OK, So I have just been told by a brother of mine at the lodge that he can machine some moulds for me if I had some plans for what I would need... this being said, is this something I can get plans for? And also, what material should I get them made from assuming it can be done by him? I will be wanting to get moulds for several calibers. The .243, .257 roberts, .223, .380, .300 winmag, and probably .454 round ball. should I go this route?

Thanks for any info,
Jason, SC

Kingjasn you can go to Mountain moulds web site and draw them only you will have to work out the numbers on the drawing Forest Punch

I think if your friend is going to make them, but has no experience, it will be a lot easier on the both of you if you just buy a couple for him to look at. Used ones on E-bay will be fine. The inexpensive Lee molds with one and two cavities use a special aluminum extrusion you would find a lot of work to copy, so I would stay away from that kind. You will also need to read up on the vents and how the sprue plates work. You will want to get a pair of handles and make them to fit those handles.

Thanks uncle nick. One thing I do a lot of is read, so I will read up on and probably take your advice and purchase a used mold or two for investigation.

You'll discover that RCBS and Lyman and Lee and Saeco and others have made several different sizes of handles for their molds, and some make more than one size, depending on how many cavities the mold block accommodates. The smaller mold makers, like NEI, usually don't make their own handles, but just groove their mold blocks to use handles from one of the bigger companies. I recommend you aim at sizing your mold blocks to use the Lee handles sold for their six-cavity molds. They are sturdy handles and are the most economical removable handles you can buy, AFAIK.

Since I own a lathe and some other machinery, I have often thought about making my own molds. I concluded, however, that it would be a difficult process without first making a tracer attachment of some kind for the lathe. Otherwise, you are into building a jig to squeeze two blocks together exactly equally around a cherry cutter, and, of course, making the cutters. I don't know any way around making both special fixturing and tools unless you have a CNC lathe and programming software at your disposal. In that instance, lathe-turned single-cavity (best for rifle bullets, IMHO) nose-pour molds, similar to the Hoch molds (http://www.hochmoulds.com/), would not be too hard to do. You would just need to invest in a few special boring tools, and might be able to buy those off the shelf.

Jason, I have made my own mold blocks before, and had someone bore them for me. The size of the blocks depends on the caliber of the bullets you want to cast. My blocks are 2.000" square, for the .729" diameter 12 gauge. For caliber of les than .600" you can make your blocks 1.500" wide per set, giving you .750 thick halves, and 1.750" long. The height can be variable, depending on the OAL of the bullet. I seem to recall most molds are 1.500-1.750" in height. The long bullets for BPCR need tall blocks.

You can checl NEI handtools, I think they also list mold dimensions. I changed the way my molds were designed after the first few. The aire relief is ground in with a surface grinder. The size varies, but I am using one relief ground into each block, .0005" deep by .375" wide. The bullets will not "fin" with this setup. The relief will also not get clogged, like machined grooves. I have one big 1043 grain mold, that recuired 3 grooves, but that is an extreme case. If I can be of any help please email me.
Thanks Greg S

I like the idea of the shallow wide air vent. Good thinking! Surface grinding is the only reliable way you could do that*, and doing it to aluminum would require a soft stone (if you can still find one somewhere) and a lot of Crisco.

By the way, have you ever tried annealed CRS for block material? Just curious whether it remained stable enough after a single-heat annealing?



* Well, O.K., not really, but it would take half a week of your spare time to scrape it precisely.

I wouldn't use CRS, as it tends to have residual stress from rolling. It might warp, even after normalizing or stress relief. I use Durabar 65-45-12 cast Iron. You can get it for a $50 minimum order direct from the local supplier. You can check them out on the web.
Greg

Right. The stress is why I asked about annealed CRS? Guy Lautard's book, The Machinist's Bedside Reader, had a description of stress relieving CRS to stop the warping. My recollection is he just soaked it an hour per inch at 1100°F, same as stress relieving a barrel after button rifling, then cooled it gradually. The iron doesn't sound like too much cost, though, and would save all that bother.

Some years ago a friend of mine had to build a grinding robot that was extremely precise. It had six collet spindles equally spaced around the perimeter of a large rotating platter that was about three feet across. The spec called for the spindles to be within 50 millionths of an inch of their nominal diameter as well as of their circumferential location. He got a gray iron casting made for the base, and I recall him saying it had to be reheated for stress relief 12 times before it stopped changing shape enough to let the rest of the machine hold tolerance. The old fashioned way is to age the iron long enough to stress relieve itself, but they had a deadline. An aerospace machine shop had to do the machine work. IIRC, they got the spindles within 50 millionths of their circumferential spacing, but could only hold 80 millionths across the diameter. But they made do with that, somehow.