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Based on quite a few home made die posts my guess is cutting the point forming dies .004 under than the finished size, than lap/polish. Remember is a summation, not a fact. I've never cut a reamer and am preparing to, and hope I can be successful. I too will try core seating and round over dies which should be a little easier. Any information is welcome.
Bill
I have been moving to the same goal. It seems like the numbers are fuzzy.
Starting with O-1 tool steel, you turn to say .308.
With heat treating that diameter may change, pretty much have to try, and see what happens.
So far I have built a radius cutting tool for my lathe and cut a couple lengths of drill rod to about 5r curve.
Right now side tracked by other projects.Attachment 226695
'Re read Smith's paper, he used graphmo for the dies and drill rod for the reams. .004 is his number.
Once you make your die and its a little under sized if you use a lead slug to swage and check for size as you are polishing dont polish up to final size. Stay a little under. What i found is that when you make the actual bullet it will be a little bigger that the lead slug. Seems there is a little spring back with the brass, not much but a little.
As far as staying .004 under that depends on how good of a job you did on your reamer. I like the three flute reamer. Takes some time to make but worked the best for me. It has to be polished and sharp before heat treating. I found the better the reamer the better finish and means less flaws in the die to polish out before you end up too big. Ive been there done that. I dont made the D reamer's any more.
There is a long standing theory that cutting tools with odd numbers of flutes are less prone to chatter, the fly in the ointment is that they are harder to measure :-). I saw one posters square block he made to hold his reamers while fluting, the square provided the index. A piece of Hex stock, or even some Hex nuts modified to fit the tool holder would provide a 3 flute index. Again though long standing theory on reamers is that the flute spacing should not be exact either...in the book "The Modern Gunsmith" by Howe he details how much to "throw off" the flute spacing. I have seen it specified as a certain number of holes on a dividing plate head.Quote:
Originally Posted by lead chucker
For a 3 flute index slightly modifying one flat on the hex would provide that intentional mis spacing.
One way to true up a reamer after heat treat might be ream some aluminum with it, carefully polish the inside profile,
then load the aluminum ID with clover lapping compound, the part just cut will then become a lap, and careful use would allow you to lap the cutter that just made the hole, or to lap another one that was very similar but not exactly the same due to being hand made and not a machine generated profile.
I have used aluminum like that to lap a radius on lathe steady rest fingers so they did not "slap" when running them on an aluminum ring that was split for a pinch bolt. The aluminum charged with clover cuts way faster than one would think.
The profile lapping process if done carefully would look like a spun ground profile, I'd rotate the lap in the lathe chuck and control the reamer against the tailstock center just like we were chambering a barrel, and only let it very gently touch the lap. I'm going to have to try this, IMHO it will work slick :-).
When lapping the abrasive will always load into the softer material...any loose abrasive wandering around is bad and should be rinsed out.
Bill
I built a radius tool based on the idea Cane_man had in his .308/7mm post. It's a monster. It's good for repeatable radii. Right now it's a great paper weight.http://castboolits.gunloads.com/show...=1#post3903736Quote:
Originally Posted by clodhopper
D reamers are out of the question at this time. I have a piece of hex stock ready to be drilled to use for 2,3 or 4 sided cutters. I'm leaning toward 3, however 2 would be easier. I'm trying to wrap my mind around this aluminum idea, however at this time it's adding to information overload.
Bill
I made my point die reamers with 3 flutes and core and core swage with 6. All turned out great and cut 01 like butter!
Nice cutter Bill, I have this set of collet blocks, but have not used it yet making reamers.
https://www.ebay.com/i/112194207638?chn=ps
And a set of 5C collets
Faret, a six flute cutter. You must have a milling machine.
Just think of it as an outside lap :-). I have made a few laps to repair damaged shafts before.Quote:
Originally Posted by just bill
Bill
Yes. Used the nut method described above.Quote:
Originally Posted by just bill
One could index "by hand" using a variety of methods, better if you get all the milling done in one go and do not need to re index, with the benefits of inexact indexing it might even turn out better than one made on a dividing head. One way that comes to mind to hand index would be a simple degree wheel..like you use to setup a camshaft but smaller to fit the situation. The nut may be easier though :-).Quote:
Originally Posted by Faret
Will, a couple things, if using the aluminum method, you heat treat the ream, cut the aluminum, load the bored hole with clover, carefully lap the ream, then do you re sharpen the ream then ream the die. Then lap the die?
Clover is around 280 grit, how does this compare to permatex gray valve compound?
I am going to take a rabbit trail, I'm planning to make a prototype punch and holder that involves much the same lathe work as a reamer, however I'm going to try it with grade 5 bolts. Would it be best to temper the bolts before turning.
My guess is that it won't need heat treated since it is just for reshaping anealed brass.
Bill
This is how I do it:
https://www.dropbox.com/s/yk8mjckxd7...ntDie.MP4?dl=0
Thanks
Clover actually comes in a bazillion grades :-). Most of it is Silicon carbide too which breaks down really quickly.Quote:
Originally Posted by just bill
https://www.kemet.co.uk/blog/lapping...parision-chart
The valve grinding compound made by Permetex is also Silicon Carbide...I was thinking the old school stuff in the double ended can was carborundum which is aluminum oxide ?
https://441py33rout1ptjxn2lupv31-wpe...lish/80036.pdf
But if/when I try it I will create a round OD, probably by turning and polishing. Then back it off to a hair land..which would be say .01" or less of the round OD remaining, then heat treat. Then with ream aluminum with it..leave it right in the lathe after. Then load the aluminum with abrasive...a rough turned blank from the making reamer state might work. Then rinse out any loose abrasive..thinking some kind of container under the part so we do not get abrasive on the lathe ways. Then turn the loaded lap in reverse, put the newly created reamer on the tailstock center, and very gently press it to the loaded spinning oiled lap....then let everything settle while the chuck spins. Not so much that anything is rattling around loose. Our hair land will get a little bigger..we may need to go back and relieve more after. But really it is just a controlled touch up to make sure all the flutes are exactly the same contour.
Just thinking anyway :-). The other cool thing about it is that once created the tool would allow duplication of a contour...in my case I want to make a "near net" bullet mold....presuming that reamer dia will be different than the reamer for the swage die.
Bill
Grade 5 are made for toughness, looks like they are 25-34 Rockwell C...I would expect some stress included from the thread rolling process.Quote:
Originally Posted by just bill
Grade 8 and 33-39 Rockwell C
Socket head capscrews sometimes are referred to as grade 8 but they actually have their own spec, Hardness: HRC 39-45 (through ½”), HRC 37-45 (above ½”) .
I deal with broken 1-1/4" socket head capscrews at work sometimes, they are really a pain to drill into...they eat plain old HSS twist drills for breakfast :-). HSS endmills cut them a little better but will still suffer. I will have to drill into one to use an Easy Out and at times I will have to drill with a 3/8" drill till it refuses to cut, then flat bottom with a 3/8 HSS endmill, then a new 3/8 drill, then the endmill...repeating until I get enough dept for the easy out to work. Even more fun is sometimes they are 12' up from the floor and the whole machine is heated to 200F+ :-).