Ouch-Repair suggestions.

[MOA]

Picked up a slightly scored mold. They are fixable, just not sure how long it would take with wet/dry paper on glass to clean it up. As you can see the scoring has crept into the boolit base area. If I can finish with a 400 and 800 grit, I'm sure it will be sufficient. What grit should I start with? What would be the best progression of grits I should use so I finish this fix sometime this year. Lol. A machinist who understands molds would be great but money's just not there and I do have time to hand work this problem fix unless this cannot be fixed except by machining. Thanks.

https://i.postimg.cc/hP4R9YmY/20220513-014438-1.jpg (https://postimg.cc/bd55P330)

https://i.postimg.cc/RCLzJmWf/Screenshot-2022-05-13-01-53-13.png (https://postimg.cc/SjRPHw7N)

[hawkenhunter50]

If it were me I'd probably start at 220 and see how it goes. May need to go more aggressive. As far as progression I wouldn't skip too far ahead. If 220 works I'd probably go to 280 320 400. Was always told when lapping to go in figure 8 pattern. Good luck.

[MOA]

Good info hawk.

[country gent]

I would start with a coarse grit metal grade wet dry paper around 150 grit. With this and the next couple grits I would glue the paper don with rubber cement. I would wet the paper with water to keep it from loading up. Grit progression 150, 180, 220, ( these would be glued down as there a lot of grab to them) 320, 400, 600,800, and possibly 1000. Watch the patterns as when it becomes consistent its time to go to next grit.Once you get the scoring out with 150 the rest will go fast. Once you get the pattern then its just getting the new finer finish. Switch directions often left right circle, make 6-8 strokes rotate 90* 6-8 strokes then 6-8 circles this keeps the lines "crossing" over and gives a better finish faster.

[MOA]

Very helpful CG.

[G W Wade]

When lapping parts, I use a piece of glass for my backer under the paper. Mine are extra lenses from welding helmet with large lens. About 5x5 GW

[gwpercle]

That doesn't look too bad ... I have a sneaking suspicion that you will not need to completely remove the marks to cast good boolits . I would get a small assorted pack of Wet-R-Dry , start with 220 and work through to 400 ... then make a few test castings ... if OK finish the job with 600 .
Do all on a piece of plate glass to keep it flat and use water or oil on the wet-r-dry abrasive paper when polishing .
Gary

[skeet1]

When I had a lathe I chucked one up and milled one that way. Even though it was an interrupted cut it turned out very well.

Ken

[imashooter2]

I would start and finish with 80 grit. Any scratches left are vent lines.

[littlejack]

You know anyone with a milling machine? Thats a ten minute job. Any high school with a metal shop maybe? In the past, I have milled projects with a drill press and a cross slide vice. Turned out purty nice too. Necessity is the mother of invention.

[Jeff Michel]

PM sent

[Harter66]

Might be a good time to buy a diamond sharpening stone .

Ovals or circles 5-10 or the length of the stone , turn the mould 180° , 00000/length of the stone , turn 120/90/60° repeat . Turn the stone around start again . The course side cuts very fast but fills up just as fast . Be aware of that .

[ascast]

I have done a few like this. Surface grinder is nice if you can get to one. Grind the back side ( bottom) first so the top will lie flat. By hand, C.G. is right. I bought a glass plate about 12" by 12", two sided tape to keep it on the table, lead weights to keep the paper on the glass. I start with small, fine grit. It will tell you to go up to bigger grit if needed. I use a figure " 8 " pattern and rotate block 90 degrees every 4 or 5 "8's". Be sure that pins are nice and tight before you start. Also, clamp the halves together somehow. I have used vice grips or small " C " clamps. I have always gone dry. It goes fast once your set up. you may need to debur the holes when done, just a wee touch good luck

[Winger Ed.]

I'd get a sheet of 220 and 320 wet or dry.
Lay them out on something flat like glass or a piece of formica counter top.
Keep plenty of water going onto them so the slag rinse away and the grit doesn't clog.
Use the 220 first until it's worn out, then do it again with the 320.
That might get you where you need to be without major surgery.

Then come to grips with the sprue plate also.

[MOA]

Amazing the approaches possible for this kind of fix.

[405grain]

I've got a set of Lyman #375449 with exactly the same problem. The scoring is so deep that the sprue plate won't sit square on the top of the mold. I'd thought about sanding down the top of the mold with some wet/dry sandpaper and a surface plate, but was worried that it might make the gas check shank too short. After reading through these posts I realize that sanding the top of the molds is the best solution. It's very likely that the shank will still be long enough for the gas check after the scoring's been removed, and because the mold in it's current condition is unusable I really don't have anything to loose by trying it.

[Winger Ed.]

It's very likely that the shank will still be long enough .

I'd measure the height of the check, and the depth allowed for it in the mold.
It'll tell you how much you can shave off.

[Wilderness]

When I had a lathe I chucked one up and milled one that way. Even though it was an interrupted cut it turned out very well.

Ken

A friend cleaned up a couple of Lyman double cavity blocks for me this way also - squared it all up in a four jaw chuck and turned off enough to get it clean and level.

The pin that stops the sprue from swinging has to be pulled or drilled and replaced at the end.

In both cases there was enough spare gas check shank that everything worked OK afterwards still.

After that, make sure you leave the sprue plate with enough play so it can sit flat on the blocks under its own weight, i.e. don't over tighten.

[georgerkahn]

I acquired a garage sale mould years back with similar gouging. Bion (actually, easy for me :)) I made it worse! "How?" By not being smart enough to maintain perfect planeness and keeping all square. I ended up with a relatively flat end result, void of the scratches, but no matter how tight I squeezed handles there was always enough space on one side to guarantee a large fin.
I then bought some wet n dry paper which I folded so cutting side is up on top and bottom, and ran that thru hoping it would fix things. It didn't :(.
Good luck to you -- my "hindsight" thought was had I adroitly cut a square in a hardwood block to drop the offending mould half in -- a tight fit in perfect alignment -- perhaps I could have run it as such on wet paper on a sheet of glass to have achieved better result. The large wood piece would have avoided tendency to not maintain requisite parallelism. ("Yes!" re suggestions vis milling machine) Again -- just a thought here. Good luck!
geo

[Rapier]

I have a Bridgeport mill, so would mill the top to repair the scoring grooves and wet/dry the bottom of the sprue plate on plate glass to prevent a repeat of the scoring. I have a 18” square plate glass table, that I made, to do finishing on, you measure the surface height off the glass, corner to corner, to get a perfectly flat and parallel surface that is flush with the mold body when finished.

Times like these, I wish I kept the surface grinder…..a three phase, only have two phase and one converter at the moment.

[deltaenterprizes]

Paint with a magic marker the top before you start so you can see if you are leaning towards one side or the other!

[rintinglen]

Figure 8's on a flat surface with the 180 and 220 glued down with steady, even pressure. 280 and 320, no need to go much finer in my view, it's a mold not a mirror. Of course, if you have a mill and the skill to use it, it is easy-peasy. As has been said, it is a 10 minute job then. But sand paper will work, and it won't take too much time. That lee aluminum is soft.

And just as a hint, don't forget to clean up the sprue plate as well. I won't say how I now know, but trust me, you don't want to make extra work for yourself.

[justindad]

I’ve repaired one like this with a Lansky knife sharpening stone. I have the 5 stone kit, and I used the 2nd finest grit (red stone). It is necessary to confirm your stone is flat, and not all 5 of mine are flat.
*
It was not necessary to remove enough material to completely remove the gouges. Just polish off the high spots and it works fine… a little bonus venting to help cast square bases.
*
You have burrs protruding into your cavities now, and how you choose to repair this may create more burrs. The stoning method does not create burrs, but the stone is good for removing burrs. You will want to be very gentle here. I basically used the weight of the stone only, and did not apply any additional pressure by hand. Burrs gone, mold works.
*
A more gentle way of removing burrs is to get a biodegradable butter knife (from Stackman on Amazon), and rub the face of the mold with the side of the knife. What you are doing here is using the edges on the mold to shave material off the biodegradable knife. This is a slow process, and it would be a challenge to harm your mold with this method.

[rbuck351]

Knock down the high spots but no more using a piece of glass with a piece of 600 wet or dry taped to it. Polish the bottom of the sprue plate the same way. Then lightly leement the bottom of the mold cavity.

[Cap'n Morgan]

+1 on using a lathe. Much easier to find someone with access to a lathe, than a mill.

You don't need a 4-jaw adjustable chuck ; a normal 3-jaw will do. Just make sure one of the claws are perpendicular to the cavities
It doesn't matter if the mould is way off center as long as the top flat is parallel to the chuck face.

[MOA]

Figure 8's on a flat surface with the 180 and 220 glued down with steady, even pressure. 280 and 320, no need to go much finer in my view, it's a mold not a mirror. Of course, if you have a mill and the skill to use it, it is easy-peasy. As has been said, it is a 10 minute job then. But sand paper will work, and it won't take too much time. That lee aluminum is soft.

And just as a hint, don't forget to clean up the sprue plate as well. I won't say how I now know, but trust me, you don't want to make extra work for yourself.

It's an rcbs mold. Not aluminum by Lee.

[truckjohn]

Be very careful of lapping or grinding these. It is really easy to get the geometry totally out of whack.

I would clean up any lead residue and just try casting with it before you do anything else. Next step would be to is use a shot of dry mold release in the rough area to lube and sort of clog up the gouges. They look bad, but are probably smaller than you think. They may not really even cause a problem so long as the sprue plate is in good shape.

[Bent Ramrod]

I definitely would cast a bunch of boolits first, and, if they cast OK, see how they load and shoot. It may be that the marks at the side of the boolit base will iron out in sizing/lubing, or, if they don’t, lapping the first band of the cavity slightly might minimize or eliminate the marks.

As long as the sprue plate lies flat on the blocks and no metal flows into the galled area, I’d just treat the situation as cosmetic and ignore it.

[gwpercle]

I've got a set of Lyman #375449 with exactly the same problem. The scoring is so deep that the sprue plate won't sit square on the top of the mold. I'd thought about sanding down the top of the mold with some wet/dry sandpaper and a surface plate, but was worried that it might make the gas check shank too short. After reading through these posts I realize that sanding the top of the molds is the best solution. It's very likely that the shank will still be long enough for the gas check after the scoring's been removed, and because the mold in it's current condition is unusable I really don't have anything to loose by trying it.

The shank is usually enough longer than the height of a gas check where you can remove enought of the block and still have the check seat .
Measure length of shank and how tall GC is ... there should be plenty of metal ...
could always buy short checks !
Gary

[MOA]

I definitely would cast a bunch of boolits first, and, if they cast OK, see how they load and shoot. It may be that the marks at the side of the boolit base will iron out in sizing/lubing, or, if they don’t, lapping the first band of the cavity slightly might minimize or eliminate the marks.

As long as the sprue plate lies flat on the blocks and no metal flows into the galled area, I’d just treat the situation as cosmetic and ignore it.

I cast about 1000 boolits. Only about 300 were even usable, just barely.

[405grain]

300322 300323 I'm glad I read this thread. I had a few thousandths milled off the top of the mold blocks and now the mold is good as new. The gas check shank is still plenty long enough. Always such good information on this site.

[SSG_Reloader]

I had a couple I needed to fix a little bit. I started at 220 and then finished with a 400 grit.

[farmbif]

ive got very similar to what moa shows us. its a Lyman 429667 dont remember where I got it, but was thinking a surface grinder or mill with a fly cutter would clean it up. since ive got a couple others including my current favorite mp 432640 ill probably put it up on S&S since I no longer have a surface grinder or a mill.

[MOA]

Found a S.A.S.S. shooter that had some milling machines and a surface grinder. Just picked it up yesterday. Not all of it is gone. The gouge was about 7 thousands deep. I'll see how it casts. There's always the glass and 320 grit.

https://i.postimg.cc/brnPmTz6/20220526-133036-HDR-1.jpg (https://postimg.cc/zHq4BTHW)

[Jeff Michel]

Looks great Barry, nice save.

[john.k]

An old mirror with a peeled silver coat ,couple of sheets of good quality abrasive paper ,and maybe 10 minutes .....and use a bit of beeswax on the sprue plate pivot while casting.......RCBS moulds are made of soft cast iron,not much harder than ally moulds(should say used to be......they are steel now.)

[alfadan]

If you haven't fixed it already, maybe search craigslist or something for some granite counter cutouts. I picked up a couple really cheap just for lapping. They are plenty flat enough for these purposes. As said, use figure-eights and swap end for end constantly. Dont apply a lot of pressure, just a nice even pressure or the corners will round off.

Or ship it to me and I'll fly cut it on my bridgeport for free...if you dare![smilie=l:

[MOA]

If you haven't fixed it already, maybe search craigslist or something for some granite counter cutouts. I picked up a couple really cheap just for lapping. They are plenty flat enough for these purposes. As said, use figure-eights and swap end for end constantly. Dont apply a lot of pressure, just a nice even pressure or the corners will round off.

Or ship it to me and I'll fly cut it on my bridgeport for free...if you dare![smilie=l:

Thanks so much for the kind offer alfadan. Hopefully it's fixed. Will run some through it next week. See image in post #34.

[alfadan]

Good deal. You might check the hole edge for burrs.

[MOA]

Good deal. You might check the hole edge for burrs.

Yes. I was wondering what I should use to lightly abrade it.

[alfadan]

I think its a best-judgment kind of thing. If I didn't have any deburring stuff, just use a pocket knife VERY lightly around the edge

[MOA]

I think its a best-judgment kind of thing. If I didn't have any deburring stuff, just use a pocket knife VERY lightly around the edge

I've a couple of deburring tools for brass cases after case trimming.

[alfadan]

Probably stating the obvious, but don't want to chamfer the edges too much or you end up with bell-bottom bullets!

[rintinglen]

It's an rcbs mold. Not aluminum by Lee.

Well, it'll work the same way, just take longer.;-)

[popper]

You fixed it but being a GC mould, I wouldn't worry. You're going to 'replace' the base with a GC anyway. Worst you could get is some flash on the shank.

[gwpercle]

Just use a small section of abrasive paper to soften the edge / remove any burrs ... a flat base , sharp edge is preferred . The gas check will go over the base .
I wouldn't use a chamfering tool or even a pocket knife .
Run a cotten Q-Tip around the edge ...it will snag any tiny burr's .
If the Q-Tip doesn't show any burrs ... leave it alone or very lightly smoot the edge with wet-r-dry abrasive paper .
Gary

[MOA]

Just use a small section of abrasive paper to soften the edge / remove any burrs ... a flat base , sharp edge is preferred . The gas check will go over the base .
I wouldn't use a chamfering tool or even a pocket knife .
Run a cotten Q-Tip around the edge ...it will snag any tiny burr's .
If the Q-Tip doesn't show any burrs ... leave it alone or very lightly smoot the edge with wet-r-dry abrasive paper .
Gary

Think I'll get a small diameter wooden dowel and lightly drag it over the sharp edge. That should be the ticket.

[beagle]

Right on. Milling machine with a fly cutter. 10 minute job once you get it dialed in.

Question. Have you tried it as is? May be all right./beagle


You know anyone with a milling machine? Thats a ten minute job. Any high school with a metal shop maybe? In the past, I have milled projects with a drill press and a cross slide vice. Turned out purty nice too. Necessity is the mother of invention.

[GregLaROCHE]

What does the bottom of the sprue plate look like? It could probably use a bit of attention too.

[405grain]

On my RCBS molds, if the bottom of the sprue plate's worn I'd lap it flat again. But on a Lyman the "mold repair kit" is so inexpensive that I just replace the plate. The repair kit is available from many sources. Here's just one of many examples: https://www.midwayusa.com/product/1010248998