I have been looking into getting a hexapod for a while now and I haven't been able to find one that I like. I have looked at lynxmotion and in a few other places on the internet, but I cannot seem to find any hexapods that are built with micro servos (like the HS-81 or HS-85). They're all built using standard size servos, which tends to cost more due to the increased size and weight of the robot, requiring strong servos. I work at a hobby show so I get a discount on servos and the Hitec micro servo line is pretty cheap on discount. I would really like to build a hexapod that uses these servos. It's too bad you guys don't sell kits (I do understand why though). Does anyone know where I can find a hexapod kit meant for micro servos?

Thanks in advance.

-Dan

Hi Dan,

I came REALY close to finishing a mini sized servo hexapod kit about two months ago. Unfortunately I have too much film work on at the moment and I had to put the kit to one side.

I was basing my kit on Multiplex servos, specifically the Tiny-S and Tiny-MG range. These are really good servos for the price, however, If your planning alot of use for your hexapod, I suggest metal gear servos such as the Tiny-MG. I may consider releasing a kit of platic machined parts with no servos for beta testing with no servos, however, it is machined to accept Multiplex Tiny-S or Tiny-MG only.

As you may already know I based my V2 and V2b hexapod design on the Hi-Tec 85 servos, I didn't have much luck with these servos as they tended to fight each othere and the hexapod would go into oscillation. I beleive this is caused due to the way these servos are tuned for speed.

One other note, in my experience, I have found that there little cost difference between building a hexapod with mini or standard size servos. The biggest weakness in most hexapods is the servo gearbox, not the rated torque of the servo.

cheers,

Matt.

Sounds great! If you don't mind, I would like some basic info like what material is it made out of, number of servos required/what size (I'm guessing 18 servos and Hitec HS-81 size), dimensions, etc. It would be greatly appreciated! Also, any idea of a release date? 6 months? A year?

Hi Dan,

The size would be similar to my V3 hexapod, with 18 servos, body and leg material will be 5mm acrylic. Servos will be Multiplex Tiny range, equivelent to HS-85 size. I would hope to have some test kits ready within 6 months. I will take some pictures of the test kit I built and post them on a new page.

Matt.

I´m interested in hexapod construction; i understand electronics circuits and have some simulation about servo control; but my challenge is the leg.

Can you give me some information about leg design?.

thanks in advance.

Hi Man,

I will send you the hexapod V2b construction guide if that is of use to you.

M@

Hi Man,

I will send you the hexapod V2b construction guide if that is of use to you.

M@

--- mdenton 

Could you send me a copy of that too?

Thx in advance

not sure if you can see the e-mail in previous post... ;)

Done. :)

got it, thank you very much :)

I would also like a copy of that. Also are the high torque servos necessary? I was some on e-bay that were 1.6kg/cm for 18/$100. If I shorten the leg segment that connects to the body it should be OK. I plan to make my own hexapod based on your design, as you don't have any kits. 1kg seems like a lot of weigh to me. How big is the battery you are using? I was planing on using a li-po (I have three already for my helicopter).

Thanks,

Justin

Also, I will give credit to the origin of the idea also. You can see my progress once I start on http://coilgunpower.com/.

Thanks again,

Justin

hi :)

1,6kg isn`t too much :/ it means that your servo can handle 1,6kg on 1cm lever... if leg or arm length of your robot is 10cm this servo will be able to handle only 160g at the end of it...

Hi Justin,

I am away at the moment, and won´t be back until the 10/01. I will email you the guide upon my return.

General rule of thumb with servos.. buy the best you can afford! through years of experience with servos, I find the saying "buy cheap.. buy twice!" is often the case.

Cheap servos offten suffer from having poor potentiometers in them which give poor linearity. This can be a real headache when trying to get your robot to perfrom well!

Matt.

You will be back the 10th of Jan. right? Not the 1st of Oct. I appreciate you sending me the guide. I'll try and get some HS85-BB then. Do you recommend metal geared servos? I heard they get play in them quicker than nylon.

Also if I used the 1.6kg/cm servos and a 10 cm arm it could lift 160g at a 0 degree angle (horizontal), but at a 35 degree angle it could lift 195g. With a 8cm long arm at a 35 degree angle it could lift 244g.

torque/length of arm*cos(angle)=lifting force in kg

ex. 1.6/10*cos(0)=0.16 or 160g

1.6kg/cm is still not very much, I agree but with shorter legs it could work. As I said though I will try to get the HS-85BB servos with 307g of lift with an 8 cm arm at 35 degree angle.

Thanks,

Justin

HS-85BB servos with 307g of lift with an 8 cm arm at 35 degree angle.

I meant to say 458g of lift. Also the formula should say

torque / (length * cos(angle))=lifting force in kg

Sorry

Hi Dan,

The size would be similar to my V3 hexapod, with 18 servos, body and leg material will be 5mm acrylic. Servos will be Multiplex Tiny range, equivelent to HS-85 size. I would hope to have some test kits ready within 6 months. I will take some pictures of the test kit I built and post them on a new page.

Matt.

--- mdenton 

Hi Matt.

I would be interested in building a hexapod too.

I like the overall look. It's not ugly like many of the kits available commercially.

Price... The high price for any kit at all interesting is too high.

Supply of servos and electronics is crowded, I would like to continue to support my local suppliers for that.

Would it be possible to buy just a kit of the mechanical parts... Legs, matching body etc. and allow a hobbyist to customise the electromechanicals, electronics & software. ? (Tamiya don't supply servos in their car kits).

The idea of having the servo splines fit directly into the legs makes for a clean look in the design. I'm a bit concerned about the risk of damage to the servos. What happens you shake a leg or two?

Some kind of mechanical overload release or clutch would be good, especially if incorporated into the leg design. (Tamiya kits provide a simple plastic release ring for the servo.)

Noel...

Also if I used the 1.6kg/cm servos and a 10 cm arm it could lift 160g at a 0 degree angle (horizontal), but at a 35 degree angle it could lift 195g. With a 8cm long arm at a 35 degree angle it could lift 244g.

torque/length of arm*cos(angle)=lifting force in kg

ex. 1.6/10*cos(0)=0.16 or 160g

--- Justin 

good to know :)