tumbler mill

[Steve Bookout]

Had an email last night asking what brand of file do I use for my tumbler mills.  For the record, I use Sandvik rasps.  I love them. 

[bob in the woods]

This is an absolutely marvellous topic, and the info so far is outstanding!   I have made only one lock [flint] from scratch, and freely admitted to opting to use a a Siler tumbler on it  in the end. That was the one "store bought" piece.   Now I have no excuse for not making a new tumbler for my  lock . 

[whetrock]

Hank, this is great stuff! Thanks!
And thanks to the rest of you, too, for your great tips on files, stress relief, tempering, etc. All very helpful.
Hank, earlier today Jim asked about the intersection of the cutting edges with the central hole. I have the same or a very similar question. In one of your photos it looks like the cutters are set at a slight skew angle, rather than coming straight off the axis. Something like B, instead of A.

I notice the same thing in an old diagram for a handmade hollow mill for cutting the shank of a breech plug (from the Steele and Harrison book that I mentioned earlier). I’m not a machinist and I don’t know the technical term for that angle. (I can’t seem to find it on the web, either.)
I’d appreciate it greatly if you could you comment on that angle. Is that part of the design in the original that Gary brought to the class?

Could any of the machinists out there direct us/me to info on optimum angles for such things? The contemporary hollow mills that I see on the web intersect the hole straight on, but it seems that in a hand powered tool having a skew angle could be very helpful.

[James Wilson Everett]

Guys,

Here are three photos of Hank's mill.  I am now busy making a nicer tumbler mill that will have cutters similar to Hank's, but I am putting two opposite handles on it to make turning the tool easier.  Thanks to Hank for these detailed photos of a very nice and sophisticated tool.  Remember, guns are just by-products of really nice tools!

Jim



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[whetrock]

very helpful. Thanks, Hank. (and Jim for posting them) Also easy to understand the "top hat" in these photos.
Looks like both cutters cut as the mill is turned in clockwise motion (with tumbler not moving). If you wanted to stop the cutting action of one or the other, I guess you could open the thing up and add a brass washer, so as to stop that side from cutting for a minute until the other side could catch up.

The brass tumbler in the photos shows a raised bearing surface (or that's how I interpret it).  Was that cut on a different mill? The cutters shown in these last photos seem like they would only cut a flat surface. In my own limited experience, I cut the initial surface with one mill hole, and add the bearing surface with another mill hole that has has been counterbored. (I'm talking about a simple mill made with files.)

[helwood]

I will try to answer the questions in order as I see them presented.  First Whetrock:  Illustration "B" is closer to what I tried to discribe.  Yes, Steele and Harrison's-"The Gunsmith's Manual" is a great source and referr to it frequently.  The design of the cutter is/was the same as the one Gary brought from C.W. for us to study.  A good friend of mine Bob Sherwood who made many locks from scratch felt that the mills made from files or similar in construction were best used for Finish Work rather than roughing out.  And Yes, the bearing surface with another mill or cutter.  By the way the tumblers made at C.W. the shafts were 5/16 & 3/16 = .3125" & .1875", Mine turned out to be .32" & .17" pretty close.     John asked about lubricant.  In JHAT I Gary talked about using CHALK and a very good friend, Fred Dimke now passed, Showed me it's ADVANTAGE on all my metal files aka "white smithing".  I won't put my files on metal without it.  I buy it by the gross from ENCO, it's sold as Railroad Chalk Markers-Color White-Part No. 80500 by Markal.  This is the longer part--- it's from  Arms & Armour, Vol.2,No.1,  2005  ISSN: 1741-6124 pg.89,92  By David Williams  "British Tumbler Mills"     Examination of the cutters highlights a number of significant features.  Four of the six cutters are will made, two are more clumsily finished and are clearly replacements (as may be the others).  Most cutters show evidence of final finishing to shape with a file before hardening.  The cutters have ten, eight, (three of six), seven and five teeth.  Most of the teeth of the cutter are set "OVER CENTER" to improve the finish produced and reduce clogging.    Goodrich and Stanley observe:  The teeth of hollow mills (same as our tumbler mill) should be radial or ahead of the center.  With the cutting edge ahead of the centre the chips as produced are caused to move outward away from the work and prevented from disfiguring it.  With the cutting edge below the center, rough turning will result.  With the edge geatly above the center chattering is produced.  About one-tenth of the cutting diameter is found a good average amount to cut the teeth ahead of the centre.    A replica hollow mill grinder photographed in Brumfield shows very significant clogging of the teeth(JHAT I).  Interestingly the teeth of three of the six cutters have an additional form or relief at the centre of the hollow mill similar in form to amodern chip breaker.  This form has probably been created to reduce clogging at the centre of the cutter---this will have additional consequence of improving the surface of the final product.   This is the most I've thought about this in years.  After making  this a friend and I got started making Air Rifles thought to have gone on the Voyage of Discovery, the  first was the Lukens, made 3 and just as we were finishing that Dr. Beeman's research lead him to the Girardoni designed in 1780 for the King of Austria, so we made 2 of those, these  projects took 9 years. And just haven't been back in this neighborhood of projects, it helps me think of all these concepts again.    Hank   

[shortbarrel]

This is all great stuff, wish I had all this information back in 1975 when I made a cap lock. Only info I had was Steel & Harrison and a Diderot. I Found out fast that a crude bean drill would simplify the process. As for the tumbler mill, I Just made one out of a half worn out file. I made all the tools to make the tools to make the lock. Drills,reamers,taps, dies (jam taps & jam dies). Wrought  iron was what I used and a side blast furnace to heat the iron to form the parts into workable pieces. The finished lock is in  English standard craftsmanship.

[Sawatis]

Hey Hank...now that you mention the air guns...were you out at the BBQ at Terry Leeper's in KY 2 weeks back??  If so, we spoke for quite a while! John

[helwood]

Yes,  I was at Terry Leeper's a few weeks ago.  And I do remember talking about the air guns there.  One of my wishes is to remember everybody's name and face that I meet when I'm there, it drives me crazy.  Hank

[Sawatis]

Yeah Hank, I was the guy that just drove in from TX that afternoon. Enjoyed the chat...quite intrigued by these airguns now! John

[James Wilson Everett]

Guys,

I certainly became interested in making a nicer tumbler mill after seeing the really beautiful ones posted here.  This is the new one, but I have not used it, yet.



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I will let you know how it works, later.

Jim

[Acer Saccharum]

Jim, you certainly didn't procrastinate on that idea!

[Curtis]

Great looking tool, Jim!  What did you file the cutters from?  Did you case harden them?

Curtis

[helwood]

Jim that really looks great.  I can't believe how fast you were able to get it together, out standing.  I'm looking forward to see how it works.
Hank

[James Wilson Everett]

Curtis,

The cutters were made from W1 tool steel rod, 1-1/8 inch diameter (just because that what was on hand).  They are fully hardened - heated to bright orange, about 1500F and hotter than the magnetic transition, quenched in brine.  There is no tempering.  I used the idea posted by Hank to angle the cutter edges to bring the cutting chips away from the shaft.  I really had to think about which way to sharpen the teeth because one cutter is a leftie and one is a rightie.



This photo shows all the pieces.  The tubular stops are set to give a tumbler thickness of about 0.29 inch.  When I get a round tuit making the first one, I will shorten the stops until I get a tumbler thickness of about 0.26 inch.  Remember, you can always cut things shorter, but not longer.

Jim

[Mark Elliott]

Jim,

I hope it works.    That is just a weekend project.  

Mark

[David R. Pennington]

Wow Jim that was quick. Great job. I'm sure it will work. The cutters remind me of the way burs are cut on millstones.

[whetrock]

Oh, Jim, now you've done gone made the rest of us look bad!    We're gonna have to scramble just to keep up!
(Nice work!)
Whet

[David R. Pennington]

Great stuff! Glad I initiated this thread! I just went through and saved a bunch of this to a file. I was planning on lathe turning a tumbler for a lock I am building but now I may have to build a mill and forge a blank!
Thanks again fellows for your willingness to share all this valuable information. I'm thinking ALR is sort of like the modern equivalent of an 18th century apprenticeship, where we learn "the art and mystery of the craft".

[Bob Roller]

 I believe the lathe was developed because of the labor intensive nature of
 primitive methods like the tumbler mill.Ditto for deep hole drills and various
milling machines and their tools.

Bob Roller

[Jim Kibler]

From a metallurgical standpoint, it's always a good idea to temper even at a very low temperature.  For only a very slight decrease in hardness a considerable amount of toughness is obtained. 

[Ky-Flinter]

........  I'm thinking ALR is sort of like the modern equivalent of an 18th century apprenticeship, where we learn "the art and mystery of the craft".

Yes, indeed!

-Ron

[James Wilson Everett]

Jim Kibler,

Of course, your observation is completely correct.  After I finished the tool and posted the photos, I tempered the cutters at 300F in my kitchen stove.

Jim

[helwood]

Jim, yes keeping track of the direction of the cutters was something I had to watch closely when I was making them too.   Also if I remember correctly Wallace Gusler said thet the differance between 18th Century tech. and 19th Cent. "industrial revolution" was that tools made in the 18th century and earlier were designed and used for one purpose.  Whereas 19th Cent. tools were designed for many uses.  A lathe can be used for many industries.  Think about the tumbler mill.  It will make a tumbler faster and easier than a lathe,  you're cutting two shafts of differant diameters still in the same axis plus cutting two surfaces perfically parallel to each other.  In the tumbler mill you only put the rough forging  in the mill once.  Think about cleaning up castings in a lathe, you cut one shaft and then turn it around to get the other one and make sure you have the tumbler the right width and true. We are fortunate that we can order out different parts from different makes to make different schools if we had to tool up everytime we sure wouldn't be making as many differant styles.   Hank

[James Wilson Everett]

Guys,

Now for the first test of the new tumbler mill.  I forged another "duckfoot" of W1 steel, but with a longer shaft since the new mill cutter is a lot thicker that the file of the old mill.



I clamp the blob with the shaft upright in my bench vise and using only the lower half of the tumbler mill I round the shaft almost to the blob.  Actually most of the metal removal is still done with a file, using the mill half so show where to file away metal.



This is what the shaft looks like as the cut nears the surface of the blob.  The mill is not removing very much metal as you can see.



Now the whole tool is assembled and the shaft clamped securely in the vise.  turning the tool clockwise starts the action.  I feel sure that I will still remove most of the metal with files and rely on the mill only for marking and for the finish cut.  You can see how far the cut must be made until the screws bottom on the stops.



Time to rest now, but I am begining to think that tumbler mills made from files are only for use by lowlives and scoundrels!!

Jim