First mold and lessons learned

[Zaneiel]

I have been playing with making molds over the last few weeks as I get time and posting pics to the fellas on chat for kicks.
I figured I will start a thread so I can share some of the things I have learned and maybe get some tips along the way.

So here goes, I'm not sure how much detail you guys like so I will start off light.
I started off with a light prototype of the bullet profile in mild steel as a proof of concept but i cut the flutes upside down apparently :)

https://www.dropbox.com/sc/ypvflg3za3be9ic/AAB83SV5nxaPsTP8llX-ZLc1a

I tried it out and as I thought it dulled after the first cavity was cut. but it got her done :)

https://www.dropbox.com/sc/m3dmp55e022a444/AAAdOKQjqDaR1s1fTkXLKXuqa

I decided it was time to break out the tool steel and try again.

I will leave you with the profile and layout of the tool steel as I have to go to work right now but I will post more pictures later.

https://www.dropbox.com/sc/m7u34xorengd1ds/AADHy7LgdevPP0ssCpdQFhqRa

[Nueces]

Very nice. You can't include too much detail.

[Walter Laich]

remember you can always clamp the mold together with C clamps and do a practice cast to check out the dropped size of the bullet.
Great job by the way--I'm lucky if I can use a commercial mold to say nothing of making my own

[Zaneiel]

Ok, Sorry to leave you hanging but I had to run to work this morning before I could get to much of the good stuff.
Thanks for the comments:

@Nueces : I will add a bit more detail. With that said I should back up a little and explain how the mould was made and the cavity cut for the 2 different runs I have done so far and Also next steps on how I am planning my next setup.

@Walter, A test pour is a great idea and I actually did that at a later time to check my size, I will elaborate later as not to insert a spoiler too soon :)

I should explain in a little more detail the process and expectations I had.

This is a Keith style .358 boolit I am playing with for my stainless steel Ruger new model Blackhawk 357 Magnum.
https://www.dropbox.com/s/9049fyq60s7par2/20141101_140342.jpg?dl=0
Here is a drawing of the style but most of you are probably familiar with it.
https://www.dropbox.com/s/via982alx6sxrlb/358429.jpg?dl=0

I used my mini mill to true up the mold blocks, I milled handle slots and drilled holes for pins to keep the mould halves true, cut 5/16" round rod and pressed them into the holes. Here are some pics of the first mold :)
https://www.dropbox.com/s/rg82ls8qjuadyfl/20150117_180838.jpg?dl=0

Like I mentioned in the first post, I turned the bullet profile on a mild steel rod for a proof of concept.
I then took a dovetail cutter and put the rod in my milling vise and cut slots in it hoping to form cutting edges.
I actually got this idea from looking at a commercial reamer I have but I had the dovetail cutter on the wrong side so I ended up with a left hand turning cutter (good thing my mill will run in reverse).

I pre-drilled the mold cavities so I would have a guide for the cutter. I used a drill press vise as I didn't have a double action self centering vise. (I found out you really don't need one but it might make things a bit easier).

I didn't get quite finished with the first cavity before the mild steel cutter edges got dull. Aluminium is tough on mild steel.
It actually took quite a while to get the first cavity cut and by the time I did have it finished, there was no way the cutter was going to cut the second cavity so I pretty much had to start over.

On to Tool Steel! ----

So where we left off in the first post, I posted a picture of the nose formed and layout lines for the crimp and lube grooves on the shiny new piece of tool steel. This O1 is amazing stuff and a pleasure to work with I am impressed and hooked. It is easy to machine and takes a great finish. Here is a pic of the finished tool steel blank next to some cast boolits for size comparison.
https://www.dropbox.com/s/ujzfrwvo1ezk23n/Tool_steel_357_keith.jpg?dl=0

So some of you may know how this next part is going to end before it even begins but lets say I decided to change my plan of attack slightly.
I turned my brand new shiny tool steel profile into what they call a D reamer. I cut 1/2 of it away, got it red hot for a couple of minutes, then quenched it in vegetable oil to harden it. Then when it cooled i cleaned it up a bit (it gets a black scale over it kind of reminds me of the bluing process we do on our guns) I then played a propane torch flame over it carefully to turn it to a light straw color and quenched it again to draw the temper back a bit (if you don't do this step your cutter can shatter like glass because it is too hard).

Here are some pics. Heating in my furnace, the black scale color on it, and the finished D reamer cutter.
https://www.dropbox.com/s/pz1iveav8spz01r/20150124_115946.jpg?dl=0
https://www.dropbox.com/s/0888n3bfhilztu8/20150124_121024.jpg?dl=0
https://www.dropbox.com/s/8xh9zalp9avpgmr/20150124_121033.jpg?dl=0

The cutter was sharp as heck, and when I ran a file over it, it felt like I was sliding over glass, it even scratched my file (yup its hard, good stuff!)
I prepared a 4 cavity mold block this time thinking I had my new super cutter!
Believe it or not, machining a mold block however trivial it may sound actually takes considerable time to measure both pieces, true up the pieces so they are nice and smooth and the same size, cut and press in the pins, mill the mold handle slots, and pre-drill 4 holes. whew! How many hours do I have into this thing now?!? ok now to cut the cavities....
https://www.dropbox.com/s/5pnprj9cdpuky6p/20150125_000145.jpg?dl=0

So i setup my drill press vise and start the cutter slow. well the sucker doesn't even want to start, with half of the round profile cut away, it is just that, a reamer!.

After some thinking I ended up clamping one of the mold halves into my milling machine with the cutter in the quill and I get the profile deep enough on both mold halves to get started.

I put the mold back into the drill press vise and baby the thing for almost 2 hours, turning some of it by hand.... lets just say Lesson learned.
It took me like 3 hours of fiddling with this thing to get 1 cavity cut and now I am back at square one with one mold cavity cut and a cutter that I don't want to spend 9 hours cutting the other 3 cavities!

So here comes another hitch. I decided maybe I can salvage some of the project and make myself a single cavity mold. So I closed the mold and poured my wheel weights in to check for size. My cutter largest diameter was at the base of the boolit and measures .360 as per the drawing I have. The boolit measures .356 coming out of the cavity! well that just wont do unless we are shooting heavy 9mm bullets or something so now I need to compensate and cut a little larger size next time.

I will insert a pretty picture of little silver boolits that I cast from the first mold that the mild steel cutter cut (again undersized and unusable measuring .352 ugh!)


https://www.dropbox.com/s/1h454opcmdltm98/20150205_070733.jpg?dl=0

So I have Spent a couple weeks of time, not much money to speak of as the materials I am using I had on hand and I can melt the aluminium back down if I care to. But I have learned a ton of useful information through the process and hope to pass it along for those who might be interested or just like a good read with their morning coffee :)

Next Steps:

I have taken my D reamer and ground it down to just a cutting edge.
I have made a single cavity mold block to test with.
And I am ready to setup in my lathe. I plan to center the mold in my 4 jaw chuck, pre-drill the cavity, then run the cutter in and then out like a boring bar form cutter (since thats basically what it is at this point).

I will carefully take the mold out and do a test pour and measure the resulting boolit.
Place back in the lathe and cut more if necesary, rince and repeat untill I get a good boolit.

If I plan to make a 4 cavity mold I will make another cutter out of tool steel (after measuring the cavity in the mold that I like) and cut the flutes (the correct way this time) and try the old cherry and drill press vise again.

It may turn out that a fixture and the lathe is a better way to cut them, we shall see.
Well this post is getting a bit winded so I will leave off here. More to come when I get some time to play!