DbyDs Summer Project #1 - Camera Boom!
With no school and no work I have no excuses for not actually working on some of the projects I have been meaning to get to. Up first was a boom mount for making cool videos Cool. Thanks to Jeff OB for the inspiration.
I raided Rob McKenzie's hang glider bone yard for some tubbage and came up with a few pieces, an old washout strut and tip batten, that made up the boom. To mount the camera to the boom I just got another Ultra-Pod II [http://www.rei.com/product/777250] and bolted to the end of the boom.
The tricky part was mounting the boom to the basetube. I needed something strong because even though my camera only weighs something like a half pound, it creates a rather large moment when put at the end of a 4 foot boom. I didn't think a vario mount would be strong enough, they are not designed to resist large moments. I cut up a cardboard box and built several mock-ups before finding something that I thought would work and I would be able to build. Here is the bracket:
I machined it down from a solid block of scrap aluminum. Wall thickness is about .25 inch. Pressed, threaded inserts were used because tapping into aluminum is only good for the first time you over tighten the screws. thumbsup . The holes were precision drilled with a CNC Mill Cool, one in the center and 5 more spaced 30 degrees apart. This allows the boom to be adjusted in 30 degree increments. The grooves on the top are for the zip ties I use to attach it to the basetube.
The mouth shaped grooves were also cut using a CNC Mill. I got a cross-section drawing of the basetube from the WillsWing website and imported it into SolidWorks to trace the profile:
With the help of an experienced machinist, a family friend Larro Russo (Ace Precision Products) we created a CNC program from the SolidWorks drawing using MasterCam. Making the cut proved to be tricky because it was difficult to mount the part in the machine in a way that it did not vibrate too much. We had to take light cuts, 0.050" at a time. Here is a crappy cell phone picture of the cutting in action:
and the Bracket again (I lined the inside of the "mouth" with double-sided tape with the backing still on. This adds some friction, makes a tighter fit and keeps the bracket from scratching up my basetube.):
Next up is the part that joins the round boom with the flat basetube bracket. At first I tried just hammering the end of the boom flat, drilling holes and bolting it down, but it was way to flimsy. So I went over to the scrap metal shop and bought a $5 bar of round aluminum. Cut it down to size and turned it in the lathe so it would fit inside the boom. Then Milled the end flat on both sides and drilled some holes:
here it is assembled and on the glider:
Its a bit wobbly so I tied a string between the camera and the keel where the downtubes join. In this position the string does not interfere with any part of the glider's operation. The string works good at getting rid of the up/down movement, but it still wobbles side-to-side. Its not too bad though as the test video will show Wink.
I decided to try the boom out on the training hill first, but with no Rob around with the Gator I had to do it the old fashion way and hike my glider up the hill. The glider flew fine and I did not notice any trim changes. But then again I was flying faster than trim for the whole flight.
Overall I am pretty pleased at how it came out. I built the bracket in such a way that it could be a sort-of universal mount for what ever in the future I may dream up. I may also build several booms each with a slightly different camera angle (I would like to see more of the wing in the frame.)
Test Video
I raided Rob McKenzie's hang glider bone yard for some tubbage and came up with a few pieces, an old washout strut and tip batten, that made up the boom. To mount the camera to the boom I just got another Ultra-Pod II [http://www.rei.com/product/777250] and bolted to the end of the boom.
The tricky part was mounting the boom to the basetube. I needed something strong because even though my camera only weighs something like a half pound, it creates a rather large moment when put at the end of a 4 foot boom. I didn't think a vario mount would be strong enough, they are not designed to resist large moments. I cut up a cardboard box and built several mock-ups before finding something that I thought would work and I would be able to build. Here is the bracket:
I machined it down from a solid block of scrap aluminum. Wall thickness is about .25 inch. Pressed, threaded inserts were used because tapping into aluminum is only good for the first time you over tighten the screws. thumbsup . The holes were precision drilled with a CNC Mill Cool, one in the center and 5 more spaced 30 degrees apart. This allows the boom to be adjusted in 30 degree increments. The grooves on the top are for the zip ties I use to attach it to the basetube.
The mouth shaped grooves were also cut using a CNC Mill. I got a cross-section drawing of the basetube from the WillsWing website and imported it into SolidWorks to trace the profile:
With the help of an experienced machinist, a family friend Larro Russo (Ace Precision Products) we created a CNC program from the SolidWorks drawing using MasterCam. Making the cut proved to be tricky because it was difficult to mount the part in the machine in a way that it did not vibrate too much. We had to take light cuts, 0.050" at a time. Here is a crappy cell phone picture of the cutting in action:
and the Bracket again (I lined the inside of the "mouth" with double-sided tape with the backing still on. This adds some friction, makes a tighter fit and keeps the bracket from scratching up my basetube.):
Next up is the part that joins the round boom with the flat basetube bracket. At first I tried just hammering the end of the boom flat, drilling holes and bolting it down, but it was way to flimsy. So I went over to the scrap metal shop and bought a $5 bar of round aluminum. Cut it down to size and turned it in the lathe so it would fit inside the boom. Then Milled the end flat on both sides and drilled some holes:
here it is assembled and on the glider:
Its a bit wobbly so I tied a string between the camera and the keel where the downtubes join. In this position the string does not interfere with any part of the glider's operation. The string works good at getting rid of the up/down movement, but it still wobbles side-to-side. Its not too bad though as the test video will show Wink.
I decided to try the boom out on the training hill first, but with no Rob around with the Gator I had to do it the old fashion way and hike my glider up the hill. The glider flew fine and I did not notice any trim changes. But then again I was flying faster than trim for the whole flight.
Overall I am pretty pleased at how it came out. I built the bracket in such a way that it could be a sort-of universal mount for what ever in the future I may dream up. I may also build several booms each with a slightly different camera angle (I would like to see more of the wing in the frame.)
Test Video
posted by David Aldrich at
10:27 PM
