Wurkkos

Mokume Gane Mule

Original_Copy

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Mar 2, 2015
Messages
59
Well, this post is a bit overdue.

I've always loved the BMI Ti Mule that Fred posted and dreamed of owning something like that (as well as a petite killer). I've also been infatuated with exotic/rare metal flashlights, knives, pens, etc (i.e. Ti, Mokume, Damascus, Mokuti/Timascus, Zirconium, etc). So a while back, I inquired about this and that through forum/email/phone about the possibilities of my very own Photon Fanatic build. From beginning to end, Fred has provided a first class experience. Throughout the entire process, I have received updates with narratives and pictures...and in the end a delivery package.

I've actually have had this build completed for a little while now.

And, here is my story...(WIP emails from Fred)

After getting a solid plan in place, I ordered some Mokume Gane round bar from SakMar and had it delivered to Fred.

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Original_Copy

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Joined
Mar 2, 2015
Messages
59
Fred sent me the following narrative (in bold) and pictures...

I may have sent you this before, but this is our starting piece. That was cut into two main pieces, with a small piece leftover, which will be used later for testing the various finish options, before you choose the one you want.

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So this is one of the main pieces, the head of the light I believe. The black Sharpie line was used to mark the minimum length for the cut. Now is in the chuck and about to be 'faced', i.e., the end face will be cleaned up and made perpendicular to the axis.

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A couple of cuts later. You can see the chips on the cutting insert.

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And done, down to the length I want for now. The end piece lets you see how Mike Sakmar layers the materials and then twists the rod to give us the pattern.

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Now begins the long process of removing the interior of the head. Since there will be much machining on the outside of the head, i.e., the flutes and the Trit slots, the bevel down to the battery tube and the bevel to the lens at the front of the light, I will need a way to hold the piece to do all that machining. The solution is to use an expanding internal collet. So here I have drilled out part of the interior, close to the diameter of the collet that I want to use.

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Once I have that diameter, I also faced off the bottom of the head.

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And a final check to make sure that the collet fits perfectly in the drilled and bored interior.
 

Original_Copy

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Joined
Mar 2, 2015
Messages
59
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Close-up of the expanding collet inside the head. The closer the fit, the better the collet will hold the piece true.

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So the chuck has been removed from the lathe spindle and now the expandable collet is in the spindle. As the collet is drawn into the spindle, it expands and holds the head tightly. First operation then is to face the end, which will be the top of the light.

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And then the entire head is reduced in diameter. The final diameter is going to be 30mm, but I like to leave some wiggle room as I work on the light, so I'm turning it down here to 31mm in diameter.

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Close-up showing the surface finish. Not great, so I will use a sharper insert for the final diameter.

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Good enough for now at 31 mm.
 

Original_Copy

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Mar 2, 2015
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The collet is only inserted about 20mm into the head, so that means that I can now drill into the top and open up where the light will exit.

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I bored that out so that I could turn the head around and put the bevel in the bottom of the head. That will mate with the right diameter of the battery tube, eventually.

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I've learned over the years that a good, sharp end mill does a better cut of cutting the bevel, rather than trying to cut the bevel with a tool holding an insert. What is hard to see here, is the set-up; but the head is held in a rotary indexer, which is on a rotary table. So the head can be angled properly to the spindle and the end mill and then the head itself is rotated against the end mill to cut the bevel.

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Here's the big picture so that you can see the set-up. My lathe is from a Swiss company, Wahli, and is rather different in that the headstock, where the spindle is, can be raised and lowered. So in this case, I've removed the usual the cutting tool and placed two item on the cross slide. The cross slide is what normally moves the tool either along the axis, or when facing an end, perpendicular to the axis. For any angle other than that, one needs the rotary table--here seen angled slightly to the spindle. On top of the rotary table is the indexer, which allows me to freely rotate the head along its axis, so that the end mill will cut the bevel around the entire circumference of the head.

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If you can understand the mechanics of that, you will probably enjoy machining. :)
 

Original_Copy

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Mar 2, 2015
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The actual machining of the bevel. There is a yellow clothes pin holding up the retaining pin that would normally sit in one of the 18 holes around the rotary plate. When I turn that by hand, the end mill cuts away the metal, creating the bevel.

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Now the rotary table has been turned so that the axis of the head is perpendicular to the spindle. The square end mill has been replaced with a ball nose mill and that will be used to cut the eight flutes into the head of the light.

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The view from above, showing the already cut flutes, with one more about to be started.

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And doing the same operation, but in the battery tube.

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View from the other side of the lathe. Five flutes down, three to go.

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Original_Copy

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Mar 2, 2015
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And now the work on the Trit slots in the bottom of the light. I cut the length of the battery tube piece a bit longer than normal. That let me do some test cuts to see if I had all the distances and angles correct in my drawings. First I scribed a line in the bottom of the light, which I would use to measure if I had moved the headstock up, or down, the correct amount for the two triangles. You can see the scribed line--it looks a bit dark and angles up to the upper righthand corner.

I actually cut the smaller triangle first, then the outer triangle second. I was a bit concerned that the second triangle might be too close to the inner triangle, so I had already increased the gap on the drawing before I started cutting.

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Once I was satisfied with everything, I could just mill the slots deep enough for the width of the Trit, plus some extra for the facing off that I would do on the bottom of the light.

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All slots done.

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And now back to the head, which still needed some features added, like the bevel shown on the very top circumference of the head.

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And then I milled the two 2 x 12mm slots for the Trits on the head.

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One thing that I do, that makes life easier for the one doing the Trit installation, is that I also mill, using a round nose end mill, a very shallow (0.25mm deep) channel inside the slot. When it comes time to install the Trit vial, you put a little NOA in that channel and then put the Trit vial on top of it. Capillary action will draw the vial in place and hold it well. You might need to slide the vial up or down in the slot to center it, and then you hit the slot with your UV source. Now the vial is locked in place and won't move around when you apply the rest of the NOA to cover the vial completely.


 

Original_Copy

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Mar 2, 2015
Messages
59
Well, I didn't mean to let so much time pass between posts...

Anyway, here is the final results of the build.

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