Rigging a HD rangefinder servo to your helmet

Jimmy BufFETT

Well-Known Hunter
This question has been popping up fairly often, but I don't know how many tutorials there are for this (if any.) Well, Laan recently asked me to rig up his Hyperdyne remote controlled servo to his helmet. So, I thought I'd post a tutorial of ONE way to rig it up if anyone ever decides to do this or do something similar. Here are the items I used:

1) Hyperdyne Bounty Hunter Servo Controller
2) Hollow rangefinder stalk by terminal fettler.

Here is the inside of the helmet with the most of the kit (less the servo) installed:

Right off the bat, I will note the switch right below the batteries is the power on/off switch. I put it there for easy access while wearing the helmet. I also taped the wires down so they won't catch on anything.

The chip at the far left is the servo controller board, and next to it is the transmitter / receiver board. I just used a small amount of hot glue in each corner to hold each board to the helmet. It works really well as it will take a lot of effort to remove a board. I used industrial strength velcro to hold the batteries in place.

A couple of notes about the servo controller board:

The switch there is NOT an on/off switch! It's a "manual/automatic" switch. Positioned to the right like pictured is "automatic" mode meaning the rangefinder will go up and down with just the push of the remote button. Positioned left is "manual" mode meaning the rangefinder will move only when the remote button is HELD down.

Secondly, note the three prongs next to the switch. The servo plugs into that, but note which way:

The black wire is towards the side of the chip, and the yellow wire is towards the center.

Next step is to rig the servo to the stalk. TF's stalk comes with a screw at the end. The key is to secure the screw to one of the pieces that comes with the rangefinder like so:

There is one critical thing here: make sure the screw is centered up!!! I found it is easy to do this first by using some superglue so the screw can be moved around and then set. Once it is set, use some JB Weld to secure the two parts (let it dry overnight.) Yes, this bond is strong enough:

This piece easily attaches to the servo:

And here is how the piece will attach to the stalk:

Yes, it just screws in. I recommend using medium strength Lock Tight threadlocker (blue.) Medium strength will produce a strong bond, but not to the point where it will be impossible to loosen should it ever need to be loosened.

The last step is to rig the stalk and servo to the helmet as described above. NOTE: I strongly encourage this step be performed AFTER the helmet is painted. Otherwise it's going to be difficult to paint with the rangefinder stalk already installed.
1) Insert the stalk through the hole in the earcap (make sure the hole is big enough.)
2) Put some of the threadlocker on the screw, and screw the connected servo piece and screw into the helmet. Let the threadlocker dry!
3) Make sure the stalk and servo are BOTH in the UP position, and then connect the servo as described above. Use hot glue (and super glue if needed) to hold the servo to the helmet.

Here is a picture of what the finished product will look like. I used my helmet to show the finished product here:


Active Hunter
(y)Woo hoo! Looks great bud. I can't thank you enough for doing it for me. Now on to superjedi for the paint!!
You are awesome bud! Thank you thank you thank you!(y)

When you are on my side of town let me know, Ill get the 1st round :cheers

Jimmy BufFETT

Well-Known Hunter
i don't know that my head would fit in there with all that stuff :)

This is also a good point to bring up. Before even attempting this, make sure there is plenty of space in your bucket for all of the components. It's not the boards that take up much space (heck the MQ1 circuit is probably just as thick), it's the servo motor that will stick out a little ways.

Jimmy BufFETT

Well-Known Hunter
JB, you don't shrink wrap the boards to protect them from condensation?

I live in Phoenix ... that is rarely a problem (even with my head in the helmet.);););). HOWEVER, it would probably be a good idea to do this if you live an in area where the humidity usually is high.


Active Hunter
This is great. I did a tutorial for the hard wired setup I used one mine a while ago. No worries of someone else operating on the same frequency and making your RF go up and down whan you dont want it to. That's the only reason I didn't go for the RC setup.


Active Hunter
That's a really cool way to rig one up but I know for a fact that I don't have that much room in my bucket.

I was wondering if a set up like this would work, the top thing represents the servo arm on the stalk and the bottom is one connected to the servo its self with a bar to connect the two. Does anyone else think or know if this will or will not work?


Please forgive my microsoft painting skills...


Active Hunter
Looks workable to me. Might I suggest you do a mock-up on a piece of wood just to see how the rotation issues work? You might find the shaft doesn't do exactly what you want it to, and might have to make some structural adjustments.

Jimmy BufFETT

Well-Known Hunter
Does anyone else think or know if this will or will not work?


You've got a good idea, but there is a problem that could arise (especially if the two servo pieces are not aligned or are not rotated the same number of degrees as each other.) Here is a demonstration of what I mean. Here would be the rangefinder in the up position:

And this would be the rangefinder in the down position:

Here is the problem. You run the risk of this situation occurring when putting the rangefinder back into the up position:

If that situation ever occurs, you are going to sustain some significant damage to at least one part of the assembly because the rangefinder will continue to go down, the ear cap will stop the rangefinder from going down any further, but the servo will continue to run. (n)OUCH!(n) Here is my proposed solution: use TWO servo arms, and have both servo pieces rotated 45 degrees:

Two important things:
1) Make sure both servo arms are the exact same length.
2) Use a lubricant of some type where the servo arms insert into the servo pieces as the arms will actually be rotating.

I think with that setup, you should be good to go!;)(y)


Active Hunter
Thanks man. Now with the HD servo is it allready programmed on where to start and where to stop or is that something the new owner will have to do?