Well my resize die is Crap

[DebosDave]

Ok, so I finally got around to running some brass through my resize die, and I did something vastly wrong. I ran the brass through a .284 expander button first, so I would be able to form a false shoulder for fire forming. Well, that went fine, then when I put the brass through my die, I couldn't feel the 6.5mm expander touch in the neck at all. Sure enough, the 6.5 bullets will just fall right through the neck.

I am guessing that the resize reamer walked when it was cutting the chamber. My process is below, perhaps you can tell me which part of my process sucks. I have a hunch I already know, but would like feedback. I am going to use a die blank with a precision pilot hole from Pacific Tool & Gauge for my next attmept.

Here is my process:

I first took some 1" 12L14 stock. I cut a piece off that was apporximately 1" longer than the die was to be. I center drilled one end, and chucked the other end (about 3/4" worth) in the 3-jaw. I then turned it down to .875" and then cut the groove and end of the die down to the minor diameter. I then threaded the section. Finally, I cut the unturned 1" off with a band saw.

I then took the basically exterior finished blank and chucked it in a 4-jaw with aluminum shims. I indicated this in to the minor diameter at the end of the die. I then re-touched the center with a center drill, and then ran a 1/4" drill through the entire length of the die. after starting the drill I re-checked the concentricity and it was good. I then ran a 15/64 chucking reamer through the die. At this point, I then chucked up a 5/16" bit and ran that about 1" into the end of the die. I then used a small boring bar, and enlarged the hole to .4xx just slightly smaller than the shoulder of my resizing reamer (I don't remember the exact measure at the moment). I then figured at this point, even though the hole through the die was larger than the pilot on my resize chambering reamer, that the initial hole that was bored would guide the reamer into the hole. I put the resize reamer into a Dave Manson floating reamer holder, and ran the reamer just past the benchmark on the reamer. I then faced the die end until the go gauge extended .142" past the end of the die.

Before starting this process, I made sure my tailstock was inline. I put a live center in the spindle and in the tailstock and after shimming a slight bit, they were dead nutz. Even with the tailstock indicated in, drill bits and the chucking reamers seemed to climb a tiny bit as they entered the die blank. I am wondering if I need to indicate the tailstock with the chuck in?

I am guessing the major problem is that I didn't have a proper pilot hole in the die blank, allowing the front of the reamer to walk a little during chambering?

Thanks for taking the time to read all that, and hopefully comment on where I went wrong.

Dave

[DebosDave]

Oh, when I measure a piece of brass that came out of my die it measures .290" and when I measure it out of the standard grendel die it is .285", which makes me think my die must be out at least .007". My die doesn't re-expand the neck on the way out, while the grendel die does, so thinking this may cause a .002" spring or so?

[38_Cal]

Not having the pilot supported allowed the reamer to slump some in the floating holder, which is probably why the reamed cavity is over sized. A better method would have been to drill & ream for the pilot dia. + .0005", and not try to rough out the cavity. Unless you're going into production, doing dozens of jobs per year with your reamers, roughing reamers or roughing out a barrel/die for a finish reamer are a waste of time and money. Let the reamer's front end be properly supported by the pilot in the barrel or reamed pilot hole, use lots of cutting oil and clear your chips every .040" to .070", and run the reamer at about 125-175 rpm. Use of a floating reamer holder will allow the reamer to follow the bore if it's not perfectly straight. This is the method I've used for the past 30 plus years, and have had good success with it.

David

[DebosDave]

How many chambers can you ream before the reamer needs to be re-sharpened?

Thanks

[38_Cal]

Depending on the steel, rpm, lube, feed, how often you clear chips, and even which pair of teeth you hold your tongue between when working, you can expect 25 to 150 barrels or dies. This is from information that Dave Manson shared with me over the years when I worked for Brownells tech department.

David

[rws]

DD, I usually buy a die blank from Newlon or a couple others, it just takes a few steps out of the process. But Ihave made them from stock.

The first thing I do is drill a hole through the stock blank. Run a reamer through to take out rough spots, and reference everything else from this drilled hole. While still in the chuck, I cut a 60* using the compound. Flip it around, indicate the other end using the hole, and cut another center.

I then chuck a scrap piece, turn a mating center, and use that with a dog to turn the OD and thread the blank.

I am not in the floating holder crowd. I believe in getting the tailstock aligned, and using a dead center to drive the reamer. I also pre-drill a chamber short of the shoulder, single point bore until the hole is within about .010" which also takes out any imperfections in the drilled hole. Bring on the reamer and it will follow that drilled hole perfectly. Minimal wear on the reamer and your chamber will be exactly concentric with the hole which you indicated. I a barrel where the bore is not straight, use an indicator where you can get far enough up the barrel/hole to indicate where te throat will be. Your chamber will be right there as well. In the die, the same methods are used.

With a barrel, the groove is the critical point to reference. With a die it's the bored hole.

Also, with pre-drilling and single point boring the chamber, you really don't need bushings, the reamer has it's guide already established. I have seen, and anyone else can too with a .0001" indicator, often there is a land higher than the others. If you use bushings, the reamer will follow that bore diameter, not the groove diameter.

It works, a little more time involved, but this methods is used by many top benchrest smiths.

[DebosDave]

RWS,

Why didn't my reamer follow my bored hole in? Do you think it was due to the floating reamer holder? I did basically what you are saying aside from turning the outside to the inside, I turned the inside to the outside. Maybe my hole wasn't true to the exterior? The hole in my die was too large to guide the pilot bushing on the reamer.

Thanks

DD

[rws]

How did the rest of the sized brass look, not counting the neck? Did you try it in the chamber?

The reason I ask, was the resize reamer intended on sizing the neck, or was it intended to be a bushing die?

I re-read your initial post, and you did follow good procedure, sorry I must have rushed through the read.

If the rest of the die sizes properly, you might be able to convert it to a bushing die to size the neck.

Since I don't use a floater, I can't say whether the reamer drifted or not. I think the concept of using a floater is for the pilot bushing on the reamer to do the steering. Since your hole rendered that mute, I assume it could have not followed straight.

Did you harden the die, just curious?

[DebosDave]

I didn't harden the die ever, wanted to test it before I did that. so I could make changes as it stood. I think I need to measure the neck of the reamer and see what it gives compared to the chamber die. I haven't done that yet. I am just posting another thread here discussing how I turned this die into a hydro-forming die

Thanks for the help, I am going to try again with a pre-made blank, so hopefully it will just follow the precision pilot hole and give me good results. I will update at that point.

[DebosDave]

Well, in trying to eliminate variables in my process to give me a clue as to what to do differently, It occured to me that I should measure the neck diameter on the reamer. It turns out that the reamer has a neck of .290", which is exactly why my finished brass comes out right about .290". This means that my process is intact, and that the chamber I reamed is in good condition. The reamer didn't walk, it was just spec'd slightly too large in the neck. I am sending it back to get re-ground, so I will be able to try again soon!