How Hard Should it be to Cut a Sprue

[Saint]

I keep hearing about people cutting the sprue by whacking the plate with a stick. I don't know if I am doing something wrong but I have never had to strike the plate. I have left balls in the mold for several minutes and still find that I am able to cut the sprue by hand with just firm thumb pressure on the cutter plate. I s there any benefit to whacking the plate as opposed to this method?

[dubber123]

I am guessing by saying you are casting balls, and the pics of the black powder pistols in your avatar, you are casting with pure lead. Wheelweights or anything harder make sprue cutting much more difficult than cutting a pure lead sprue. On a 6-cavity Lee mould for example, letting a batch of hot cast wheelweights fully harden I'm pretty sure would get you some broken mould parts trying to cut the sprue.

[Bob Jones]

Wanna see pictures of those broken mold parts? [smilie=1:

My first Lee 6 hole mold I let them cool too long and broke the sprue cutter cam device right off, learned my lesson.

There is a BIG difference between a 2 hole mold and a 6 holer when cutting sprues also. With the two holer a little tap will cut them right off, the 6 holer can take some strength, even when running right.

[Saint]

I actually cast with 75% pure 25% WW(about) but I have 2 single cavity and 1 double.

[9.3X62AL]

The antimony in WW or other alloys seems to be the main suspect in making sprue-cutting more difficult. My small amount of lead/tin casting gave no noticeable difference in sprue-cutting effort from that needed to cut unalloyed lead sprues. 92/6/2 takes more prompting, and Linotype can be a real bee-otch if left to set up for several minutes.

I use a rawhide mallet to open sprue plates with the relatively short strike arm of the stock Lyman mould sprue plate using antimonial alloys. This is more a tap than a strike, per se. My own thoughts are that the minimum force required to get the sprue cut and the plate pivoted is the best possible method for getting the job done.

[fourarmed]

Another thing that makes for hard sprue cutting is the shape of the pour holes in the sprue plate. A lot of my older Lyman 4-cav. molds have a short (maybe .020"-.030") parallel-sided section at the bottom of the holes.

[Sundogg1911]

There are a lot of variables. If you're using harder alloy, it will be harder, the bevel angle in the sprue plate makes a difference, if you're a weakling like I am.....whack it! ;-)

[Dale53]

I use a stick just until the mould is up to temperature (and that is not very long as I pre-heat my moulds). Then it is strictly hand twisting of the sprue plate. I am age 72 and certainly not a "Charles Atlas" (although no none kicks sand into my face:mrgreen:).

I wear a pair of leather gloves and have NO difficulty cutting up to and including 4 cavity moulds. The Lee six cavity moulds have the assist handle, that helps you open with its cam-lock. There IS a considerable difference between a mould up to heat and a cold one, tho".

Dale53

[Larry Gibson]

I do the same as Dale53.

Larry Gibson

[kawalekm]

I gave this a try the other day when I was casting Lyman's 358477's. I was surprised to see that I could actually just turn the sprue off with my thumb. So, yes it works, even for regular bullets. After a few rounds of casting by hand, I forgot about it though. I could start to feel the heat coming through my gloves and I still had to tap the mold handles anyway to drop the bullets. Later, I switched to a Lyman 4 cavity mold. Definately mallet only! To me, it's more of a "Oh yah" kind of thing rather than something I'd really want to do.
Michael

[Dale53]

I actually get much nicer bases when "twisting the sprue plate". Further, some moulds have "too thin" spure plates that are easily bent and NOT so easily straightened.

Lyman 4 cavity moulds and metal must be "up to heat" before you can successfully use the "twist" method. However, once they are up to heat it is a piece of cake.

Dale53

[garandsrus]

I use a gloved hand to cut the sprue also on 2 and 4 cavity molds without any effort... I cut them right after the sprue on the final cavity turns color. I return the sprue directly to the pot also. I got this idea from Bullshop a while ago and it works very well.

I do use the handle on a Lee 6 cavity though, mostly "because it's there". There is no increased effort to cut sprues on multiple cavity molds (2 and 4) as long as they are up to temp. This is the main reason I pre-heat my molds. It is a whole lot better for them than beating on them!

John

[FISH4BUGS]

I cast a bunch with H&G moulds. The 4 cavity ones are fairly easy to whack the sprue plate. I use a 1lb lead hammer to open the sprue - thanks Tom! (let's not start THAT thread again!.......). I also have a polypro rod about two inches in diameter and about 18" long that I use occasionally also.
The 6 cavity and the 10 cavity H&G moulds are kinda hard to open, and the warmer they are the easier it is to open the sprue plate.....but boy can you do a pile of bullets with a 10 cavity mould!.........but they take forever to come up to temperature. The sprue plate on a 10 cavity H&G mould must weigh a few pounds!
The easiest one that I use is the 4 cavity 358156 Lyman. Once that one comes up to temp, I can actually just sort of tap it with my hand and it comes open. Too soon and it smears....too late and it needs a mallet..........a very fine balance no doubt.

[John Boy]

Saint, other's method may vary ... I use a glove hand to cut the sprue and like to keep the mold temperature so the sprue hardens after a 5 second count. Find that the bullets drop within a 1 grain average when the sprue hardens within this time frame

[jtaylor1960]

I was using my hands to cut the sprue on my single cavity molds.I tried it on the doubles and it was not bad when the mold was very hot.I went to do it on a four cavity and about sprained my wrist.