Problem with my MP 359130 mould

[EMR]

I’m brand new to casting and picked up the above mould a few weeks ago. I’ve cast maybe only about ~400 boolits with it.

I’ve broken it in with heat cycles and lube it with 2 cycle oil every time.

Today the Sprue plate started to separate from the mould. No matter how I adjusted the Sprue plate screw, there was a gap causing flashing at the base of my boolits. I’m fairly certain that I’m smacking the plate square on with my wooden stick. The bottom of the plate and the top of the mould are pretty clean.

Can anyone point me in the right direction to fix this?

[runfiverun]

you have the bolt too tight.
there should be a set screw.
back it out.
back out the plate screw until the plate lies flat.
make sure there is a small amount of tension on the plate screw.
tighten the set screw.

the plate should swing open and closed with a slight friction fit to the mold.

[EMR]

Thanks for the reply. I tried loosening the screw as well. The gap was still present. Maybe I didn’t loosen it enough? I’ll have to try again tomorrow.

[ChuckO]

I’m brand new to casting and picked up the above mould a few weeks ago. I’ve cast maybe only about ~400 boolits with it.

I’ve broken it in with heat cycles and lube it with 2 cycle oil every time.

Today the Sprue plate started to separate from the mould. No matter how I adjusted the Sprue plate screw, there was a gap causing flashing at the base of my boolits. I’m fairly certain that I’m smacking the plate square on with my wooden stick. The bottom of the plate and the top of the mould are pretty clean.

Can anyone point me in the right direction to fix this?

I hope that you didn't really mean "smacking the plate", but have been smacking the hinge bolt on the mold handles when releasing the bullets from the mold. Hitting the plate is a good way to slightly bend it right at the bolt hole.

Remove the sprue plate and place it on a flat surface. If you can slide a .001 feeler gage under it near the pivot hole then you have a slightly bent plate and it won't sit flat without being fixed. At this point, the pivot hole would not be square to the surface of the plate. Enlarging the hole might allow the plate to site tightly on the mold again.

[EMR]

I hope that you didn't really mean "smacking the plate", but have been smacking the hinge bolt on the mold handles when releasing the bullets from the mold. Hitting the plate is a good way to slightly bend it right at the bolt hole.

Remove the sprue plate and place it on a flat surface. If you can slide a .001 feeler gage under it near the pivot hole then you have a slightly bent plate and it won't sit flat without being fixed. At this point, the pivot hole would not be square to the surface of the plate. Enlarging the hole might allow the plate to site tightly on the mold again.

Smacking the plate to open it before it’s fully warmed up. I use my hands when it is. I hit the hinge bolt to release the mould.

I don’t have a set of feeler gauges, but it sounds like I should probably pick some up. Thanks!

[runfiverun]

I have that mold on loan from another member that I have been picking at from time to time.
the sprue plate was my first hurdle.
I still have a venting issue to work on, I can deal with it because of how I run my stuff but as a normal timed fill on a machine it won't vent the air fast enough.

anyway the top picture is illustrating your problem.
the plate being level on the mold top will stop the finning.

[EMR]

So I took off the plate and I may be hosed. I think I over tightened and scoured the brass.

No matter how loose/tight the screw is, I can rock the plate on the mould.

So what happened last night was the set screw popped out and I noticed I immediately started to get flashing. So “logically” I thought to tighten the plate screw and maybe cast another 5-6 times.

[Cherokee]

I don't think you are hosed. Did you check to see if the sprue plate itself is flat, as suggested above ? If its flat, then you had too much tension on the hold down bolt. Looing at the picture, looks like the mold is gouged under the sprue plate. Others might have a better idea but in such cases, I have used 350 gr wet/dry sand paper on a flat glass surface and lightly run the top of the mold over it to make sure it is flat and to highlight the surfaces that are flat...then you can see if the gouges are raised burrs or not. Also check the bottom of the sprue plate, might need to knock off any burrs there in the same way. Once you think everything is smooth, clean, reassemble w/o the hold down bolt to see if the sprue plate is flat on top of the mold. If so, install the hold down bolt but keep it loose so the plate will remain flat. Try casting some.

Edit: I just noticed you said the tension screw popped out. Are you referring to the hold down bolt or something different ? The hold down bolt should not just pop out, it has screw threads. I'm confused...

[EMR]

I don't think you are hosed. Did you check to see if the sprue plate itself is flat, as suggested above ? If its flat, then you had too much tension on the hold down bolt. Looing at the picture, looks like the mold is gouged under the sprue plate. Others might have a better idea but in such cases, I have used 350 gr wet/dry sand paper on a flat glass surface and lightly run the top of the mold over it to make sure it is flat and to highlight the surfaces that are flat...then you can see if the gouges are raised burrs or not. Also check the bottom of the sprue plate, might need to knock off any burrs there in the same way. Once you think everything is smooth, clean, reassemble w/o the hold down bolt to see if the sprue plate is flat on top of the mold. If so, install the hold down bolt but keep it loose so the plate will remain flat. Try casting some.

Edit: I just noticed you said the tension screw popped out. Are you referring to the hold down bolt or something different ? The hold down bolt should not just pop out, it has screw threads. I'm confused...

I haven’t had a chance yet to check it with feeler gauges, but it looks like the plate lays fairly flat on glass.

I was referring to the small screw holding in the screw for the plate. I was tapping the bolt to release boolits and the tiny screw fell out. I honestly didn’t even realize that screw existed until it fell out!

[dragon813gt]

The screw that fell out is the set screw. It's what keeps the sprue plate bolt in place. It looks like you've been operating the mold w/ lead stuck to the underside of the sprue plate. That's why there is lead on the edges of the mold. I've found Mihec's sprue plates to be perfectly flat and burr free almost every time. Different story w/ NOE where I have to stone every sprue plate.

All is not lost. Try stoning the bottom of the sprue plate. Any high spots will be immediately noticeable because you will remove the bluing. Using the mold will reblue the plate so it's not a big deal. No matter what keep lead off the bottom of the sprue plate when operating it. It can cause damage to the blocks quite easily.

[EMR]

The screw that fell out is the set screw. It's what keeps the sprue plate bolt in place. It looks like you've been operating the mold w/ lead stuck to the underside of the sprue plate. That's why there is lead on the edges of the mold. I've found Mihec's sprue plates to be perfectly flat and burr free almost every time. Different story w/ NOE where I have to stone every sprue plate.

All is not lost. Try stoning the bottom of the sprue plate. Any high spots will be immediately noticeable because you will remove the bluing. Using the mold will reblue the plate so it's not a big deal. No matter what keep lead off the bottom of the sprue plate when operating it. It can cause damage to the blocks quite easily.

I’ll definitely try the stoning.

A lot of that leading popped up when my plate started separating.

[EMR]

So I took your guys’ advice and stoned the surfaces and really played with loosening the plate screw tension. I’m finding that I can lift up on the Sprue plate with minimal effort, but I’ve considerably closed the gap and the boolits have minimal/no flashing. Lesson learned. Thanks guys!!

*side note: I got my RCBS thermometer today and wow does this make a difference! This Lee 4-20 fluctuates like no ones business! I guess a PID is in my future if I can figure it out.