Sprue plate question

[Lefty SRH]

Whats the purpose of the trough cut into the some sprue plates?
I have some molds with and without them and I can't tell a difference. I made 2 plates for 2 of my RCBS molds and cut a trough between the pouring holes, but I really don't have a preference or understand its purpose.

[41 mag fan]

I would think it's for channeling from one cavity to the other. I have one on my 45-420 from Accurate. Love the mold, hate the channel. I need to get a replacement sprue plate for it.
But IMO or mind, it helps to keep your sprue right there, and not spread all over the plate.
When I use mine, I keep the flow going, just moving the mold to the next cavity

[stubshaft]

Like 41 mag said it is to alloy lead from one cavity to transfer to the other(s). H&G molds were fond of this, but I prefer to pour over each cavity myself.

[MikeS]

As H&G moulds were really designed for ladle casting, perhaps the trough is better when ladle casting? Personally I hate the trough, but on the couple of moulds I have that have the trough, I've just gotten used to casting with it.

[gbrown]

My take on this is that the trough is for multi cavity molds. I have and have had molds with the trough which was deepened by a previous owner. (which I like) tilt the mold at a very slight angle and pour the upper mold. When full, move to the lower mold, trying to leave as little sprue as you can. The early Lyman 1 cavity molds were for using the Lyman spout ladle to fill one mold. Put the spout in the opening and tilt mold and ladle to fill.

[MikeS]

But leaving 'as little sprue as possible' is not a good thing. Leaving a larger sprue keeps the sprue plate up to proper casting temp. Having said that, I do find that when using a mould with a trough that I tend to keep the sprue within the trough, but that's just how it works out, it's not by any design on mine.

[beagle]

H & Gs were the first that I ever encountered with the slot milled between the sprue holes. I've heard two theories.

The first was that it allowed overflow to flow to the next cavity. Now, I kinda discount that as the flow would be somewhat cooler when it got to the second cavity and probably not completely fill out the bullet.

The second theory was that since H & G moulds originally came in multiple sizes from four on up, the weight necessitated the use of a casting table. The table was adjusted to place the mould close to the spout. The mould was then placed to align the spout with the first cavity. After filling, the mould was pulled toward the operator until all cavities were filled. The slot gave clearance for this method.

And, my theory....... it allows a good puddle to form and allow additional metal to suck into the mould to insure good fill out.

Guess we'll never know for sure./beagle

[Le Loup Solitaire]

I never ran into the trough until I went from RCBS and Lyman molds to H&G. I found it difficult at first to get used to it, but learned to live with it and make it part of what needs to be done. Somewhere in the jungle of years and many things read, I once found a tip that said that when you have pulled the mold (H&G four cav) thru the stream of melt and reached the end cavity...to push the mold back thru the stream so that the melt again flows over the solidifying sprue....melts it again and adds to compensate for any more shrinkage. It at least sounds sensible in theory, but I have never tried to test it all in any way....I just have continued to do it that way. The bullet bases are always good; the sprues are big. When test weighing bullets the weights are close together which usually indicates if there are voids below the base surface. It might be worth a try just to see if it improves your casting quality. LLS

[geargnasher]

Like 41 mag said it is to alloy lead from one cavity to transfer to the other(s). H&G molds were fond of this, but I prefer to pour over each cavity myself.

Ditto. I don't like the trough either, it takes half the head pressure away from the sprue well on those otherwise nice, deep plates. I also get more culls when some splashes over prematurely into the next hole. I've tried to pour lead in the middle of the trough between two holes and let it run into the cavities, but it always gives me poor fillout and rounded bases.

Gear

[geargnasher]

I never ran into the trough until I went from RCBS and Lyman molds to H&G. I found it difficult at first to get used to it, but learned to live with it and make it part of what needs to be done. Somewhere in the jungle of years and many things read, I once found a tip that said that when you have pulled the mold (H&G four cav) thru the stream of melt and reached the end cavity...to push the mold back thru the stream so that the melt again flows over the solidifying sprue....melts it again and adds to compensate for any more shrinkage. It at least sounds sensible in theory, but I have never tried to test it all in any way....I just have continued to do it that way. The bullet bases are always good; the sprues are big. When test weighing bullets the weights are close together which usually indicates if there are voids below the base surface. It might be worth a try just to see if it improves your casting quality. LLS

I always run my six-cavity Lee's that way, I cycle the valve once to fill each cavity plus the sprue well (barely) and then quickly pull the mould back under the stream to connect the dots. This keeps the sprue soft for a second, makes it easier to cut, prevents shrinkage voids to some extent, and makse the sprue easier to manage without all the little hot silver Hershey's Kisses flying everywhere.

Gear

[LAH]

But IMO or mind, it helps to keep your sprue right there, and not spread all over the plate.
When I use mine, I keep the flow going, just moving the mold to the next cavity

It does help in that you can have a large sprue with less likely hood of the caster loosing control of the sprue & it overflowing the side the mould. This is also only MHO.

I cast using mostly 4 cavity moulds from Lyman & Ballisti Cast which have completely different sprue plates. I use the same method of casting with either & really see no difference between the two except the above statement of perhaps better control of the sprue. As a note my furnace uses a double pour spout for multiple cavity moulds...............Creeker

[bobthenailer]

If my moulds did not have a trough between the sprue plate holes, they do now ,

[Moonie]

I was curious about this feature after having purchased a couple of 6 cav lee's and doing one pour to fill all 6. I ordered a 3 cav 245C from Accurate with the trough, I actually do like it quite a bit, it works well in that mold. I have found that trying to do that with the 4 cavity NOE 221 doesn't work very well as the cooler metal coming into the mold does cause nose fill out issues on that small little boolit.

[theperfessor]

I have an 8 cavity H & G w/ a trough. I lower the mold guide under my Mag 20 and lean the mold forward a little, then fill the lowest cavity furthest away from me and then each slightly higher cavity working towards me. Keeps the cold over-fill lead out of adjacent cavities. Not much tilt, just a little works fine. I do like that it makes a single sprue that is easy to deal with.

[MikeS]

Even without a trough I always fill my moulds by opening the valve, and filling all cavities before closing the valve on my bottom pour pot. This creates a single sprue for all cavities even without the trough. I have a mould with a trough, and it took a little bit of getting used to, but it works about the same as my other moulds. Originally I was going to get a replacement sprue plate for it, but have decided I don't need to.

[LAH]

The Ballisti-Cast trough

http://i66.photobucket.com/albums/h244/Creekerpics/Loading%20Room%20101/Casting%20Equipment/DSC02694.jpg

http://i66.photobucket.com/albums/h244/Creekerpics/Loading%20Room%20101/Casting%20Equipment/DSC02695.jpg

[Jon]

I haven't seen that before, but it seems as though it would give you more even fillout. I usually connect the holes on my LEE molds, but that's a nice feature.

[GLL]

I have an 8 cavity H & G w/ a trough. I lower the mold guide under my Mag 20 and lean the mold forward a little, then fill the lowest cavity furthest away from me and then each slightly higher cavity working towards me. Keeps the cold over-fill lead out of adjacent cavities. Not much tilt, just a little works fine. I do like that it makes a single sprue that is easy to deal with.

Although I ladle cast I use this exact same tilting technique on my 4-cavity Ballisti-Cast and H&G molds as well ! The sprue plates are VERY thick and I mound up a little extra alloy over the trough for good measure.

I also like beagle's "theory" that it allows a little extra to puddle in the trough to be "sucked" in during drawdown ! :)

Jerry

http://www.fototime.com/143A68122019505/orig.jpg

[theperfessor]

I've always thought that the best way to keep a mold hot and bullets bases filled out is to pour a good sized sprue. I have a screw-in thermocouple that I have used on my molds to monitor mold temp for my PID controller. It's amazing to see the temperature go up and down as you pour and then eject the bullets. The temperature rise can be easily doubled by pouring a generous sprue vs a minimal sprue. I try to cast as cool as possible and still get good fill out, big puddles help that.

By the way, casting "as fast as possible" to keep the heat up in a mold is not necessarily the best way to do that. I found out that my mold temp went up several degrees more when I waited for the max temperature rise to occur, which was three to six seconds after the sprue froze. If I opened it as soon as the sprue froze it was several degrees lower.

The biggest temperature drop occurs when the mold is opened. You've increased the surface area by a large amount by exposing the inner faces to the atmosphere, you've cut down the total mass and you've cut down the distance the heat from the inner core has to travel to the surface. It's a matter of rhythm. If you want to keep the mold hot while casting at the lowest temperature consistent with good fill out then keep it closed a few seconds after the sprue freezes and then get the bullets out and the mold shut again ASAP. This is the real value of having a mold that drops bullets easily and quickly.

[44man]

H & Gs were the first that I ever encountered with the slot milled between the sprue holes. I've heard two theories.

The first was that it allowed overflow to flow to the next cavity. Now, I kinda discount that as the flow would be somewhat cooler when it got to the second cavity and probably not completely fill out the bullet.

The second theory was that since H & G moulds originally came in multiple sizes from four on up, the weight necessitated the use of a casting table. The table was adjusted to place the mould close to the spout. The mould was then placed to align the spout with the first cavity. After filling, the mould was pulled toward the operator until all cavities were filled. The slot gave clearance for this method.

And, my theory....... it allows a good puddle to form and allow additional metal to suck into the mould to insure good fill out.

Guess we'll never know for sure./beagle
Right on about too cool lead entering the second cavity. Makes funny boolits.
However I never depend on sprue puddles to feed cavities. I use molten lead in the ladle for that. The groove would stop ladle pouring right soon.
A sprue will normally set up sooner then the boolit in the hotter cavity and will no longer feed as the boolit shrinks. The ideal is to see no divot form on the sprue other then from only sprue shrinkage. My sprues are almost flat.
Everything must be super hot to feed two cavities at once. A problem with most bottom pours because the lead from the spout is not as hot as from a ladle. The ideal pot has heating elements in the bottom, not to be had with RCBS, Lyman or Lee.

[MikeS]

Actually if using a Lyman 2 cavity mould with one of their newer thicker sprue plates it's fairly easy to fill both cavities at the same time. If you look at one of those sprue plates you will see that the 2 sprue holes are almost touching each other, and if you place the mould so that the lead stream from the pot is centered between the 2 cavities it will fill both at the same time! I personally prefer moulds with more than 2 cavities, but when casting with a Lyman mould, at least it has that one saving grace that I can fill both cavities at the same time, so I can cast faster with it than if I filled each cavity separately.