Question on how to make this extractor.

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paulj84003
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Re: Question on how to make this extractor.

Postby paulj84003 » Mon Feb 29, 2016 7:00 pm

Years ago I made the wax's and took them to a foundry which cast my parts
"a wise man learns by experience, a wiser man by the experience of others"

TheGreenMan
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Re: Question on how to make this extractor.

Postby TheGreenMan » Mon Feb 29, 2016 11:26 pm

Doing some measurements and some math (not my strong suit) it looks like the three deeper radii of the 'spoon' were cut with a 1'' diameter. It looks like a 1'' diameter side cutter or slot cutter would work. As long as the shank or arbor of the cutter was 0.5'' or less it should be able to cut even the deepest section as long as the curve in the tip of the extractor is already cut. The tail should not be a problem because it is not bent until all the machining is done and just before heat treating, which gives it the spring it needs to work correctly. When the tail is strait the ridge does not have much more elevation then the rest of the tail, as the tail thins toward the tip. The two shallow radii on the tail were cut with a larger diameter cutter, I get about 1.2''.

With a lot of set up I may be able to do this on a lathe. Getting the cutting tool far enough away from the chuck may be a problem. An arbor for a side cutter would be nice but I could not find any side cutters with 0.5'' holes, all I see have 1'' holes, not to mention an arbor with a 0.5'' diameter that I could run from the chuck to a center. I haven't even seen one of those that would work for a 1'' diameter hole, except a homemade on with no directions or plans shown and only 3 poor pics. A slot cutter may work but then I am real close to the chuck with little room to work.

I already have a homemade milling attachment for my lathe similar to this one (half way down the page): http://www.varmintal.com/alath.htm
It may do the trick holding and moving the piece with some experience. The cutter end of it seems to be the main sticking point.

Harold_V
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Re: Question on how to make this extractor.

Postby Harold_V » Tue Mar 01, 2016 1:15 am

TheGreenMan wrote:Doing some measurements and some math (not my strong suit) it looks like the three deeper radii of the 'spoon' were cut with a 1'' diameter. It looks like a 1'' diameter side cutter or slot cutter would work. As long as the shank or arbor of the cutter was 0.5'' or less it should be able to cut even the deepest section as long as the curve in the tip of the extractor is already cut.

Are you implying that the three radii shown in the last picture, the three in the center, are all ½" radius? If so, I don't think so, as that doesn't make sense unless the cut isn't intended to mate with another surface. If it is intended to do so, it wouldn't make contact in the center, and the sides would conflict with contact unless you machined the piece too deeply, then the center wouldn't make contact. I expect that the cuts each have the appropriate radius for that reason, so the deep portion could not be cut successfully with a 1" radius, to say nothing of the shank interfering with the cut if you tried.

It is my opinion that you don't understand the problem with running this part in a lathe. If I'm wrong, forgive me, as I may not understand your intentions. However, from my perspective, here's how I see it. A boring bar will work ONLY if you don't swing the part, as you don't have any room to get the bar in a hole that is, for all practical purposes, the same diameter as the bar. If you could get the bar in the hole, you couldn't feed it to make the cuts. In order to do that, you must have enough clearance for the bar to move away from center the amount you must bore, and that precludes any chance that a boring bar will work with the work turning. That's why I said the bar needed would be too slender.

With the part stationary, plunging in to a rotating cutter, yeah, it can be done, as all that is required is for your tool to be set at the proper radius, and the bar no larger in diameter than the diameter of the radius cut in the extractor, plus a few thou for clearance. In this case, the bar must rotate on center, otherwise you face the same problem as you would if the part rotated.

For the reasons I mentioned, above, you would be best served to make a milling cutter. It's not all that difficult, and would be a good and valuable lesson in making functional tools. This tool would resemble a stack of cutters, but machined to the precise radii required to make the part, with proper lengths held. To perform well, you'd want a small amount of side releif on the teeth, which wouldn't be a problem. If you found that generating the teeth for the cutter was a problem, you could make two cutters, one for each radius. That would simplify making the tool, but necessitate changing of cutters when running a part. You could get around making two cutters by properly staggering the teeth on a single cutter, which would provide the necessary clearance to machine and grind the teeth. The cutter need not have a lot of teeth, although the more teeth, the longer it will last, assuming you don't allow them to tarry in the cut.

This cutter could be made on a lathe, with the teeth generated using a milling attachment, but you'd be well served to have a cutter grinder sharpen the teeth after heat treat.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

Magicniner
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Re: Question on how to make this extractor.

Postby Magicniner » Tue Mar 01, 2016 5:13 am

Don't think engineering, think trench warfare, dirt and poor maintenance by tired grunts ;-)
The mauser extractor runs in the straight length of a locking lug slot with the bolt turning but the extractor only moving forward and backward.
It's actually advantageous to have clearances under things rather than a nice "fit", contact with the bolt on two edges with a space underneath makes for a rifle which still works after being dropped in the mud.

- Nick

hanermo
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Re: Question on how to make this extractor.

Postby hanermo » Tue Mar 01, 2016 6:21 am

Lots of people melt steel in a coffee can, with charcoal and a hair dryer.
Its not hard, for small parts.

Never done it.

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steamin10
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Re: Question on how to make this extractor.

Postby steamin10 » Tue Mar 01, 2016 11:58 am

hanermo: People do not melt steel in coffee cans. I have 3 furnaces and have played with charcoal and other delights, and assure you, casting is not that simple for any quality. Pieces like this one, are usually forgings, with machine work for finishes. A one off can be made with a hammer and file. The question was mandrels and lathe abilities. I do not see, or know that path. I ran a press department, that made many odd shaped parts in cold dies, not forgings. So while I do not have specific experience, It is not happening in a coffee can.

I only challenge your premise, to keep information accurate to the board and readers.

Thank you.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
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Harold_V
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Re: Question on how to make this extractor.

Postby Harold_V » Tue Mar 01, 2016 4:44 pm

hanermo wrote:Lots of people melt steel in a coffee can, with charcoal and a hair dryer.
Its not hard, for small parts.

Never done it.

Figured you hadn't.

I'm no stranger to melting metals, although my background is not related to foundry.

I refined precious metals for many years (after abandoning my machining career). Gold and copper (each in their pure state) melt just under 2,000° F, but must be heated slightly higher for pouring. It's easily accomplished in a fuel fired furnace. Mine were fired by natural gas.

Take a step up to what you're discussing, which doesn't yield steel, even if you start with steel. What you propose yields cast iron, assuming you are melting directly in the furnace (no crucible, with the charge in direct contact with the fuel). What you described is a miniature cupola. If you hope to pour steel, you must not allow the charge to be in contact with carbon, as it readily alloys with iron, changing its chemical composition. The difference between steel and iron is the amount of carbon contained within, with steel having 1% or less carbon in solution, while cast iron tends to have more, which precipitates upon solidification as free carbon (graphite). There is no free carbon in steel.

Cast iron can be melted and poured well under 2,800° F, but that won't allow for pouring steel, as it requires a much higher temperature. And, if you melt in contact with the fuel source (charcoal or coke), what you end up with isn't steel, but, again, cast iron. Like it or not, that's the nature of the beast.

In order to melt and pour steel you must be able to achieve a temperature above 3,000° F. About the same temperature required for melting platinum. It is a dazzling white heat, from which you are subject to radiation burns. Melting and pouring steel should not be confused with melting and pouring (cast) iron.

While I expect a home shop can cast steel (an arc furnace can be used for melting), precious few will have the courage to attempt such a project, for obvious reasons. For that matter, precious few attempt cast iron.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

TheGreenMan
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Re: Question on how to make this extractor.

Postby TheGreenMan » Wed Mar 02, 2016 9:21 pm

Harold_V wrote:Are you implying that the three radii shown in the last picture, the three in the center, are all ½" radius? If so, I don't think so, as that doesn't make sense unless the cut isn't intended to mate with another surface. If it is intended to do so, it wouldn't make contact in the center, and the sides would conflict with contact unless you machined the piece too deeply, then the center wouldn't make contact. I expect that the cuts each have the appropriate radius for that reason, so the deep portion could not be cut successfully with a 1" radius, to say nothing of the shank interfering with the cut if you tried.

I was saying that in the last picture the center one is 0.5'' radius and the two on the outside have a 0.6'' radius.
But after my brain caught up with me I just measured the bolt head which these radii are cut to fit around. The area that the center radius fits around is about 0.888'' in diameter. The area the outside two fit around is about 0.662'' in diameter.
These are not cut to ultra close tolerances as they need to operate while dirty but they are fairly close. The outside two radii are what bears against the bolt. The center radius has a very slight gap between it and the bolt so it doesn't bear on anything.
So the outside two radii are going to need to be about 0.66'' in diameter and the center one will need to be a few thousands more than 0.888''.
There is a bit of variation with these parts. Not enough that they were hand fit but there is a bit of variation in size.

It is my opinion that you don't understand the problem with running this part in a lathe. If I'm wrong, forgive me, as I may not understand your intentions. However, from my perspective, here's how I see it. A boring bar will work ONLY if you don't swing the part, as you don't have any room to get the bar in a hole that is, for all practical purposes, the same diameter as the bar. If you could get the bar in the hole, you couldn't feed it to make the cuts. In order to do that, you must have enough clearance for the bar to move away from center the amount you must bore, and that precludes any chance that a boring bar will work with the work turning. That's why I said the bar needed would be too slender.

I am some what new to all this.
But I haven't said anything about using a boring bar to cut the part. You were the one that mentioned that. I have only mentioned using a milling cutter or similar tool.

With the part stationary, plunging in to a rotating cutter, yeah, it can be done, as all that is required is for your tool to be set at the proper radius, and the bar no larger in diameter than the diameter of the radius cut in the extractor, plus a few thou for clearance. In this case, the bar must rotate on center, otherwise you face the same problem as you would if the part rotated.

Yep. This looks to be the best route if I never get a mill or want to do this before then.

For the reasons I mentioned, above, you would be best served to make a milling cutter. It's not all that difficult, and would be a good and valuable lesson in making functional tools. This tool would resemble a stack of cutters, but machined to the precise radii required to make the part, with proper lengths held. To perform well, you'd want a small amount of side releif on the teeth, which wouldn't be a problem. If you found that generating the teeth for the cutter was a problem, you could make two cutters, one for each radius. That would simplify making the tool, but necessitate changing of cutters when running a part. You could get around making two cutters by properly staggering the teeth on a single cutter, which would provide the necessary clearance to machine and grind the teeth. The cutter need not have a lot of teeth, although the more teeth, the longer it will last, assuming you don't allow them to tarry in the cut.

This cutter could be made on a lathe, with the teeth generated using a milling attachment, but you'd be well served to have a cutter grinder sharpen the teeth after heat treat.

Harold

Making a milling cutter may sound like a good lesson, though trying one with multiple cutting radii is most likely beyond me at the moment. Even making a single radius one will be 'interesting'. Two cutters is probably the way to go for me. And since the diameters of the cutters will need to be a strange diameter making my own may be the only way to go.
Don't know if I want to purchase a tool and cutter grinder.... A bit much for something I'm not sure how often it would get used.


For a little more info:
Here are some pictures of the bolt assembly.

The bolt from the top with the bolt head extended.
This is a strait pull bolt, a forerunner of bolt found in semi- and full auto guns. Only the bolt head rotates. The bolt body and extractor only move back and forth.

Image

Several bolts with the bolt heads in the 'in-battery' and extended positions.

Image

A close up of the interface of the bolt head and the extractor.
You can see how the deeper, center radius fits over the bolt lug.

Image

Same from another angle.

Image

Some of the inner workings.
The tail of the extractor sticks into the bolt body along with the back end of the bolt head. The inside surface of the bolt body compresses the extractor slightly against the bolt head. That is the reason for the slight increase in thickness about halfway down the tail of the extractor. The ridge on the extractor tail fits into the lower of the horizontal (in this picture) grooves. When the bolt head is rotated to the closed or 'in-battery' position (clock-wise when took at the face of the bolt head, which is out of frame to the right in this picture) the ridge is force out of the lower groove and the bolt head rotates until the ridge falls into the upper groove.
The camming action is provided by two large ridges on the inside of the bolt that fit into the helical groves that run around the bolt head. As the bolt body is pulled backward this forces the bolt head to rotate. Resistance to rotation is provided by the ridge on the extractor tail. The cocking piece and a spring inside the bolt head make the bolt head want to rotate to the 'in-battery' position.

Image

TRX
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Re: Question on how to make this extractor.

Postby TRX » Thu Mar 17, 2016 11:25 pm

Google "US Rifles and Machine Guns" by Colvin & Viall. It's out of copyright and downloadable as a .PDF from many sources.

It's mostly about the manufacture of the Springfield rifle, which is a close-enough Mauser variant. There's a whole section on making the extractor, from the chemical composition of the forgings (!) to the heat treat and surface finishing, including drawings of all the fixtures and cutters used.

There's also a series of articles on the manufacture of the '95 Mauser, but you'll have to dig through old issues of "American Machinist" on Google Books to find them. They're very similar to the Colvin book, though.

TheGreenMan
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Re: Question on how to make this extractor.

Postby TheGreenMan » Mon Mar 21, 2016 6:29 pm

Thanks, very neat. It does look like the extractors were made with milling cutters.
Is there something like this for the M1 Garand?

art.h
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Re: Question on how to make this extractor.

Postby art.h » Wed Apr 20, 2016 6:36 pm

Before the bend was created the part would be held in a fixture on a horizontal mill with a dedicated mandrel tool set up and then a vertical plunge cut made. If quantities were small maybe just a mandrel with a single cutter with the right dia. and several plunge cuts to various depths and locations and a second set up to do the angle on the head end of the part. Art

TRX
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Location: Central Arkansas

Re: Question on how to make this extractor.

Postby TRX » Thu Apr 28, 2016 10:07 pm

Colvin & Viall's "US Rifles & Machine Guns" has pictures of each manufacturing step and all the tooling and feed rates for the manufacture of the 1903 Springfield extractor, which is very similar.

The part started as a "near net" forging and then all the internal cuts were made at once with a stack of gang cutters on a horizontal mill, biting a cut the length of the extractor. Then it was flipped the the curved top surface was cut. After that, the hook area was profiled.

The design of the part was partially determined by the tools available to the designer. If you simplified the shape to be flat underneath instead of curved it would be doable with end mills and some imaginative fixturing with a lathe milling adapter.


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