sprue sticking to top of sprue plate

[johnho]

on a "new", from Ebay, molds I can not get the sprue off the top of the mold without prying it off. The molds appear brand new, is there something I should do the them to "season" the top? . I was using what I was told was linotype put i doubt it as it only has a hardness of about 14-15.

[stocker]

johnho:

How much standing metal is there between the bottom side of the sprue hole and the angled sides of the hole on the top?. If this is excessive sprues will hang up particularly if the plate is a tad too loose or not properly flat on the bottom surface. When cutting the sprue can you see any burring of the sprue on the underside of the plate? You can lay some 400 grit paper on plate glass and work the sprue plate back and forth to square it up. After a couple of strokes on the paper a quick look at the surface will show you if there is any unevenness or high spots.

There may be machining marks that are creating a mechanical lock on the sprue. IE: a circumferential groove or grooves that are deep enough for the sprue to get a bite in. Make up a hardwood dowel with the tip tapered to the same angle as the sprue hole. Chuck it in a drill press and apply some valve grinding compound and polish it until the walls of the hole are bright and shiny. Degrease it and give it a coating of soot from a butane lighter and you should be good to go.

Even before that try just the soot on both sides of a degreased sprue plate and see if that is adequate.

You might also contact Bullshop here and ask about using his special mould lubricant on those surfaces.

[Bullshop]

Another thing that can cause the problem even if the plate is perfectly flat is having it too tight. If you will do this test you will see.
First loosen the locking screw for the plate hinge screw. Now loosen the hinge screw so you can easily turn it with your fingers. Back it out enough so there is no pressure on the washer at all.
Now hold the blocks up to the light, sun light work best if you have it. If the top of the blocks and the bottom of the plate are flat with the plate resting on top of the blocks you will see no light between the two. If you do you will need to resurface one or both.
If you do not see light between the two continue by turning the plate pivot screw with your fingers until you feel it tighten. At this point you will most likely see light comming through from under the farther side of the plate from the screw. Keep turning the screw in and out until you find the spot with the screw that sets the plate flat on the blocks with no light showing.
Now when you tighten the locking screw be shure to hold the blocks up to the light again as if there is any loosness to the pivot screw the locking screw can tip it enough to lift the plate so you will have light again.
If this happens you will have to turn the pivot screw just a bit looser than when it just sets the plate on the blocks when adjusting.
This should fix the problem if you are getting a flange on the sprue under the plate.
If the problem is roughness on the top side in the beveled pour hole it will have to be polished out. Bull Plate will help the problem but wont cure it.
The proper adjustment of the sprue plate goes a long way in preventing problems and excessive wear especialy with aluminum blocks.
BIC/BS

[45 2.1]

In addition to what you've been told, rub a soft pencil all over the top of the sprue plate to graphite the top flat and sprue hole. Heat your sprue plate by dipping the tab in your molten lead for about 10 seconds. Now your sprue won't stick.

[Slowpoke]

In addition to what you've been told, rub a soft pencil all over the top of the sprue plate to graphite the top flat and sprue hole. Heat your sprue plate by dipping the tab in your molten lead for about 10 seconds. Now your sprue won't stick.

If the pencil gets to wearisome think Dry Graphite spray.

A word of caution is in order, its habit forming.

But it sure makes time with the Silver stream more enjoyable.

Good luck

[johnho]

I appreciate the responses and will check mold for them. the sprue plate is very flat against top of mold but the funnel areas feeding the mold are rather course so will smooth those out. agian thanks

[buck1]

Bullshop doesnt give his product enugh credit !! I just used it for the first time and am very happy with it!!!!.....Buck