Attaching Battery Harnesses

Another quick post with old work, this time on how I attached the battery harnesses to the boxes.

If you’ve been reading any R2 blogs for any length of time you’ll notice that most builders love silicon. It’s a very versatile and used to attach all sorts of things on your droids.

I’ve found out the hard way that not all silicon is created equal. Victor highly recommends GE Silicon II, and I have to second that. I’ve tried the generic brands and found they sometimes do not dry as well, especially if it’s a used tube, and often it will not bond well to aluminum or pull away after a while. This could be my lack of experience, but I’ve yet to have a problem when I’ve used the GE product.

I don’t think you need much silicon to hold the battery harnesses in place. I decided to add some to the top and the back side of the top swivel bracket.

And then gooped inside the lower bracket

I then moved the around until I was happy with the position and clean up the excess silicon before it had time to set.

Posted by Chris on March 29th, 2008 in Feet | 2 Comments

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Attaching Battery Boxes

Here’s a quick run down on how I attached the battery boxes to the feet.

I have the steel feet from JAG which include pre-cut key mounting holes for the battery boxes. I’d already fixed screws to the boxes when I cut out the holes for the motors.

But one of the problems with using the screws/key holes is that’s it’s almost impossible to set them correctly to get the boxes to fit (and hold) the boxes tight to the feet. I think if I didn’t have the NPC motors sticking well into the boxes, then the setup would work, but with the motors in place just getting the boxes on is challenge enough – without worrying about the key holes.

The other problem I had was the boxes were not even close to being straight/true, so when the front was tight to the foot the back had a gap, and vis versa. I’d tried tweaking them without much luck.

Originally I’d tried using some large beefy magnets to help fix the boxes to the feet. They kind of worked, but were easily pulled apart and had a problem getting the front and back to sit flat due to the warped boxes.

Gerard gave me a great tip to just screw the box from the back inside to the bottom of the foot – and it worked a treat.

I just held the box in place, marked and drill a hole in the box and thru to the foot

I tapped the hole from the underside of the foot

I’m still using the side key holes as well, but the new screw holds everything in place and stops the boxes from springing away from the feet.

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Posted by Chris on March 27th, 2008 in Feet | Comments Off on Attaching Battery Boxes

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Stacks of Magnets

I’d ordered a bunch of super strong ‘earth’ magnets last week and they arrived today. I’m hoping to use them in quite a few spots, hence the tall stacks.

The larger 3/4″ discs will be used to secure the battery boxes to the feet, the rods will be used on the removable back door, and the small 3/8″ discs in various spots, like securing the shoulder hubs to the legs for easy removal, and holding the front blue panel around the vents. I’m also going to experiment with using them to hold panels and doors closed, but they maybe too strong.

Posted by Chris on December 20th, 2007 in General | 3 Comments

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Finishing Battery Boxes and Feet

I’ve been busy the last few days and not had much time for building. I did get to work on the ankles and legs a little bit more and I think I’m pretty much done, minus one small piece that I need to buy something for to fix.

I’ve mentioned this before, but now that the ankles are back attached the to the feet it was hard to slip the battery boxes over the motors.

The right box went on no problem but I had to make a small adjustment to the left one one and open up the hole a tad. I also had to shave a little bit more off the top of one of the motors, to get the box to sit flush with the foot.

The boxes are really springy with the hoses attached and and there is no way the two screws that are supposed to push fit into the slots will hold the boxes flush to the feet. At least I couldn’t get it to work satisfactorily.

I think I’m going to have to come up with another method of securing the boxes, and will probably use some super strong magnets. That way I don’t need to fiddle with setting screws in tight spaces.

I ended the evening with attaching the legs to the ankles. I used pan head bolts, lock washers and fender washers instead of the countersink Phillips. This will hopefully give them more substance and grip on the legs. The 10-24 Phillips work their way loose way to easy even with thread lock glue, and I’ve had a few wiggle loose during a single outing and sheer off. If this fix doesn’t work I’ll knock out the 10-24 threaded inserts in the legs and use 1/4-20’s bolts instead.

I’m going to try and paint the bolts and washers white to hopefully hide them a bit.

That just leave the battery harnesses and back foot strips to silicon in place, and of course the magnets to hold the boxes.

Posted by Chris on December 10th, 2007 in Feet | Comments Off on Finishing Battery Boxes and Feet

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More Assemble – Feet and Ankles, Return of the KHF

More re-assembling tonight after painting last week. I did a mix of things from the feet to working on some skin panels.

I got the feet and ankles back together, and using the hex bolts worked out great. It was a breeze installing the ankle details.

Feet and Akles re-assembled

With everything R2, there’s always a few steps back with a dozen forward. Today it was the braided hoses. I’d planned on using these expanding rubber plugs to hold the cables in place, but they didn’t quite work as I’d hoped. For some reason rather than bunching up and expanding the nut inside just moved/ripped up the rubber with minimum expansion as shown. The ‘bulge’ at the top being the maximum width.

Back to the drawing board and Ace Hardware tomorrow to look for an alternative. I was tempted to try Douglas Olson’s KHF System again, but space is very tight and they’ll not work for me with the JAG feet and drive system.

The other problem I had was once I tried to install the battery boxes they wouldn’t fit over the NPC motors. All the test fittings I did while filing down the tops of the motors was done without the ankle on the foot, so now I have less room to bend the box over and down onto the motors. An easy fix, but I was hoping to get the feet, ankles and legs back together tonight and now I can’t.

I also worked a little bit more on the frame and got the front vents installed and attached to the frame at last. Not sure how I’m going to fix in the blue surround at this point. Maybe silicon, but I want to be able to remove it easily with the skins. The fit is tight and I can see when removing the skins that it may get pulled off with little effort.

Posted by Chris on December 3rd, 2007 in Feet, Legs | 1 Comment

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NPC Battery Box Cut Out Template

Here’s a quick template I created to help mark out the hole in the battery boxes necessary to accommodate the NPC-2212 motors and the JAG/Dave Painter Foot Drive System.

Download and print the file at full size on 8.5″x11″ paper without scaling. I can’t stress enough not to scale or alter the margins.

JAG NPC Battery Box Template

I used a Dremel to cut out the hole and if I had this template to start with I’d probably saved myself a few hours work and a bunch of cutting wheels.

[PDF Template]

Note: Your mileage will most likely vary. This is not an official builders club document but based on my experience in cutting my JAG Battery Boxes. Everyone has a slightly different way of building a droid, so best check then double check all measurement before cutting.

Posted by Chris on November 13th, 2007 in Feet | 2 Comments

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From Feet to Painting

Weather has turned a little cold and we’ve had some rain, so I got to work in the garage this last weekend.

It was a mix bag, from cleaning up space to work to jumping between painting some parts, cutting the skins and fitting the battery boxes and hoses. I also tried to troubleshoot some issues I’m having, like the dome speed rotation, but more of that later.

First up I really needed to make space to totally disassembled R2. I’d been dreading it and a few events throughout the summer kinda gave me an excuse to avoid it. Even though he’s not finished it’s still been fun driving him around and people love him.

So I started off by breaking him down and inspected parts for wear, missing screws etc.

I never did get a coat of undercoat on the center foot before C4, and some surface rust had set in. I was also surprised how well the omniball castor’s have held up given the terrain I’ve run him over.

Center Foot

Center Foot omni ball

A once over with some sandpaper removed the rust from all the center foot parts and I was able to give them a coat paint.

I also inspected my center ankle for any problems. George Luck broke a JAG center ankle right after C4 and I was a little worried about mine, but all the joints looked fine. I’ve heard of two ankles breaking now, and both times the droids had done a long cross country trek for C4. I’m wondering if that’s the problem rather than every day wear and tear. To be on the safe side I had ordered a spare center ankle from Jerry just in case, but hopefully I’ll not need to use it anytime soon 🙂

JAG Ankle - Weld Inspection

Next up, I finally drilled the holes in the outer feet for the Knurled Hose Fittings (KHF). I had a bit of trouble securing the the foot on my drill press, so had to use my cordless hand drill instead, problem was the drill bit would not fit. I had to use my stepping bit instead. I don’t think it like it much as the steel feet are pretty tough – but it got the job done.

The Kurled Hose Fittings only just arrived last week from Doug and they have a nice feature where the hose is easily secured with a screw-in plug.

Knurled Hose Fittings

With the KFL I also got some new braided hoses, but I wasn’t too keen on how gold they were. I much prefer the original copper one’s I got some time ago.

I had to insert some tubing into the braided hoses to make sure they held their shape and secure the hose in place inside the KHF.

Now comes the kicker with the KHF – there’s always a kicker right? They hit the main drive wheel once I got things back together

I even switched out to using regular nuts, but it looks like I’ll need to trim the KHF’s down by half

I decided to move on to cutting the back of the battery boxes to accommodated the big NPC motors. I couldn’t find a template anywhere, so it was a bit of trial and error. I started off with cutting the smallest hole I could, traced from the matching hole in the foot. It wasn’t big enough to slide down and over the motor so I gradually made things bigger until thinks worked. Once the box is in place you’ll not be able to notice the hole.

I’ll try and create a PDF template later tonight to share [update – here’s the template]

Cut Battery Boxes

I also had to grind down the motor in three spots. In the Dave Painter tutorial it looks like you only need to grind the top sides of the motor, but I also had to grind the bottom outside edge too

So here’s the first foot assembled with the motor encased in the battery box ready for painting. Next step battery harnesses.

As I said at the start of this blog entry, I did a lot more on R2 over the weekend, but I’ll stop here for now.

As always more photos in the gallery section.

Posted by Chris on November 13th, 2007 in Feet, Finish/Paint | 6 Comments

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