Daylight between the mold blocks?

[Murphy]

I just received a 4 cavity mold (Lyman) I picked up off Evilbay. A tad of rust in the cavitys but nothing I shouldn't be able to clean up fairly easy with a bit of #0000 steel wool.

I was inspecting the mold and held the blocks together, then held it up to the light to see how well they fit together.

I can see a very slight amount of light between the mold blocks, from just about any direction I care to hold it up to the light.

A few weeks ago, I was doing some casting and found the same thing with a 2 cavity Lyman #358156. I ran the mold fairly hot (frosty boolits) and never got any fins on any of the boolits.

After all these years, I've never truly paid much attention to this unless I was getting fin's on the boolits and then I'd find some alloy on the block faces that was causing the real problems.

Is the fairly normal on Lyman molds?


Murphy

[IcerUSA]

I would say yes to it being normal as the molds are made to a standard that has a tolerance , and as we all know tolerances can overlap and you could very easily get a little light between the blocks .

As long as it doesn't hurt the overall boolit configuration , no biggie , if it is just bothersome to know you have light showing adjust the pins inward slightly to see if the light getting thru goes away , if not you might have to do a little face work on the blocks .

One or two thousands can let alot of light thru , for a test , take a mould that shows no light passing thru and place a .002 shim under one side of the blocks and look again . :)

I would use it as is as long as everything works good .

Keith

[Doc Highwall]

What is more important, are the boolits big enough for your gun. With the pins holding blocks apart is the same thing as beagling. Also check to see if the previous owner closed the blocks too hard leaving a burr on the alignment holes. These can be cleaned up with a inside case deburring tool, after that you will have to reset the alignment pins deeper to eliminate play between the blocks.

[35remington]

See if something is preventing the mould from closing all the way. Look at your alignment pins, and also for the usual burrs around the mould halves. Sometimes if the pins are freshly or recently driven out to present more cylindrical bearing surface the moulds might be a little iffy about closing until the pins wear in.

Close the mould with handle pressure. Then, gently tap the side of the mould with a plastic headed mallet and see if that closes them all the way. Back the mould on a block of wood to direct the impact.

If it does close fully, you have some work to do. If it doesn't, you still have something to look into.

[missionary5155]

I have several molds that are light passers... but the Boolits all shoot well... It aint broke so I aint-a-gonna fix it !

[Murphy]

Thanks for the replies gentlemen,

I got the mold cleaned up and fired up a pot of lead this evening. Seems the holes where the alignment pins went in, had rust in them preventing the mold from fully closing.

On a rather sad side note, the person who attempted to 'clean' the rust off the mold apparently used a wire wheel on a grinder or something simular. Once the mold was warmed up and the alloy flowing well, I had rounded edges on the boolit sides creating a nice permanent fin, and a nice 'ridge' on the nose of the boolit :(

I haven't posted feedback on the Ebay seller as of yet, and fully intend to contact him to see if he'd care to make things right. Although he did state in his auction, he didn't know anything about bullet molds and was selling them for a friend.


Murphy

Damn I hate it when things like this happen...

[HeavyMetal]

A possible repair: a surface grinder!

If the boolits are casting large enough to give you some playing room that is.

A good surface grinder can take .002 off per side of mold which may be enough to remove your fins. Sadly you have to cut new vent lines but if you find a guy with a surface grinder he can probabely fix that at the same time.

The down side is if your mold is droping almost at "size" your done!

Hope my idea helps. Good luck getting the e bay guy to help out.

[Calamity Jake]

If Lyman is still making your mould, they may replace it. Give em a call.

[w30wcf]

One of the first thyings I do after purchasing a used mold is to take a large flat file and run it across the face of that half of the mold without the alignment pins. More often than not, there is raised metal around the alignment pin holes. I then chamfer the holes very slightly and, if required, adjust the alignment pins to suit.

Regarding rounded mold cavity edges / excessive flash, I have found that better bullets can be made by drop pouring into such molds.

w30wcf