How do you measure mold temp?

[Jtarm]

When measuring mold temperature, where do you apply the probe? Side of the blocks? In the cavity?

I’m about to embark on building a block oven and need to figure some things out.

[porthos]

i don't belive that mold temp tells you much. i never did it. i warm the mold, cast a few molds full. by then, the bullets are filled out. when they are; i keep a steady cadence. my bullets weight +- .1 (1 tenth) some a very little more. don't know what the mold temp is and don't care. some molds cast hotter or cooler than others. i do have a pot thermometer.

[kevin c]

I agree that maintaining whatever temp your mold casts your alloy well is a matter of maintaining a cadence that works for the alloy temp and environmental conditions you’re working with. I find that happens around 400° F for my molds, and a K-type thermocouple in one of the cavities while the mold prewarms (or rewarms: I find it challenging to maintain a perfect cadence) lets me hit that on the nose from the first pour.

[slim1836]

P.I.D.'s, one for the pot and one to rotate with the powder coating oven or mold heater.

Slim

[OS OK]

Much depends on the cast profile, whether HP or solid & whether long slender rifle or fat pistol cast.
I've found that a 300º ~ 350ºƒ preheat temperature on the mould will get you good casts in the first or second casting. Having your pot stable at 715º ~ 750ºƒ is a good place for both profiles & the cadence will keep the mould at a steady temperature.
I think drilling the mould for a thermocouple temp. reading is a bit over the top...excessive effort. A good hot plate with a proper setup, skill saw blade and gallon size tin can with a BBQ analogue thermometer is about as simple & dependable as it gets.

https://i.imgur.com/bg5Nk9vh.jpg

[Rapier]

If you set the cold mould with handles attached, on top of cold alloy in the pour pot, then turn the pot on. When the alloy is ready to cast so is the mould. You just put through about six rotations, pour, drop, pour dumping the bad bullets and sprue into the sprue box and the top of the mould gets hot enough to cast keepers top to bottom.

Cold mould and hot alloy does not work.

[Hossfly]

In the cavity is what I do. On top of hot plate with aluminum plate to distribute heat. When it reaches 400’ start casting. Maintain cadence, Then set ingots on top of aluminum plate, to start warming, so pot temp. Stays up when refilling. Also wear gloves , or pick up with channel locks But be careful those hot plates can and will melt alloy. Ask me how I know.

[Jtarm]

In the cavity is what I do. On top of hot plate with aluminum plate to distribute heat. When it reaches 400’ start casting. Maintain cadence, Then set ingots on top of aluminum plate, to start warming, so pot temp. Stays up when refilling. Also wear gloves , or pick up with channel locks But be careful those hot plates can and will melt alloy. Ask me how I know.

Thanks.

Are you measuring plate, or mold temp? I.e. where is the tip of the thermometer?

[metricmonkeywrench]

Generally my testing method is unintendedly done utilizing my thumb on the sprue plate, if it hurts but doesn't leave a mark it's too cold it it leaves a brand is generally just right.

Otherwise its just a preheat on #3/4ish on my Wally world hot plate and start casting till (if ever depending on the mould/cavities) I start getting frosted bullets or i run the pot down on lead. I dont really have a mould target temp prior to casting.

I did figure out this weekend that the temp control on my Wally World hot plate went out and now has one setting when plugged in (always on full) and the mould I was warming was definitely on the HOT end

Perhaps someday if i get more organized and consistent on what lead is in the pot I may make some notes on alloy, temp and mould for that session, however being that through seems too much like work to me.

[JonB_in_Glencoe]

When measuring mold temperature, where do you apply the probe? Side of the blocks? In the cavity?

I’m about to embark on building a block oven and need to figure some things out.

NOE bores a hole in the mold blocks for temp probe.

Personally, I judge mold temp by watching the sprue puddle freeze and the frostiness (or lack there of) of the boolits

[gunarea]

Hey Jtarm
Although you will be scoffed at by many, I am sympathetic to your quest to go beyond "Good Enough for me". Temperature control is a temperamental bitch. Monitoring can also be somewhat dodgy. Single cavity moulds present fewer variants and are easier to keep in control. The various materials employed also eliminate across the board universal answers. The original question posed is "How do you measure mold temp". OK here goes.
Fluke, double pickup, K type thermocouple, 4" probe and C type surface contact. CME, quick change, mid range direct connect couple. DMS, quick change, mid range, L type thermocouple with magnetic ceramic pickup. Mypin averaging SSR, K type thermocouple, 4" probe. The points of monitoring are, alloy reservoir, mould exterior, mould interior, pot spout, heat sink used for mould cooling. It can become tedious to keep up with it all. An assistant is an invaluable aid in monitoring and recording the multitude of data. To become a competitive shooting champion, many things must be pushed to greater levels than "Good Enough".

312039
Good skill to you.
Roy

[popper]

Sprue late temp is more important. If the plate is up to temp, mold is also.

[hornetguy]

Much depends on the cast profile, whether HP or solid & whether long slender rifle or fat pistol cast.
I've found that a 300º ~ 350ºƒ preheat temperature on the mould will get you good casts in the first or second casting. Having your pot stable at 715º ~ 750ºƒ is a good place for both profiles & the cadence will keep the mould at a steady temperature.
I think drilling the mould for a thermocouple temp. reading is a bit over the top...excessive effort. A good hot plate with a proper setup, skill saw blade and gallon size tin can with a BBQ analogue thermometer is about as simple & dependable as it gets.

https://i.imgur.com/bg5Nk9vh.jpg

Does it matter how many teeth the saw blade has? :razz::kidding:

[OS OK]

Does it matter how many teeth the saw blade has? :razz::kidding:

I think the old axiom is..."More is always better with everything!"

[hornetguy]

I was also wondering how many 12V power pacs it took to run the hot plate..... sorry... couldn't help it...

Serious question.... I never thought about covering the hotplate with an enclosure... do you find that it heats up the sprue plates as well?
Even if I heat my mold, I have to mallet the plate open for the first 8 or so casts, until it gets hot enough to push open by hand... That would be a good thing if the can enclosure eliminated that...

edit: and I agree, more is always better.... except for traffic... more is not better with traffic...

[GregLaROCHE]

I don’t measure any temperatures. I’ll put a mold on top of the pot and when the alloy is melted, I start casting watching how the boolits turn out. I use the method of heating the alloy until the boolits start to frost and then back off the heat a bit. If the sprue looses it’s normal shape and gets thin, then I know that the mold is too hot.

[Cast10]

I have a saw blade laying on a burner plate. I turn it up until my temp gun says the blade is in the 300-350 range. I lay the mould on top. I hit it with a temp gun. When its anywhere from 280 or over, and my melt is up to temp (PID), I start.

[Mike W1]

Don't think it matters that much where in the block you drill. Probably depends on size of mould as much as anything. Mine are all 2 cavity and this worked for me. That's just a q-tip in there for clarity and there's a set screw to secure it too. I have also used the flat surface K but the probe works just fine.

Long as we're rambling on I built an insulated "hut" to sit the mould in and my opinion is that unless you're casting OUTSIDE in the open air they're not going to speed any heating up process of the mould and they're nuisance in the bargain.

312126

312127

Should add to avoid the cavity area to this. Otherwise just the front or side of the block whichever is handier for your setup.

[Shanghai Jack]

When measuring mold temperature, where do you apply the probe? Side of the blocks? In the cavity?

I’m about to embark on building a block oven and need to figure some things out.

Never worry about measuring - if the bullet's lumpy the mold is too cold, if it's frosty its too hot. If neither, its just right. Perfect goldilocks casting.

[farmbif]

the way I test mold temp is when the bullets start coming out well formed and shiny or frosty i quit putting them back into the melting pot and pile them up in a towel lined basket ready to be lubed

[Mike W1]

Amazing! 19 replies so far and about 3 of them said something pertaining to the original post.

[OS OK]

I was also wondering how many 12V power pacs it took to run the hot plate..... sorry... couldn't help it...

Serious question.... I never thought about covering the hotplate with an enclosure... do you find that it heats up the sprue plates as well?
Even if I heat my mold, I have to mallet the plate open for the first 8 or so casts, until it gets hot enough to push open by hand... That would be a good thing if the can enclosure eliminated that...

edit: and I agree, more is always better.... except for traffic... more is not better with traffic...

Yes, it does. You can't see it but there is a box fan on the floor on the other side of the casting bench blowing across the garage towards the double door opening...it makes a draft that pulls the fresh air from behind me across the hot plate and lead pots, pulling any vapors or smoke out of the shop so I don't inhale it.
Without the oven (tin can), there's a draft there on top of the moulds they don't heat evenly top to bottom...having them inside the tin can the draft can't affect them. I know it looks awkward but it works well...it beats the hell out of casting mould after mould full untill the mould cast properly. To me that approach is a waste of time.

[Carrier]

Amazing! 19 replies so far and about 3 of them said something pertaining to the original post.

That usually happens. I haven’t drilled any holes but have started to use a bead probe in one of the cavities through the sprue plate hole. Probably not as accurate as a probe in a snug hole but works for now.

[imashooter2]

You’ve been on the board since 2008 and you are amazed? [smilie=l:

[Mike W1]

That's right, some folks also "smelt" on here.

[gc45]

Sorry I can't help, but do agree with Porthos as I cast the same as he does. good luck with the project.

[JonB_in_Glencoe]

Amazing! 19 replies so far and about 3 of them said something pertaining to the original post.
You're Hilarious :)


That's right, some folks also "smelt" on here.
I use to use that term, but recently in a discussion about it, someone used the term Schmelt...and I glaumed onto it and use it whenever I can :p

[ulav8r]

Well, if you schmelt it, what did it smell like? Everyone knows that schmelt is the past tense of smell.

[Outpost75]

I pre-heat mold blocks on a Proctor-Silex hot plate having a 6" square of ceramic tile placed over the Calrod to distribute the heat evenly. I use a 400°F Tempilstik crayon to mark the sprueplate and once up to temp I alternate between a pair of 4-cavity gang molds to.establish a cadence. I use two 10kg Ohio Thermal bottom-pour pots, casting from one while the other comes up to casting temp, checking with a Keithley digital thermocouple thermometer. I run a pot down to about an inch from the bottom before adding sprue and culled bullets back to the pot. After the scrap has remelted I top off the pot with fresh alloy, flux with Vitaflux, skim and pour crushed clay over the melt and change off to the other pot which is up to temp and waiting.

[OS OK]

https://i.imgur.com/MYwjVCul.jpg

[JonB_in_Glencoe]

Well, if you schmelt it, what did it smell like? Everyone knows that schmelt is the past tense of smell.

well ya, you don't want to be down wind :p

[Kraschenbirn]

Molds preheated on a $4 electric hotplate from a yard sale and temp measured with my trusty(?) HF Infrared Thermometer. Works for me.

Bill

[Land Owner]

I can' take it anymore...

...put your Index finger in your mouth. Get it wet. Stick it on the mold body.

If you hear it go "tsss..." remove your finger PRONTO. It's hot enough.

[jsizemore]

I stick the end of the thermocouple through the sprue hole into the cavity to check the temp while on the hot plate. I start casting when the temp is between 375-400. The sprue cut tells me when the temp is right during the casting run.

[Cosmic_Charlie]

Never worry about measuring - if the bullet's lumpy the mold is too cold, if it's frosty its too hot. If neither, its just right. Perfect goldilocks casting.

Yes, and when your boolits start sticking, the mold is too hot.