Why is this happening....?

[doghawg]

Can anyone tell me why my RCBS .44 SWC 245 will run hotter on the sprue plate bolt half of the block? My alloy is WW's with some tin added. The sprue side will actually start frosting while the other side is shiney. The driving bands on the cooler side are not as crisp and sharp either. The blocks are thoroughly clean and should be broken in by now. I've experimented with different temps, added a little lino, more tin etc. Even tried tilting the block some to get the stream directed on the cooler side. These bullets shoot very well but the less than 100% driving band fill out is buggin' me. :roll::???:

[Hardcast416taylor]

You might check your mould vent lines on that side, or lightly scratch them out deeper. Robert

[HeavyMetal]

You can also try dipping the "Cool" side of the mold in the melt for a few seconds.

This should help even out the block temp.

[inuhbad]

I'm just a newbie, so I was wondering...

Couldn't you just touch that side of your mold to a damp sponge for a quick fraction of a second to cool that side down?

I mean, the moisture will evaporate in almost no time at all if you close your block & sprue plate, and then quickly touch the top to a sponge, wouldn't it?

There shouldn't be any problem with splattering lead if the moisture converts to vapor almost instantly given the heat of the mould & plate, right?

[Ricky P]

Iam going to have to go with the vent lines are not allowing enough air out to fill the mould fast enough before the lead starts to harden

[JIMinPHX]

Do you always fill the same cavity first? If so, is the side you fill first the one that gets hotter?

[303Guy]

You might check your mould vent lines on that side,How would the vent lines influence fillout, if I may ask?

Regarding temp differences in the two halves, the side with the larger mass would tend to stay hotter, I should think. Add cooling airflow in the right direction and it would get worse. But whether that would make a noticeable difference .... ?

[sundog]

303, actually vent lines can play NO role at all in fill out if venting is through the sprue hole, i.e., stream diameter is smaller that sprue hole diameter. Blocks with no vent lines can produce exceptionally good boolits. That means the stream has to be elastic enough not to freeze and glob up (that's a technical casting term) as it passes the sprue plate. Depending on what you are doing, heat and tin are the obvious things that make it easier.

JiminPHX, my RCBS 30-180-SP definitely PREFERS the back cavity (nearest the handle hinge) first. So, that the way I do it, and it makes some fine boolits.

[doghawg]

Do you always fill the same cavity first? If so, is the side you fill first the one that gets hotter?

I've tried filling the near cav first and it made no difference. Both cavities are showing less than perfect fillout from the right side block. Fillout becomes better when the mold is good and hot (actually too hot) and the alloy temp is getting close to 700 but even then I'll get frosting and sticky release....on the sprue bolt side...and shiny and not always filled out castings on the right.

Vent lines appear even and have been brushed out with a brass brush. I'll try dipping the right side block in the melt the next time I cast with it.

I loaded this bullet over 17 gr. of 2400... sized to .431 (actual .4305) and lubed with BAC for 1240 fps from a scoped SRH. The 25 yd groups were under an inch (didn't try longer range yet) so I have no reason to complain. Just can't figure out the obvious temp difference. As a rookie caster it could be technique....[smilie=1:

[mooman76]

Are you doing top or bottom pore? You could try turning up the heat a little until the heat evens out and then turn back down or try castin faster, you may be moving too slow and the mould isn't getting heated up fully. I don't know about bottom pore but if you are ladle poring try leaving a bigger puddle on the sprue, it helps with fill out.

[Blammer]

pour onthe cooler side first an the hot side last, or alternate what one you pour first.

[JIMinPHX]

Don't be afraid to run at 700 or even 720 degrees if needed. Also, how much tin are you adding?

[leadman]

Almost sounds like he has some zinc in his alloy.

[runfiverun]

i think he is tipping his mold to the side when filling it and the hot alloy hitting one side of the mold is heating it up more then the other side.
i have seen hot spots in a mold from this. wher you get just one little spot on the boolit that is frosted.
try tiooing your mold so the lead hits the cold side first and go head and turn up the heat to 750 on the alloy.
also chec the casting area for a draft. use a lighter or match to see if you have a slight breeze.

[Slow Elk 45/70]

Have you tried preheating your mold ? I have several RCBS molds, and several other brands also, I like to use a hot plate to set my molds on while casting and I use 2 molds and rotate them. This keeps the heat where I need it on the mold, then I adjust the melt Temp as needed. It sounds like you may have some issues with your methods , Heat is your friend , a little frost never hurt anything. I agree you need to be up around 750* or better for best results. Hang in and try some of the suggestions above, I bet you find out what the problem is.[smilie=1:

[doghawg]

Almost sounds like he has some zinc in his alloy.

I sure hope not. I've been melting at low temp and hover over the pot to catch "floaters" as soon as possible. I foolishly stacked three seperate melting sessions ingots all on one stack though so I can't identify a "bad" batch. :roll:

[45r]

You could try putting the sprue hole up tight to the nozzle for a second or two then lean the block a little and pressure pour the lead in.Adjust the stream of flow to be slightly less than sprue hole.Lean the sprue hole to nozzle against the cool side.Keep your pot over half full.Put your mold on a hot plate when refilling the pot and when fluxing.I flux every half hour with printers flux and stir with a wooden stick.My boolits fill out too good sometimes and whisker.I back off the nozzle if that happens.Some molds fill out better if you have the mold about a half inch off the nozzle.Try different methods till you find what the mold likes.I cast at around 750 degrees or a little hotter for 405 to 500 grain 45-70 boolits.They always seem to like the sprue up tight to the nozzle,especially my rcbs 405GC.

[montana_charlie]

I have a mould that was being very obstreperous in a way similar to yours. I continued to increase the alloy temperature in an effort to get better fillout and remove some small wrinkles. I reached a temp that was causing some spotty frosting, and the problem had not yet disappeared.

It was about then that I paid close enough attention to see that the wrinkling and rounded edges were always in the same area...on the right block.

So...I cleaned the entire mould one more time and it started casting properly.

CM

[leftiye]

Plus one on mold cavity surface condition. Clean with a bore brush (spin, don't stroke longwise - not that you would), and then steel wool on a q-tip. Wipe with lacquer thinner, or brake cleaner, acetone, etc..

The oxidation (seasoning) may not be the same on both blocks. If cleaning it doesn't even thangs out, try polishing the cavity in the hot block, and blue the cavity in the cool side. If this doesn't make enough difference, coat the cooler cavity with graphite from a number 2 pencil.

[hpdrifter]

Because your sprue plate bolt and sprue plate are holding more heat?

[anachronism]

The cuts for the handles may be deeper on one side of the mould than the other. I had a similar issue with an RCBS 300 gr 44 mould. The mould would get hot & the bullets would start frosting in a perfect line on one side with the handle cut out. Both cavities.

[doghawg]

Thanks for the responses! I'll use it again this weekend and now have a few things to try...Starting with another thorough cavity cleaning. I bought this mold and the RCBS .41 SWC at the same time....both new. The .41 has been a jewel right from the start while the .44 has been tempermental.
The handle cuts appear to be uniform.