Round ball shrinkage when casting??

[doverdog]

I have been kicking around the idea of getting a bag mould, they come in .001" increments, and was wondering if I should order one in a larger size to allow for shrinkage after cooling. I have a Lyman .562" mould that turns out balls measuring .557". The Lyman mould has the standard heavy steel blocks but the bag mould would be much smaller. Would that make much difference? At the price they are asking for the moulds, I want to get it right the first time. I would like to duplicate the .557" balls as a finished product. Any first hand experince out there with having your balls shrink? :shocking: :blah:

 

[Stumpkiller]

Whew! I know it happens, but I don't have any data. I'll see if I can't dig up something. My WAG would be something like 0.002" for shrinkage from the mold cavity for, say, a 0.490" ball. So, something like you're looking at maybe 0.003".

I'll poke around and see if I can get you some info. Seems this was discussed last summer, maybe.

 

[Stumpkiller]

Hey! Found it.

Cherry

I would think that if you're ordering a finished mould, they would have already compensated so it throws a ball that is the proper dimension when cool. You shouldn't have for work it out yourself. Worth asking them first.

My .490" mold produces .490" balls, and my .530" mould produces .530" balls. Guess I'm glad they're not Lyman moulds!

 

You can't see .001.

You can't feel .001

I have seen two different people mike out more than .001 on a single item using the same mikes.

Industry standard tolerance is +-.002 on most forearms and a mold cherry will wear more than .001 on each use.

Switching from pure lead to a polluted mixture will give you more than .001 shrink without you even knowing it, and most lead is polluted.

My experiences with most "bag molds" is that they will not give you a really round ball to start with.

Your worry will be out of round balls rather than shrinkage.

You are paying for something to "show" for your shooting bag.

You can't cast more than a half dozen balls from one of those things before you have to let it cool down anyway.

Use your good blocks for real casting and acknowledge that the bag mold is for show and don't get all tweeked up worring about an amount of "shrinkage" that you probbly can't even measure anyway.

:imo:

 

[doverdog]

Ghost, probably a good idea. I was just planning on having it for a CYA item in case of a Ranger Run match. If I really needed any more balls at a match or rondy I would just go to the car/pack mule and get some. It may never cast a ball. ::

 

[pepperbelly]

" Any first hand experince out there with having your balls shrink? "
Ya know, now that you mention it, ever since it got cold I have noticed that problem.
Jim

 

[fatboy]

I had this problem the other morning when hunting It was to cold out!!!!!! :crackup:

 

[strongarm]

Actually, I 've never had a ball "shrink", although many have expanded and do all the time. Shrink is based upon as Ghost said, the way the mold was made to begin with. Expanded is what happens with impurities in the lead and the problem is to find pure, pure lead anymore. I cannot.
My lead is around 95%. I use lead pipe 1 inch or smaller and roof vent lead. Those two seem the most plentiful and the purist.
My ball usually come from a .530 mold by Lee Precision and are measured to be .533. Now try to measure from the opposite direction and Ghost again is right in that no ball is perfectly round.

Lee told me the other day that their tolerance is + or minus .003 and to get a .530 ball I must use pure lead! :m2c:

 

[KyFlintlock]

I had this problem the other morning when hunting It was to cold out!!!!!! :crackup:

When Casting? Have had it happen when fishing for sauger in Jan/feb. :haha:

 

[kentucky bucky]

Mine disappear altogether from 20 degrees F on down! :what:

 

[750k2]

shrink has nothing to do with the mould it is what alloy you are using... Lymans bullet casting book has a lot of information on the casting of projectiles. If your using lead 95+% you should not see .005 shrinkage.. :imo:

 

[smokeblower]

Had a friend who wore pantyhose to prevent ball shrinkage in below twenty degree temps. A bit untraditoinal.

 

PS:
DON"T use pantyhose for patches either, it will melt in the barrel when shot and make a mess. :nono:
Leave them pantyhose in the wife's drawer. :crackup: :thumbsup:

Woody