Fly-cutter or end mill?

[Alchemist]

I recently obtained a used mould that has a small ding on one half at the top of the mould. It appears to have been dropped or struck with something. Anyway, it doesn't close completely and leaves a slight fin on the boolits. It also has a too small GC shank. My thought is to take off 6-10 thousandths of an inch in small increments until I get rid of the damage and get the GC shank diameter that I want.

Which tool from the thread title would be best? I have a combo lathe/mill that I'm just starting to play with. I'm going to consider this mould a "sacrificial lamb" to my machining education. (Although this mould is an old Ideal that has no vent lines. Collector value?)

Any help or suggestions would be greatly appreciated.

Thanks

[deltaenterprizes]

Try a piece of scrap first.

[leftiye]

File it? Only the metal extruded out into thw was of something that closes/articulates need be removed.

[longbow]

If there is only a small "ding" I would just use some fine emery cloth on a flat surface and gently work the offending mould half on it to remove the raised bit or as leftiye says, you may be able to use a fine file.

I would not recommend machining the whole face of the mould. If you remove metal from the whole face the boolits will be out of round and unbalanced. If you do not get it exactly flat and even it will be worse.

Longbow

[theperfessor]

If the GC shank is too small, won't machining the block face make the bullet and shank even smaller?

Maybe I misunderstand. I'd use a fine die makers file or a fine stone to dress down a bump.

[blaser.306]

It sounded to me that the op was intending on "cutting" the mould blocks to be a little shorter. And whith that making the gas check shank that is (usable) a little "fatter" where the check crimps on. Just my opinion and I have been wrong before !

[Char-Gar]

Either will do the job. You will probably get a little better finish with the end mill.

[theperfessor]

Pictures?

It is probably just my conservative nature, and I'm saying this even though I have a shop full of metal working equipment to use, but I would more inclined to work on the fit-up problem with a file or abrasives by hand. The GC shank size problem could be approached as a separate issue.

If the blocks won't close properly how do you expect to clamp/hold the blocks together to mill down the top? Seems to me that as soon as the lump was removed your blocks would shift a little, and you would have to take at least one more cut to have a truly flat top.

As stated, maybe I don't understand the exact problem and proposed solution.

[dragonrider]

A picture of the offending lump would save a lot guesses here and provide you with a definitive method to fix it.

[Alchemist]

It sounded to me that the op was intending on "cutting" the mould blocks to be a little shorter. And whith that making the gas check shank that is (usable) a little "fatter" where the check crimps on. Just my opinion and I have been wrong before !

BINGO!

I'm talking about cutting down the TOP of the mould. I would practice on some scrap first. I have already tried polishing off the bad spot on 400 grit on a flat surface. No joy with that technique.

Another question...will the tool "grab" when it gets to the cavities as I move the cut across the top of the mould?

[deltaenterprizes]

Fill the cavities with lead before milling the top.

[Cap'n Morgan]

I once shortened a mold using the lathe. Just clamp it the chuck (make sure you have solid contact with all three jaws) and face-off as much as needed. Don't run it too fast as it will be somewhat off balance. Of course you could just use a real faceplate, but where's the fun in that [smilie=s: ?

[JSnover]

With the proper setup and a light cut, you could use either tool. It won't grab the cavity if you go easy on the feed. On a lathe, I'd try it with a four jaw chuck or a face plate. I've cleaned up a set of mold blocks using a surface grinder. The owner couldn't cast a clean base because someone had scraped the top of the block.

[KCSO]

For this job I prefer using the lathe and centering the bullet cavith in a 4 jaw chuck but a mill will work too. If you use a sharp tool a fly cutter will work but it works best with power feed and I assume your mill drill doesn't have power feed. A good sharp new end mill would probably be best for you here. Use plenty of do drill or such and go slow and you will come out just fine.

[Alchemist]

Thanks to all for the responses...I think I'll try using the lathe since I have a 4 jaw chuck. How would the mould block be attached to a face plate? I also have one of those, but have never even seen one in use. As I said before, I am just beginning to experiment with this lathe/mill. If you all think this is over the head of a beginner, let me know. I really don't want to destroy this mould (or my tools) but it is pretty well useless as is.

[JSnover]

This is a very simple facing operation and you should have no problems. It will take longer to get it setup and dialed in than it will to make the cuts, although you won't need to get it on center since you're not boring it out. Close is good enough.

[theperfessor]

Buckshot has posted pictures at various times showing a mold held in a small toolmakers vise with the vise clamped to the faceplate. This is a pretty good way to do it. But as has been suggested here by JSnover, holding it in the jaws of a chuck will work just fine.

[KCSO]

I thought he was modifying the gas check shank and would need to center.

[JSnover]

Alchemist, one request: When you're finished, no matter how it turns out, could you post a picture? There are some talented folks here. Based on the results you will get some good advice and commentary if some of us can get a look at the finished product.

[Alchemist]

Alchemist, one request: When you're finished, no matter how it turns out, could you post a picture? There are some talented folks here. Based on the results you will get some good advice and commentary if some of us can get a look at the finished product.

I'll try to get a picture or two up in the next few days. It takes me a while to do pix, especially so when trying for good quality. The proposed lathe work most likely will be some time coming as well. I'm going to have to get some tooling to have any chance of getting it right. Stay tuned.

[Alchemist]

Update:

After considerable examination and fiddling around with this mould, I think the problem with mould closure lies in one of the alignment pins. It looked kinda peened...flat on the tip. I used a punch to tap it out and chucked it up in a hand drill, then ran it against some 400 grit. After re-installing the pin, the mould seems to lock up tighter with less "wiggle" when manipulating the mould by hand. It's now on handles waiting for this weekend when I'll have time to heat it up and check the results. If the finning goes away, I'll try opening up the gas check shank area with some 400 grit. If that fails, I'll go ahead with the facing of the mould top surface. Still haven't given up on pics, but my first attempt didn't have enough resolution to show anything helpful.

[Flinchrock]

BINGO!

I'm talking about cutting down the TOP of the mould. I would practice on some scrap first. I have already tried polishing off the bad spot on 400 grit on a flat surface. No joy with that technique.

Another question...will the tool "grab" when it gets to the cavities as I move the cut across the top of the mould?

A properly sharpened fly cutter will give you a better finish than an end mill,,,IF you get you speed and feed right,,,you biggest problem is making sure that your perpendicular and square, last thing you need is a slanty bottom bullet.

Ya need to check your tram,,,and I'm not too sure if your machine is rigid enough!
That's why some have suggested that you use the lathe option, even then you have to check your plate for true, or just make a truing cut to make sure. And then check your setup! Good luck!!! This stuff aint easy when your just starting out with little training and flexy machines.