Problem with Lyman 280473 fins

[Jal5]

This is the first rifle mold I have tried. 280473 planning to use it in a 270 Win.
The double mold threw good boolits for the first couple of tries, but then the finning started on the tips especially. The base didn't fill out correctly either.
These were ladle poured using range scrap ingots that I made last fall. I don't have a thermometer, but the temp was approximately what I have used successfully before with pistol molds- the dial was 3/4 on. Got a good sprue but the bases didn't fill all the way on most of the 30 boolits I made. The two mold halves felt like they stuck together slightly when I opened them to release the boolits- it was noticeable after the first 3-4 pours, like when it fully heated up. I used Bullplate on the sprue cutter and a little on the two pins. The sticking felt like it was at the pins too. I have had this sticking problem on another Lyman mold too- that one I had used for several casting sessions successfully before this sticking problem started to occur.

This mold fit together flush with no gaps when it was cold; as it heated up from casting the problems started.

Any ideas on what is causing the problems? Sorry the pics aren't clearer, but you can see the fins in the 1st one and 2nd & 3rd shot shows the ones without fins.

Joe

[plainsman456]

I had that problem with a 38 swc mold.
All I did was squeeze that sucker a little bit harder and they went away.

[Bent Ramrod]

It sounds to me like the alignment pins have either gotten burred or are out just far enough so that when the mould heats up they keep the halves from completely closing. That sticky feeling when you open them could be explained by this. It doesn't take much to allow the lead to get in there when everything is hot and the lead is flowing well.

You might also have a fleck of lead in an alignment hole that splashed onto there while you were casting. Check for silvery spots and remove with a toothpick.

I hold the mould up to the sunlight (I cast outside) and look to see the tiniest amount of daylight when the halves are squeezed shut. Burrs around the alignment holes can be smoothed with a Swiss file. The alignment pins can be driven back into the mould half with a bench block, a brass punch and a small hammer.

[Jal5]

Ramrod I think it is something about the pins too on both of these molds. I will inspect the holes really good and see what I find. I am pressing the handles together pretty consistently tight but the space between the blocks does not go away. And that sticky feeling doesn't go away either.

I would think I could smooth the burrs out with the tip from the dremel tool rotated by hand?

Joe

[Jal5]

Still working on this problem. today I heated up the mold really good and took a wooden skewer from the barbecue to clean out those alignment pin holes. Couldn't see if anything was embedded in there- I ordered a magnifier which should be delivered later this week. Tried casting 20 more but they were still finning and that sticky feeling of the alignment pins as the mold is opened is still there. I am sure that is the problem as the faces of the mold are clean no drops of lead anywhere.

[Jal5]

I heated up this mold, checked it under a 10x magnifier and only found tiny pieces of lead on the block face. I removed those and it made a difference in how the mold closed up. Great! Tried to cast with it again and in about 30 boolits again with the finning at the boolit tips. It is really frustrating. I looked at it under magnifier again and cannot see anything, but I can definitely see light through the blocks again.

What should I try?

[Bret4207]

Get your magnifier and start looking. There are likely burrs somewhere.the other possibility is that that mould is warped, but in 30+ years of casting and looking at a LOT of moulds I have yet to see one that was actually warped.

Check and make sure your handles aren't holding the moulds apart somehow too.

[williamwaco]

It is 98% probable that there is either a burr, a piece of lead, or something very small and hard to see on the face of the mold. When the mold is cold. check it very carefully with your magnifier and also with the tip of your finger. You might be able to feel a burr you cannot see.

You state the mold closes completely and the faces are flush when you close it. Hold it up to a very bright light source and see if you can see any light shining between the faces.

If you are sure there is no gap when you close the mold, it is sometimes possible to create a misalignment by squeezing the handles or pressing on the sprue plate sith the ladle.

[nanuk]

here is a thought, can you remove the mould from the handles and then seat them together and check for light between the blocks?
also wiggle them around using your hands. easier to feel without the handles on.
You can also feel how they seat, like do the kinda snap into position and then need a bit of effort to pull apart, or are they coming apart easy but you can still feel the tightness


just a thought... or three

[Jal5]

I took the blocks off the handles and I can squeeze them together but still see light. The blocks sort of rock back and forth a tiny bit top to bottom. They fit together without snapping together or any effort to pull apart. I cleaned out the pin holes earlier today and now there is no snapping together, but before cleaning they kind of stuck together when aligned.

JOe

[nanuk]

I took the blocks off the handles and I can squeeze them together but still see light. The blocks sort of rock back and forth a tiny bit top to bottom. They fit together without snapping together or any effort to pull apart. I cleaned out the pin holes earlier today and now there is no snapping together, but before cleaning they kind of stuck together when aligned.

JOe

kind of sounds like you had something in the pin holes, but now also still have something on the mould face. the moulds should not rock. and if you can see light, there is something holding them apart.

can you rock them side to side, then top to bottom and imagine if you will where a burr would have to be to be a fulcrum at that imagined point. also, using bright light, you may be able to see where the light is being blocked in the line you see, and a burr could be there.

take you magnifier and inspect very closely again in that area. Feel with your fingers.

then concentrate on that area and use techniques discussed elsewhere.

here is why I think something is holding them open. when the mould is cold, no finning. when mould is hot, finning, as the alloy has more time to bleed out, as it does not freeze instantly against a cold mould.

perhaps I am way out to lunch here... just thinking out loud, and trying to imagine myself inspecting it

[Jal5]

I can feel a raised edge around the pin holes with my fingernail, one more so than the other. And I think that is the burr causing the problem.

"here is why I think something is holding them open. when the mould is cold, no finning. when mould is hot, finning, as the alloy has more time to bleed out, as it does not freeze instantly against a cold mould."
This is exactly what is happening!



What is the best way to smooth that out? I tried the eraser method but that did not do it. I cannot see or feel anything else on the faces that might be causing this.
What about using a piece of Emery cloth to gently smooth those down? I don't have a small enough file to do it. Or maybe one of the tool heads from the Dremel kit using it manually instead of in the dremel itself?
Thanks.

Joe

[Jal5]

I tried the tool head from the Dremel kit and that worked fine to smooth down those burrs around the pin holes. then I worked on the pins themselves and adjusted them to fine tune the fit. Cast about 100 boolits and not one fin!

Now I am working on the bases which are a little rough in some respects, but that might be just the alloy I am using, range scrap with a little tin added. I will try the mold with straight ww and see how that works out.

thanks.

Joe

[nanuk]

good to hear

as for the bases, others on CB have the answers. just wait and they will chime in soon

[Love Life]

An easy fix I found to eliminate fins on a couple molds I have is to put just a smidgen of bullplate in the mold block faces around the cavities. Cleared the problem right up for me. YMMV.

[Bret4207]

I tried the tool head from the Dremel kit and that worked fine to smooth down those burrs around the pin holes. then I worked on the pins themselves and adjusted them to fine tune the fit. Cast about 100 boolits and not one fin!

Now I am working on the bases which are a little rough in some respects, but that might be just the alloy I am using, range scrap with a little tin added. I will try the mold with straight ww and see how that works out.

thanks.

Joe

Could you describe what you mean? Rough on the base or base band?

[Jal5]

Bret- the bases don't have a crisp edge, some were rounded. Others had a rough spot like a divot was scooped out while others had extra lead there like a hump. I will try to post a picture tonight that shows it better than the one I already put on the original post.

But it must be an issue with the sprue plate I think. I have to examine it more for burrs on the hole, could be scraping out extra lead. Or I am cutting the sprue too soon digging out on the base.
The plain range scrap alloy I am using may be a little soft for this application too. Do you have any advice about that?

This mold is more tempermental than the others I am used to using.

[Doby45]

Your sprue plate needs to be as hot as the mold itself for the base to fill out well. Make sure you are putting an ample sprue puddle on the sprue. Guys that do ladel casting normally have nicer looking bases because they pour more lead on the sprue plate and that helps keep the temp up on it. When you bottom pour you can be more "neat" but it actually harms your base fill out.

If you have divots in some bases and humps in others it tells me you have not found a good cadence in your casting. A divot will normally mean you are cutting too soon and tearing the base and a hump normally means you have allowed the cast to cool too much and instead of a good clean cut your sprue plate will move a bit and not cut your sprue nice and flat. This is one of those things that 50 people can tell you what you should be doing but you will be the only one casting with your molds that will know the exact timing that you need. Some people say you just need to let the sprue puddle get solid and frost a little bit and then cut. Others will tell you that you can cut sooner and depending on how you cut your sprues it will be a beautiful base.

Do you cut the sprue by hitting the sprue plate with a stick of some type or do you use a gloved hand? Those two items also affect how your bases can come out and when you should cut your sprue. With a gloved hand you can cut your sprues a little sooner because you actually apply some downward drag on the sprue plate as you open it and it can make bases that look smooth as a mirror. You can do the same with a whacking stick but you have to wait longer because you will tear the bases.

This is one of the aspects of casting that makes it an art more so than a simple mechanical process.

[Bret4207]

Boy! Doby hit everything I can think of! Good post!

[Jal5]

Thanks Doby, good advice.

I used the gloved hand to cut the sprues. I did vary my cadence in that casting session, trying to see if it affected the bases. I will try it a little faster and put some pressure on the sprue plate to see what that does next time.

With the GC for those boolits can I still use those with the divot or hump imperfections?

Any thoughts on my alloy for these boolits?

[Doby45]

You can use the divots if you are not looking at mega sniper accuracy. The only issue you would have there is the weight varying. I would not try to put a check on the ones with a hump on the base as the GC will not seat square or well.

Your alloy should be fine. Lots of people get great boolits from range scrap but you may want to sweeten with a touch of tin if you are not getting good fill out on the driving bands.

[Jal5]

thanks for all the help guys! I will give you a range report once I get them GC and loaded up.