sprue plate material

[farmbif]

I picked up an old Lyman rn flat point 44 cal machine mold, the only numbers on it are "448" that is missing the sprue plate. my friend want to convert it for hand tong use and we were wondering what kind of steel is best used to make a new sprue plate

[Rickf1985]

Pretty sure they are nothing special and can be made from a piece of flat bar from the hardware store. I have filed them on Lyman molds and they are not hardened.

[Charliemac]

Lyman sells mold repair kits that include a sprue plate. I don't know the difference between a Lyman machine mold and manual one? Maybe it will work for you?

[William Yanda]

Thickness of the material selected will determine the heat retention capability of the cutter.

[country gent]

They can be made from cold rolled steel from the hardware store but I prefer A-2 or O-1 ground gauge stock, the finished surface is already flat and smooth dosnt need to be worked down.It also isnt as prone to shifting under heat. If desired it can be hardened for longer life but I cant recall wearing a sprue plate out. A-2 or O-1 also machines better than cold rolled. Made one out of D-2 but was a pain to machine and grind. I normally make mine thicker from 3/16" ( .187) stock.

Buy your stock to match the length of the blocks
cut to length to include the ear for the sprue plate then only the cut out to form the ear or leg has to be cut. then its 2 maybe 3 holes to drill the actual sprue holes chamfer I finish in the press by hand turning the chuck by hand slowly with the countersink this allows any chatter to be removed and a very good finish can be achieved.

If you want hardened easily use 4140 pre hard it machines nicely finishes good and is around 35-40 rc.

[20:1]

Oddly enough, there's another thread here about an Ideal marked mould that's only marked "444", which is not an Ideal/Lyman design number.

[PopcornSutton]

I converted a mold from base pour to nose pour (with country gent's help) and I used O-1 ground plate I found at Online Metals. Machinable and very flat. Worked great.

[country gent]

Happy top have helped PopcornSutton, Hope the conversion met your expectations.

0-1 is ground tool steel much flatter and square to start with. Hence it saves having to square and true the stock. its also more stable as to warping and size. It machines to a better finish.

In the method I posted above you can clamp the old plate to the stock and spot hinge hole and srue hole thru drill and bolt together. with 3-4 layers of tape cut around Then file in to size. SInce you have the hinge and spue hole you now need to chamfer the sprue hole close to depth then by hand turn the chuck by hand slow finishing the sprue chamfer. Now bevel the edges anbd polish the plate on a flat surface. This can all be done with simple hand tools and a drill press. A mill makes it easier but isnt needed.Polishing on a flat surface with 600 grit wont take but a few mins on each side and is to remove burrs and raised edges from drilling and cutting.

[TomAM]

I made a test plate using 3/16 7075 aluminum for a 5 cavity mold. It works just fine.

[Bent Ramrod]

I did the same as TomAM after reading an article titled “Aluminum Sprue Plate Rated High” in that American Rifleman collection of bullet casting articles.

It worked very well, as it turned out. I find in a lot of casting scenarios that once I get going, I need extra cooling on the sprue after the lead seems to have frosted over or I will see lead smears at the top of the blocks when I cut the sprue. I used to touch the plate to a damp cloth, but the water kept needing renewal and the process would generate fine rust on the steel plate. Now I have the furnace setting in a stainless baking pan and touch the sprue to the edge of that, but it’s an extra step best avoided if possible.

The aluminum plate sheds heat very quickly without taking enough out of the blocks to cool them unnecessarily between pours. Also, the aluminum sheds the casting sprues easily, while sometimes a steel plate will stick them, and need polishing or lubrication.

[TomAM]

For a second or two I considered offering 7075 aluminum plates on my molds.
Much cheaper to make; but it would be extremely difficult to get folks to give it a try.