How do you tune a sprue plate?

[RustyReel]

I was reading pks45's thread below about Lee molds and saw a mention of needing to tune the sprue plate on new 2 cav Lee molds. I've always had good luck with Lees but this recent 410 mold has been a PITA, smearing lead across the top on the third pour. So, how does one go about tuning a sprue plate?? Thanks for your help.

[Bazoo]

For a lee 2 cavity, I will deburr the edges all the way around, and lightly lap the block side on my diamond stone to remove high spots. If the cutter hole doesn’t go all the way to the underside of the plate; ie, it has a reverse chamfer, I use a punch from the top to move metal toward the bottom and puff out the hole opening a bit. Then I lap that high spot down. It cuts good normally after that.

[gwpercle]

Smearing lead across the top happens when you cut the sprue and the lead isn't fully set up into a solid ... the semi-liquid metal gets smeared across the top of the block and the underside of the sprue plate . Using a Lee double cavity mould @ about 750 - 725 degrees , I cast , leave a generous sprue puddle and long count to seven ...one-thousand one , one thousand two , one thousand three ...
after reaching one thousand seven, I can cleanly cut the sprue with no smearing .
If you cast hotter , count longer ...cast cooler , count shorter .
You will have to work out how long it takes for your mould and alloy temp. to completely set for a clean cut ...once you do just keep the cadance .
When you see a smear ...STOP ...clean it off , if not it just gets worse and will score the top of an aluminum block and damage it ... clean off smears as soon as possible .
Gary

[gwpercle]

For a lee 2 cavity, I will deburr the edges all the way around, and lightly lap the block side on my diamond stone to remove high spots. If the cutter hole doesn’t go all the way to the underside of the plate; ie, it has a reverse chamfer, I use a punch from the top to move metal toward the bottom and puff out the hole opening a bit. Then I lap that high spot down. It cuts goo normally after that.

Bazoo has it down ... I've never head it called "tuning" but do this !
Gary

[georgerkahn]

I concur 100% with Bazoo, and having had scratches develop on a few brass moulds now it is standard procedure for me to put a new piece of 600 grit wet 'n dry paper, moistened, and laying on/water stuck to a piece of plate glass -- then moving the sprue plate on it a dozen or two strokes. It is incredible how one can see the circlesabout the pour hole(s) is/are generally not in same plane... causing the scratches. I then follow/finish with a few seconds with a not-treated cotton wheel on a 6" buffer which -- again, with no compound -- making the bottom mirror bright without rounding any edges. This total effort takes less than three or four minutes -- very much (inho) worth effort. I have received brand new, costly brass moulds which already had (at least) the start of a scratch!

[RustyReel]

Bazoo, thank you and the other guys as well.

gupercle, sprue was hardened, third cast, mold was still "cold".

[pjh421]

RustyReel, someone recommended in a different thread regarding mould prep/treatment, to apply a very thin coating of silicone paste. I did so and was amazed at the improvement. Lead (at normal boolit casting temperatures) will absolutely not stick to metal coated with silicone paste. As long as your casting and sprue are solid when you cut (like you said), this treatment should eliminate any smearing as well as improve any sticking cavities. Obviously it won’t take the place of lapping-in a burred cavity that won’t release cleanly but on an otherwise good mould it makes for a huge improvement. I put it on cold with a Q-tip and use a clean one to remove any excess. I put it on the vented mould faces, mould top, pins, pin recesses and sprue plate as well. A little goes a long way. Seems to clean the mould a little more in the process too, as the Q-tips become discolored.

[WRideout]

RustyReel, someone recommended in a different thread regarding mould prep/treatment, to apply a very thin coating of silicone paste. I did so and was amazed at the improvement. Lead (at normal boolit casting temperatures) will absolutely not stick to metal coated with silicone paste. As long as your casting and sprue are solid when you cut (like you said), this treatment should eliminate any smearing as well as improve any sticking cavities. Obviously it won’t take the place of lapping-in a burred cavity that won’t release cleanly but on an otherwise good mould it makes for a huge improvement. I put it on cold with a Q-tip and use a clean one to remove any excess. I put it on the vented mould faces, mould top, pins, pin recesses and sprue plate as well. A little goes a long way. Seems to clean the mould a little more in the process too, as the Q-tips become discolored.

So, PJ, do you have a brand name, or usual source of supply for the silicon paste?

Wayne

[mdi]

The only things I've done to my aluminum molds is a very thorough cleaning. And a bit of 2 cycle oil or bullet lube on the top (very sparingly) or the sprue plate screw and alignment pins. When needed I have used emery cloth w/oil on a flat surface to clean up, square the sprue plate . I have a couple times squared the top of the mold draw filing. Nothing goes in the cavity but a few times I have made a paste of Comet and oil to "hone" a cavity. I rarely have any troubles with my Lee molds (12)...

Perhaps spell check turned "true" into "tune"?

[pjh421]

Pic failed to upload but the brand is 3M. It’s an 8oz brush bottle and I think it came from Amazon, although some automotive stores should carry it too.

[Bazoo]

Glad I was able to offer help.

I also color the sprue plate bottom, and top of the blocks with a pencil before reassembly, to help with the occasional smear. When it happens, I wipe it with my rag and reapply the graphite via my carpenters pencil.

[alfadan]

On my moulds, once I deem it broke in and the sprue cutting and opening how I like it, I let it cool and use a small punch mark to reference it's postion. I then remove the screw and file a small flat so the set screw has a good positive place to tighten and I never have to touch it again.

[WRideout]

Pic failed to upload but the brand is 3M. It’s an 8oz brush bottle and I think it came from Amazon, although some automotive stores should carry it too.

So, I went to the auto parts store to look for silicon paste, but could only find the little packages of silicon dielectric bulb grease at the checkout counter. I went ahead and bought some, just tried it this evening with a Lee mold. SUCCESS! This particular two cavity 38 WC mold had always been difficult to get the boolits to release. After the treatment, they just fell out of their own weight. It made casting so much more pleasant. Many thanks, PJ.

Wayne

[GhostHawk]

First thing I do with a Lee mold is take a file and smooth down the edge that travels over the mold blocks. Put a slight radius on it so it does not scrape or gall the blocks.

Fill holes get smoothed out with some 0000 steel wool. If necessary, steel wool and a dowel in the cordless drill to turn it.

Last thing I do is give the entire top surface a coat of BLL. Let it air dry. Lead does not like to stick to that stuff once it has hardened.

By the time the mold is up to temp the BLL will be baked on hard. Doesn't migrate or cause problems. Same thing happens to the fill holes. Sprue's drop off clean, leave no lead flashing behind.

Look at Lee molds as a kit. With some additional work, they will function fine for years. But you need to prep them.

[charlie b]

Are the Lee sprue screws still left hand thread?

[Gtek]

All of mine have the LH up in the corner top. As stated above, a little time spent on plate and blocks on new to me either used or new sure slicks them up. Being in aviation for almost 4 decades introduced me to good hardware years ago. I have also replaced all the pivot bolts with an AN6-7, supplied bolt has threads to head and a little small on OD. AN bolt it rides on shank and those couple thousandths remove about all the double close feel and line up blocks a little better and just feels better to me.

[Carrier]

First thing I do with a Lee mold is take a file and smooth down the edge that travels over the mold blocks. Put a slight radius on it so it does not scrape or gall the blocks.

Fill holes get smoothed out with some 0000 steel wool. If necessary, steel wool and a dowel in the cordless drill to turn it.

Last thing I do is give the entire top surface a coat of BLL. Let it air dry. Lead does not like to stick to that stuff once it has hardened.

By the time the mold is up to temp the BLL will be baked on hard. Doesn't migrate or cause problems. Same thing happens to the fill holes. Sprue's drop off clean, leave no lead flashing behind.

Look at Lee molds as a kit. With some additional work, they will function fine for years. But you need to prep them.

What is BLL

[BK7saum]

Ben's Liquid lube.

[Walter Laich]

always felt Lee molds were really "Need some Assembly Kits."

not a dig at them, figured a bit of sweat equity was a cheap price to pay for the lower costs of them.

I've got a bunch of them--must mean I'm happy with them

[Horseman]

My experience is similar to gwpercle's - a smear tells me I'm getting in a hurry and just need to wait a bit longer for the sprues to harden. Understanding that you may only have one mold or need for one bullet, my solution has always been to wait until I'm getting low on a couple different styles and then cast with two molds, letting one cool while emptying and refilling the other. Eliminates the smears and reduces overheating/frosted bullets.