and knew that my Pro-melt had a pretty sizeable dead band. It didn't matter until I got some 4c aluminum molds. I think that the 'sweet spot' is more narrow for 4c aluminum molds (especially hp) and the PID definitely makes life easier. I think for my 1 and two cavity iron/meehanite molds the pro-melt was just fine without PID. I cast a lot of bullets over the years with the Pro-melt before the pid came along.

[gandydancer]

Frozone does PID kits, just ordered mine.

http://castboolits.gunloads.com/showthread.php?t=155381

Springs I've got from any DIY/hardware shop.
Thanks kindly sir.

[J.Louis]

Plug your pot into a 1000 Watt dimmer switch and either bypass the factory thermostat or leave it maxed out on high if it will get you to 800 or past it. The dimmer switch provides a constant amperage and thus a constant tempreture.

http://img.photobucket.com/albums/v300/Schuetzen/001.jpg

J.Louis

[trixter]

WOW what a great idea, inexpensive and accurate at the same time.

[OuchHot!]

I am glad that dimmer solution worked for you. For me, things started getting pretty hot as I drew the pot down.

[Frozone]

I am glad that dimmer solution worked for you. For me, things started getting pretty hot as I drew the pot down.

Exactly, that rheostat solution is no better than the 'infinite control' LEE uses.
The LEE control reads current through it and shuts on/off to maintain that amount.
The Dimmer has the disadvantage of constant power drain as it works by resistance.

[J.Louis]

All I can say is the alloy temp. remains constant so I'm not sure what the disadvantage would be.

I knew there would be a nay sayer jumping in it never fails and that is unfortunate as it works very well and has done so for me as well as others for well over 7 six years now and it most certainly will do the same for others. Gentleman take it for what it's worth and I won't be coming back to answer any questions you might have at this point but I will add it needs to be a 1000 Watt Dimmer not just your every day dimmer switch to control your living room lighting. Mine only gets warm to the touch so someone is not using the correct commercial dimmer switch.

Having the pot cycle on and off cannot and will not keep a constant alloy temp. it is not possible as the alloy is on a never ending heating a cooling trend and I have seen alloy temp swings any where from 20-50 degrees, my personnel experience.

I hope this informaton was helpful to the gentleman that was having the problem.

Yours Sincerely
John Louis

[Frozone]

You may find this enlightening:
http://www.physicsclassroom.com/class/thermalP/u18l2b.cfm

The different amounts of lead in the pot requires different amounts of heat to maintain a given temp.
It takes more wattage to maintain the temperature of 20# than it does 5#.
Your constant current control will cause the temp to vary (raise) as the pot empties - just like the LEE control does.

But you are correct if you don't cast any boolits, the pot will stay at a very constant temp with your dimmer.

[J.Louis]

But you are correct if you don't cast any boolits, the pot will stay at a very constant temp with your dimmer.

Now that right there was a very intelligent comment Troll and it gave you a one up on the neighbors three year old. Pat yourself on the back you should be proud of yourself.

[MGySgt]

I don't have any experience with the RCBS Pro melt - I have a Lyman MAG 20 dipper and it hold the temp with in a 20 degree reading. This pot is about 20 years old.

Close enough for me.

(I just tested it again on Friday.)

[wymanwinn]

Very Nice!

Set my RCBS up with my PID tonight. Turned the RCBS dial up to max and plugged in to PID. Temp was holding +/- 2 degrees from where I had it set. I REALLY like the RCBS Pro Melt now!

+1....got mine setup on Saturday....purdy dang accurate....

thanks Buddy for the help...:bigsmyl2:

wyman

[mktacop]

+1....got mine setup on Saturday....purdy dang accurate....

thanks Buddy for the help...:bigsmyl2:

wyman

Any time sir! BTW, just bought a Master Caster....I may have to duplicate your design....again.

[wymanwinn]

Any time sir! BTW, just bought a Master Caster....I may have to duplicate your design....again.

NICE!!!!!

standing by My Friend.....:bigsmyl2:

[shotman]

WOW the spring WORKS
next as for temp problems
remember that is a thin stainless pot . I put some insulation around mine on back and rt side and that worked for me