Made a CPL pellet sizer and "D" reamer! Real long wandering post!
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Made a CPL pellet sizer and "D" reamer! Real long wandering post!
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Topic: Made a CPL pellet sizer and "D" reamer! Real long wandering post! (Read 2817 times))
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Real Name: Ed
Made a CPL pellet sizer and "D" reamer! Real long wandering post!
«
on:
July 03, 2015, 04:35:07 PM »
I've made a couple pellet sizers for my 7.9 grain CPLs, one reduced the pellet head to 4.54mm and the other reducer reduces that pellet head to 4.52mm and expands the skirt to 4.63mm at the same time. Here are a couple pics of the 4.52mm sizer.......
Uploaded at Snapagogo.com
Here are the sizer parts all cleaned up and the "ram tip" profile refined.......
Uploaded at Snapagogo.com
Uploaded at Snapagogo.com
This pic shows the 1/16" long "4.52mm part" of the die seen as a faint line at the top of the pic. LOL....there is
VERY LITTLE
difference between the 4.52mm "head sizer" and the 4.53mm "skirt expander" part of the bore in the die!.........
Uploaded at Snapagogo.com
Here the CPL has the head sized (notice the flat on the edge of the pellet head) and the pellet skirt was expanded when the "ram" pushed the pellet head through the stepped die. Anywhoo......the bore in the die was cut using a small home made boring bar fabricated from a masonry nail that was "extra hardened" after grinding to shape.
I found that it was really tedious to bore the "step" in the die to size and this was done by boring a bit, pushing through a new CPL, boring a bit more and pushing through a new CPL, so on and so forth till the pellet head was the size I needed. The problem is that the "pellet head sizer" part of the die didn't produce a perfectly round pellet head but it a bit oval at 4.52mm x 4.50mm (as measured by my digital calliper). I'm not very concerned about the "finite size" only that the CPL head would be reduced from 4.52mm (as measured with my digital calliper) which was rather snug fitting in the leade to a fit that was still tight but not "thumb hurtin' tight". I also wanted all pellets to be exactly the same size whatever that size ended up at, plus the skirt expanded a bit. By lapping the die with a brass lap and some JB Bore Paste I was able to get the "ovality" of the sized pellet head to 4.52mm x 4.51mm which actually works really well, however I bought a #2 taper reamer for my next pellet head sizer thinking that the bore in the die would be very "round" and nicely finished without a
LOT
of lapping. Here is the reamer before even using yet.....
Uploaded at Snapagogo.com
Well...when researching "taper reamers" I found this post in a "gunsmith site" where folks were making "D" reamers for chambering their barrels.......
"I have been making a few D-bit chamber reamers, they work great. I shoot mostly cast bullets so I have been messing with a longer throat (0.200 - 0.300") that is a bit on the tighter side (~0.002" under bullet dia) and doing a ~1-2 degree lead into the rifling.
I have been mostly working with surplus prechambered barrels from places like Numrich. When I have done chamber castings I find these chambers have little to no throat ahead of the case neck and the angle leading into the rifling is in the 30 degree range. Sometimes there is just an angled cone from the OD diameter of the case neck to the top of the lands, no throat and a really aggressive angle. A really aggressive angle can work OK for jacketed, not worthy for cast bullets in my experance. I have been taking off a bit of these barrels so they are “short chambered”, then I am able to cut them to how I like them with one of my homemade D-Bit reamers.
I will be the first to admit that I don’t have a clue when it comes to chamber design. Most of what I know I glean from Mike Bellm’s website (Home). He has many thoughts on chambers alignment and design which make sense to me and I have embraced.
Hopefully I will get a few photos to post up in a few days. If you are learning and time is not an issue you can cut a great looking chamber (the chamber casting even measures up really well). I would never buy a reamer for these one-off projects I am doing, but a d-bit chamber reamer lets these projects happen.
What I do: Fully turn the profile that I want for the reamer. I am turning these out of ˝” O1 tool steel. I make sure to leave a full diameter section of the tool steel at each end. I then clamp these full diameter sections into a V-block at either end of the just turned reamer.
Then I will mill off slightly less then half the diameter (~0.005-0.008” under halfway). I then cut off the full ˝” diameter part from the pilot end of reamer(the part that I had clamped to the V-block) and heat treat the O1. BTW, I don’t take off the burrs from the milling operation, I feel like they add metal that protects the cutting edge from burning off during heat treating.
Personally I don’t bother with the whole drill press assembly. I take a 10” long piece of 1” ID steel pipe, mount it vertically in a vice and suspend my reamer large size down in the middle of the pipe by a piece of iron wire. I then put a propane rosebud torch into the bottom of the pipe and heat the reamer up to a nice red. The color is very easy to read in the dark pipe and the heat is very even, the reamer comes up nice and slow in colors, no hot spots like I would get with and oxy-act torch.
I will temper the steel in the same oil that the quench in (you heated your quench oil up to ~120 F right?), I just put my metal quench pot on the stove and heat it up to ~300 F, I never take out the reamer that I just quenched. This may do nothing, but my heat treating book tells me this tempering does drop it to RC 62 and I have so much time in the reamer by now that it makes me feel like the extra bit of time is worth it.
After heat treating I will clamp the reamer into a vice and lovingly stone the flat surface of the reamer until it is all even and bright at the cutting edge. I put no relief on the round part of the reamer, it has not been necessary for me, they cut great in barrel steel, nice curls come off.
When reaming a chamber on the lathe I find that I must use a dead center on the back of the reamer to keep it from gouging into the chamber wall and making things look all chattered up and crappy. (you did put a center hole in the back reamer so you can put a center on the reamer, right?) I have no idea if a floating chamber reamer holder would work or holding the reamer in a collet or Jacobs chuck. I like to be able to hold the reamer with a wrench and feel how much it is loading up. I don’t want to bind things and snap it or roll a curl under the reamer and mean woman up the chamber.
Yes, it cuts slowly and requires frequent cleaning, but no big deal. This is a hobby (at least for me) and it does not take that long to cut a custom chamber to whatever crazy specs you think will work best for you."
The decision to made to create a "test D reamer" from a piece of scrap 3/8" O1 drill rod and it worked a treat!
Well.....I'm amazed at how nice of a finish I could get with the "D" reamer alone when cutting on a scrap piece of pot metal!
Uploaded at Snapagogo.com
Uploaded at Snapagogo.com
Taking a piece of 3/8" O1 drill rod I first milled the flat almost half the thickness of the rod using my small milling machine, then I heated the "cutting end" cherry red and quenched it in oil. After cooling, the hardened end was polished and then annealed to "blue color", then it went to the grinder, and finally honed.
LOL.....after seeing how easy it was to make this reamer, and since I work slow on my bench top lathe anyway, I'm thinking of using this approach for a boring bar instead of what I've been using. With a boring bar in my relatively small lathe I would get a lot of chatter unless everything was set up perfectly, however with this "D" reamer I did all reaming at 1000rpm and nary a chatter!
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USA, North Carolina, Rougemont
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Made a CPL pellet sizer and "D" reamer! Real long wandering post!