What Sprue Plte Thickness

[kywoodwrkr]

Assuming you could make a sprue plate any thickness you want what would that be? Why?
Also any thoughts on hole size, shape and ?
Finally, smooth bottom on the sprue plate or left with milling marks.
Number of cavities have an impact on the answers?
Thanks.
Dave

[Le Loup Solitaire]

I have successfully made sprue plates for one, two and four cavity molds out of Alu and steel/iron. I have found that thicknesses of 1/4 and 3/8 worked best for me. I believe that the ability of the thicker material to hold more heat and for longer is the key factor. Hole size is an area of controversy; some folks prefer larger holes and ladle casters have opened up Lyman and RCBS ladle holes to facilitate pours as they believe that the increased flow/pressure is beneficial to better fill-out. Other opinion is that it makes for a larger diameter sprue contact to have to cut through. It is debated. Some casters also set the sprue cutter to the position where the pour is on the edge....an effort to obtain a more level and undisturbed bullet base. Opinions and beliefs are varied. I don't recall any discussion as to the shape of the sprue cutter hole, but would appreciate learning myself if there is any experimentation on record and what the results might be. On the subject of smooth sprue plate bottoms I would vote for the smooth being more desirable as mill marks might contribute to lead smearing. All mine are smooth so I have gone with the.."if it ain't broke, don't mess with it". Number of cavities; shouldn't be a factor if the alloy, temp, and rhythm and other important factors are all correct. LLS

[leadman]

I had a Saeco mold that was hinged on the side with smaller holes in it. It was a 357 cal. mold and filled out great and the sprue cut well, could barely tell it was there.
The new, thicker Lyman sprue plates are left with milling marks on the bottom and this seems to help base fill out. With Bullplate lube on the plate there are no lead smears.

[theperfessor]

I don't think you want to leave too many mill tool marks on a steel sprue plate for an aluminum mold. The hardness difference means the top of your mold will get scarred up. Steel on steel or steel on iron is not so bad. They will wear in much more evenly. Easy enough to vent the top of the mold by other means than to use too rough of a surface finish on the bottom of the sprue plate.

[cbrick]

I really like the thick plates on the MP & NOE molds and that they are polished smooth.

There is a trick to them though. They do take longer to get up to proper casting temp than does the thinner plates of RCBS, Lyman etc. If they aren't hot enough poor base fillout is the result. If you know this going in there isn't a problem. Properly pre-heat the mold including the sprue plate and pour a large sprue puddle when casting and these thicker plates are a joy to use.

Rick

[MikeS]

One problem that I've had for a while is the sprue sticking to the sprue plate. Even when I have a mould that the boolits jump out of, I've had problems with the sprue. Once I started using thicker sprue plates that problem has mostly gone away. I've since replaced the thinner sprue plates on all my Lyman 2 cavity moulds with their newer thicker plate, and now the sprues don't stick to the plate anymore. The first time I cast with a Lee six cavity mould I was amazed at how the sprue just about jumped off, just like the boolits usually do. I don't know if it's because the Lee six cavity moulds have an aluminium sprue plate, or the thickness, or what. I had a similar experience with an MP mould that I just got, and it's sprue plate is steel, but about as thick as the Lee plate, so it must have something to do with the thickness. Another feature of the Lee six cavity moulds that I really like is the cam lever to cut the sprues rather than either cutting them by hand at just the right time (too soon and the sprue isn't really hardened yet, too late and it won't open by hand), the cam basically makes the timing of cutting the sprue less critical than a normal sprue plate. I really hate having to use a mallet to get the sprue plate to open.

[Lee S. Forsberg]

Assuming you could make a sprue plate any thickness you want what would that be? Why?
Also any thoughts on hole size, shape and ?
Finally, smooth bottom on the sprue plate or left with milling marks.
Number of cavities have an impact on the answers?
Thanks.
Dave

I had some sprue plates made for my SAECO, Lyman, and Lachmiller molds. They are 3/8" thick with small holes with a 30 degree leade to the hole and vent lines and extra long handles for more leverage. I wanted sharper bases on the bullets.
At the right temp they work very well provided the bullets are large caliber and heavy and the mold blocks are not too large. With one of the the light 30 caliber Lachmiller molds it is possible to cast bullets with perfect bases and wrinkled noeses, can't keep the mold hot enough. That's one of the brawbacks, keeping everything hot enough.
Also the better the finish on the sprue the better it slides over the surface of the mold the cleaner the cut and the better it releases the sprue.
Lee