Thoughts or sprue plate hole ID

[Wayne S]

It is my openion that the holes in sprue plates shouldn't be any larger that 35% of the bullets Dia. up to .125" for normal heavy wt..44/.45 bullets
RCBS,Lyman & Saeco all use their set hole dia. because of cost, "one size fits all" theory.
I wonder if there is a big enough market for aftermarket sprue plates ??

[Red River Rick]

And you've come to this conclusion HOW? Scientific formula? Trial and error?

RRR

[44man]

I start my holes way larger then that before cutting the taper.

[Wayne S]

And you've come to this conclusion HOW? Scientific formula? Trial and error?

RRR
Trial & error, I've got an OLD {Walt era} NEI mold that came with an alloy sprue plate that has .110 holes that I modified to work on RCBS 2 Cavity molds . Both the 7 MM 145 and the 30 Cal 165 Sil. bullets useing the small hole sprue plate would shoot on an average .75" MOA smaller groups in side by side compairson with the OME sprue plates out of my scoped XP's and 14 +" scoped Contender BBLs.

[scb]

Is there a difference between the ID and OD of a hole?:kidding:

[Calamity Jake]

For the best accuracy you need to use half a hole then the spru is half size :kidding:

[Wayne S]

For the best accuracy you need to use half a hole then the spru is half size :kidding:

I'm glad two of you'll find humor in this , CJ, TRUE, the half hole on the side of the base has been written about, photographed ect. BUT it has to be limited to a single cavity AND any imperfection will turn up on the edge of the base, which is the worst place for a spinning object.
BUT you'll have a few chuckles

[canyon-ghost]

I prefer Lyman molds just for the larger sprue plate hole, all the RCBS rifle molds that I've tried have smaller holes and more trouble filling out the bases. Nothing scientific here, just the way the casting ladle pours. Whaddyathink?

[mooman76]

I would think there would be more to it than size of bullet vs. hole size. Does it matter say if the mould is aluminum and a bigger bullet mould heats up quicker and stays hotter easier so I would think the hole doesn't need to be as big maybe as rifle bullets because with the added heat the lead would flow better and not solidify as quick.

[tommygirlMT]

All I know for sure is that almost all mold makers make the spruce plate hole too (*%&$(%&*$*^*$%R&(%(*^% small with the notable exception of Mountain Moulds when you order a WW alloy mold --- now that's a spruce plate with a big enough hole !!!! All my other brands of molds I usually end up reaming out the hole to a larger size sooner or later --- pain in the neck though because you have to use a special drill bit with the right tapper angle and then polish it up with lapping compound afterwards or the spruce sticks to the spruce plate.

P.S. --- most of my casting is large caliber --- 45cal and upwards.

[madcaster]

Intresting,as I will need to make some sprue plates for several moulds soon.:coffeecom

[tommygirlMT]

Oh, yah, forgot to mention I really hate the spruce plate style that "Brooks Moulds" uses on his molds. They have sort of a spill-over trough ground out to one edge so that any excess flows off to the side --- might work okay for pressure ladle casting but drives me insane using a bottom pore pot because I can't get a nice big pool on top to ensure good fill out. I've fixed all of mine with a wire-feed welder and grinder to fill up the trough, grind it flat and then re-smooth the pore hole --- still trying to talk my man into letting me fix his 12ga. slug molds Brooks cut for him.

[canyon-ghost]

TommyGirl, that's what I'm saying! I use all single and two-cavity cast iron molds. Without lino or tin, it's not easy to get them to fill out right. I'd like to use custom molds but, that's expensive.

And, Wayne, what caliber are you shooting in the silhouette pistol?
Just curiousity.

[crabo]

I use a 90 degree countersink to open up my sprue holes. The bigger the boolit, the bigger the hole.

[shotman]

Lyman done that for several years. I just got a 429348 and it had a somewhat larger hole in the original plate. I changed the plate because it was mangled on the top. Put another plate that had a small hole and it would not fill the mold out. I took a counter sink and cut the hole same as old and worked good.
There you go RRR it is SK and after that I did a few more

[44man]

When I use my hard alloy and cut too soon the sprue will pop off but the plate still cuts lead. I get a tiny bit of little holes in the center where the sprue broke. If I just let it harden more and use little taps the boolit base will be smooth.
Softer lead is much easier to get a smooth base.
I have not found and difference in accuracy between a torn base and a smooth one.
I do not make little bitty boolits so I imagine the smaller the boolit, the smaller the hole should be. But if cut at the right time any base can be smooth. A little patience makes better boolits.

[HORNET]

35%, you say? Lets see, on a .22 that'd be about .063"? I don't think that'll work very well.
I've made a BUNCH of sprueplates (did another this morning). I usually start with a sprue opening that I figure is probably too small and try it. I open them up a little at a time with a 90 degree c-sink (using number drills as gages) depending on casting results. The final diameter that I end up with varies depending on alloy, boolit diameter, boolit weight, and sprue plate material & thickness. IIRC, most of the Ideal, Lyman, & RBCS molds use around .150.

[Wayne S]

35%, you say? Lets see, on a .22 that'd be about .063"? I don't think that'll work very well.
I've made a BUNCH of sprueplates (did another this morning).
Hornet,
What would you charge to make 2 & 4 cavity sprue plates ??

[Cap'n Morgan]

I only use one or two-cavities molds and prefer fairly large holes - this leaves plenty of room for escaping air when you bottom-pour.

[Red River Rick]

Trial & error, I've got an OLD {Walt era} NEI mold that came with an alloy sprue plate that has .110 holes that I modified to work on RCBS 2 Cavity molds.

That doesn't prove your theory. You didn't say what diameter the holes where in the original RCBS sprue plate to start with. There has to be more to the equation than your letting on.

As Hornet mentioned, 35% of .224 is pretty small, and I doubt you'd get good bullet fillout trying to pour thru such a small hole, if the lead will even flow thru, because it'll freeze.

The whole intent is to fill the cavity as quickly as possible, having as large a hole as possible in the sprue plate will will ensure that.

Once the lead starts to "Skin" over when it hits the mould, you need to get it into the mould as fast as possible. Then as it starts to cool and contract, it needs something to "draw" from in order to prevent internal voids.

The larger the sprue hole and the larger the "Well" (the sprue itself) the better the fillout. I've made and sold hundreds of replacement sprue cutter plates for all makes of moulds, no one has ever complained that the holes were too big.

RRR

[HeavyMetal]

I played with larger holes in the sprue plate years ago.

Up side was the mold filled a little faster/better.

Down side was the bigger the hole the harder it was to open the sprue plate.

In the end I found anything larger than about .200 was a waste of time on most standard pistol and rifle molds. Now move into the bigger stuff like slugs or black powder rounds and a a whole new world opens up.

In the end it's going to be more than hole size. You will also need to deal with alloy composition, temp's on the alloy and mold.

I can see someone putting a .300 diameter hole in the sprue plate and then trying to cut stright lino with it. can't do that by hand ( at least not for long) and not sure what condition the base will be in after it's cut.

You'll also have to deal with the stress this going to put on your mold when you start "whacking" that sprue plate around to get the boolit out. I don't think many aluminum molds are going to stand up to a steady beating without breaking at the pivot point!

Thought about this for awhile and think that a preheat warming station ( read hot plate) and a steel plate to help maintain heat, dipping the mold in the alloy for each pour, I think these "techniques" will assist in fill out on very large molds once the sprue holes are opened to a reasonable size.

On a 12 guage slug for example, steel Lyman, I might start at a .230 dia. and see what happens.

[Uncle Grinch]

Interesting thread... too bad it just died.

I recently picked up a DC RCBS mold for my 375 Win and it is a pain in the *** to fill both cavities. I believe the sprue plate holes are too small.

[Le Loup Solitaire]

An article in the NRA Handloading book written by Col. Harrison discussed his work with opening up the size of the sprue plate hole and the inside diameter of the ladle that he was using. He definitely cites better bullet fill-out with either adjustment and the best results with both of them being enlarged. LLS