Gettin Flat Bases

[4thebrdz]

I seem to be gettin a bit of a hump on the bases from the sprue. Any suggestions about how to get a good flat cut?

The boolits are filling out great and look VG the only problem is the base.
I use WW and a bit of tin @ 725* to 750*. Usually 2 double cavity molds in succession. While the one mold is filled it sits aside the burner while I drop and refill the other. All are water dropped.

Thank you

[Dale53]

When I started twisting the sprue off with my hands (in welder's gloves) I immediately noticed better bases. Much nicer sprue cut off. The mould has to be up to heat before you can do this easily, but once up to heat it is a piece of cake.

Dale53

[44man]

Dale's method works but when the sprue gets real hard from using 2 molds I make a lot of little taps with a slight downward direction with a wood tool. Don't make one big whack!

[joeb33050]

Open the sprue plate, get rid of the sprue.
Close the sprue plate partly so solid sprue plate is over the base.
Whack the sprue plate with your mallet.
The base is now perfectly flat.

Beware, the "You'll bend the sprue plate/damage the mold/heat up the oceans" guys are on the way.

I've done this with a plastic mallet for thousands of bullets, and so far, not a single problem.

joe b.

[jtaylor1960]

I also have see bumps when waiting a little longer for the bullet to cool before cutting the sprue.I usually count to six and then cut it.If you cut any sooner or if the mold is a little hot the base will smear.Timing can help prevent bumps.

[Morgan Astorbilt]

Make sure the sprue holes are countersunk down to the bottom, giving you a sharp edge. If not, buy, or find someone with a large center drill, about 7/16" of 1/2", and drill down until you have a sharp edge. I've had to do this to several molds, one of them a NEI Meehanite four cavity. My problem with them, was the sprue hanging up in the plate.
Morgan

[Newtire]

I found to not tighten down the sprue plate too tight and block off your venting n the first place. Make sure you get a good sprue built up & then the push the sprue off using gloves right away instead of rapping it. You have to cast a few first to get the mold up to temp & then it works great. I seem to get good sprues and when it takes too long to cool, I cool down the mold using the BruceB method.

[Backgear]

Go with Morgan and Newtire.

[Buckshot]

..............You can go to your hardware store and buy a countersink (and then you'll have if for ALL your moulds) that's intended to be used in a drill motor. Don't use the drill motor as it's too fast and difficult to control. Buy a file handle along with it and put the two together. Be sure to use the countersink straight to give you a good edge, but not knife edged as a hard alloy may ruin it.

If using something to strike the sprueplate over, tilt the blocks to your left to about 60 - 70 degrees from the verticle and strike almost straight down. This will cause the sprueplate to be pressed down against the top of the blocks at the same time it's pushed across the blocks to shear the sprue.

If using a soft enough alloy, using your gloved hand is the way to go.

...............Buckshot

[Bret4207]

Here's a excerpt from a post I made some years ago in the "Shop Tips"sticky of the "Gunsmithing" section on sprue plate sharpness using a cheap Dremel type stone available at Wally World. A flat. sharp sprue plate is essential IMO. The BruceB speed casting technique helps too, again, IMO.

JoeB- Your method works for you, but operator error could cause the issues you mentioned. Ie- define "whack". To me it means one thing, to some one else my "whack" might be a "tap" or "pound". Given the right circumstances I've no doubt it would work.


Sprue plate sharpness- A nice sharp sprue cutter is good. Dull is bad. Dull makes holes in the boolit base among other things. Get a cone shaped stone designed for the Dremel tool at Wally World or where ever. DO NOT PUT IT IN A DREMEL TO DO THIS!!!! Read the last sentence about 10 times. Take the sprue plate off the mould. Using yer fingers twist the stone in the sprue hole till you just feel a ridge start to form on the bottom of the sprue plate. Give it about 3 more twists. Stop there! Now you have to flatten the ridge you just formed. When you bought the stone you also bought at least one sheet of 320 grit abrasive paper, at the auto parts store if the hardware or Wal Mart ain't got it. Finer paper will work and give you a nicer finish, but don't go coarser if you can help it. A FLAT sharpening stone will also work. Put the paper on a FLAT surface, like a piece of glass, stone counter top, or if nothing else is available the side of the mould itself. That will be very small, but it can work in a pinch. Gently rub the sprue plate in a circular motion, a small circle with not a lot of pressure. All you are doing is knocking that ridge back a little. You'll see the ridge as a shiny spot around the sprue hole at first. Then after 5 or 6 circles check it. If the shiny ring is about gone stop there. Thats all there is to it. That sucker should cut like a hot knife through butter. Try it and see.
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[44man]

The guys are right on about getting it sharp. I don't see where a little dimple or even a small tear out will hurt anything anyway.
I just don't want a bump if the boolit takes a gas check. I consider the edges more important then the center.

[4thebrdz]

Thanks for the replies. I have flattened the sprue plate on 600 grit paper on glass. I have seen the bright rings around the sprue holes. I have cleaned up the counter sunk sprue hole on top. I may be waitin to long to cut the sprue. I shall try it a bit faster, and with my gloved hand to see what happens.
Again Thanks.

[38 Super Auto]

I seem to be gettin a bit of a hump on the bases from the sprue. Any suggestions about how to get a good flat cut?

The boolits are filling out great and look VG the only problem is the base.


One thing that helps me is to insure that the sprue plate is reasonably tight where she bolts into the mold. I use Lee 6-cav molds, which have a levered handle on the sprue plate. With these molds, I believe it is easier to keep the sprue plate tighter to the top of mold.

I think this is why Dale53 gets better results using gloved hand to cut the sprue.

The other thing the Lee 6-cav molds allow is, you can hold the sprue plate tight against the top of mold during pour and solidification.

I don't know if it's posiible to keep top pressure on spue plate during alloy solidification with Lyman, RCBS, and other molds?

[S.R.Custom]

The guys are right on about getting it sharp. I don't see where a little dimple or even a small tear out will hurt anything anyway.
I just don't want a bump if the boolit takes a gas check. I consider the edges more important then the center.

Indeed, the center is almost irrelevant, providing of course the sprue bump is actually in the center, and not off to the side somewhere. Good edge fillout is everything.

But as Buckshot noted, if your sprue plate is true and sharp, a down-and-over rap style makes it a non-issue anyway. Making your rap on the sprue just micro-seconds after the sprue solidifies seems to yield the best results.

[Dale53]

One thing becomes obvious to me when relatively large numbers of good casters discuss these issues. There is more than one way to get good results.

We all have our prejudices. I, for one, HATE single cavity moulds EXCEPT when casting for a precision bench rifle - then, I am willing to put up with that for the ultimate in precision.

Casting for pistols and revolvers:

I can stand to cast in a double cavity mould but find it terribly slow.
Four cavity moulds as put out by Lyman, H&G (now Ballisticast), and Saeco produce plenty of bullets in a reasonable length of time and I find four cavity iron moulds are about the weight limit that I want to use.

I have a six cavity H&G mould (one) and find it too dern heavy. "Back in the day" when I couldn't justify the expense of a six or eight cavity H&G, I lusted after them. After I got one, I am thankful that I wasn't able to get one in the past (be careful of what you wish for...). They are just too dern heavy for me. Others disagree and just flat love them. Not me.

The Lee Six cavity moulds, with proper care and lubing, do a fine job and REALLY produce lots of excellent bullets if they have the designs that you like. I have a bunch of them and use them with a smile on my face. Their "cam opening handle" makes it easy to do with six cavities what I do with up to four by hand.

I have one custom LBT mould and it is OK but quite pricy for what you get. A kind of cult following has grown up around the LBT moulds and owner by users of these moulds. I do like some of the innovative designs but often you can get fine moulds for half the price (Lyman 4 cavities) if the available designs please you.
Veral Smith has written an excellent book on bullet casting and hunting with cast bullets that is worth a read. It is a permanent part of my library. He covers a number of important issues with casting that you will not find anywhere else in print. My LBT four cavity mould's individual cavities are near perfect mates. Note that LBT's moulds are custom made to specific dimensions and that is quite important to many.

I have several NEI moulds in both two cavity and four cavity. They are fine, precision made moulds and I much prefer their sprue plates over LBT"s stamped sheet metal sprue plates.

There are smaller manufacturers that also have good moulds. As a for instance, the single cavity "Made to order" precision bench rest moulds produced by Borton and Darr can hardly be excelled. That is my current preference for a REAL schuetzen bench rest mould. Borton is one of the best, if not the best, schuetzen best rest shooters in the country. He DOES know what it takes to make a rifle run.

Pioneer Products make extremely nice moulds and are particularly nice for serious Black Powder Cartridge Rifle shooters. The owners are Fred Leeth II and III and are both very accomplished BPCR silhouette and long range shooters.

The point of all of this is we can reach the "same place" by more than one path. "I" find that twisting the sprue plate with my leather glove covered hands (up through four cavity moulds using 15 brinnell bullet alloy) after the mould and alloy are up to heat is a superior way to operate and reduces the wear on a mould, whether iron or aluminum. I have cast tens of thousands of bullets using this method and for me, at least, consistently gives me better bases. It is not tiring and you don't have to be Arnold Schwarzenegger to do it, either (contrary to popular belief). This method has been used with all of the mould designs and makes listed here.

This is not meant to be controversial and if you have a way that is working for you, then continue it. However, if you give this method an honest chance, I believe that many who have not tried it will like it.

Hey, what do I know? I was never enamored of Marilyn Monroe. Now, Ava Gardner, that was a REAL woman:mrgreen:. See, there is more than one way to "skin a cat"...

Dale53

[Newtire]

The thought occurs to me that if there is a raised portion in the center, then the edges aren't filling out. I will try anything so long as it works and usually stick with it until something better comes along. I like using all these little tricks. I think we are all in agreement that we will eventually find our own methods. Nice to hear the different ones I say.

[GP100man]

i use 2 cavity molds & use a gloved hand when it gets to temp,you can tell its time to cut by the color of the alloy itll look like it greys over, thats when i push the plate over.
when it all gets too hot i cool em the BruceB way

GP100man

:cbpour:

[44man]

Newtire, the little bump is caused by a dull cutter or a loose plate or both, when just cut straight across without a small downward motion. The cutter will ride up into the sprue a little as it cuts, raising the whole plate.

[grumpy one]

I agree with 44man, but I also think if you let a hard alloy cool off in a Lee mould, cutting the sprue without ending up with a bump in the middle is going to be pretty difficult. My solution - and I think many other people's - is to cut the sprue by hand-pressure just after it solidifies but long before it hardens. That way there is no bump.