For those that wanted a mould build post.

[Catshooter]

Nice work. How-It's-Done-With-Pics is always very educational.


Cat

[trapper9260]

I was always wonder how it was made and all thank you for shown it and looking forward for more.

[websterz]

Well, I changed my mind about the form tool I made yesterday. I tumble lube all of my boolits so a single lube groove doesn't really make much sense. So today I made a new one.


Now it's off to the mill to get a set of blocks drilled and ready for the lathe. More pics to follow in a few minutes.

[FLHTC]

Good job websterz. I like the flycutter ventlines, as opposed to using a shaper. Was that one pass on those ventlines with a real slow RPM?

[websterz]

Yep, about 350rpm and as fast on the table as my power feed will go.

[FLHTC]

Excellent job

[websterz]

I need to mill the handle slots anyway so I'll go ahead and do that now. Kerosene makes a great cutting fluid for aluminum.




Next I put one block in the vise and use an edge finder to locate the center line between the two blocks so the center drill hits right down the middle.


These holes are used to accurately locate the blocks in the lathe later. The sprue plate I'm using had the pour holes .700" apart so I find the middle of the blocks and drill my holes .350" on either side of center.







.

[websterz]

Now I chuck up the blocks in my four jaw chuck and begin adjusting one of the holes dead center. This is critical for the finished mould, otherwise the cavities end up off center and are useless.


With the blocks where I need them I start by plunge cutting a cavity with a 1/4" end mill. I only go about 80% of the final depth so the nose profile is cut cleanly with the form tool.



Next the form tool is carefully fed to the final depth of the cavity, letting it dwell so it produces a smooth finish. Now the tool is drawn back towards me to bring the cavity to the final diameter. This is also where the lube grooves are formed. I stop frequently to check the hole diameter with a small hole gauge and micrometer. The tool is fed back to the center of the hole before withdrawing it to keep from wiping out the lube groove ridges. A smooth boolit mould would be easier to cut but I don't powder coat or use HiTek so I gotta have grooves.




The first cavity is done!



Now I repeat the process for the second cavity.



The finished product!



Tomorrow I'll get the handle and sprue plate holes drilled and tapped and it'll be time to cast some boolits.

[Boolit_Head]

Nice I always wondered how that was done!

[Rifle 57]

Very nice job!!

[btroj]

That is absolutely awesome. This is better than I hoped.

[dragonrider]

Ecellent work websterz,

[Sticky]

No.. this is bad... really bad.. cause I am an amateur machinist and work closely with a CNC shop. I can see more costs in the near future, dammit!

Thanks Websterz for sharing your process, that is an outstanding process you have worked out. I 'specially like the wireties as a safety in the 4 jaw process!

I do have one question tho... is there a reason you choose to alternate the mold pins?

[freebullet]

Very impressive work sir! Thank you for sharing.

Do you think you could pull that off with just the mill?

[websterz]

No, no real logic behind the alternating pins. It just seemed like it ought to be that way. LOL As for the zip ties, I'd be totally lost without them!! I have a gallon zip lock bag full of them. They are aerospace grade with the stainless steel tab. I got them from Boeing surplus years ago.

[websterz]

Very impressive work sir! Thank you for sharing.

Do you think you could pull that off with just the mill?

You are most welcome, and thank you for the kind words!

You could do it with just a mill but it would be a ton more work. Your only options for cutting the cavities would be to run the form tool in a boring head or to use a self centering vise and a cherry. The latter would be the preferred method of the two but only if you already had the prohibitively expensive vise. IMHO the lathe is the only way to fly!

[Sticky]

No, no real logic behind the alternating pins. It just seemed like it ought to be that way. LOL As for the zip ties, I'd be totally lost without them!! I have a gallon zip lock bag full of them. They are aerospace grade with the stainless steel tab. I got them from Boeing surplus years ago.

I would kiss the man that invented zipties... I swear!!! LOL

[websterz]

I don't think I would.

[websterz]

This morning I got the new mould mounted and cast a few test boolits. To my surprise I achieved the near impossible. The boolits vary a mere .2 grains between cavity one and two and the length is dead nuts between the two! The average weight is 140.1 grains. Functionally the cavities are identical and I cannot tell the boolits apart. They are slightly out of round so I will lap the cavities now but I call this one a success. I'm going to make up a couple of dummy rounds and see how they chamber while I wait for the mould to cool.

[websterz]

At 1.095" the rounds plunk and chamber perfectly in my SR9. I think this is going to be an awesome boolit!