View Full Version : Speaking of lathe boring moulds
05-02-2005, 12:39 AM
This is a Lyman 12 gage slug mould that one of the members here (I think Leftoverdj) entrusted to my tender mercies. What he wanted was 3, that's THREE drive bands cut into it. If you look close:lol: you'll probably count 4 of'em. Please remember I'd only had my lathe a few months when this job came up.
I was heavy on theory, being an avid reader and this isn't the great unknown. I did a pretty good job in fabricating a toothed boring bar to do the cutting. And I also sucked it up and got over the absolute terror of trusting the dial indicators in sticking it down into the cavity where you cannot see. So what happened? It's the simple things that mess you up. I failed to figure in the width of the boring bar when advancing it for the next cut.
I believe it was while actually cutting the 2nd band when that sinking feeling in the pit of your stomach comes over you. Like it being the end of the first week of a 2 week cruise and you suddenly remember you left the bathtub filling? Yeah, that kind of feeling. Added in on top of the initial terror of blind metal removeal on someone else's property.
While it turned out looking good, and I was reassured on my process, it was wrong, and NOT what the customer had ordered. I felt real bad about that but he refused replacement and said that it shot better. I can't help but feel that it may have been even better yet with only the desired 3 drive bands? You may believe me when I say that now everything goes down on paper and the process is worked through in steps before metal meets metal!
05-04-2005, 03:28 PM
Bothered Buckshot a lot more than it did me. I wanted .735 diameter and a leading ledge to roll crimp against and that's what I got. Three drive bands or four made no nevermind to me.
Since I have one of those #(*&%$ undersized Lymans and a lathe, and since y'all now have EXPERIENCE in doing one, how would you do it differently?
How does it cast? (I assume that you still have to use a tourch on the center plug to keep it warm enough for it to fill out.) How much draft on the grooves and do you find the 0.735 is the right diameter?
Ballistics in Scotland
05-10-2005, 02:24 AM
My use of mine got preempted by finding out how well a 16g. round ball in a 12g. plastic shot-cup wad worked. I always thought, though, that if you were making it to a closer fit in the bore, it would work better if the hollow-base plug were slightly conical. Besides having the alloy pouring into a wider and more tapered space, you could use a harder alloy that would fill the edges of the cavity better.
I always thought the logic behind making the thing so undersize was a bit fishy. If it expands to fill the bore, what good does being undersize do? If it doesn't, why does it need that long, almost parallel skirt? I think they just wanted to protect themselves after an accident due to being loaded with charges no slug gun can be counted on to stand.
I suppose you would true up the lathe on a round pin which fits and extends from the base-pin hole?
05-10-2005, 02:23 PM
Everytime I look at this post I wonder how well that slug would shoot from my fully rifled Ithaca.
05-12-2005, 12:18 AM
............Trk, "Since I have one of those #(*&%$ undersized Lymans and a lathe, and since y'all now have EXPERIENCE in doing one, how would you do it differently?"
Well uh, first I would remember to add in the width of the boring bar when advancing the carriage for the next cut[smilie=l: One of the more basic fundamentals of machining in cutting internal grooves for snap rings and things. Also the danger that lurks in machining in areas you cannot see!
Kind of like one of those mistakes made in writting code for a CNC milling operation. When after making a pass you forget to have the tool retract but tell it to move to a different spot. You break the tool and possibly ruin the workpiece or maybe you machine a nice big slot across it, and ruin the piece.
Setup oopsis, and forgetting simple details will have your personal butt in the frying pan, mo-skosh.
So if there are no changes to groove form or OD, then my point of aim will be groove diamter of the bore and probably three bands.
I've got one in 20 and one in 12 - the 20 is headed for a single barrel fully rifled and the 12 for a rifled screw in choke for a Browning UPS.
05-12-2005, 09:50 PM
The cast iron is here TRKand Buckshot. I just finished 4 sets of Aluminum blocks for 12 gauge. They are 2.000 by 2.000 by 1.875". They would have been 2.000" square, but I didn't leave enough room to clean up after the saw parted the block sets. I machined them in matched sets of 6. I already cut the material for you TRK, it is in 3 pieces 12.750" long to allow for the saw to part the sets of 6. I started machining them to finish up at 1.000". What thickness did you need? The bar was cut at 2.125" by 1.125"to allow for cleanup to finish at 1 by 2. Greg You can email me with your contact info, so I can ship it to you. Greg S
Many thanks for the call! Took me by surprize, but the information you shared was most helpful to me (just getting started in mould making).
You have a wealth of information and experience - I'm looking forward to your posts and pictures here!
05-25-2005, 09:21 PM
Something you might try is paper patching the undersized Lyman slug.
I have done some experimenting with pretty good success. Basically the same operation as for the old hollw base slug gun bullets - use a heavy cotton or linen bond paper of the right weight to allow 2 or 3 wraps so the wrapped slug will fill the bore, cut the patches about 1 1/2 lengths of the slug, wet with water or saliva, wrap the slug with the excess length of patch extending past the hollow base, twist and tuck into the hollow base, let dry and load.
I have to do some more experimenting but results so far have been promising.
05-25-2005, 09:35 PM
I used to make those, and still do some sinew backed Indian bows. Good to see a traditional shooter in the bunch.
05-26-2005, 09:54 PM
I was in the shop today making mold blocks. I used the Durabar cast iron, grade 65-45-12 for the molds. It machines well, and is very clean, without hard spots. It reams funny though, Some reamed holes are oversize, even though the reamer was undersize. The funny thing is about half of the holes are .0005 oversize, when the reamer was running true, and was .001" undersize. I will use .001"oversize pins. If I order some do you need any? I am using Holo-Krome Allen 3/16 Dowel pins. You just have to grind a taper on one end.
The new blocks are 2.000" cubes, and will allow for a 1.200" long big bullet before the cavity even comes close to the handle slots. I can use then for an 8 gauge If I wanted. They dwarf most single cavity molds. The handles are .500" from the bottom of the mold blocks. I am going to try cutting shallower handle slots, that will still use the RCBS handles. The sprue plates are .250" Oil hardening steel.
I am going to program the CNC mill for my next run of blocks. That way the mill can automatically move the drill for the holes. I have been making the blocks in sets of 4-6, and cuttingthem apart later on the saw.
I sent 2 sets of blocks out to be bored, for me in 12 gauge, .730" and .740". I ahve different barrels, and need the 2 diameters to shoot in the right gun. I will let you know about the quality of the cavity when I get it back in a month or two. Greg
05-28-2005, 02:02 AM
"............I was in the shop today making mold blocks. I used the Durabar cast iron, grade 65-45-12 for the molds. It machines well, and is very clean, without hard spots. It reams funny though, Some reamed holes are oversize, even though the reamer was undersize."
Setup issues? Reamer loading up? Reamer slightly warped?
".............The funny thing is about half of the holes are .0005 oversize, when the reamer was running true, and was .001" undersize."
Ah, I get it. The reamer was an undersize but giving you a hole a half thou overspec? You miked the reamer on all flats all the way around? Who made the reamers, L&I, Cleveland Twist or Huang Lei-Nakong Happy Worker factory # 11 ? :-) In my collection of reamers I have some of the later. Mike the flutes. It's a wonderous thing.
05-28-2005, 01:03 PM
Hi, guys, how ya doin'? Reamers will cut oversize when everything seems to be okay when the cutting edge relief angles are not all the same angle or are not all dimensionally symetrical. The only part of a reamer that is supposed to cut is the front of the lands. The edges of the lands along the sides of the body of the reamer are not sharpened and the lands act only as bearing surfaces. The flutes act as a reservoir for stray chips and lubricating oil. The body of the reamer is theoretically a very, very light press fit into the hole that is being reamed. When everything is going the way it should, the hole will be the same diameter as the reamer and very straight. When the cutting relief angles are all different on the reamer nose, one cutting edge will cut more than all the others. A combination of high cutting pressure on that one cutting edge along with the chip build-up in that one flute will push the reamer off to one side against the inside of the hole, making the other side of the reamer cut a diameter larger than the reamer diameter. Cast iron does this worse than most metals, hard yellow brass the least. The cause of the cutting edges being all different on a new reamer is worker ineptness of the guy who sharpens the reamers not keeping the grinding machine indexing detents clean and the indexing is unevenly spaced when the cutting edges are sharpened. Sometimes you see reamers with odd numbers of flutes, and the reason is to help prevent over-size holes since 180Â° opposite from a cutting edge is a flute. That way when the reamer gets pushed off to one side there is an open space instead of a cutting edge. Odd fluted reamers are not all that common, though, because cutter-grinders can't measure them without a special micrometer.
Something you might try is paper patching the undersized Lyman slug.
I've done that. It took 8 to 12 wraps of heavy paper to bring it up to a sliding fit in the 12ga cylinder bore single shot - 18' bbl.
Excellent results - I could hit bricks at 35 paces (without any sights) 4 times of 5.
Since the patching was so thick, I thought it would be much better to change the mould.
05-29-2005, 08:16 AM
Your Lyman mold must be smaller than mine. Mine casts at .715 so it only takes a few wraps of heavy paper.
Another thing I have tried recently is to accurrize .69 cal round ball. Ballistic Products makes a very nice smootbore slug they call the AQ and it shoots real well but is a little pricey for just shooting. The AQ is essentially a slightly undersize ball with a plastic base/fin attached similar to a Brenneke slug design.
SInce I like to shoot and make my own stuff I decided that I could use a .69 cal. ball set into a short paper tube (sort of paper patched like) then fill the tube with hot melt glue. That gave me a kind of "AQ" copy. The first test wasn't so good as the glue must not have bonded to the balls well, so the second time I drilled the balls and put a short brass screw in then the hot melt - good groups. It isn't near as much trouble as it sounds as the balls cast real fast compared to hollow base slugs.
I doubt it would work well in a rifled barrel or rifled choke tube but looks good in a smoothbore.
Also, due to the solid nature of the .69 cal ball I wouldn't shoot this through anything more than an improved cylinder choke like on my slug barrel. The Ballistic Products AQ slug is actually hollowed out to attach the "fin" so it should collapse if it hits a choke but they don't recommend shooting through a choke either.
I used Ballistic Products .69 cal. ball load recipes and let the hot melt replace some of the wad in the recipe. Messing with shotgun loads can be dangerous but this .69 cal. "slug" is really no different than the .69 cal ball load - just some of the filler wad is attached.
This should also work with a smaller (16 ga.) ball or "other" slug of the right weight (.58 cal.?) if the paper patched hot melt is the right diameter and the "slug" is the right weight there should be no problems except centering the slug in the paper tube. Just use published recipes for the weight of slug you are using - this is a slight wad column change. This would be safer if it accidentally got shot through a tight choke. There are lots of load recipes available for anything from 7/8 oz. to 1 1/4 oz.
05-30-2005, 10:06 PM
The reamer was new, and miked before use. The holes were reamed dry, and a little at a time, while using a chip bruch to clean it. Some of the holes are okay, but others are a little oversize, I am just going to order some .1877" pina and be done.
I have been thinking about the sprue plate pivot. Do you really need the lock washer on it? I am planning on using a 5/16 slotted head shoulder srew, and am debating on whether to leave room for a washer. If I leave minimal tolerance on the head, I shouldn't need the washer, and the screw will stay tight on the shoulder. I have left a hole in the blocks for a set screw if I need one in the future to keep the pivot from backing out. What do you guys think? Cost isn't a factor in the decision, I am trying to make the best mold I can. Thanks Greg
05-31-2005, 09:33 PM
...............For the sprueplate pivit on all my moulds (except Lee) I place a brass washer and then a wave washer on top of the sprueplate. Makes it very smooth and ther is no possibility of galling.
In this case, this was an abused set of blocks that had to be flycut, and the factory pivit pin was also trashed, so it too was replaced. I had opened up the pour holes so the brass washer in this instance is a bit closer to it then I like, but it worked fine.
05-31-2005, 09:45 PM
I ordered some 5/16-18 shoulder screws with a socket head for the pivot. They have a .375 Diameter shoulder and .312" in length for the shoulder. The hole screw is a bit over 1 inch. I also got the matching wave washers for it. I will try a small pice of brass shim stock to prevent galling, if space allows. The screw should not need a set screw to maintain tightness. As long as the sprue plate is thick enough, the shoulder shoud bear enough tension. The socket head should lessen stripping. I'd rather have a slotted head screw, but for convenience I ordered it all from the same place. Slotted head screws are easier to clean the solidified lead out.
I will let you know how it works out,and perhaps post pics if My brother can help me. I have no clue how to post the pics here. I will work on it as the time allows. Greg S
trk Your Lyman mold must be smaller than mine. Mine casts at .715 so it only takes a few wraps of heavy paper.... Longbow
Just miked one (Lino) 0.699 " diameter. (Think I cast that one in '79.)
06-04-2005, 07:19 PM
"I ordered some 5/16-18 shoulder screws with a socket head for the pivot. They have a .375 Diameter shoulder and .312" in length for the shoulder."
Are those the precision stainless ones? Geez, those things must be costing you $8 each! I use little ole 1/8 x 1/8, 8-32 versions for locking the HP stem flange and they cost a couple bucks from MSC.
Do some reading on the "TESTING" forum about posting photos. So far as I know, they have to be currently hosted on the web someplace. You then create an address for the photo. In your message screen here you can type and then paste the address in between the 2 bracketed IMG deals you added. It would look like: Photo address
06-04-2005, 07:23 PM
On reaming holes, I have generally found on cnc tools the more feed you have the smaller dia they cut, within limits, I usually started at .01" per rev. feed, and 80sfm for most steels
06-05-2005, 06:22 PM
The shoulder screws are stainless, and cost about $3 each as I recall. Igot them from www.sdp-si.com . They are reasonable, and have a tech support line if you need helpselecting the parts. You have to order online to avoid the $50 minimum on phone orders. I think they are going to work very well for the pivot.`I used a stainless wave washer, but had to grind the OD to make it not overhang the Sprue plate. Greg.
06-06-2005, 02:38 AM
...........Willbird, interesting. I don't know if I'd read that before, and that's where my info would have come from. I haven't been into this machining 'bidness' long enough to have found that out for myself.
Greg, thanks for that address.
Ballistics in Scotland
06-06-2005, 03:32 AM
A very useful source, with pictures of fastenings etc., is www.mcmaster.com . Not for me, unfortunately, unless my needs are ever large, since for overseas orders they now use a freighting service with a $60 minimum charge.
The website is of .pdf files, and not really good for browsing, and their print catalogue is such a massive doorstep of a book that I would think they only give it to large customers. If it can be paid for, it is certainly worth having.
06-06-2005, 07:31 AM
When the reamed holes came out oversize, my Grandfather said I probably fed it too fast, forcing it out of line. I was backing the reamer up every .375" or so and cleaning it. He said cast iron reams very tight when using sulferized cut oil, so we did not use it. He said it often pulls the reamer out of the chuck with the cut oil. I will use a .002" undersize reamer next time.
I looked at the McMaster-Carr site, and got pins from them for the molds. Their Shoulder screws were 2X the price, and the y didn't say where they were made. Their technical assistance crew could not even give me the specific diameter of the 3/16 .001 oversize pins. I asked if they were .1872,.1875, .1877" (common) or .188+. They said they had no idea, and sent me the pins free. I just wanted them to be a tight fit, but not too tight. Most pin manufactueres will quote the pin as to the .0001" that way it isn't such a pain to drive in the hole.
06-06-2005, 05:23 PM
...............BiS, McMaster-Carr catalogs are sold on E-bone:D. You are correct that they don't just hand them out. Should you like a similar massive hardcover 'We have it all' type catalog, ask for one from MSC. It's about 4.5" thick and they send it by merely asking for it.
Another nifty one is the Rutland Tool (owned by Airgas) catalog. It's about 2" thick but printed on more expensive coated stock and is in full color. I like their catalog but they pissed me off so I don't buy from them anymore. And that was a big problem for them as at the time I was trying to buy (it seemed) one each of every machine tool accesory known to mankind.
06-06-2005, 09:23 PM
Another hefty catalog I got a couple of is from J&L Industrial Supply. They were free and they sent me a couple of them although I just ordered a small amount from them.
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