Nasty sprues

[chaos]

I am new so please be gentle.

I raised the temp on my pot as suggested by some member here. Bullets look Perfect.....Almost....Some of my sprues are actaully tearing into the bullet when I hit the sprue plate causing a gouge in the base. All of my bullets weigh within 2 grains of each other. If I pick out the good ones without the gouges, they are all within 4 tenths of a grain. This is a brand new RCBS 240gr semi wad cutter gas check mould. I washed the sheeeeit out of it with acetone and heated it up on the top of my pot and stared casting with it. Using wheel weights. These particular weights were the 50/50 blend that Carpetman so highly recommended.. 50% free and 50% given to me.

When I got the mold the sprue plate was hard to move even with a mallet, hard enough she put impressions on my mallet. I backed it off a bit to save my mallet and this is when the tearing began... I think, It may not be related.

What do I need to do?

Let the bullets sit in the mould longer?

Ajust the sprue plate?

Any and all help is greatly appreciated ( especially suggestions that actually help my situation)

Thanks, Chaos

P.S. A special Thanks from my better half...goes out to Carpetnman and Buckshot who have officially got me hooked on this hobby. It's kind of a middle finger thanks, but I'll try and keep it civil for her. :mrgreen:

[garandsrus]

Chaos,

It sounds like you are making progress! I think that if you let the sprue sit for a couple more seconds before whacking it that things will be "mo betta". It sounds like the alloy is still pretty hot when you are opening the sprue plate. On the other hand, it could have already cooled down too much :)

I have never had to do it, but folks have reported good results from "sharpening" the sprue plate opening a tiny bit when necessary. I believe that they just use a standard chamfer bit to just barely touch the hole. You would need to make sure that a burr isn't created on the bottom of the sprue plate by sanding/honing it after sharpening the sprue.

I would try just shortening and lengthening the time between casting and opening the sprue plate to see if that helps. I normally open all my sprue plates with just a gloved hand right after the sprue on the final cavity turns color to signify that it hardened.

John

[trk]

I open the sprue plate with my thumb. (Gloved hand of course) That gives me the abiltiy to feel the pressure it takes and to delay the timing to let the sprue harden to the point where I get a clean cut - instead of early when it wil tear a bit - or late when it takes a mallet to open.

Doesn't work at first - mould has to warm up first.

[carpetman]

Sounds like you are in deep poo poo. You might need an appointment with Dr Kavarkian---glad I could help.

[floodgate]

Sounds like Catpetman is off his meds - again!

[hiram]

I have occasionally sharpened the sprue hole by turning a counter sink in the hole BY HAND. I do this with the sprue plate open or off the mold because the sharpening can/will push a small burr up on the underside. I then use a slip stone and lightly stone the bottom of the plate. Hold the stone FLAT across the whole plate. You'll see shiny spots where metal is removed, and it will probably be removed from around the sprue hole and the edge of the plate. You will also probably notice that very little stoning takes place between the hole and the edge of the plate. Running your finger tip before and after the stoning will indicate that sharpening has taken place.

[runfiverun]

let em sit a bit longer and a quick twack with your opener will cut clean.

[randyrat]

The first ten cast boolits are harder on a mold than the next 10,000 for a new caster. Your mold is not hot enough. You should let mold heat up considerably before you try and cast. The results of a cold mold; POUNDING to open the sprue plate. After you pour let it cool enough to see the sprue puddle to sink and turn a dull gray then push it open with a gloved hand. I'm still upset about ruining my first mold. A gloved hand will work unless you have some dang hard alloy for armor piercing bullets, then you may need a tap with a wooden dowel.

[JIMinPHX]

The picture below shows 3 boolit bases. The sprue was cut from the left one too early. Notice the grainy craters in it. The middle one was cut at just about the right time, although now that I look at the blown up photo, I see that it has a small defect too. The one on the right was cut too late. Notice the half moon shaped gauge out of it towards the top. This gauge has a smooth finish, not like the grainy finish of the defect on the left. These were .22 cal slugs, which are kind of particular about exactly when the sprue is cut. Since they are so small, the sprue mark takes up most of the base diameter.

Sharpening the sprue plate makes the mold less fussy about cutting the sprues. I prefer to sharpen them with a stone.

Also make sure that your sprue plate is not too tight & that you lube it. It should move freely when it does not have lead to cut. The preferred lube among members here on the board seems to be bullplate lube from bullshop. If you don’t lube under the sprue plate, you will eventually gaul the top of the mold blocks & that is not something that you want to do.

[chaos]

The picture below shows 3 boolit bases. The sprue was cut from the left one too early. Notice the grainy craters in it. The middle one was cut at just about the right time, although now that I look at the blown up photo, I see that it has a small defect too. The one on the right was cut too late. Notice the half moon shaped gauge out of it towards the top. This gauge has a smooth finish, not like the grainy finish of the defect on the left. These were .22 cal slugs, which are kind of particular about exactly when the sprue is cut. Since they are so small, the sprue mark takes up most of the base diameter.

Sharpening the sprue plate makes the mold less fussy about cutting the sprues. I prefer to sharpen them with a stone.

Also make sure that your sprue plate is not too tight & that you lube it. It should move freely when it does not have lead to cut. The preferred lube among members here on the board seems to be bullplate lube from bullshop. If you don’t lube under the sprue plate, you will eventually gaul the top of the mold blocks & that is not something that you want to do.


I was cutting them too early. I lightly took some emory cloth to the sprue plate as well, then some steel wool. It had a couple of big ass burrs on it. This is a two cavity mould and the front cavity cast perfect near every time. Every other one in the rear cavity (Doesn't sound right) has some sort of defect. Now opening with a gloved hand..

Thanks

[Wayne Smith]

Chaos, BruceB's method of having a wet sponge or cloth near and touching the sprue plate to it before opening works well when the mold is running nice and hot and you don't want to slow down. I've found this most helpful with big boolits, 450gr and bigger.

[Sundogg1911]

Bull Plate lube between the top of the mould and sprue plate, and everything will be fine. I swear by the stuff. I use it for that, lubing my Master caster, lubing the hinges of hand moulds. I wouldn't be suprised if this stuff could cure cancer. It's liquid gold if you ask me.
(I know....no one asked me) ;-)

[dromia]

Ditto Sundog.

Bullshop Link at the bottom of the page, get some and go.