Low profile ground-based pan/tilt..

[Rootz]

Hi guys,

Well, my attempt to make the world's smallest p/t worked, after a fashion. That's to say, it worked on the bench. ;D. Didn't take me long to realise that it was just too delicate for fitting to the E-Revo.

The main reason I wanted to make it small was that it needed to be low-profile because I wanted to place the camera as close as possible to the driver's head position - As close as possible to the right-hand side window and mid-way between the wheels. If I was also going to be able to angle the camera up to look through the roof ( more of that some time later ), the p/t needed to be low. I decided I also wanted it to be reasonably fast and I wanted some decent bearings on the pan servo because there would be a fair bit of weight in the pan assembly. I ended up with a Savox SC1251MG. It's about as low as a standed-size servo goes, has good bearings and metal gears. I don't expect (EVER!) to have any problem with this. It's built for 1/10th scale steering so this application won't exactly tax it.

I'm sure I could have chosen a cheaper and lighter tilt servo but, once again, I wanted something robust, with decent bearings and, ideally metal gears. The Turnigy TGY-S712G fits the bill nicely and, because it's slim, it fits nicely on the back-plate of the HobbyCity P/T ( Large )

The P/T is cheap, well designed and light. It's a little flimsy, so I reinforced the base plate with a piece of 2mm carbon fibre. The circular servo horn goes through both plates and the whole lot is held together with Shoe Goo which, once it's set, has just enough "give" but holds things securely. What's more, you can peel the whole lot off if you want and start again. It's great for test-fitting CF components!

The tilt servo linkage for the HK P/T is a little flimsy so I replaced it with some M2 hardware that, I believe, comes from a Kyosho helicopter.

Anyway. here she is...



Vital statistics:

Weight: 109g

Height ( aimed up ) 91mm

Height ( aimed straight ) 70mm

Footprint ( diameter ) 76mm

I'd be interested to hear if you have any suggestions / comments. Also, any suggestions how I can get 180 degrees or more rotation from the pan servo would be very welcome.

Cheerz!

Rootz

[Derrick]

Check out this pan/tilt design... it uses gearing to get the desired rotation, it also takes the load off of the pan servo (this will help out if you want this to be a robust design). Based on what you did to the pan/tilt that you built above you should be able to rig something up. Good luck! keep us posted on your progress.

http://servocity.com/html/spt50_sub-...an___tilt.html

PS you can get gears from this site that have servo splines built in.

[Rootz]

Check out this pan/tilt design... it uses gearing to get the desired rotation, it also takes the load off of the pan servo (this will help out if you want this to be a robust design). Based on what you did to the pan/tilt that you built above you should be able to rig something up. Good luck! keep us posted on your progress.

http://servocity.com/html/spt50_sub-...an___tilt.html

PS you can get gears from this site that have servo splines built in.

Thanks Derrick. That gives me something to think about. The pan servo has a total 160 degree operating range so I might try for a good 200+ degrees.

Thanks once again.

Rootz

[Rootz]

Well, it took me a couple of days but here's my attempt to replicate the servo city design.

Why didn't I just buy some bits from Servo City? I was about to, and had all the right components in my shopping cart before I realised that SC wanted to charge me $45 for shipping to the UK!! I ask ya?! $45 for a couple of gears, a couple of bearings and a shaft! Man!!

Anyway. The SC design inspired me to try it myself and here's the result with some build notes in case someone fancies copying it..

The main gear is a spur from a Sportwerks Recoil / Carisma GT14. It's 60 teeth, 48DP. I cut down a Savox hex horn and, guess what?! 3 of the mounting holes lined up perfectly!! I decided I'd use a 1/8" shaft, as I have loads of spurs for 1/10th touring cars etc. The shaft came from an old Traxxas Titan motor that came from my E-Revo and lasted precisely 20 minutes on LiPo. Getting it out was easy enough. The biggest bind was unwinding the windings and removing the laminates on the rotor. There's a brass collar at one end, which came in useful to "stop" the shaft at the bottom, as it goes into the lower bush. talking of which, these also came from Traxxas Titans ( Yup! I managed to kill plenty of 'em before I wised-up and went brushless. ). I ground a flat on both bushes which keeps them located against the pan servo case.



The upper bush is held in place by a couple of CF offcuts that I stuck to the servo using my old friend Shoe Goo.



There's another small piece of CF forming a base for the P/T, which is stuck to the bottom of the servo and also holds the lower bush flat, with help from some epoxy putty.



The "spur" is a 35t gear, so I get around 1.7 degrees of the tilt head for each servo degree.



There are a few tweaks, like reinforcing the angles of the tilt head with epoxy putty, grinding the bottom flat and covering it with Teflon coated glass fabric so there's very little friction as it rotates against the top surface of the large gear. It seems very robust indeed. Hardly any backlash in the gears etc. Rather too late, I realised that the servo doesn't rotate around it's full range. Even with 120% EPA, I get around 170 degrees but I can easily alter that with another pair of gears. For instance, 61/33 gearing would give me around another 10 degrees each side. My main problem now is managing the wires so they don't snag. Any ideas??



Cheerz!

Rootz

[Derrick]

Rootz,

I like it, and best of all it was your own work that made it! the best way to manage cables is with a "service loop". Basically it is a loop of wire that you tie off strategicly that will allow full range of motion and not bind or get into places that it isn't supposed to.


Hope this inspires you a little more. Good luck!

Derrick