Utility Arm Pivot Point Micro-Adjustments

Lest I give the impression that I know what I'm doing, I needed to perform some minor fixes on the pivot point holders for the utility arms. Once everything is glued down and screwed down, sometimes everything doesn't line up perfectly. You don't have to be off by much to run into trouble.

Last night I applied a little JB Weld to the MDF holders on the bottom utility arm, the hole seems to be a bit too wide, or at least forcing the rod over a bit helps keep the arm from running into the skins.



Today I used a utility knife to scale the JB Weld back a little, and smoothen it out. The end results is that the bottom arm swings open and closed without bumping into the skins.



For the top utility arm, I found that the bottom pivot point bracket's hole was a bit too large, there was a slight gap between the rod and the bracket. It's hard to see, but it's there.



I decided to glob a little JB Weld into the hole. I will sand to fit as necessary once this is dry, and then hopefully the top arm will be swinging freely as well.

Glued Styrene Pieces for Octagon Port Mounts

Not much, but as promised earlier, I glued some small strips of styrene to the paddles that are used to mount the octagon ports.



These are needed to press the octagon ports forward, against the skins.

Glued Down Tops of Shoulder Planks

Today I glued down the top sides of the vertical planks on the frame.



Pretty much the same as yesterday.

Glued Down Bottoms of Shoulder Planks

Tonight I finally got around to at least starting to glue down the shoulder planks into their slots. These really don't move much at this point since everything else on the frame is glued up, and there are four short dowels that lock them in place. Nevertheless, until tonight, they hadn't been glued down.



I glued around all four bottom sides of each planks.



Soon I'll glue the top sides of the planks in place.

Cut Styrene Side Pieces

Tonight I cut the styrene pieces that will cover the holes at the bottom of the left and right sides of the skins.

Each piece is about 4.5"x5.0"x1/16".



I used some scrap wood from the skirt to sand a beveled edge into the edge of the styrene. This helps to slide the piece into place on the frame and skins.



Time for a test-fit. Looking reasonably good.



Eventually there will be a small wooden post glued to the back of the styrene, and onto the bottom of the frame.

Finished Installing Servo Rods

Tonight I worked on the rod that will help open the top utility arm under servo control.

Recall that yesterday I drilled the hole in the arm slightly mispositioned. I had filled the hole with JB Weld, so tonight I sanded that smooth.



I drilled a new hole in the proper spot on the end of the utility arm. The blue tape on the drill bit helps me to drill to the proper depth.



I decided to try using another 1/16" drill bit to drill the hole for the paper clip, having broken the bit I used yesterday. This time I was successful.



The rod has been JB Welded into the hole, and is drying as I type. Barring any unforeseen problems, all that I need to do now is paint the arms.

Started Working on Servo Rods

Tonight I attached the last aluminum angle bracket to secure the top arm, and started work on the segments of 3/16" steel rod that will allow servo motors to open and close the arms.

The first step is to drill a somewhat shallow hole into the end of the arm. I lined the vise with a towel and clamped the top arm down.



As you shall soon see, I botched this hole for the top arm, I didn't drill the hole in quite the right spot.

I did manage to hit the mark for the bottom arm, so I cut a segment of rod to size and did a test fit.



A hole needs to be drilled near the end of the rod, to allow a paper clip to slide through. One day in the future, the paper clip will be attached to a servo motor (see here for more info). After breaking a 1/16" drill bit while trying to drill through the end of the rod, I switched to a 5/64" drill bit, and drilled a hole near the end of the rod segment. The hole is kind of wide, but hopefully not too wide. I guess I can either wrap something around the paper clip when the time comes, or maybe use a toothpick to apply a tiny bit of JB Weld in there. We shall see.



As I said, I botched the hole for the top utility arm, so I filled the hole with JB Weld. I'll let it dry overnight, sand it smooth and try drilling again.




The rod in the bottom arm is good to go, so I JB Welded it in, and it too will dry overnight.

Cut and Installed Aluminum Pivot Rod Holders

Today I mostly finished installing the utility arms.

The main task remaining was to cut the 1"x1"x1/16" aluminum angle rail into segments, and then cut and drill the segments to size.

So first up, cutting four segments.



I decided to trim the overhang off, so I marked and cut the extra length from each segment.




Next, it was time to drill a semicircle for the 3/16" rod. This matches the MDF holders that I glued down the last few days.



I used some 220 grit sandpaper wrapped around the rod stock to finish up the semicircle.



I measured and marked the locations on the segments for where the holes go to accommodate a 3/4" #6 wood screw. One of the segments is a bit taller than the others, I'll explain why in a moment.



Time to install the segments. I used a 5/64" drill bit for the pilot hole for the #6 wood screw.



And finally, the wood screw locks down the segment around the pivot rod in the arm.



There is a 1/4" MDF rib above the top utility arm. I'm concerned about its strength when inserting a wood screw into it, so I decided to cut a small piece of 1/2" plywood and glue it down on top of this rib. I made sure that it does not interfere with the Large Data Port.



This is why one of the segments was cut taller than the others. I'm going to have the wood screw go into the 1/2" plywood once the glue has dried tomorrow, and then installation will be done. The only arm work remaining will be to drill the holes for the 3/16" rods on the pivot end of the arms that allows them to be opened and closed by a servo motor. And painting, of course.

Glued in Top Utility Arm MDF Pivot Point Holder

Time to glue down the MDF holders for the top arm. Same procedure as for the bottom arm.

First apply the glue.



Then affix the holders to the adjoining ribs.



Finish it up by using the ancient quarter trick to prop up the arms.



I'll let this dry overnight. I still have a little work to do,including cutting and drilling the aluminum tabs that lock the pivot points in place, drilling and gluing in the segment of rod for the servos to pull the arms open and closed, and probably some minor filing where the arms still sometimes rub up against the skins as they swing open and closed.

Glued in Bottom Utility Arm MDF Pivot Point Holder

Tonight I glued in the MDF holders that help secure the pivot rod on the bottom utility arm. I decided to take it one arm at a time.

I blobbed a little glue on the side of the MDF that will go against the rib upon which it sits.



Both MDF holders are in there now.



Utility arms: The new coin slots. A quarter helps ensure that the arm doesn't sag while the glue sets.



This will take a bit longer to finish up than I thought, as I won't have too much time to work on the arms in the near future.

JB Welded Pivot Rods in Utility Arms

Tonight I JB Welded the pivot rods into the utility arms.

I whipped up a batch of JB Weld, and used a toothpick to apply it on the inside of the pivot holes in the arms.



Next, the segment of rod goes in.



Finally, I lined everything up so the arms are perfectly centered vertically in the skins.



I used some quarters to make sure the arms don't sag as this all dries overnight. Won't it be amusing if I JB Welded a couple of those quarters to the arms? (I think not.)



Hopefully tomorrow I can finish up the arm mounting, we shall see.

More Utility Arm Finishing Work

More of the same - I sanded down the Evercoat from yesterday. Too boring for pictures. Shortest post in quite some time.

Filled and Sanded Utility Arms

Tonight I did some utility arm finishing work.

First I used Evercoat to fill in minor bubbles and imperfections. I overdid it with the Evercoat, making more work for myself to sand the excess off.



After I finished sanding the Evercoat smooth, I sanded down the top utility arm in the area that bumps into the skins when the arm swings open.



Here's a close up of the affected area.



I finished with some spot filling with more Evercoat. I'll sand that down tomorrow, and then go for a final fit in the frame and skins, before the gluing and final attachment begins.

Cut MDF Holders for Utility Arms

Today I cut the MDF holders that will help anchor the pivot points for the utility arms. The usual disclaimer, I'm copying Mike Senna as much as possible here.

I drew a series of intersecting lines, about 0.7" apart and 0.4" from the edge of a board of MDF, and then drilled holes at the cross points.



I only need four of these, but I cut some extras just in case.



Next, the fun task of sanding these to size. I used a scrap skin panel to contour the MDF to the correct shape.



The theory is that the outside face of the utility arms should be flush with the outer skins. Likewise, the outboard edge of the MDF holder should be flush with the inside edge of the inner skin. Therefore, the MDF needs to be sanded until the two skin layers fit perfectly between the outer edge of the utility arm and the MDF holder.




And that's pretty much how it works out in practice, give or take a hundredth of an inch here or there.



I'm pretty happy with the location of the arms, I think they are pretty even with the skins. Nothing is holding it all together other than friction at this point. Soon I will JB Weld the pivot rods into the holes in the arms, and I'll glue the MDF to the ribs.