Problem with first casting session

[woodmann]

First casting session today went pretty well. The only problem I could not completely overcome was occasional rounded corners on the bases. Maybe 20 percent. For no apparent reason, I would get a rounded heel instead of a sharp one. There did not seem to be any rhyme or reason. I was casting with a 230 grain truncated cone Lee tumble lube 2 cavity and a 30 cal 200 grain Lee 2 cavity.

The only thing I can think of is I need to find some tin. I'm using straight clip on wheel weights.

Any input would be appreciated.

[Le Loup Solitaire]

Welcome to the forum. Tin could solve the problem...1-2% is all that is needed to improve the "flow-ability" of the alloy. Another possible factor is the tightness of the sprue plate...if it is too tight then it does not allow the air in the cavity to exit freely. Another possible demon is the diameter of the stream of pour... if it is too big it floods the feed hole and again obstructs the exit of cavity air. Last but not least is the presence of (a little too much) zinc which loves to create rounded corners and all sorts of weird things that make you cuss. Try working with these possibilities and see if there is any consistent improvement. LLS

[Yodogsandman]

The only other possibility I can think of other than the great info LLS has offered is that the sprue plate needs to be kept hot. Leave a big sprue puddle each cast and it will keep the sprue plate hot.

[Mike W1]

My experience has been that the flow has to be steady, need to develop a "feel" for it and bottom casting I can tell if a bullets going to be bad if I don't hit the center of the sprue hole. And I've sometimes had to up the temperature by as little as 10° and that made the difference. Another reason I prefer my PID controller as you aren't gonna control a pot that closely without one.

[brassrat]

Great tips LLS thanks

[rsrocket1]

Leave a big puddle on the sprue plate. You'll sometimes see dimples as the cooling lead sucks in metal from the sprue down into the cavity as it hardens. Without that excess reservoir of lead, you can wind up with rounded corner.

[DrCaveman]

Thanks to some great threads on this forum, i have begun using a more strict cadence between pouring and breaking the sprue. About seven seconds for most of my moulds, depending on size and material. This is much longer than i used to wait.

When combined with a healthy sprue puddle, the number of round bases i see has plummeted. Of course this only works when the mould and sprue plate are up to proper temp. Ive found that doing the seven count also maintains a more consistent temp in both mould and sprue too.

Mess around, you'll find a good count that will work for your mould

[mongoose33]

If some boolits are ok and some not, I'd be looking at something other than tin percentage, though that may help.

I'd be looking at whether the mold is up to temp or not.

The suggestion about the hot sprue plate is a good one. Someone noted this elsewhere about a large sprue puddle, wish I could remember who to give them credit, but the comment was don't think of a large sprue puddle as pouring alloy....think of it as pouring heat.

I'm generous with my sprue puddles, they all just go back into the pot anyway. :)

[woodmann]

I think LLS is onto something. When I cleaned the molds, I lubricated them as directed with anti-seize. In addition to the recommended locations, I brushed a light coating on the bottom side of the sprue plate - to lessen the chance of scratching the top of the blocks don'tcha know. There were definitely times that I had an issue with airlocking, as I had some slugs come out only 2/3 filled even though I had a nice puddle on top.

I'll try cleaning off the top of the blocks and underside of the sprue plate and see what happens. Maybe play with sprue tension too.

The other thing I should have included in my original post was that the rounded ones did not consistently come from either of the mold holes (?). It would be the 1st one one time and the back one the next. But, 95% of the time the second of the two would be perfectly sharp across the base so I think my temps were okay. I was hesitant to suggest tin because of this , but did not know what else would cause the poor fill out. I didn't realize that the molds vented under the sprue plate.

Also, I melted the WW myself and went thru them one by one. I had two zincers make it into my melting pot out of 5 buckets. They were removed without incident. None of my bars show signs of contamination. Not that I'm a pro, but I read a LOT here and watched many Youtube videos when it was too cold to be outside, before starting this.

How do you guys lube the sprue plate at the pivot screw? I took the screw out and dabbed some around the corner of the mold block, then re-assembled. Now I'm having a little trouble keeping tension constant on the sprue plate. I wonder if it originally had a mild thread locker applied?

Thanks for all the great replies. I'm not discounting the others, but I'm going to start with LLS's idea based on my observations above.

[GP100man]

Consistent speed of pours , being new I bet you`re stopping to admire your new hobbys labors & the sprue plate kools a bit , if ya gonna take time to look at ya boolits at least close the mold & plate so heat will be retained somewhat better.

And don`t worry , we`all did the same thing !

The only other thoughts I have is the alloy temp being maintained ??

Congratulations on your freedom from the masses of bullet manufacturers !!!!!

GP

[Ken in Iowa]

Welcome to the crowd!

I am fairly new to this as well with about 10 casting sessions under my belt.

Excellent advice above. As for sprue plate lube, Bullplate is the gold standard around here.

On my first casting session, I used Permatex anti-seize. I was too liberal with it and things did not go well. A little bit got in the cavity and it was a pain to get it out.

Bullplate is much more forgiving and simple to use. I believe that NOE sells Bullplate or the equivalent as their sprue plate lube.

NOE also has a reasonably priced casting thermometer. A thermometer is one of the best investments you can make. ;)

Lastly, understand that every mould has it's own personality, even moulds that are similar. For example, I have 2 RCBS 45 moulds. The 45 230 CM likes it hot! 700-725 degree melt, lots of over pour to keep the plate hot. My 45 200 SWC likes it cooler. 650-670 is about right and don't get the plate too hot! Following these basic rules resulted in excellent boolits and few culls.

Don't get discouraged. Practice makes perfect!

[matrixcs]

I am no expert , all the comments here are great advice. My 2 cents are simple hotter sprue plate and mold and bigger sprue puddle..
I find I have this problem myself when I am tired or not paying attention.

[Echo]

But realize that the sprue plate can get TOO hot! When the sprue flows off like water, it's too hot! Keep a rag soaked in water handy, and when needed, turn the mould upside-down on it and let it steam for a couple of, maybe 5, seconds.
I made a little tray out of HD Al foil and folded up a rag into it. At the start of the casting session, I soak it in H2O, and it's handy when needed.