Re-cut a sad old mould today

[Ian]

Bought this once-nice Ideal 357446 single-cavity off of a SS board years ago, it was kind of an orphan and priced right. Unfortunately, the person I bought it from decided to knock the faint surface rust inside the cavities with a WIRE WHEEL. Jeezless people. When it arrived there was a big ridge of metal piled up on one side of each cavity edge. I tried to peen the metal back into place, but one side was too trashed. See the bullet cast from the mould down at the bottom.

I wanted to try a heavy .45 Colt bullet design that's been running through my head lately so I figured why not try to fix this one. I had one more piece of 3/16 tool steel from KeithB's grab box so I ground a profile tool and.........(hours of fiddling and nail biting) I got just what I wanted, almost. 300 grains/.454" was the goal an it ended up 310/.455. I undershot the diameter the first time and had .003" taper toward the front so back in the lathe it went. I also wanted the bands a bit wider so I plunged the cutter some. It was perfect except I forgot to pull the cutter back to zero to clean up the undersized portions left from enlarging/straightening the cavity, so back in the lathe for a third time, and this time I had to get it indicated perfectly on axis because I was out of lee-way to clean it up again. Finally I got it where I wanted it but ended up over-shooting a thousandth. That's ok, it cleans up fine in the sizer.

The final test batch I cast in a hurry and didn't get the bands really sharp, but that's no reflection on the cut of the mould, it turned out nice and I'm really happy that this fine old tool can work again.



By the way, this is an absolutely screwball way to cut a mould due to the incredibly high tool load and I'm not sure it would be realistic to do multiple cavities. I can only imagine that Tom and others who lathe-cut their moulds use a cnc setup and a single point tool to make multiple passes.

 

[Brad]

Nice work Ian. That goes well beyond reworking a mould.
I will be interested to see how the new bullet shoots.

 

[Ian]

That's about as much bullet as I can cram into my Henry, we'll see. It will likely shoot a few inches high at close range in my revolvers, which is not ideal, but again we'll just have to see at the range. I was having trouble all three casting sessions getting sharp bases, not sure why because I was running the sprue plate pretty loose. I did enlarge the sprue hole and went a little too far, so that could be allowing metal to suck the wrong way as it cools. Maybe I'll break the blocks with a file and see if that improves things.

The middle band is a little tough to get to fill completely all the way around, I may have plugged up a vent line or something, or it may just be the nature of narrow, deep lube grooves. Originally they were a radius but I narrowed them to get more driving band width so they're kinda pointed now. If I'd thought about it when it was on the lathe last it would have been possible to scooch the tool out a bit and just kiss off the tops of the lube grooves with the driving band cutters to square and reduce them a bit, but it will be fine as-is (better probably) if I can just learn to cast with it.

 

[KeithB]

Wow Ian, that really came out good! I agree with the high tool load observation, that's what happens when you use a profiling vs single-point tool. Might I offer a suggestion for making a stronger profiling tool? Instead of starting with a flat/square piece of tool steel start with a piece of 4140, O1, or A2 round stock. Turn the profile of the bullet but to a smaller diameter. Cut a 90* section out to make a single cutting edge. (If you looked at the end of the tool the cross section would look like a pie with a 90* wedge cut out, instead of looking like a D). This normally requires a milling machine but I'm sure you can figure out how to hold an endmill in your lathe chuck and mount the tool bit in your tool holder. Be sure you cut the flat a little below center so when you raise the edge back up to center there will be a little clearance behind the cutting edge. You may have to relieve a little material from the top of the tool but that should be no problem.

You would have to heat treat the tool, but 4140 and O1 are among the easiest to get a good heat treat job with basic equipment. I estimate that leaving a "spine" on the tool more than doubles the strength.

Hardened 4140 or O1 will cut enough aluminum or malleable/cast iron to do many molds, and any edge wear can be taken up by cross slide travel to get the proper diameter. You can even use the tool to cut identical shaped bullets in different calibers, ie .41/.44/.45.

 

[AMTom]

Sounds like the way Veral Smith (LBT) does it.

 

[Ian]

Good advice, Keith. I've heard of that before, but didn't quite understand the part about cutting the step below center, relieving the top, and bringing the edge back up to center to create the necessary relief for cutting. I had envisioned removing metal all the way around except for the cutting edge, which seemed tedious. This was a little bit of a challenge in that I chose not to bore the hole out first, so I made a tool that cut on the end and edge and use ONLY the tool in the photo to modify the cavity. A tool such as you describe might have worked if I had used a bottom-cutting end mill to plunge the hole out to a larger diameter first. First I scratched the nose deeper and wider and when I got to the depth I wanted, started working the cross slide and playing with rpm and lots of compressed air to clear chips. Flood coolant would have been a huge plus here, not that the tool got hot at all in this material, but to keep the fine dust from sucking through the cut.

 

[Brad]

I am really impressed Ian. Bullet looks pretty good to me.
Making a tool Like Keith mentioned is currently beyond me as I lack a proper heat source for hardening.
This is what makes casting fun. If it doesn't work we can change it.

 

[Ian]

I'd have to brush up on that but have done a few small gun parts by heating to dull cherry with a torch, quenching in water, and then tempering slightly in the kitchen oven at 400-450 for an hour. Different temps/colors for different metals but same basic principle applies. No kiln required, iow.

The tool I made sang like an angry cockatiel and made some sickening pops here and there as material sucked through the cutting edge, no matter how slow I went or what RPM I used. A spine on the back side would have made a lot of difference I think. One thing that exacerbated the popping problem was the crack at the parting line on one side from missing material that had been wire-wheeled away...the whole reason the mould was totaled. Every time the loaded tool edge passed the gap and sprung into it, it would pop and skip. Once I finally got through that part (about .040" or so of cross slide travel) it was a lot better.

 

[Brad]

Ah yes, the singing tool. I know that song well. I have learned that a quiet tool is a happy tool.

 

[KeithB]

Interrupted cuts can be a real pain and are a major source of tool breakage.

Heat treating small parts made from 4140 or O1 is pretty easy. I don't know if a propane torch would get hot enough but I know a small oxyacetylene torch will work fine. Heat the part up to a dull/medium orange color, (needs to be 1450-1500F or so) hold it long enough that a magnet will not stick to the part, then quench it in room temperature oil. When it gets cool enough to handle with your bare hand put it in your oven at about 400-450F for about half an hour, then let air cool.

Heat, hold, quench, temper. No harder than reloading a cartridge once you do it a few times.

 

[L1A1Rocker]

Cool. Another mold saved!

 

[smokeywolf]

Very nice job Ian. Very impressive. Looks like a slightly elongated 454190 with a crimp groove.

Thanks for doing that drawing Keith. I initially learned AutoCAD because all my freehand sketches look like they were done by a 4 year old.

By grinding the shape depicted in Keith's picture you can start with a larger toolbit. Drill rod might also be a good choice to create a form-tool such as that.

When heat-treating O1, I always shot for 1550F. Greater the mass the longer it soaked. Had a quench-tank, about 8 gallons, filled with a fish oil (high flash-point). I also had a pretty nice Rockwell hardness tester that, like a dumbass, I didn't take with me when I closed the Studio Machine Shop.

 

[Ian]

First group with the Henry using these bullets. Shot to exactly the same POA and same group size as 255 grain bullets do with Universal. Nice to see the groups staying together at 310 grains/75 yards. The first shot was after all the powder-coated dry bullets I shot last weekend, no wonder it was a flyer. The far right flyer was called by me because the rifle slipped off the Nylon bag as I pulled the trigger (too lazy to drag the rests and bunny bags for this quick range test/chrono session). Now to fix the venting and cast some better bullets!



I loaded enough to run a cylinder full through my Ruger New Vaquero @15 yards, drilled a 1.5" hole offhand, very happy with that since this revolver never has grouped very well with anything except the Lee 340. Not so happy with them printing 4" high, though, but expected as much.

 

[fiver]

Mapp gas burns hotter than propane and can be screwed onto the same little torch heads.
it should get smaller pieces hot enough to quench and harden before the draw down.

 

[freebullet]

Nice work!

 

[Pistolero]

Very nice job, Ian. The bullet looks just great. Now you need some aluminum mold block blanks. I wonder if
this might be another product for Keith?

I think Keith has shown us the hot setup though, with the idea of turning a piece of 4140 for a cutter. I can then
put it thru the mill to remove the 1/4 and then slice a bit off the top, then harden. Hardening isn't difficult at all.
The tempering is a bit more tricky. I recently needed a punch to knock out the roll pins on S&W M&P .45 (modern
semiauto). A regular punch seemed likely to gouge out the plastic without the guide bump.

I turned it down from 3/8" rod 4140, left the little guide bump, heated the whole smaller end red and quenched. Then buffed
to a shine with 350 grit sanding cloth, so I could see the tempering colors. I wanted impact resistance, no brittleness, but hard so
I tempered to purple color, just waving it through the propane flame until it got the right color. Purple is about 500F, and gives about
40% elongation at break with 4140, should give Rockwell C of about 50. The punch worked great. With a 400F temper
it would be more like Rc 52 or so, better for a cutter. No trouble getting the part hot enough to harden with propane torch.

I really enjoy seeing you leap ahead now that the shackles are off and you have a lathe.

Bill

 

[KeithB]

Only one shackle off. I'm waiting for him to decide he really needs a small mill! Then we'll see some interesting projects happen.

I love 4140. It works so well for so many things. Years ago I made a 1-1/4" star drill from 4140, I had to run a pipe through two 8" thick poured concrete walls. Young, dumb and poor, I made a hand tool instead of renting a powered impact tool. After using a sledge hammer to drive it through both walls I looked at the edge and it was still very sharp, no discernible wear. I heated and quenched it in oil but left some of the handle exposed. It was about 12" long and I put it 8" or so into the oil. I pulled it out and let the heat in the handle reheat down the piece to temper it. That left the pointy end hard enough to break 'crete and the hammering end soft enough to spall a little but not shatter.

For all its virtues if you plan to use it as a cutting tool O1 might be a better choice for lots of reasons.

- It's easier to get short lengths - not a problem if you use many feet of it but for a hobbyist being able to buy 18"-36" at a time makes sense.

- It machines as easily as 4140, and finishes off well.

- It heat treats just as easily as 4140, both HT well with basic equipment and are fairly forgiving.

- The hardened microstructure of O1 is more abrasion resistant, it forms beneficial fine carbides (ceramic particles) that are dispersed through the material and that are very hard.

- It won't soften quite as quickly if it gets heated a little too hot while cutting.

Both work fine, I keep various sizes in stock for special projects. If I plan to make a form cutter I grab the O1, for almost every other "tool" I use 4140.

 

[Ian]

I mentioned in another thread how a lathe is only good for making a person realize how desperately they need a mill. I made an aluminum Weaver mount for the barrel of my Savage hog hunter, bored it to the exact taper of the barrel so it centers near the fore-end tip, and did it all on the lathe. I used the cross slide to carve out the diamond and then hand turned part of the sides off, part of a revolution at a time. The hole was bored off-center to allow material to shape the mount surface, so I couldn't turn the main body down. I'm almost finished with it and will post pics when it's done, it's a forward mounting base for a thermal optic so needed to be sturdy and far enough away from my middle-aged eyes that I can actually see it without glasses.

This mould project was a grand experiment (I look at life in general as a grand experiment!) and used what I had on hand. Like I mentioned previously, to make and use a proper cutter I would have to have bored the hole out to lube shank minimum, or near it, to make room for the tool to work in the hole. Making the tool out of small square stock enabled me to simply plunge and bore the existing hole.

 

[Pistolero]

4140 is available to me in many sizes, any length at my local "Metal by the Foot's store.

I should get some O1 and try it, but will have to mail order it. Thanks for the info on O1, I
am aware of it but never used it.

Bill