Machining in Tenths

[BT Sniper]

Yes tenths. As in tenths of thousands .0001 Impossible? Anything is possible but lets take a moment to think just how small that is!

a sheet of notebook paper = .003 as in 3 thousands or 30 tenths
measure a strand of my thinning hair = .002 or two thousands or 20 tenths

So what sort of tollerance are we talking about when it comes to swage dies? What sort of tollerances do bullets need to be at? typically I go for +/- .0005 from nominal bullet diameter ie. 30 cal= .3075-.3085 usually going for .3080 - .3085.

So it amazes me just what is possible and what sort of effort it is to make that sort of machining possible.

Lets talk about my latest project. A 22 cal core seat die. The internial pin is .2230! That leaves me .0010 tollerance since I need to be bigger then .2230 for the pin to fit the die and smaller then .2240 (final bullet diameter) I don't know about you other machinists but that can be a bit stressful. Don't go to big or you have effectively made a very nice fishing weight.

So a lot of the skill/art comes down to lapping and polishing. Again don't go to big! and this is all before the die is heat treated. It is all a bit of a gamble spending an hour or more to lap a die using up severial different componds and laps and then in the end when the finish is glass smooth you realize you didn't take enough off and have to start over again. As for heat treating, just ask anyone who has had a piece of steel heat treated the odds of it growing or shrinking. A swage die that is not heat treated? well make sure you know what you are spending your money on!

So my first set of 22 cal dies is going out soon! lets take some measurements with a high dollar Mitutoyo micromiter! I can get readings to .0001, it just so happens that the measurements end in 0 or 5.

Internial pin is .2230
Ejected seated core is .2235
Final bullet diameter is .2240

I'm luckly that I got a professional heat treat company that are very good at what they do. I get little to no measureable change in the die before vs. after heat treat. This has a lot to do with the quality of the steel too I'm sure. I use quality 4140 tool steel.

Now once the die comes back from heat treat we are not done yet! While at teh heat treat company the die gets a trip threw a sand blaster or high tech dry honing they call it. This gives it a mat finish and gets ride of what little scale there is on the die after heat treating. Even after vaccum tempering. When I get the dies I finish them off with a good polish inside and out to bring it all to a high glass sheen. Well I don't know how small the sand particals are but they will scratch the inside of your couple hundred dollar die if you don't get it all removed. Don't ask me how I know this!

So when one asks why are swage dies so expensive or take so long to make or why they can't be done CNC? well the only answer I have for you all is because we are dealing with a tolerance of less then 1/6th the thickness of a sheet of simple note book paper or 5 tenths as in.0005 or less!

And how do I know when a die is worthy of selling? Because this is the third core seat die I have worked on today after scratching the other two and this one is "perfect" and I want it for myself. :) That's when I know it meets my standards, this one is ready for the customer. I won't sell it if it is not better then what I use myself, you know who will be using those scrathed dies right :)

It is quite stressfull at times but when it turns out this good it sure feels good!

May this die make severial thousands of great bullets to the lucky customer! Wish it was mine, oh well, I can always make me one later right!

Good Shooting and Swage On!

Brian

[Utah Shooter]

So why not .00001 ? :)

[Mooseman]

So why not .00001 ? :)

Because it isnt ROCKET Science, or Model airplane engines !!!

BT, as a Machinist/Gunsmith I can sympathize with the fun and Joy close tolerance work brings , and how it can make you lose hair... LOL
Keep up the good work !
Rich

P.S. I know a " Machinist" that ruined a $16,000.00 Gun because he machined .001+ off a barrel On a Custom German gun , when it only needed .0002 to .0004 stoned off by hand to index the barrel properly . He wasnt a gunsmith...

[BT Sniper]

Thanks Moose. It has certainly tried my patience and added quite a few grey hairs as well :)

I do enjoy it though. Only wish I could fill orders faster. I think that is actually causing most of the grey hair, keeping customers waiting. I would have no problem spending hours, weeks, even a year to complete a die if I got to keep it when I was done but putting that much work and love into a die only to ship it to the lucky customer when I'm done..... well I get all the satisfaction I need from the good looking bullets my customers make and shoot, so I'm cool with it.

I got me a good collection of bubba sporterized 1917 enfields with some very nice ones as well. Someday the next thing I want to perfect is gunsmithing skills, all though looking at some of the so called gunsmith work that was done to these old riffles it makes me think the title of gunsmith is passed on pretty loosly. Maybe that was just the case back in the day, I'm sure there are plenty of very good professional GS out there.

Good shooting and swage On!

BT

[marten]

To machine these tolerances are not that difficult if you are set up to do it, tenths need more than just a 'high end' micrometer, they need a tool room with a constant temperature - that is machines metrology and the room. Then you will have some repeatability in your measurements. Ask me how I know...!!!!

I am in the process of making my own .22 dies, have completed the nose form and its punch I'm about 2/3rds of the core swage - only needs the bottom punch - have figured a better way to approach that little problem.
Core seat is reamed and lapped to size. I am also doing my own heat treatment and making my own laps...so far so good!

[BT Sniper]

Cool! Keep us posted and be sure to make us look good by telling everyone how challenging it is :) or at least make me feel better :)

Good shooting

BT

[Mooseman]

If you have Lots of money , I bet you could use one of these and speed up production...http://www.sunnen.com/horizontal-honing/mbb-1660

We used one similar for precise Racing engine tolerances where everything was blueprinted as far as rods, bushings, etc.
Sunnen Honing machines are amazing for close tolerance work and a perfectly round hole they produce with a fine finish for bearing surfaces.

Rich

[BT Sniper]

Yep I don't even need to click the link. I have looked and considered it. Maybe some day when I'm rich :) or tired of doing it by hand! They are a good lookign piece of machinery and I'm sure it would speed things up. Matter of fact I am pretty sure there is a member here that has one.

BT

[Mooseman]

I know... Used ones run about 6000.00 + shipping which isnt bad if you are in full blown production as it will pay for itself.

Keep on machining Brother !

Rich

[Lefty SRH]

I've used a Sunnen before and they are nice machines, but personally I prefer a Moore jig grinder.

[Reload3006]

When dealing with extremely close tolerances you should be doing your finish work after heat treat. Believe it or not Heat treat will change the dimensions of your dies. Its also easier to lap hone hardened metal after heat treat than before.

[marten]

When dealing with extremely close tolerances you should be doing your finish work after heat treat. Believe it or not Heat treat will change the dimensions of your dies. Its also easier to lap hone hardened metal after heat treat than before.


That is the way to do it!

[GRUMPA]

BT,

Yep it's a pain in the neck trying to hold a tolerance like that, that's pretty much all I did for a living. Being a precision grinder for over 25yrs a person gets rather "Picky" about the things they do either for reloading or pretty much anything else for that matter.

Oh boy can I tell you stories about materials, coolants, techniques that for the average person would go right over there head.

But it does teach someone like me on how to improve on things to make them last longer. And for an example when I make 300 Blackout, I start in the early morning and by around noon when the temperature increases by 20deg the ram on my press actually grows .015. Good thing I was a precision grinder all those years with all that experience under my belt the average person would in all likelihood wouldn't or couldn't figure it out till it was to late.

And heat treating at times is hit and miss, all that work that a person does can be ruined so fast it isn't funny. We've had entire orders get scraped and we're talking in the thousands of dollars. Ever buy 100k worth of specialized material? trust me it's an eye opener for sure, especially when you have to have certifications for it.

Bt, the stuff I had to do was a bit beyond what your doing. This is what I had to do, and for most, well they wont comprehend it that well, I had to hold alot of parts with a .0001 sphericity call-out with a 6 finish. I wont bore the heck out of you but that isn't all that easy to do. And any given day I would run out jobs worth 1k and sometimes over 50k and think nothing of it. 1 job in particular I did was a titanium landing gear for the SR-71 and just that one part was over 50K and I had pallets of them right behind me, and yes the tolerance was +-.0005, talk about having to really focus on your work.

With all the knowledge and abilities a person gets doing that type of work really sticks with them pretty much for life. And so do the tools of the trade, I still have most of my equipment, indicators, mic's and so on, even Diamonds which we used for re-sharpening the grinding wheels and I've worked on machines that had 3' dia. grinding wheels all the way down to 4" dia wheels.

And your right BT, that so-called title of "gunsmith" is a very loose term in todays world. Folk ask me if I would work on there stuff and I have to tell them "NO". Not because I don't want to do it but because I don't want the liability or the hassle of all that red tape that seems to follow you when you work on something like that. You know around here to float a barrel they charge $350 locally? Heck I do mine in an hour with my bubba'd tooling and it comes out great. How these so-called gunsmith's around here can get away with charging so much is beyond me.

OK that's enough for now I can really go on typing on this thread.

[dragonrider]

Recently saw a Sunnen hone on Craigs list for 400.00. Almost bought it. But for the amount of size dies I make it would not have been an economical purchase. So I will continue as before.

[mdenz3]

One of these is indispensable for holding tenths on OD work:
http://i.imgur.com/62w6L.jpg
Using one of those and my 17 year old Okuma LNC8 I held +.0005 -0.0 over a 6,000 piece run with <1 minutes of cycle time.

Low tolerance ID work is just annoying. :p


Recently saw a Sunnen hone on Craigs list for 400.00. Almost bought it. But for the amount of size dies I make it would not have been an economical purchase. So I will continue as before.

Should have bought it just to resell it, that is about scrap price.

[Red River Rick]

.......................:popcorn:

[BT Sniper]

How is is going Rick? I see you got some good looking bullets availble now. Looks good!

Would love to hear from anyone their personal experience with machine work. There are a lot here just like I was years ago that just don't realize just how tight a thou is let alone a tenth. Seems like I have been working toward improving my skills ever since I left the airlines in 08. I'm getting better evey day and have been using the lathe nearly every day since I got it. There is a lot to learn that's for sure, I think it is probably more of an acquired art or skill that is probably very hard to teach and probably is learned more over time and by doing?

I suppose there are other machining forums like practical machinist that cover such topics but it is fun to discuse it as how it pertains to shooting.

I seem to recall in a conversation with Dave at CH-4d that reloading dies have a tollerance of like 7 thousands. Don't know if I remeber that # correctly but with the difference between relaoding die tollerances and swage die tollerances it is easy to understand the large difference in cost is the point I'm trying to make I guess.

Good shooting

BT

[Reload3006]

Most of my career has been in Machine Shop/ tool n die. Every one cries about how expensive swaging dies are. I however am not one of those people ... I know what it takes to make them. I also know how expensive the tooling is that you have to use to make them Its not as straight forward as many think. You dont just chuck up a chunk of any ole steel and cut away and end up with a working Swage die.

[frnkeore]

The only thing that I can add to this discussion is about the metals used.

4140 is not tool steel. If you want tool steel that won't distort or leave much scale, you need to use A2. Another good one (my opinion) is 50100, it comes mostly in bar stock. It's not listed as tool steel but, it's what most ball bearings are made of. Neither are easy to machine like 4140 but, will last MUCH longer. The top end tool steel for this application would be D2 but, it's harder to work with than either of the above. P20 tool steel (for injection and rubber mold work) is similar to 4140 but, is not for this type application.

There are others TOOL STEELS but, I haven't worked with them. For hardess and wear resistance you need at least .80% carbon content.

Frank

[M-Tecs]

And for an example when I make 300 Blackout, I start in the early morning and by around noon when the temperature increases by 20deg the ram on my press actually grows .015. Good thing I was a precision grinder all those years with all that experience under my belt the average person would in all likelihood wouldn't or couldn't figure it out till it was to late.


You have a press with a 116.2 inch ram?

The expansion rate of steel is 0.00000645 per inch per degree F. With a 20 degree increase we take 0.00000645” x 20 = 0.000129”. This is how much a ram 1 inch in length will increase for a 20 degree temperature increase.

You stated your ram grows 0.015” so if we divide 0.015” by 0.000129” we get a 116.27906” ram.

A 11.6” ram would grow 0.0015 for a twenty degree increase.

The expansion rate of cast iron is 0.00000655 and the expansion rate of brass is 0.000010” . The brass will grow 0.0000036” per degree per inch more than the steel die. On a two inch long shoulder the headspace would increase by 0.0000144”

A 11.6” ram would grow 0.0015 for a twenty degree increase. The press frame also expanded at almost the same rate so the cam over did not change enough to worry about.

The die and the brass expand at different rates so the headspace would increase by a tenth or a tenth and a half.

Since I am just an average person what am I not figuring out until it is too late?

[mdenz3]

The only thing that I can add to this discussion is about the metals used.

4140 is not tool steel. If you want tool steel that won't distort or leave much scale, you need to use A2. Another good one (my opinion) is 50100, it comes mostly in bar stock. It's not listed as tool steel but, it's what most ball bearings are made of. Neither are easy to machine like 4140 but, will last MUCH longer. The top end tool steel for this application would be D2 but, it's harder to work with than either of the above. P20 tool steel (for injection and rubber mold work) is similar to 4140 but, is not for this type application.

There are others TOOL STEELS but, I haven't worked with them. For hardess and wear resistance you need at least .80% carbon content.

Frank

I do a fair bit of work on D2, and have never had any real trouble. You can't beat it for wear resistance and holding size during heat treating (though it will have to be professionally done in a vacuum furnace). Personally I wouldn't make dies out of anything else.

[M-Tecs]

You can’t go wrong with D2 or D3. For extreme wear resistance I like Carpenter's Hampden® No. 610® (D2) Tool Steel.

http://www.cartech.com/toolsteelspowderprod.aspx?id=2432&terms=*d2*

http://www.matweb.com/search/datasheettext.aspx?matguid=111038b5eb8c4191b20978b 56266bde1

http://www.suppliersonline.com/propertypages/D3.asp

http://www.matweb.com/search/datasheettext.aspx?matguid=592c004a0da34ac0a79c908 dc11154e6

[Red River Rick]

Brian:

What can one say.........looks like you have everything WELL under control!:happy dance:

I see some very nice products. They look well made, and not whacked out in the back shed with a drill press and a file. Reviews have been positive as well, so you must be doing something right.

I have a few items I'd like to discuss/share, but I'll do that in a PM.

Question: When you check your dies for hardness, after heat treating, do you use the "Concrete Floor" method? ;-)


RRR

"Don't Melt..............Squeeze"

[BT Sniper]

LOL Good to hear from you Rick. Wish I could send some bullets your way. If you ever make it down to a US address let me know.

BT

[MBTcustom]

Once you get your head screwed on strait, machining in tenths is no harder than thousandths. It definitely takes more skill, but once you get the hang of it its NBD. Machining big stuff that weighs several hundred/thousand pounds is the same way.
What's hard is working in a job shop where you might go months doing +-.005 parts that you can hold in your hand, and then one day you have to make a super precision +.0001-.0000 part and you have to shift gears real quick and dont screw up. In my present day job, I work with tight tolerances all the time. It becomes very important to maintain a consistent temperature throughout the fabrication and assembly process, because a change of 5 degrees can through your part out of tolerance.

[BT Sniper]

Yep lots of factors to take into consideration and I am happy to maintain a bullet within +.0005 - .0000 of nominal bullet diameter.

BT

[MBTcustom]

I'm sure you already know this, but diamond lapping compound makes short work of long lapping jobs.
It sure is cool when you get things going your way!

[mdenz3]

If anyone of you hobbyists are interested I have four WNMG 432 style inserts for free.
They are from an old promotion and I'll never use them for production so I'll offer them up for anyone who can use them.
Pic here: http://i.imgur.com/WDmKY.jpg

PM me if you want them.

[Rangefinder]

Brian---all of my machining right now IS on a drill press with a file, so to speak---I set up my wood shop, haven't had time or money to even address the metals side of it yet. Got plenty of know-how Dad was a master machinist for Westinghouse Corp once upon a time and his shop was my daycare, but currently it's like trying to paint the Mona Lisa with an Ace Hardware brand paint roller. SO, that being said, YOU ARE NOT ALLOWED to get burned out before I gather enough change from my couch to get the dies from you on an ever-growing list! For fair warning, it could take a while to complete my list ;). We both may be bald by then...

[BT Sniper]

I've got to much $ and inventory invested to get burnt out. I got enough work with all the inventory for probably better then 3-4 years worth of work to keep me busy.

BT