mould size versus bullit size

[jbunny]

how much over bullit size do u make a mould for say WW lead to compaensate for shrinkage??
thanks
jb

[Calamity Jake]

.001-.002 over desired boolit size.

But .003-.004 is better because WW alloy changes with the wind.

[jbunny]

.001-.002 over desired boolit size.

But .003-.004 is better because WW alloy changes with the wind.

thanks. i would think there must be a rule of thumb formula. it would be differant
for 22 and 6 mm bullet compared to 44 cal i would think.
jb

[theperfessor]

Best cheap short term solution? Get a mold made from the material you plan to use in a caliber close to what you want. Measure the cavity. Cast some well-filled out bullets with the alloy you plan to use. Measure the bullets. Adjust from there.

If you have the capability to accurately make a mold you have the capability to accurately measure an existing mold and bullet. Put in the work and come to your own conclusions.

[jbunny]

Best cheap short term solution? Get a mold made from the material you plan to use in a caliber close to what you want. Measure the cavity. Cast some well-filled out bullets with the alloy you plan to use. Measure the bullets. Adjust from there.

If you have the capability to accurately make a mold you have the capability to accurately measure an existing mold and bullet. Put in the work and come to your own conclusions.
mr perfessor. i don,t have the instruments that small to measure inside a mould.
the moulds that i plan on building are going to be layered and use chucking reamers.
i did not want to reinvent the wheel and save myself a lot of work. i thought this group was
for shareing info?? would u care to post your findings on your mould makeing.

[SciFiJim]

Perfessor, I will save you the effort.

jbunny, ThePerfessor is an accomplished machinist and college instructor of the same. He article on the process of mold manufacturing is here.

http://www.castpics.net/memberarticles/MakingBulletMolds.htm

Like any good instructor, he gave you the methods of finding the answer yourself instead of just giving you the answer.

[Suo Gan]

mr perfessor. i don,t have the instruments that small to measure inside a mould.
the moulds that i plan on building are going to be layered and use chucking reamers.
i did not want to reinvent the wheel and save myself a lot of work. i thought this group was
for shareing info?? would u care to post your findings on your mould makeing.

I don't think he meant anything by it Bunny, just seek and ye shall find, maybe you might find a better way to skin the cat I think is what he meant.

For a common guy with common tools, that article has a lot of awe factor to it.

[jbunny]

Perfessor, I will save you the effort.

jbunny, ThePerfessor is an accomplished machinist and college instructor of the same. He article on the process of mold manufacturing is here.

http://www.castpics.net/memberarticles/MakingBulletMolds.htm

Like any good instructor, he gave you the methods of finding the answer yourself instead of just giving you the answer.
thanks for the link Jim. excellent post on mould makeing however the cavity
dia versus bullet dia is lacking. i have done the work. pure zinc bullets run about
.004 thou smaller than frosted WW bullets. zinc-.434, frosted WW .438.
non frosted WW bullets .436.
jb

[kywoodwrkr]

There is published information concerning the 'shrinkage' of the various alloys in boolit casting in I believe the Lyman # 3 casting handbook. The alloys if I remember were their #2, WW and linotype.
Maybe another lyman book?
I have a copy of the page as well as an EXCEL spreadsheet, but heavens only knows where they are at.
Bottom line is there are some published values.
If I run across them I'll either put up here or send to you.

[jhrosier]

LOOK ABOUT HALFWAY DOWN THIS PAGE FOR SHRINKAGE INFO:

http://www.lasc.us/CastBulletNotes.htm

Jack

[jbunny]

thanks Jack and kywoodwrkr. now to put the SWAG formula to work.
jb

[theperfessor]

SciFiJim hit it on the head. I was trying to point out the simplest and most direct way for you to find the solution to the problem you face, using your alloy, equipment, and casting methods. Apparently my choice of wording wasn't well received, but what I said wasn't meant to be taken as a personal comment.

I do find it inconceivable that someone is trying to make a bullet mold without having any tools to measure the inside diameter of a cavity. Since you apparently already have some way to measure the outside diameter of a bullet, then all you need is a set of simple and rather inexpensive tools called "small hole gauges". Check out this link:

http://www.use-enco.com/CGI/INPDFF?PMPAGE=358&PARTPG=INLMK3&PMITEM=615-6260

The Import model 615-6250 is on sale right now for $22.95

The advantages to using these is that the same tool is used to measure the gauge and the bullet - your outside mike. The downside is that you can't measure the ID of a hole if certain features are present, such as grooves. You can, however, easily measure the base band or a featureless cylindrical hole quite easily and accurately.

You're a little optimistic if you think that the hole your chucking reamer makes is the same size as what is marked on the reamer, or even what the reamer measures. Sometimes they do, most times they don't. And without a way to measure the hole, how will you know what is wrong if your bullet comes out the wrong size?

If you choose to buy a set and need help on learning how to use them properly I and many other people here will be glad to help you out.

By the way, I am in the process of "doing the work" to get a better handle on the problem you face:

http://www.castboolits.gunloads.com/showthread.php?t=88160

As to your question of how I determines the size to cut my first mold. I did it the engineer's way. I calculated how much the aluminum would expand and how much the lead alloy would shrink. I then compared the results to an existing mold and bullet size just as I suggested to you to do. I also figured that "local conditions" (uneven shrinkage, etc.) would create some differences between the "book" answer and the actual result - and there were some. Hence my efforts to get a better answer to my question by "doing the work" and generating more empirical data to work with - which I will freely share with everyone here.

Jbunny, remember it isn't personal, it's business.