Need advice to make a die

[Lplates]

Hi Team.
So I'm trying to make my own geometry on bullet swaging dies, and have had some requests locally from other bullet makers. (For copper jacketed bullets.) However I'm finding them incredibly difficult to make. I'm using 4140 and a custom form cutter I've had made, I drill in multiple operations on a manual lathe then finish with the form cutter by hand, but during polishing they are ending up too big internal D after running in with a custom form cutter.

I made the mistake of under-estimating just how much the part could grow whilst polishing. (Bore polished out to 0.2665 instead of 0.264.) The cutter was made at 0.264 hoping a gentle lap would suffice but I clearly not.

I'm thinking I need to have the cutter made at 0.262 and polish, however, I'm still feeling tooling marks in the bore too.

As you can imagine it is a very small bore to polish, 223/6.5mm etc. Anyone got any tips for polishing very small bores evenly??

I'm wondering if 4140 isn't the best material to use here, however I think it's important that the dies are either nitrided or hardened post machining. If anyone has seen a Wilson die, they are polished to a brilliant polish. I'm looking for a similar finish but don't know what metal they are made from.
Any tips or right-direction-pointing would be wonderful.
Thanks
Lplates.

 

[mhajicek]

4140 is a great material. I'd surface that cavity with ball mill for a nice, shiny surface finish with no polishing. If you're stuck with manual machines it's gong to me much more difficult.

 

[implmex]

Hi Lplates:
Your problem is a bit like chambering a barrel...You have a similar requirement for a gouge-free surface and a similar requirement for geometric fidelity.
You're also using a similar material.

The chambering guys almost all pump oil through the barrel from the muzzle end to keep chips from catching in the reamer flutes and scoring rings into the chamber.
They also use HSS multi flute tools run at low speed under tight axial control and piloted to keep them from running out radially.

Now I know exactly nothing about the swaging dies you hope to make but I do know a bit about form reaming.
Obviously, the more meat you can remove before finish reaming, the better, so the finish reamer doesn't have to cut so much.

D bits are often recommended for these kinds of jobs...I have been unimpressed.
Holding size is more difficult and they tend to wander and wobble too, on relatively small machines.
I've done better on average with a bigger lathe than with a smaller lathe, just because everything is so much stouter that it can't flop around as easily.

I've always tried for at least a 2 flute (preferably more) tool with zero rake and minimal relief.
If the rake is too big they dig in and break more easily; if the relief is too big they chatter more easily.

The chambering reamer guys have this tool geometry down to a fine art...if you can score a reamer, you can copy what they did.

Last, I'm unconvinced 4140 is the best choice for your needs.
It's oil hardening and doesn't get that hard.
It distorts like hell during heat treat compared to air hardening steels.

Knowing pretty much nothing about the application, I'd be likely to try either A-2 or D-2 for this.
Both are air hardening and both are used extensively for punch dies.
Both will get really hard (over 60 RC) and are very tough.

A-2 is easier to work with in my opinion.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining


BTW...if I was making these, I'd rough them out with a drill and then burn them with the sinker EDM and polish.
No gouges, no chattermarks, easy geometry control.

MC

 

[TDegenhart]

Hi Lplates:
Your problem is a bit like chambering a barrel...You have a similar requirement for a gouge-free surface and a similar requirement for geometric fidelity.
You're also using a similar material.

The chambering guys almost all pump oil through the barrel from the muzzle end to keep chips from catching in the reamer flutes and scoring rings into the chamber.
They also use HSS multi flute tools run at low speed under tight axial control and piloted to keep them from running out radially.

Now I know exactly nothing about the swaging dies you hope to make but I do know a bit about form reaming.
Obviously, the more meat you can remove before finish reaming, the better, so the finish reamer doesn't have to cut so much.

D bits are often recommended for these kinds of jobs...I have been unimpressed.
Holding size is more difficult and they tend to wander and wobble too, on relatively small machines.
I've done better on average with a bigger lathe than with a smaller lathe, just because everything is so much stouter that it can't flop around as easily.

I've always tried for at least a 2 flute (preferably more) tool with zero rake and minimal relief.
If the rake is too big they dig in and break more easily; if the relief is too big they chatter more easily.

The chambering reamer guys have this tool geometry down to a fine art...if you can score a reamer, you can copy what they did.

Last, I'm unconvinced 4140 is the best choice for your needs.
It's oil hardening and doesn't get that hard.
It distorts like hell during heat treat compared to air hardening steels.

Knowing pretty much nothing about the application, I'd be likely to try either A-2 or D-2 for this.
Both are air hardening and both are used extensively for punch dies.
Both will get really hard (over 60 RC) and are very tough.

A-2 is easier to work with in my opinion.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining


BTW...if I was making these, I'd rough them out with a drill and then burn them with the sinker EDM and polish.
No gouges, no chattermarks, easy geometry control.

MC

I agree with the above with the sinker, For polishing try mold polishing shops.

Tom

 

[TheBigLebowski]

Are you swaging (resizing via squeezing into tighter bore) just the bullet? Or are you talking about the entire bottleneck cartridge? Or are you cold forging your own bullets from scratch?

If it's just resizing the bullet It should just be a simple die button with the target diameter thru and a slight lead in to get the bullet started correct? I don't see why you would need a special cutter if this is the case but I might be missing something.

As for material I would go with A2 over D2 as Marcus suggested. D2 has a lot of chrome in which can cause some funky issues when interacting with other material at high pressures (surface can get so hot it anneals and galls)

 

[Bobw]

I'm wondering if 4140 isn't the best material to use here, however I think it's important that the dies are either nitrided or hardened post machining.

There is your problem.

4140 is sticky and gummy, likes to rip and tear in the annealed or normalized condition.
And 4xxx anything twists up like a red chile covered gummy bear in heat treat (don't
laugh, they are actually pretty good).

Rough, heat treat, finish.

Also, I don't know how hard you are hammering these things, but 4140 might
not be the best choice.

Some of that has already been said. And I'm saying it again for a reason.

 

[mhajicek]

I'd just cut it in the hard and call it done. Unless you're removing huge amounts of material, the whole heat treating mid-process thing is outdated.

 

[implmex]

Hi mhajicek:
No argument unless you don't have the means to cut it in the hard state.
Sinkering works.
Turning or milling with carbide sometimes works, depending on what kind of access you have and how little the features are.

HSS reamers do not work...at least not with something much over RC45.

So yeah...it depends.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

 

[rogertoolmaker]

Hi Team.
So I'm trying to make my own geometry on bullet swaging dies, and have had some requests locally from other bullet makers. (For copper jacketed bullets.) However I'm finding them incredibly difficult to make. I'm using 4140 and a custom form cutter I've had made, I drill in multiple operations on a manual lathe then finish with the form cutter by hand, but during polishing they are ending up too big internal D after running in with a custom form cutter.

I made the mistake of under-estimating just how much the part could grow whilst polishing. (Bore polished out to 0.2665 instead of 0.264.) The cutter was made at 0.264 hoping a gentle lap would suffice but I clearly not.

I'm thinking I need to have the cutter made at 0.262 and polish, however, I'm still feeling tooling marks in the bore too.

As you can imagine it is a very small bore to polish, 223/6.5mm etc. Anyone got any tips for polishing very small bores evenly??

I'm wondering if 4140 isn't the best material to use here, however I think it's important that the dies are either nitrided or hardened post machining. If anyone has seen a Wilson die, they are polished to a brilliant polish. I'm looking for a similar finish but don't know what metal they are made from.
Any tips or right-direction-pointing would be wonderful.
Thanks
Lplates.

D2 tool steel is a much better choice for the dies, harden to 62-64 Rc. 4140 will not stand up to the swaging operation and result in scoring the surface of the dies.

Roger

 

[Lplates]

Hey team.
I know it's been a while.
Finding most tool steels is a nightmare here in Aus.
I am wondering if 1045, 5160 or H13 will polish as well and be die-worthy for bullet swaging, I need to make sure it's a polished as possible, I think D2 wont polish as well as the others. Thanks team

 

[michiganbuck]

QT Op: The cutter was made at 0.264.
What was the reamed part size after using the reamer.?
A very well-made cutter like a multi-flute reamer will often cut .0002 larger than the measured size. Measuring is difficult because any wobble at making may cause a larger ream with not showing up in the measure. The grind roll-off will also not show up in the measure. Good to make reamer with .0002 per inch back taper. grind into the edge to +.001. cool the reamer and then reverse the spin to heal grind first coming up to the desired size. then back off heal at secondary to the desired land width.
The .0002 back taper is a common need for most reamers, and this allows one to snub off the end to make the reamer cut a smaller diameter. A reamer can also be reduced by reaming a hole and then splitting the reamed part to become a reamer lapping block,

 

[michiganbuck]

QT Op: The cutter was made at 0.264.
What was the reamed part size after using the reamer.?
A very well-made cutter like a multi-flute reamer will often cut .0002 larger than the measured size. Measuring is difficult because any wobble at making may cause a larger ream with not showing up in the measure. The grind roll-off-edge will also not show up in the measure. Good to make reamer with .0002 per inch back taper. grind into the edge to +.001, cool the reamer and then reverse the spin the blued-up reamer to heal grind first coming up to the desired size. then back off heal at secondary to the desired land width.
The .0002 back taper is a common need for most reamers, and this allows one to snub off the end to make the reamer cut a smaller diameter. A reamer can also be reduced by reaming a hole in a sacrifice part and then splitting the reamed part to become a reamer lapping block, the lap block will make a straigh reamer, so a little more lapping may be needed to restore tha back taper.

 

[Lplates]

QT Op: The cutter was made at 0.264.
What was the reamed part size after using the reamer.?
A very well-made cutter like a multi-flute reamer will often cut .0002 larger than the measured size. Measuring is difficult because any wobble at making may cause a larger ream with not showing up in the measure. The grind roll-off will also not show up in the measure. Good to make reamer with .0002 per inch back taper. grind into the edge to +.001. cool the reamer and then reverse the spin to heal grind first coming up to the desired size. then back off heal at secondary to the desired land width.
The .0002 back taper is a common need for most reamers, and this allows one to snub off the end to make the reamer cut a smaller diameter. A reamer can also be reduced by reaming a hole and then splitting the reamed part to become a reamer lapping block,

Excellent advice! Thanks. You are right too, it cut literally 2 thou oversized!

I will get another made 3 thou under leaving 1 thou for polishing and honing.

I’ve only just discovered Silver steel has some good properties and is available here plus I can heat treat it at home easy enough for testing purposes to Rockwell 60 and holds a great finish. Just wondering how deep the hardening is on it… if less than a thou I don’t want to break through it.

Cheers team!

 

[michiganbuck]

Good to post your location in your profile as that may help in the way members answer your posts.
I used to make cutters with drill rod to cherry and low red and then quench.

I think drill rod and silver steel are the same things and they get through hard/ not case hard.
But there are different kinds of drill rod, air , oil and water hardning. A-2, 01 and W-1 and perhaps other kinds..

 

[Lplates]

Since I’m basically trying to lap a blind hole with ever decreasing diameters, im
Wondering should I cast the “bore” of it once reamed and lightly polished, then cast a lead lap and have at it with diamond paste?

I made another test one today and after reaming with a .264 reamer by the time it was mirror finish it was 0.269! Maybe I need to get a 0.260 reamer?? Wowzers.

I just ordered some steel mandrels and made some aluminium ones today but still… that’s nuts. Feeling deflated. Like hitting a tolerance will be less science and more pulling it outta my ass.

 

[michiganbuck]

Perhaps it might be good to turn a bullet to .0005 and use that for a blue in template gauge

 

[implmex]

Hi Lplates:
Something is not right with your protocol if your finished size is 0.005" bigger than your reamer.
Michiganbuck commented that a reamer will often cut 0.0002" oversize, and that is the kind of result I would expect.
Your cavities are coming out with twenty five times more error than that.
Polishing or lapping a bore to make it grow by 0.005" is a big task...you have to go at it for hours.
Typical honing or lapping allowance is 0.001" or 0.0015".
Guys who chamber rifle barrels try to hold size within a tenth or so and aim for a perfect, unmarred finish without any polishing at all.

So, I'd evaluate why your form reamer is cutting so much oversize.
Once you find and correct that problem you will be able to control the cavity dimensions much more easily
Look at the geometry of the reamer and look at the rigidity of the setup.
Look also at the concentricity of the reamer with the spindle axis of the lathe (I assume you are doing this on a lathe)...since the reamer cuts on the sides, any misalignment will result in an oversize bore.

On a last note, spinning a lead lap with diamond paste in the developing cavity will only scratch rings into it.
The kind of lapping you want to do depends on axial movement as well as rotation so the scratches are not oriented radially.
You don't want those concentric rings in your cavity; you want the lay of the polishing scratches to be aligned with the axis of the cavity, so your swaged copper will not lock itself into the scratches.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[michiganbuck]

RE: Perhaps it might be good to turn a bullet to .0005 and use that for a blue in template gauge.
I don't know how long your bullet is so you may not have a wide enough wheel for this but...

Still, you might make your blue-in bullet emplate gauge between centers and make it with a straight stub at one end perhaps 3/8 diameter. Set this bullet gauge in your V block and use it to hand or roller dress your grinding wheel to that exact shape (.0005 or so). Next use the form dressed wheel to circle grind an end mill to the shape. clearance the end mill might be a handheld and eyeball grind to a .020 land.







0

 

[AD Design]

I think D2 wont polish as well as the others. Thanks team

-I can tell you from personal experience that D-2 will polish to a mirror-like surface. Diamond paste and a felt bob are required AFTER the usual steps/stones are employed for that sort of surface finish.

 

[dian]

"silver steel" (115crv3/1.2210) is an excellent choise, it machines well, is tough and hard (up to 60 hrc). w5 would be the closest, i guess.

drill rod can be any tool steel and d2 is an abrasion resistant, ledeburitic monster, difficult to heattreat, huge fe-cr-carbides and needs diamond to finish. calling it tough is quite weird. not at 60+ hrc for sure.