RCBS promelt won't get hot enough

[will52100]

Went to cast a bunch of 45's and the RCBS won't get above 700, with full or nearly empty pot. The red light on the ON switch is going out as soon as it hits 700. I've had this problem before and it was the thermostat, basically had to cut part of the stop on the rheostat so it'd travel just a bit further to make it work. This was after RCBS send a new one and it didn't work either.

I'll tear it down tomorrow and see what's what, but this is aggravating, especially as expensive as they are.

[blikseme300]

I would add a PID to solve this. Bypass the thermostat and use the PID to control the temperature accurately.

[Sasquatch-1]

Have you inquired about sending the whole thing back to RCBS for replacing?

[41 mag fan]

My lyman will do this at times. Sometimes it'll go higher than 700* other times the light goes out at 700*.

[will52100]

How do you add a PID? BTW, I really really suck at wiring anything more complex than a light switch. I can build mechanical contraptions, but something about wiring gives me fits.

[John Allen]

I would also be interested in adding a PID to my promelt if anyone has a schematic or directions.

[Cane_man]

just made a PID using this schematic and this thread for about $80 in parts from ebay:

http://castboolits.gunloads.com/showthread.php?34547-How-I-wired-a-PID-to-control-temperature

http://castboolits.gunloads.com/attachment.php?attachmentid=8509&stc=1&d=1219539013

[will52100]

Thanks, I've been reading through the PID threads, got some parts on order and hope I can put it all together. I may be screaming for help though!

[Cane_man]

^^^ no prob just let me know, not an expert but if i could figure it out just using this forum i know anyone else can!

[will52100]

Thanks, I did hot wire the heating element and it worked OK. As long as I was there to watch it and got into a rhythm casting and adding new metal to replenish and cool the pot it hovered rite at 750-775. Not ideal, but it'll do until I get the parts in.

[Le Loup Solitaire]

Of course a PID arrangement will work, but in this case it appears that the thermostat in the Pro-Melt is defective or sticking. With the warrantee/guarantee that RCBS has I would give them a ring and see what they suggest to do. They have a solid reputatio and may absorb the postage in taking a return and sending you a new pot. LLS

[will52100]

Got my parts in today, now I need to get some wires and a terminal block from Radio shack tomorrow. What gauge wire do I need for a 120 outlet? And I assume I need an on off switch?

I saw on another post where someone was selling kits, if I'd seen that first I'd have seen if he still had any kits left.

Thanks

[Cane_man]

if you are using a Lee 4-20 then 16 gauge wire will work fine... don't need an on/off switch but i added one to my unit... the kits are great but you will get far more satisfaction (and save about 50%) doing it yourself!

[will52100]

Thanks, it's an RCBS pro melt. I'm making an external box that I can plug the pot into so I can use it with my Lee 20 pound pot.

[carbine]

I have four 40 old electric pots. Two SAECOs (24 and 32) and two Lyman Mould Masters. They all work but are getting tired. Just ordered a Wage 4757 and was surprised at how reasonable the price was. Will let you know in a week.

[will52100]

Finally got time to work on it and got it heating up a pot of metal as I type. Seems to be working so far, will cast a few and see how it goes. Not as hard to build as I though. I used a 16 gauge extension cord for the plugs and wiring, and got a project box along with the PID and SSR.

Not much too it once assembled, but heres a pic anyway. I built it as a separate plug and play unit to be able to use it on other pots. The pro melt has the thermostat bypassed so it's on continuously and the PID and SSR is turning it on and off.

[will52100]

Casted a 4 or 500 45's and it worked great. Only issue is the temp is way off, like 300 deg. off. I had to set it on 1100 deg to hit 800 pot temp. Is there a way to calibrate the PID?

[Cane_man]

what type of probe did you get, is it suitable for immersion? is your pid matched with the type of thermocouple that you are using? did you get the +/- wires of the probe connected to the pid properly? also, ideally you need some type of probe holder to keep the tip a little off the bottom...

[will52100]

Not sure on the +/-, used the red I think as positive and blue as negative, the wiring diagrams on here were incorrect for the PID, but it had what was what on it. It's a high temp thermocouple, and looks like it should be fine for immersion, and I made a quick holder from tie wire, it doesn't keep it off bottom but does keep it off the walls and towards the middle of the pot. My mechanical temp probe sits on bottom as well.

One possibility is that I followed the wiring diagram on here and screwed up the PID connections and had the 120 hot line and negative line going into the thermocouple to start with. It didn't take but a minute to figure out something was wrong and unplug it. After looking at the diagram on the PID I wired it properly and it came on. I figure I was lucky I didn't fry it, but it might have thrown the readings way off.

[No_1]

You did not mention the model you have but my pid's are both Auber brand (http://www.auberins.com/index.php?main_page=index&cPath=1). These things are advertised to be "to within one degree accuracy without complicated PID parameter fine tuning". If yours is a Auber brand I suggest you check your installation against the directions and if you still have accuracy problems call the help number provided in the directions. The first time I called it was a simple wire change which fixed my backward temp readings.

[will52100]

The PID is an Aubur 1/16 pin. I'll give them a call Monday, so far it's reading fine, just off by about 300 deg F. when I run the pot up to 800 deg. F. At lower temps it's off less.