Difficulty filling a mold

[nueces5]

Today I was using the mold 314299 and I noticed that one side of the boolit in the back cavity had an area that impressed frosty and gave the impression that it had not filled well.
I measured it and indeed, it lacked filling. Here the photos.
I raised the temperature in the Lee oven and loosened the sprue plate a little, and it improved for a few moments, then it happened again.
I still don't have a lead thermometer.
Any ideas?

[Bent Ramrod]

The mould may be too hot. I find that scrap lead alloys that form that crystalline surface will sometimes shrink away from the cavity surface like that. The mould may have cooled while you reset your spruce plate, and heated back up again after a few good casts.

You might try running your alloy at a lower temperature, giving your mould a few extra seconds to cool before refilling, maybe changing alloy to a straight lead/tin mixture.

[cwlongshot]

Flux and mix that pot!

[mdi]

I noticed that the base and bands have rounded edges. Perhaps a bit higher mold temp. or add a bit of tin to the alloy to aid fillout? I can't remember any "pour" problems affecting bullet diameter, most come with temperature and alloy variations...

What mfg. mold and how many cavities? Many times variations in mold cavity areas temps. will produce variations in bullets (you mentioned one cavity making the bad bullets).

[Rattlesnake Charlie]

Clean that mold real good. I use carburetor cleaner and plastic brush or Q-tips. Nasty, but cleans good. Just a smidgen of oil in a mold will do that. Learned it the hard way.

[cupajoe]

I have a Lee 2 cavity mold for the heavy 45 cal pistol bullet, 300 grains or so. That mold will not fill completely from a bottom pour pot unless I put the magic smoke from a butane lighter in the cavities. I have tried numerous times, different temps, pouring on the edge of the sprue hole to induce some swirl, different flow rates. Always the same, just a very light smoking, not hardly enough to even see and bingo. Blasphemy I know, Witchcraft maybe, but it works!!!

[fredj338]

I use a lot of range scrap & have this issue with 4-6cav molds. Sometimes I get voids in the driving bands so I have to alternate how I fill the mold. Its weird. I use clean alloy in my casting pot & stir with a wooden stick every time I add alloy.

[Bazoo]

I have a couple moulds that acts that way. A Lyman and an RCBS. For me the solution is to pour a large sprue puddle that stays on top of the sprue plate. If it spills off the side, it does that and also has frosting on the corner of the bands coupled with slight incomplete fillout.

[onelight]

It seems to help at times with some molds to rock the mold while it is filling when my molds start acting strange I try different things.

[Conditor22]

IF you always start filling that cavity, try clearing the nozzle on the pot (squirt a short stream of lead into your catch basin) just before filling that first cavity.

Alternate which cavity you start on.

[nueces5]

Well then, I'm going to take all your advice and start by adding tin, stirring and fluxing the alloy. I'll clean that mold (it's a Lyman 2 cav 314299) but I don't have a brake cleaner, so I'll use neutral soap and hot water. I will leave a big puddle on the sprue plate. One of these tricks has to work!
Try raising and lowering the temperature. Soon I think I am going to invest in a PID, and I am going to ask for it in degrees Fahrenheit, even though I am used to Celsius, to make my life easier.
What temperature do you work at?

[KYCaster]

It's a VENTING (+heat) issue. The mold is not venting properly and is trapping air where the alloy stays liquid longest. (near the parting line where the cavities are closest together)

Make sure the mold is "squeaky clean" and the vent lines are not blocked with lead or mold release agents. It often helps to cut a slight bevel on the top of the blocks, under the sprue plate with a fine stone. (search for "Lee-menting")

Also reduce the heat slightly and/or wait an extra 2 or 3 seconds for the mold to cool before the next pour.

Good luck.
Jerry

[popper]

After all else is tried, smoke the cavity - Bic or match. If it then does good it's still a venting problem. Sometimes the vent lines don't enter the cavity at the right spot. I set my sprue plate to move by hand when cold but swing easily when hot.
Flat spot is on edge of cavity so venting.

[243winxb]

Pressure cast.

[cwlongshot]

Buy some Brake Cleaner spray!

Thing with many things you might think at good cleaners is they leave a residue. Tjis residue can be THE PROBLEM!

Soap n water is grand. But unless rinsed real real well will leave residue. That cloudiness on shower doors much of it is residue from soap...

Brake clean dosent leave harmful residue. On sale is 2" ish a can. I buy it by the case of six on sale. Any brand. Many uses from Flushing to cleaning to this. Know that it can be haful
To some Plastics.

More heat helps too.

Venting as mentioned is likely allot of this. The flushing with the powerful spray from the brake cleaner can both desolve and push out/away debris.

Tin makes the lead flow better. But allot can cause drips too. Generally WW and Lino have enough for good flow but softer lead may not.

Loads of great advice.

Good luck.

CW

[robg]

more tin run hotter

[Hanzy4200]

+1 on the brake cleaner. Soak her down real well (cold, if you like your eyebrows). Then toy with your mold and alloy temps. Bump up the tin content a little.

[DDJ]

My 405 grn 2 cavity Lee mold will overheat fairly quick. I just lower the pot temp, slow down my casting, and use a fan to cool down the mold. Just a second or 2 with an open mold in front of the fan helps.

[John Boy]

Without a thermometer, you have no idea that the mold and pot melt are the same temperature. That’s your problem ... Period!
A 5 second pour with a large sprue puddle and cut the sprue when the puddle frosts

[Echo]

Venting was my first answer. As has been mentioned lightly stoning the upper corners of the blocks (under the sprue plate) has helped me a couple of times. Just enough to make a bright line...