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GeoMax/Leica BT Handle Security & 3D Printing
My Leica robot has been generating an unspecified error message over the last couple of years. At first it happened only once every few months, but by last month it was pretty much a daily occurrence. Most of the time it doesn’t interfere with operation, but more and more it required me to go back to the gun to reboot. The last time it was in the shop the tech wasn’t able to pinpoint a cause — naturally, he wasn’t able to generate the condition — but speculated that one or more boards might be going bad. Given its age — I bought it from a colleague who bought it new in 2004 or so — I decided I’d better go to Plan B. So in December I bought a 2-second GeoMax Zoom80R with the Bluetooth handle. This is basically a Leica TCRP1202 in yellow clothing. The BT handle is really a nice step up from the 1102’s hang-on-the-tripod radio, and well worth the $1550 price tag.
However, I’m not a very trusting guy to begin with, and having written a largish check for the GeoMax I’m especially concerned about theft when the robot is unattended, which is most of the time. As with the Leica, I usually run a stainless cable through the tribrach (which has its latch screwed down and the hole plugged) and lock it to something, but that $1500 BT handle is just sitting there with only 4 spring-loaded release buttons keeping it attached to the gun. And that bothered me, so I decided to see what I could do to secure the handle to the instrument.
As can be seen in the photo below, there are 2 holes next to each button.
The holes are fairly deep, and conceal the screws holding the handle halves together. A peek at the underside of the handle indicated that these holes have sufficient wall thickness to allow thread tapping. With just a bit of enlargement, they’ll take an M6-1.0 machine screw. I figured that I could fab some plastic covers out of 1/4″ HD polyethylene and fasten them with machine screws, so I set about drilling and tapping.
The required enlargement was very minor, so used a bit held in a spare chuck and did it by hand, which gave me a comforting degree of control.
Tapping the enlarged holes was straightforward:
A poorly-lit photo of two of the tapped holes:
I rummaged around but couldn’t find a suitable piece of 1/4″ poly, so I ordered a sheet. But while waiting for the poly to arrive I puzzled over the best way to fit the flat poly to the contoured handle, until at one point I asked myself, “What would Norm Larson do?” That’s when I decided that this would be a good project with which to get my feet wet with 3D printing.
I don’t have access to the kind of design software Norm uses — and wouldn’t know how to run it anyway — so I spent $130 to upgrade my BricsCAD license to the Pro version, which give me access to the 3D functions. After that it was a simple matter of taking sufficient measurements to define the parts and then building the models (two required, one a mirror image of the other) in BricsCAD. Here are a couple of BricsCAD screenshots showing top and bottom views:
Next I exported the models as STL files and uploaded them to Shapeways, the 3D printing service that Norm seems to prefer. Here’s a shot of one from the Shapeways site:
I specified a white plastic that seemed like a good combination of strength and cost. The 4 pieces I needed came to less than $24 shipped, which seemed pretty reasonable to me.
I hadn’t settled on a screw head type, so I didn’t do anything special with the holes, figuring that I could address that later. Shapeways took a week or so to build the parts, and then the Postal Service hung them up somewhere for the better part of a week, but they finally arrived a couple of days ago:
The first thing I discovered is that I spec’d the button recess hole too small. Here’s one test-fitted to the handle. It mostly fits over the button, but won’t quite bottom out due to lack of clearance:
So I carefully drilled those out a bit to provide the necessary clearance. I had to be careful not to go too deep, as there’s only about 1 mm of cover over the buttons, so once again I did the drilling by hand.
In the mean time, I decided to use flathead Torx machine screws, but the heads were too big to fit the parts without sticking out over the edges, so I turned them down to a suitable diameter using a faux-lathe attachment that I made years ago for my drill press:
I had to counterbore the covers to allow the screws to fit flush:
Then it was just a matter of attaching them to the handle while the latter is installed on the gun:
The finished installation. You can actually see the darkness of the release buttons showing through the millimeter of plastic cover:
Now if someone wants to run off with the BT handle, he’s going to have to work a bit for it.
I realize that this project speaks more about my personality than it does the actual risk of losing the handle to a thief, but it lets me relax more while I work, which is worth the price of admission.
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14 Replies
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Jim this is absolutely genious!
Christof. -
A guy’s gotta do what a guy’s gotta do.
Excellent work!
Nice writeup too. -
Very crafty! :good:. I have had to remove the handle and clean the contacts before in the field on those guns, so keep a wrench in the bag.
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Many manufacturers are including a lo-jack type system with their instruments – some are free (Topcon) and some are not. I think your solution here is wicked cool, but before drilling into the instrument it is always advisable to see how that affects your warranty. Very impressive work.
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Adam, post: 354198, member: 8900 wrote: I have had to remove the handle and clean the contacts before in the field on those guns, so keep a wrench in the bag.
Good advice — I hadn’t thought of that.
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I’d have just toe-nailed a wood screw into the handle and standard, but what you did looks ok too.
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Jim Frame, post: 354178, member: 10 wrote: “What would Norm Larson do?”
Honestly that depends on when the question is asked. If it were asked in the last month and a half the answer is, .. “off to the man cave to play Fallout 4!” and I would make haste downstairs …
Great job, BTW! If you ever have a question, please ask. I am curious though, in reality don’t you only need to do one side? Not having the gear, I am assuming that you need to squeeze both sides at the same time to get a release
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this is how humans do in the future, and may be 3D printer will be a piece of appliance everybody has.
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Yes Jim this project says so much about you.
I absolutely love it!
One question…as a child, did you take apart everything your parents bought you?
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Norm Larson, post: 354246, member: 7899 wrote: in reality don’t you only need to do one side?
Probably, but I thought that releasing one side might allow the handle to be forced up enough to be damaged, so I went for all 4 buttons. Besides, symmetry!
John Evers, post: 354333, member: 467 wrote: .as a child, did you take apart everything your parents bought you?
Absolutely. I still take apart most anything that’s about to be discarded to see what makes it tick and to salvage parts that add to the clutter in my garage.
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Jim,
I have to wonder if you are somehow a long lost brother… I am adopted after all 🙂
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I like to see it when people get creative and adapt things to fit better and serve a purpose.
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I cringed when I saw the picture of the handle being drilled.
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as a child, did you take apart everything your parents bought you?
Of course.
John Evers, post: 354352, member: 467 wrote: I have to wonder if you are somehow a long lost brother…
I’d wonder if we were triplets, but I don’t produce such neat work, and haven’t been able to confine the “spare parts” to the garage so have too little work space left in the shop room.
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