eggy mold questions

[porthos]

i bought a lyman 314299 on this site a while back. dbl cavity and both cavities cast nose .3025- .3040. body .3136- .3150. i have 2 questions. 1 would i have any luck with the NOE bushing die system ??? (i already have the set, but, do not yet have a .303 and .314 bushing; but would buy them. 2nd question; could i lap the cavities, and if so, how would i go about it??

[Grmps]

Laping,
Id cast a bullet for the bigger cavity with linotype.
Drill a hole 1/3 through in the base, screw in a flat tipped fastener
coat the lino bullet with a fine polishing compound and put it in the cavity
spin it slowly with a drill loosely holding the mold handles until the mold closes all the way.
open the mold and wipe off the excess compound on the mold face so the mold can completely close.
Spin slowly for 15 to 60 seconds.
Do this in both cavities the same way.
clean
cast
measure
repeat as necessary
It is much easier to polish off material than it is to put it back

Check out threads on "leementing"

[Catshooter]

It always scared the heck outa me to drill into a boolit in the mould. Instead, I remove the sprue plate, place a 3/8 inch nut over the cavity opening and pour the boolit and nut in one. Then I can use a 9/16ths socket to drive the boolit. Works for me, learned it here of course.


Cat

[porthos]

most excellent idea using the nut. i have a lathe and collets; so i'll drill and tap the bullets on the lathe and probably tap for 10-32 thread. i have a lot of "irons in the fire" so, i'm slow getting things done. but i'll post the results eventually. still looking for info using the NOE bushings??

[Larry Gibson]

May not be the mould that is the cause of "eggy" cast bullets. The blocks could not be fully together, uneven temp of the blocks during casting or the alloy itself.

What alloy?

[Walter Laich]

It always scared the heck outa me to drill into a boolit in the mould. Instead, I remove the sprue plate, place a 3/8 inch nut over the cavity opening and pour the boolit and nut in one. Then I can use a 9/16ths socket to drive the boolit. Works for me, learned it here of course.


Cat

+1
this is my go-to method. when do just drop the bullet/nut combination in pot and nuts will float on surface when lead melts. No enough 'junk' on bullet to worry about getting trash in mold

I tried the 'screw in the bullet' method and bullet hung up in cavity and screw went through it and into the mold--ruined it

[country gent]

I'm old school when it comes to lapping a mould. If its a 2 cavity mould its a little different procedure than a single cavity mould materials needed are 600 or finer lapping compound ( Aluminum oxide is pefered but Silicon carbide will work) water or oil based dosnt mater you just need to know which you have. Most valve grinding compounds are to coarse here.

1) cast 4-6 good bullets Id as to cavity 1 0r 2
2) drill a hole in the base to fit a piece of 1/8" key stock drill as deep as possible and epoxy 1"+ piece of key stock into holes. I drill them in a fixture made from 2 pieces of wood.
3) once cured charge lap from #1cavity by spreading a coat of compound on a flat steel plate and roll between it and another plate.
4) Lap #1 cavity by hand with a tee tap handle on the stem, use a "tapping motion" 1/4 turn pback and forth 2-3 times rotate 1/2 turn repeat thru 3 rotations.
5) Repeat on cavity 2
6) clean mould and check pattern being cut you should see it.
7) charge lapp from #2 cavity and lapp #2 cavity as in #4
8) repeat on #1 cavity
9) clean and check pattern possibly cast some slugs to see size and or improvement
10) you can "polish" with a lapp coated with tooth paste, flitz or simichrome
Some things about lapping 1) lapping a mould removes metal 2 for 1. remove .001 and dia increases .002 so use very fine grits and go slow.
2) Lapping is a slow process and can be very accurate if done correctly
3) impregnating the lead slud is making a form file for fine work the imprenated lead slug holds the grit and cuts the steel
4) a drop of oil or water ( depending on the compounds carrier) helps with the cutting and will make the grit cut a little finer
5) the back and forth (tapping) motion helps to keep the cavities centered and round.
6) the slug/cavity rotation helps to have the same sized slugs from each cavity
Since you cant lapp with out removing metal you will probably end up needing the sizer set for this bullet. Determine which way the bullets are Out of round in relation to the blocks with the parting line or against it. I parreallel to the faces a small amount can be stoned of each block and cavities lapped round again if against the face (90*) you have to remove to much for them to gain the needed material

[porthos]

attn larry gibson. the mold blocks are together the alloy is a mix of mine that i've used for 30 years that is 18 brinell. a long time ago i scored appx 1500 lbs of monotype. and there is no way that a particular alloy can make a eggy bullet. And, Country Gent: great instructions!!

[Larry Gibson]

It was mentioned as a possibility and some other things to consider, not as what it was.

Does that mould cast eggy bullets with other alloys?

[John Boy]

Before you go lapping and other exercises ... hold the mold handles in both hands - try wiggling the handles:
If the wiggle, the handle bolt has to be tightened to bring the cavities into alignment
Also, close the mold halves and hold the mold up to a bright light. Look in the sprue hole - if you see light, the mold halves are out of alignment - determine where in the mold ... usually the pins

[porthos]

larry: this is the only alloy that i use. i have 35+ molds in rifle calibers. a few in pistol. in pistol i use about 12 brinell. never had this issue before. its the mold

[Larry Gibson]

porthos

Not disagreeing, sometimes it is the mould.........