A slightly different B9 Robot
Slightly different Legs
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Legs DONE!
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caveman_1.jpg

Robot pants? So easy even a caveman can do it!

This is the way to build legs. No plywood. No staples. No saran wrap. Some glue if you like. No real skill required. Easier then eating pancakes. You know how to eat pancakes don't ya? Even cavemen eat pancakes... To make legs like this it will cost  about $100 for the legs shown below.

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Keep in mind that this is a new construction method, not all the kinks are worked out of it. Yet.

Where this idea came from

These legs will probably be lighter then plywood/Armaflex legs and it will also be easier to use them in a robot "costume" with a person in them too.

 

You will need:

 

(13 ) 6ft lengths of un-slit Armaflex insulation 7/8” ID, ” thk wall, part 4463 K135 from McMaster-carr.

 

(3) 10 ft lengths of 1/2" PCV water pipe (its really 7/8” OD, Try Home Depot)

 

(3) 10 ft lengths of 7/8" clear vinyl hose. (7/8” OD, 5/8" ID, Try Home Depot)

 

(72) barbed hose connectors for 5/8” hose. McMaster-carr part 5372 K522.

 

Maybe some 3M black weather strip adhesive.

 

Lengths for the pipe, hose and insulation are in the chart below. But keep in mind that you may need to use slightly different length pipes and hoses to get a leg assembly that works well with your particular tread section and waist plate. I included the Excel spread sheet Leg_tube.xls file if you want to play with the dimensions.

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click here to download LEG_TUBE.XLS file

Leg outside dimension is the distance from the outside edges of the Armaflex. Obviously the lower section, where the "legs" are separate, have extra dimensions. The area in yellow are the cutting dimensions for the PVC water pipe and the clear vinyl tubing. Do not pay too much attention to the insulation length, this is only calculated to make sure the 6 ft length is not exceeded.

 

1. Cut the water pipe to length.

 

2. Insert barbed connectors. A heat gun will be required. With my heat gun each end had to be heated for 20 seconds. Heat for 20 sec, push barbed fitting in, let cool.

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3. Cut vinyl hose to length.

 

4. Assemble hose to pipes. Note that on the upper leg pipes I bent the front and rear pipes a little with the heat gun.

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5. Disconnect one end of one of the vinyl tubing from one of the barbed fittings. Slide the pipe assy into lengths of the Armaflex. Better to cut the insulation a bit longer then shorter! I tried to cut the Armaflex just as long as the assembly. Put the tube back onto the barbed fitting.

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Notes:    Its probably a good idea to try and observe the natural curvature of the clear tubing and insulation and position it to work with you.

 

On the upper sections where there is no way to hide the ends of the insulation you may want to glue them together with the weatherstrip adhesive. I made a slight bevel cut, glued it together and positioned it right in front. Or is it the back?

 

With this method you are also free to make a slight bend in the center of the pipes for the upper sections to get a look like the season you want. Make a deep bend for season 1, less for season 2 or 3. Just to be slightly different I did a slight bend both front and rear.

 

After a few experiments I decided that the best way to connect the sections to each other was (Yuk) glue. The only thing I have against glue is that it can be messy, watch out that you do not get any glue on your hands and then somewhere that it will show!. The gluing method that worked best was to stack up the sections and then apply a bead of RTV silicone adhesive to the gap/joint between them. The glue I used is shown below:

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Probably any RTV silicone adhesive will do, black might be nice if you can find some, I used clear. While I could have used a full size caulking gun that would of been tricky to use inside the legs, the smaller tube worked fine but I did need 4 of them! The other glue used is 3M weatherstrip adhesive, use this to glue the ends of the Armaflex to each other.
 
The sample below shows what you want to try and do (sort of reminds me of a log cabin!):

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Don't try to get the RTV inbetween the sections, there is risk of squirting it through to the outside. Glue on the outside will show and may not take paint well. And if you use your finger to smooth out the RTV you will just end up with a messy finger that will end up getting glue on the outside of the legs where it will show and not take paint well. So apply it and leave it alone!
 
Before you start with the RTV first use the weatherstrip adhesive to glue the ends of the Armarflex together!  Use it per the instructions: apply to both sides, allow to dry for 1 min, apply again to only one side and then press together holding pressure for a minute or so.
 
Start with stacking the lower 4 sections of the individual "legs". Position them as you want, make sure they are right, and then start gluing. 
 
A good way to do this is to first "tack" the sections together with glue in small areas and then allowing it to cure overnight. This way if you make a mistake it will be MUCH easier to fix then if you did a continuous bead of glue all around. And remember, apply the glue on the inside!

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After the lower 4 sections are tacked and then done continuously stack the remaining 5 upper sections. Do it the same way, tack, allow to dry (cure really) and if its how you like apply continuous beads. Don't forget to line up the end joints!
 
With a continuous bead between each section the leg assembly will be very strong. If it were used as a costume it will bend very well with the person inside.
 
When its all done these legs weigh about 13.8 lbs which is pretty good to keep the CG low and with a little squish are about 14 3/4" high.

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