Too much Tin?

[Jaybird62]

I've tried several things to get rid of the "whiskers" on the boolits from my RCBS 200 gr. .30 Silhouette mold. I've run the pot from 750 down to 600 trying to get them to quit. My alloy is 50:50 WW:Lino.

Any suggestions?

[BABore]

Check the blocks to see if you can see daylight between them when closed. Could be lead, burrs, etc. If you don't see any lead particles, look around the alignment pins for burrs. You sometimes have to drive the pins out to hone the burrs properly. Also along the block edges where it may have gotten banged up. You should be able to see any gap, but you can also measure a boolit to see if it's running big, opposite the parting line, for confirmation. Might as well run the vent lines while your checking too.

Assuming all of this is correct, is it a pouring problem? Not all molds pour the same. Might have to back off the pressure by pouring to the side of the sprue hole or stand off a little farther with the nozzle. Too much pressure will cause the same thing as well as holding a ladle against the sprue hole too long.

[Jaybird62]

I've been working on this mold for two days. It already had the "whisker problem," though. No daylight between the blocks. The two cavities are not the same size. One drops about 2 grains heavier than the other, and one measured .3055 at the drive band 90 degrees from the parting line. The other cavity measured .3075 90 degrees from the parting line. I've got them both at .310 now after several hours of valve grinding compound, knife polish and Flitz.

There are no burrs on the pin holes, nor on the edges of the blocks. Since I've been working on these blocks I've cleaned them several times with carb cleaner, boiling in soapy water, etc. I re-seasoned with Kroil on the blocks (had it on there before, too). After about 30 castings I went ahead and smoked the molds. The worst offending vent lines are the short ones lined up with the alignment pins and on the nose. I also get them on one side of the drive band of one cavity. As you suggested, I typically pour to the side of the sprue hole after the mold gets to temp. If I dipper pour I get the same whiskers, but slightly different weight; heavier by the way. If I put the sprue hole against the spout on my RCBS pot the vent lines fill out perfectly. LOL. The boolits look like porcupines.

[Shiloh]

IS there a bind in the handles that may be keeping the blocks open?? That alloy should cast a hard, flawless boolit.

SHiloh

[montana_charlie]

IS there a bind in the handles that may be keeping the blocks open??
Especially in the bottoms of the handle slots on the blocks, at the rear corners (nearest the handle hinge) of those slots.

If one or both of the handle jaws touch the mould corner in those slots, there will be little or no pressure keeping the block faces clamped together.

In a two cavity mould, the cavity furthest from the handle hinge will see more of the 'looseness' than the other...and might even drop larger diameters.

CM

[high standard 40]

I have this issue with most of my RCBS molds. I've tried alloys ranging from 30-1 to Lyman #2 and I get whiskers with all of them. I have been told that the problem is that RCBS cuts the air bleeds too deep. I can't say with any degree of certainty but it sounds logical. Nothing I've done has helped. Let me know if you can solve this.

[runfiverun]

a lot of the new rcbs molds have been coming out with the guide pins too far out of the mold half.
i have a new 22 cal mold that was this way,try driving the pins back in a bit.
i finally got frustrated: a chunk of 2x4 on top and one on bottom and a 4 lb hammer fixed it up, it now pours nice round boolits.
the pins were sticking out and nice didn't work.

[SciFiJim]

4 lb hammer fixed it up If it don't fit use a bigger hammer.:twisted:


On another note, a possible solution it to partly fill in the vent lines. Smoke the mold very heavily and then clean out the cavities and wipe the mold face without cleaning the vent lines. I think I saw this in one of the stickys but can't remember which one. Perhaps someone else might remember which one.

[JMtoolman]

This sounds like a warped set of blocks. Sometimes blocks bow when heated, with the outside edges only making contact. If all else fails, try making the blocks flat by driving the pins out and honeing them on a sheet of 220 grit emery paper on a very flat surface. A piece of glass, or a ground table saw table is a good place to try. I have had to do this to a couple of molds. Best regards, John, the toolman.

[montana_charlie]

Jaybird,
If you're still reading...take a look at this discussion.
http://shilohrifle.com/forums/viewtopic.php?t=14175

CM