PID Control on your Pot

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  • Last Post 24 May 2014
Uncle Russ posted this 20 May 2014

Mr. Onondaga,  I have been told by other members you have been trying to track me down concerning PID temperature control for lead melting pots.  After reading some of your posts it seems as though you profess quite a bit of knowledge on the subject yourself.  It is such a straightforward process I am a little lost on how I may be of any help to you. I must confess I have taken the winter off from casting to work on my latest interest since I retired, machining.  So I have fallen a bit behind with my cast bullet studies.  WOW!  Do I have a lot to learn about machine work, even for simple home project work. Back to you Gary.  Just reply to this post or send me a private email with your questions. True knowledge is only of any value if shared. :coffee

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onondaga posted this 20 May 2014

http://www.castbulletassoc.org/view_user.php?id=5818>Uncle Russ

Thanks for your reply. I have wanted a PID controller for a while. Pat is building me one along with the tutorial he is presenting. So, I am set now. I believe the tighter temperature control will help bullet quality in some of the bullets I cast. The very large ones and very small ones are most sensitive to temperature for me. I cast a variety from 12 ga slugs to a 55 gr bullet in 22 cal. My 6 cavity molds are also sensitive to temperature wandering.

I was previously trying to track you down to see what you have to offer. Interest in PID controllers for bullet casting appears to be growing for more than just me.Pat is currently doing the tutorial beginning the bottom of page 2 of this post:

http://www.castbulletassoc.org/viewtopic.php?id=10652&forumid=72&page=2

Gary

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mike0841 posted this 20 May 2014

Gary,

For keeping track of mold temp I am using a temp gage I purchased from NOE.  

http://noebulletmolds.com/NV/product_info.php?cPath=22&products_id=31>http://noebulletmolds.com/NV/productinfo.php?cPath=22&productsid=31

It allows me to keep the mold at the optimum temp by increasing or slowing the speed I cast at.  I have never cast .224 and my NOE 55gr 224 3 cavity mold bullets are coming out perfect when the mold is up to temp. While the pot is heating I keep the mold on the hot plate and get perfect bullets almost from the first cast. I am also making a dual PID to control a hot plate to keep ingots warm and the mold hot during breaks.  If I can find a suitable pyrometer I will include it for the mold temp.  That way everything will be in one place.   Mike

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onondaga posted this 20 May 2014

http://castbulletassoc.org/view_user.php?id=7024>mike0841

Hi Mike, I have 3 Lee pots, a 4-20 bottom pour, and a 20 lb and 10 lb plain ones too.  I have a decent thermometer that shows a 25 + degree swing in all of them when they cycle. The PID should hold temps a lot closer for me. That is why I am interested.

Gary

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vmwilson posted this 20 May 2014

Auber Instruments does carry pyrometer's I believe.  Anything else you can think of too along with good tech support if you have a question.

Mike

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mike0841 posted this 20 May 2014

Gary, Your PDI when it learns your pot's personality should hold it at +- 2 deg.  When I first set it up I had to set the actual temp against a thermometer as the PID was 100deg hotter than the thermo.  The probe probably was a little off. I use mine in a Lee Pro 20# and an RCBS 20# modified for ladle.  I took it to my friend Rudy Reyes house and we used it in his Lee 10# and cast 150 311299's and it never was more than 4deg off.  These things are incredible.  You're gonna love it. Mike

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mike0841 posted this 20 May 2014

Mike,

I bought the parts for my first one from Auber and it came to $128 with shipping.
The parts for my dual were $137 from Amazon (Prime no shipping and free 2 day). I don't think I could have gotten them cheaper on Ebay.

Mike

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vmwilson posted this 21 May 2014

Now mind you I only know what I've read about probes but if you hook them up with another kind of wire/cable you can throw the temp readings off.  How far off though,  I've never seen any actual figures.  I put the little K socket in mine so I could just plug another probe in on my lubrisizer.  I didn't trust my stem thermometer and it was way off.  Have since calibrated it against the PID but it does of course react much slower to temp changes than the PID does.  I believe what the K type probes do is send a small voltage signal to the PID.  Checked my PID with both ice water and boiling water and then put the appropriate offset into the PID.  K types aren't as accurate actually as the other type, which doesn't come to mind at the moment but are rust resistant for one thing and the others aren't.

Great gizmos anyway.  Now I look for excuses to cast bullets and I don't need any!

Mike

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Uncle Russ posted this 21 May 2014

Gentlemen, interesting come backs on my post.  I expected more the negitive. As far as accuracy on PID control lets not get too carried away here.  Lets think about this for a moment.  Are PID controls REALLY accurate or are they REALLY repeatable?  We are not in laboratories.  Does it really matter if the pot is 718'F or 719'F?  What really matters is the pot repeats the last operation cycle that was acceptable to the person using it. A person walks into the room and asks “What time is it?"  You glance at your watch and reply “7:36".  From the back of the room your buddy Rick replies “7:39".  OK, what time is it?  You really don't know.  True.  Should you really care?  Probably not.  Does it really make a difference?  No.  All is the same for the read out on your PID control.  Just as long as it does what it does the same every time. I defer to the Submariner.  He makes several good and true statements from his experience.  “Once the control learns your sequence."  This amount of time can be shortened by further programming but usually our changes are so small it does not really matter as we do not seem to notice  time increase once settled in.  In his previous line of work he had better believe his gauges and outputs!  When I used to calibrate instruments people would look over my shoulder and inform me that that the read out was off by a digit.  My response was along the lines of “Well what do you want it to say?  I can make it say most anything you want."  They would usually walk off figuring I had no clue of what I was doing.  But  they would leave me alone. Thermocouples are chosen by what range of temperatures they will operate in. Trying to pick one of mid range sensitivity.  The wires coming out of a thermocouple are not just copper wire.  They are wires of dissimilar metal that create minute electrical flow.  This flow is what you measure for a reading.  If you extend a lead it must be of the same type as the original wire and of course match polarity.  You may create your own thermocouple by twisting together approximately one inch of the proper wires and soldering the joint.  The tube on the end is merely for physical protection. My whole point here is PID units do not guarantee accuracy.  They do not guarantee they will match your Lyman/RCBS temp probe.  How do you know the probes are spot on?  What PID units do do, is give you accurate repeatability to a process.  Give them a chance.  Learn from them.  Adapt to what they do and you will sing praises with joy of the great results. Cost.  Most people think I am trying to get rich for charging $200 for my units.  The costs quoted earlier are just about spot on to what I pay for components.  Then I have to fabricate a bench mount enclosure, assemble and program and calibrate the control.  I do not know what your time is worth but mine is well worth what you pay. Now get out there and make some smoke!!!!!!!!!!!!!!!!!     

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Pigslayer posted this 21 May 2014

mike0841 wrote: Mike,

I bought the parts for my first one from Auber and it came to $128 with shipping. The parts for my dual were $137 from Amazon (Prime no shipping and free 2 day). I don't think I could have gotten them cheaper on Ebay.

Mike
Mike,      Auber is most certainly a reputable vendor . . . no doubt. But ( the proverbial but) the components can be had much cheaper on ebay if one knows what to look for. The “MYPIN” controller has a good history and can be had for about $25.00 shipped. I built mine (2 years ago) for under $50.00. Still working just fine. I am at present building one for Gary for about the same price. Pays to shop.   Pat.

If someone else had of done to me what I did to myself . . . I'd have killed him. Humility is an asset. Heh - heh.

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mike0841 posted this 21 May 2014

Pat, I have done my shopping and I am making another one with dual PID's.  One to control the pot and one for a hotplate to keep ingots hot so refresh time is quicker and also keep the mold hot during breaks.  The parts were $98.00 and I wanted an aluminum case so I bought 18ga. aluminum sheet to make the one I want.  The alum cost $39.00 shipped.  All parts except the aluminum were bought from Amazon prime (2 day free shipping) and the PID's are “MYPIN".  I am looking to add a pyrometer to keep track of the mold temp.  That will add about 30.00 with probe.  I have a hand held temp sensor with probe that does a pretty good job but I want everything in one place.  I found that with the temp kept around 425F on my NEO 225 55gr mold it throws perfect boolits from all three cavities. Mike

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Pigslayer posted this 22 May 2014

mike0841 wrote: Pat, I have done my shopping and I am making another one with dual PID's.  One to control the pot and one for a hotplate to keep ingots hot so refresh time is quicker and also keep the mold hot during breaks.  The parts were $98.00 and I wanted an aluminum case so I bought 18ga. aluminum sheet to make the one I want.  The alum cost $39.00 shipped.  All parts except the aluminum were bought from Amazon prime (2 day free shipping) and the PID's are “MYPIN".  I am looking to add a pyrometer to keep track of the mold temp.  That will add about 30.00 with probe.  I have a hand held temp sensor with probe that does a pretty good job but I want everything in one place.  I found that with the temp kept around 425F on my NEO 225 55gr mold it throws perfect boolits from all three cavities. Mike That's good shopping for a dual PID. I have found that if I go right down to the local sheet metal shop, I can pick up nice sized pieces of 20 ga. for cheap (like me).

If someone else had of done to me what I did to myself . . . I'd have killed him. Humility is an asset. Heh - heh.

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Pigslayer posted this 24 May 2014

mike0842, Been checking out Amazon for parts for future units. The prices are great and shipping free on orders over $35.00. Even though the parts are the same as those I get on ebay, the shipping is faster. Thanks for the “Heads Up".

Pat

If someone else had of done to me what I did to myself . . . I'd have killed him. Humility is an asset. Heh - heh.

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