Aluminum sprue plates....

[Harry O]

I finally got around to reading an article about aluminum sprue plates in one of my old books/magazines. Greatest thing since sliced bread. Or something like that.

Before I try my hand a making one, has anyone actually tried it and is it worth it? I have 3 or 4 thicknesses from about 1/8" to 1/4". Any ideas on best thickness? The article was kind of vague on that.

[RayinNH]

Harry, I would think 1/4" would be better. Less likely to bend or warp. It would also give you a larger countersunk area for sprue metal to form...Ray

[454PB]

I made some many years ago.....I probably read that same article. They worked fine, but I did notice that lead smears wanted to stick to the the underside edge.

[JeffinNZ]

Harry: I used 5mm '7' series alum on both my 225415 and 225462 moulds and drilled 2mm pour holes. MUCH better bullets and MUCH less variance in weight.

http://img.photobucket.com/albums/v505/JeffinNZ/Shooting%20stuff/225462.jpg

[docone31]

Jeff, that looks like a keeper.
I like the sprue holes. Looks a little easier to pour into.

[GRS1]

Maybe a dumb question, but how did you cut the sprue holes in your aluminum sprue plate.
Gord

[Le Loup Solitaire]

The original article appeared in the NRA Loading handbook as "Aluminum sprue plate rated high". It was written by Col Harrison. It discussed the advantages, workings and how to make one/them. The plate is traced and cut from preferably 1/4" aluminum plate. It can be shaped with a file. The hole for the hinge screw/bolt is marked accordingly and drilled to the proper diameter. The sprue hole or holes is/are drilled with a small drill size and then enlarged by the careful use of a countersink, but the trick is to not go to far and make the hole too big....or else you have to start over. I'm not a machinist, but after messing up a couple of tries I got it right and made some nice ones that I use to this day. A drill press makes the job easier, but a hand-powered drill (old style) can be used if you are careful. The plates work well, make really good bullets...at lower melt temperatures, the melt doesn't stick to them and of course they don't rust. As Harrison pointed out the use of anodized aluminum makes for a somewhat harder plate. They last quite a while and I suppose that would vary with the hardness of the alloy and how much use they see. But the price of sheet aluminum is not out of sight and a square foot will make a lot of sprue plates. Its certainly a worth- while and useful project that is not hard to succeed with. LLS

[JeffinNZ]

Maybe a dumb question, but how did you cut the sprue holes in your aluminum sprue plate.
Gord

Drilled the 2mm holes then just ran a regular old countersink bit in to suit. They look concave in the photo but are not.

[Rodfac]

Jeff...Visited Hawk's Bay a yr ago...lovely country...and the trout...oh my g.d. That said, did you have trouble getting complete fill out in the mold with holes that small? Regards, Rodfac

[JeffinNZ]

Jeff...Visited Hawk's Bay a yr ago...lovely country...and the trout...oh my g.d. That said, did you have trouble getting complete fill out in the mold with holes that small? Regards, Rodfac

Nope. They fill out great. Hot alloy (not too hot though) and drop the alloy from the ladle an inch or two.

http://img.photobucket.com/albums/v505/JeffinNZ/Shooting%20stuff/22base2.jpg

Left to right. New plate, old plate, old plate off set sprue hole.

[Harry O]

Thanks for the information everyone. Looks like it is something I should try. Some of the aluminum I have is 5 series (5056 I think) for the thinner pieces and some is 6 series (6061-T4) for the thicker pieces. I got about 90 lbs of scrap aluminum for $60. I have a floor mounted drill press and several different sized "work holders" for it, so they should not be too difficult to make.

I have been trying to make an AR15 lower receiver from the aluminum. If you do a search, there are detailed drawings on how to do it. I have made about a half dozen receiver sides -- and scrapped them. But I am getting closer.

I was thinking about not making the sprue plate narrower where it is hit. Glad to see that JeffinNZ had the same idea. I am also thinking of making it a little longer.

[JeffinNZ]

I was thinking about not making the sprue plate narrower where it is hit. Glad to see that JeffinNZ had the same idea. I am also thinking of making it a little longer.

HUH! I was just to lazy to shape it! Seemed like time I could be using for casting instead.

The extra length will generate some more cutting leverage and is a good idea Harry.

[Le Loup Solitaire]

Making the part that is hit/struck a bit narrower is ok especially if the plate is 1/4" or larger in thickness. The one pictured by Jeffin NZ is a solid looking plate. Making the striker part longer is beneficial as it increases the mechanical advantage of the plate and enables it to cut the sprue easier....and moreso if the plate is off center. This causes the diameter of the section of melt leading to the bullet base to be smaller. The practice of off centering the sprue cutter is used by some casters in an effort to get flat, near perfect bullet bases and they do...as seen in the picture sent again by Jeffin NZ...the group of bullets on the far right. I have made plates for one and two cavity molds only and they have worked very well. The general outside perimeter shape of the plate is not critical as long as the plate holes line up with the cavity holes (if not pouring off-center). It doesn't take much to successfully experiment with the project so give it a try. LLS

[Wayne S]

I asked some casters about finding Alum. plate and this is one of the places they sent; http://www.speedymetals.com/pc-2723-8361-14-7075-t651-aluminum-plate.aspx
I'll contact them tomorrow with the requirements of a sprue plate, and see which one they suggest.

[R.C. Hatter]

I have made both 1/4" and 3/16" aluminum sprue plates for several of my Lyman moulds and am well pleased with their performance. Be aware, however, that you may have to change the screw for the sprue plate, to a longer one due to the increased thickness of the plate.

[PatMarlin]

I think the larger the plate the better, as I always cut the sprue by hand and never use a mallot or stick on my molds.

Bull shop plate lube would be the ticket for any possibilty of smears.

Nice work Jeff. ..:drinks:

[crabo]

I made one out of steel for the RCBS 250K that was a little larger and thicker. I did it all with a hacksaw, sander, and a die grinder. It worked so well I bought a 90 degree countersink to make some more. I was going to redo the sprueplate with my new countersink, just because it would be prettier, but the one I made works so well, it's not worth the trouble.

I have used the 90 degree countersink to open up a lot of other sprue plates. It has always helped make the bases fill out better. I also make the hole a little larger if I have trouble with the bases filling out.

I don't know that aluminum would be better, but the heavier steel sprue plate sure makes a big difference. The bases fill out better and the sprues cut easier with the larger sprueplate extention. The first picture shows the difference in thickness between the old and new plates.

[HORNET]

I've made a bunch of them out of 1/8" Aluminum (2024, I think). A place I used to work at had a CNC punch press and I got one of the operators to run me a few dozen "blanks" out of some scrap. Also got him to run me some narrow spacers/washers out of stainless. I use them along with a wave washer (MSC#02566552) to make up the thickness and replace the lock washer that comes as stock. I think it gives more evenly distributed pressure on the plate.
I'm playing with different plate configurations to see if it helps the heat balance on a couple of uncooperative molds. Now that it's warmer, I can go back to trying them out.