HP casting temp??

[GP100man]

I have 3 different HP molds , 2 SC Lymans a 358156 with a 1/8" pin , a 357446 with a 3/16 pin , & a 2rg NOE

The SCs like 750f-775f while the NOE enjoys 800f-810f .

I know there`s variables in the inquerry such as casting speed & different alloys.

But what`s the temp most are casting there HPs at ????

I usually warm the pot to 800f get a good fluxing on the alloys then cover with kitty litter to hold heat loss to a min ,then start dialing down with the SC .

[TXGunNut]

FWIW I used my first Lyman HP mould yesterday. It needed a minimum alloy temp of 750 and the mould needed to be thoroughly heated as well. I have three other Lyman moulds that are happy @ 700 or a bit over. Crowbeaner (TFL) seems to have run into that before @ asked me about it.

[rintinglen]

750 + is what I have to run my pot at to get good boolits from hp molds. I only have two, one brass Miha MP 2 cavity and 1 old lyman.
Frankly, the Lyman gets no work any more--it is simply too slow bungling with that plug, and as a SC, if the boolit comes out defective, that is just another 25 seconds of your life you will never get back.

[HeavyMetal]

I have found the hard part of casting with the Lyman type HP molds is keeping the pin hot!

The two biggest defects I got were nose not filled out and / or base fillout.

Realized that dipping the pin in alloy was OK for the first few boolits but as the pot got lower it got harder to keep the pin in the alloy! Resulting in a "cold" pin by the time it got back in the mold.

To cure this issue I went to Wal Green's and bought one of thier 9.99 hot plates and at the scrap yard found a 6 inch diameter, 3/8's thick, round plate ( it doesn't have to be round I got a square one as well) and a piece of 3/4 inch diamter bar stock about an inch long.

Drilled a hole in the bar stock to make a drop in tight fit for the HP pin and then welded it to the center of the steel plate! This now sets on my hot plate, set just under medium, as soon as I turn on my casting pot.

The HP pin goes into the hole as soon as I turn it on and the mold either sits next to it or sits on the pot to come up to temp with the alloy.

When ready to start casting the corner of the mold gets dipped in the alloy, then the sprue plate, that section designed to strike to open, gets dipped in the alloy, the pin installed and the boolit poured!

It takes a while for the sprue to cool but it's not to bad. I then repeat and dip the sprue plate every second pouring.


So while it takes a few seconds longer to cast with this technique my "scrap rate" has dropped from 50 out of 100 to 3 out of 100.

Alloy runs about 700.

[TXGunNut]

Frankly, the Lyman gets no work any more--it is simply too slow bungling with that plug...Rintinglen


Noticed that, seems like quite a bit of fuss. If I ever get a better idea what that .45-90 likes I'll consider a custom mould.

[geargnasher]

I use the Lyman 452347 HP from time to time, the trick is get the MOULD and PIN hot, use a hotplate on the mould, a propane torch on the pin, then CAST FAST. By "cast fast" I mean six or seven pours a minute, cut the sprue while still soft (but set enough to not smear lead on the blocks) by hand, and use a 1" dowel rod for a sprue plate pusher and handle-hinge tapper to encourage the occasional sticky boolit to drop. This requires some dexterity, you have to hold the dowel in your right hand and work the spud at the same time. Keep the spud in the mould as MUCH as possible, don't leave it out or a second longer than absolutely necessary. Doing this, I get perfect boolits with razor-sharp bases and fully-formed HP cavities using 700 degree stick-on WW alloy.

Gear

[cbrick]

But what`s the temp most are casting there HPs at ????

For me . . . 730 degrees max. I add 2% tin and tin is expensive, I pre-heat the mold to a good casting temp and go from there. 730 degrees is well over the temp needed to get your mold to a good casting temp, a higher pot temp is not needed to do this and it will prevent your tin from doing what it's there for, reduce the surface tension of the stream of alloy going into your mold.

Leaving the sawdust ash on top of the pot when bottom pouring is a good idea to reduce surface oxidation on top of the pot, however . . . What you want your tin to do is reduce surface tension of the alloy in the stream of alloy into the mold, Yes, it's not exposed to the air very long. Yes, it will oxidize that quickly and it here that tin works as long as it's below 750. Above 750 and tin looses much of it's ability to do this even if you have the top of the pot covered.

Rick

[Jailer]

I only have 2 of Mihec's brass HP molds. Both of them like the melt run at about 710 to 720.

The molds have to be pre heated much hotter than any other molds I have and I can't cast fast enough to keep them up to temp. Once the boolits start sticking on the pins, it goes back on the hot plate to get the pins and mold back up to temp. I use this heating time to add sprues to the melt if needed to control the temp and keep it in the sweet spot.

[Iron Mike Golf]

I have a 2 cav Mihec. Using penta pins, I cast at 675. I eased the edges of the pins with 400 grit sandpaper and that seems to help release.

[beladran]

i never have a problem with my mihecs.. i have three that use pins. two hp's and one hbwc. i get the mold pre heated and set my lee pot on 7 and rock out..

[fredj338]

I cast LHP from 25-1 lead/tin alloy & cast around 750deg mark. Single pin or Cramer, seems to work fine.

[buyobuyo]

I'm still playing around with temperature, but I can run both of my two MP moulds at 750 without any problems keeping them at temp. I've run my MP-359-125-HP as low as 700 but keeping it at temp requires a pace that I don't find comfortable to maintain. However, running at 725 with that mold isn't a problem. I haven't cast enough with my MP-359-640-HP mold yet to see how low I can run it comfortably, but I imagine 725 will be doable.

I preheat the molds with my hot plate turned to 2/3 power and don't do any dipping. The first couple of sprues cool fairly quick but after that no problems.

[GP100man]

Thanks for all the input fellers ! So I`m not that far out of line .

cbrick I`ve often wondered what caused some boolits to have a frosted void sorta like a oily blow out at times , it`s the tin is`nt it , it gets to hot (mold & alloy) & causes the tin to "cook"& cause a void ????

Yep preheating is the only way to go , I try for 350 on the sprue plate but kinda don`t wanna put my molds on a red element !

& as far as casting with a SC boolit weight is closer ,more uniform & if ya get into a rythem ya can crank out purty good , nuttin like a 6 banger Lee but decent rewards for the effort !!

I think I`m gonna add 1% babbit to a pot of isotope alloy & drop temp to 725f after it all gets warmed up .

I kept the pin warm this winter by bending a coat hanger to fasion a holder on a hand held propane torch close enuff to the flame to keep it up to temp .

[buyobuyo]

From what I've read on here, the majority of people use a piece of scrap metal between the mold and hot plate element. Mine is 1/2" thick aluminum that I had a press mounted to before I built my new bench and bolted the press to the bench.

[geargnasher]

For me . . . 730 degrees max. I add 2% tin and tin is expensive, I pre-heat the mold to a good casting temp and go from there. 730 degrees is well over the temp needed to get your mold to a good casting temp, a higher pot temp is not needed to do this and it will prevent your tin from doing what it's there for, reduce the surface tension of the stream of alloy going into your mold.

Leaving the sawdust ash on top of the pot when bottom pouring is a good idea to reduce surface oxidation on top of the pot, however . . . What you want your tin to do is reduce surface tension of the alloy in the stream of alloy into the mold, Yes, it's not exposed to the air very long. Yes, it will oxidize that quickly and it here that tin works as long as it's below 750. Above 750 and tin looses much of it's ability to do this even if you have the top of the pot covered.

Rick


Everybody read that again, one of the most missed, misunderstood, and screwed up things with casting is very few people take the time to educate themselves on this simple fact about tin. This is why, no matter what you think, anything approaching 750 degrees with an alloy containing a significant amount of tin (1% or more is "significant") is both destructive to the tin itself, AND any positive effect we get from adding it as a casting aid. If you can't get WW alloy or similar to cast at 675 degrees, you need to spend time working on your casting technique to get your MOULD hotter, not the alloy.

Gear

[GP100man]

Next question , does running the temp up to blend or flux the alloy destory tin ????
or it`s affect on the metal ???

[cbrick]

Next question, does running the temp up to blend or flux the alloy destory tin ???? or it`s affect on the metal ???

No, the next question is . . . Why would you want to?

Flux at 100 degrees over full liquidus. Cast at (roughly) 100 degrees over full liquidus.

Melting temp is the temp the alloy starts to melt, liquidus temp is the temp where ALL of the alloy is completely melted and no crystal structures remain. Full liquidus is difficult to determine and it’s different for every alloy. To be sure I simply flux, cast & add pre-heated sprues & ingots at 700 degrees.

Rick

[GP100man]

Thanks for clarifying melting point & liquidus ponts cbrick , I think I`ve confused the 2 for a long time !