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View Full Version : Sprue plate material for bullet moulds



krems
01-24-2008, 09:40 PM
I've been playing around making some bullet moulds lately. If you guys were going to make your own bullet moulds what material would you be using for the sprue plates..??? The bullet moulds would be made from 2024 aluminum and dura bar cast iron 65-45-12

I've heard of people using 4140 and 01. What about stresses, warpage etc at casting temperatures above 700 degrees...???.......Also I'll probably need the sprue plate (3/16" ) that has already been ground and polished. This may limit my choices.

Any suggestions for material and machining recomendations??

Thanks..........Krems

Carld
01-24-2008, 10:00 PM
Tool steel plate and harden it after the holes are in it.

MTNGUN
01-24-2008, 10:49 PM
I use 4140, heat treated and tempered (extra long tempering time to help relieve stress) after all other operations. Heat treated 4140 is way, way overkill, though.

For the DIY-er who is just playing around, mild steel is plenty good. Mill the bottom after all other operations are done. Assuming you do have a mill .......

You are not likely to wear out a sprue plate, but warping is very common. If you have access to a heat treat oven, tempering will reduce warping -- even on hot rolled steel, because the drilling and countersinking operations work the metal and impart residual stress. If you chose to temper, mill the bottom of the plate after tempering.

I have also made satisfactory sprue plates out of 2024, though there is no particular reason to do so, since mild steel is cheaper.

The countersink needs to be cut deep enough to form a nearly sharp edge at the bottom. Failure to do so may result in the lead sprue sticking to the plate.

Don't bother buying pre-ground plate, because the countersinking operation will warp it a little anyway. Countersinking takes a lot of force. Just use rolled flat bar and mill the bottom when you are done.

Anything from 1/8" to 1/4" is fine. I use 1/4". It is less prone to warp and easier to hold in the vise.

HTRN
01-25-2008, 04:04 AM
I think Buffalo arms sells thicker, ground steel replacement sprue plates. Unfortunately, they're site is down at the moment. You might wanna check back in a coupla days.


HTRN

interiorpainter
01-25-2008, 01:39 PM
I made a sprue plate from 4mm cold rolled steel plate. 14gauge.
It worked fine for lots of bullets but the lead seemed to stick to the plate more than the RCBS plate. Polishing?
Lee plates are not that hard either.

krems
01-26-2008, 02:33 AM
I found some flat ground 0-1 steel that I think I'll try first. It is 3/16" which seems to be just about right. I found a source for 4142 prehard precision ground. That stuff is expensive. $50 for 36 inches 2" wide.

Mtngun: Do you harden / temper the 4140 steel yourself or do you buy it that way....???

Thanks for the help. That Buffalo Arms company is a good outfit. I never could find the sprue plates in their catalogue.


Krems

HTRN
01-26-2008, 03:31 AM
Thanks for the help. That Buffalo Arms company is a good outfit. I never could find the sprue plates in their catalogue.

Ask and ye shall receive (http://www.buffaloarms.com/browse.cfm/2,65.html) :D


HTRN

MTNGUN
01-26-2008, 10:13 AM
krems, I buy the 4140 as rolled flat stock, machine it, then harden and temper it. And then grind the bottom, though you could get by with milling.

No way would I machine hardened material -- sure, you could drill it, but countersinking is hard on tools and also hard on the plate because quite a bit of force is required.