Asked — Edited

How To Make Servo Brackets Like Those On Lynxmotion Robots?

How can I make servo brackets like those on LynxMotion Robots out of wood and plastic? I want to try to make a small biped robot.


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Canada
#1  

@jeffmorris Hello Jeff. I think you will find that Google will be your best friend on this... mainly because there is probably no one answer or ready made plan... but observation of others ideas and possible measurements (of the original brackets) along with trial and error with various materials will be my suggestion.

For example, I just slapped together a pan & tilt bracket out of scrap wood, screws and hot glue because I needed one "now and cheap" :)

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I hot glued the one servo horn to another servo and the 2nd horn to the cam body... holds great and easy to disassemble. (I also use heavy duty glue)

Eventualy I want to make a simple arm and will probaly use thinner plywood and such to mimic store bought brackets for the same reason as my P&T... too darn broke :P

#2  

I'm all about making stuff and if you only needed something small gunners idea is great. Your needs however are much more complicated. Given the amount you would spend on adhesive plastic and screws you have options to save time and money. Here is a simple walking robot leg bracket kit just add servos.

http://www.ebay.com/itm/261010563078?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

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Its 50 shipped. Really good deal

Canada
#3  

Ohh, nice call Josh... you do seem to be the man to turn to for ebay deals (and fiberglass:) ) I'm still going to be a cheepo and first try wood or scrap aluminum for my arm (way down the road) since $50 would go nicely toward some strong servos :P

#4  

Pololu.com power hd 1501mg servos are 240 oz in for 20 dollars or djs store for the heavy duty futuba servos that are 160 oz in for around 13 dollars I believe in the store. Either are great choices . Buy 3 or 4 at least at a time like I do so that shipping cost per servo is low.

@jeffmorris these are the same style as lynx. I've used all lynx and after trying several bracket options I would say this is the easiest cheapest way to do your first bi ped . Then if you want to make something more complicated later just use your same servos.

PRO
New Zealand
#5  

Okay Josh, with so many servos out there and my lack of knowledge how do I work out which one(s) I should purchase?

Can you, or another, explain the decision and reasoning behind choosing one servo over another?

#6  

It took me a few hours to make one "C" servo bracket from wood and plastic. I had to make adjustments to the "C" bracket so that it rotates without any problems. I have a CNC router but I'm afaid to cut non-wood materials on it. I'm afraid to buy anything from people selling stuff on E-Bay.

#7  

In choosing a servo you want one strong than you actually need so that the servo lasts a long time. Buying a standard 60 oz servo and pushing it to its limits will shorten its life and burn up the motor inside. So buying a servo that has a stall torque 30 to 50 percent more that the servo will need to push is best. You are in new Zealand so my recomendation is to grab up heavy duty servos from dj. They are great quality and he has worldwide shipping

Fyi servos are rated by speed , torque, and degrees of motion. Most are 90 degrees which is 45 degrees in either direction.

#8  

In robots speed mostly is not a concern but your torque is. If a servo is rated at 240 oz in you divide that by the distance your load is away from the servo. So 240 divided by 10 inches is 24 oz of power.

Canada
#9  

@jeffmorris Whats a few hours here or there per bracket... in a few years you will have enough:D Actually, it sounds good... post a pic or two of your effort.

Depending on your CNC router, and probably more the bit type, I think plastics should be fine as long as they don't melt. And aluminum can actually be cut fairly well with most fine wood blades... not as sure about side cutting bits, but go slow on a test piece with a bit you don't mind testing with. DIY brackets are one thing where having a 3D printer can come in very handy :)

Ebay has gone heavily commercial... stick within the USA (for starters), with highly rated stores and always pay with PayPal. You should not have problems... or at least you can get you $$ back if you do via PayPal. Also watch the shipping costs... some sites pad their "low" price with high shipping.

#10  

I know that there are different kinds of plastics. I used ABS plastic sheets for the servo brackets. Which kind of plastic is best? I don't have a 3D printer.

#11  

Abs and pvc are the strongest and most expensive. However acrylic plexiglass will cut easily between 4 and 6 thousand rpm and it is easy to heat up and bend acrylic. Acrylic plexiglass is more than strong enough once you bend it into the shapes like c brackets. 1/4 inch for heavy duty torque . 1/8 " for regular brackets.

#12  

I thought that acrylic plexiglass can crack if too much force is applied to it.

#13  

Any plastic can Jeff but I'm betting you don't have a servo strong enough. For a standard servo use 1/8" and any high torque servo 1/4" plexiglass.

#14  

I meant that acrylic plexiglass can crack if you tighten screws too much.

#15  

You predrill all holes properly to the size of the shaft of the screw. When holes are properly predrilled you will not have that problem. I work with plexiglass and other plastic often and it works great.