Mold HELP !!

[pt4u2nv]

Casting some boolits today and all of a sudden I could not get the sprue plate to cut the sprues. Poured over 300 boolits and all was great . From one pour to the next I had to hammer like hell to get the plate to cut. It was only a matter of a few seconds of the pour cooling at the same cadence i used the whole pot. Checked the sprue plate and it appeared to be fine. Not warped and no gap under it indicating it was bent. Empty the spue plate rotated easily but as soon as I made ap pour it locked up. In all my years of casting I never had this happen and cannot figure out what is causing it. Put a little more sprue plate lube on and it made no difference. Stumped ..... HELP

[pt4u2nv]

Forgot to mention this is RCBS 2 cavity mold for 10mm 170 gr

[BLAHUT]

Try loosening the sprue plate retaining screw a tad ???

[Bazoo]

Sounds like the set screw was loose and the sprue plate was turning the bolt and causing it to get tight. I’ve had mine work loose when casting and it had them symptoms.

[pt4u2nv]

I tried loosening the pivot bolt on the sprue plate to no avail. It would actually rotate by itself when mold was empty and still would not cut. Fill the 2 cavities with lead and I would have to pound on the plate HARD 10-15 times to cut the sprues.

[Bazoo]

I’ve never experienced anything like that before.

[pt4u2nv]

Neither have I , That is why I need to find out what is going on . When I use the same pot, same aloy on even a 6 cavity mold it cuts fine. Must me something with the mold , i have to assume.

[pt4u2nv]

another twist to the story is I am using a 50/50 alloy , 50% pure lead , 50% WW so the lead is not that hard to cause these issues.

[Winger Ed.]

Sounds like the set screw was loose and the sprue plate was turning the bolt and causing it to get tight. I’ve had mine work loose when casting and it had them symptoms.

^^this^^

Watch the bolt & plate as you open the sprue plate.
If the bolt head and plate move together- that's the problem.

Readjust it, and lock down the allen headed set screw in the block that holds the bolt.

[kevin c]

There may be, as those above have posted, a few causes for the problem you’ve encountered. In my case, it was a misalignment of the sprue plate openings with the tops of the mold cavities (incomplete closing) combined with letting the alloy harden up too much. The misalignment meant I lost the mechanical advantage afforded by the cam attached to the sprue plate handle; without it, cutting eight hard sprues at once just about gave me a hernia.

[brassrat]

I had a problem like this this year and it seems to me that mould temps were the problem

[ascast]

a regular lock washer on the sprue cutter screw might do that. Any visable damage or gouging marks anywhere?

[pt4u2nv]

I had a problem like this this year and it seems to me that mould temps were the problem

After trying again today and rechecking all the components, sprue plate , bolt on sprue plate , set screw and other items it did go away after using it for a bit. Appears it may have been mold temp although I never had that happen before. Thanks everyone for your help. It actually started cutting the sprue with a slight tap instead of brute force

[Bazoo]

Glad you got it going again.

[mehavey]

OOC: Is the OP using a lead thermometer?

I can't think of any reason mold temp would suddenly change in the middle of continuous
casting, unless the lead pot/heating element had quit and lead itself cooled

[pt4u2nv]

OOC: Is the OP using a lead thermometer?

I can't think of any reason mold temp would suddenly change in the middle of continuous
casting, unless the lead pot/heating element had quit and lead itself cooled

I use a PID controller so the temp is very consistant. I do not understand all of a sudden either but maybe the mold cooled down while i was doing something and i did not realize it....who knows

[1eyedjack]

Air Temperature ? If casting outside colder air or change in wind direction can affect cadence and mold temperature.

[brassrat]

My problem was reading too much about saw blades on the hotplate. I always kept my alternating moulds on the coil with no problems. I used a thicker target plate and it messed me up a lot.