Thursday, June 12, 2014

Day 84 and 85 - More fender motorization

I spent a good chunk of time drilling various bits of metal and wood, and making sure everything was all lined up.  Finally, the wheel assemblies were ready to be bolted to the rest of the frame.

The problem with that much frame, however, is that there are not a lot of places to mount casters.  I got a set of small 2" casters at Lowe's and placed them temporarily onto the topmost and bottommost wooden struts using self-tapping screws.  I then eagerly took the fender outside for a spin.

After a few minutes of loud, rough trundling, one of the back casters snapped off.  As you can see from the photos, the screws were pretty close to the edges of the wood, so there wasn't a lot holding them into place.  A rough, pebbled cement driveway extends from my townhouse front door at an angle, and that also contributed.

The next day, I described some of my progress to some of my chums at work, and one of them (who builds robots) put in his thoughts on what I could also do.  He suggested reinforcing the third mounting point on the motor casings, which I hadn't yet done.  Since the wheels are mounted on parallel metal beams running the length of the fender frame, sufficient weight placed on them could splay them apart.

So I pondered a bit on how I could solidify this, and came up with adding a length of 5/8" solid threaded rod, bolted on either side with nuts and locking washers.  It's pretty rock solid.  In fact, I had to detach the wheels to even get the rod in place.  Once re-assembled, it wasn't going to splay at all.

Another chap had inadvertently eavesdropped on the conversation at the point when I was talking about the crappy urethane casters, and not knowing where to get ones that would really be able to handle a nice solid load.  He mentioned a store I hadn't even heard of that's still here in Seattle, called RH Brown.  I'm glad he told me about them!  I went there right after work and bought 3.5" and 4" rubber casters and took them home.  I didn't yet know what size I was going to use, and they said I could take back the set I didn't use for a refund.

There was no place on the frame to put them, initially, so I decided that I was going to trim some of the workings off of my monster assemblage.  I took my metal-cutting blade off of the miter saw, threw it onto my circular saw (same size blade), and cut off the upper and lower parts of the square steel tube on which the wheel motors are mounted.  I then unbolted that and the uppermost and lowermost wooden beams.

This cleared a large area for me to add the new casters.  In order for them to be just about level with the main tires, I needed to mount them on top of two 1/2" pieces of plywood.  I chopped up some offcuts, and secured everything into place, this time with 5/16" hex-bolts (and not self-tapping screws).

It looks a lot less complicated down there, now.  Still weighs in at a hefty amount, though.  We took some video of me test-driving it, but because it was so dark, it didn't turn out very well.  Also, I need to sand off a bit from the front plywood caster mounts, because at times the middle tires weren't in contact with the ground.  On a flat surface, this might not matter, but I know I'll hit angles from time to time.

Video of me trundling around likely to be posted soon!

Sunday, June 8, 2014

Day 83 - Attaching the motor and wheels

After last night's Daleking, I pondered ways by which I wanted to attach the wheels to the fender.  I got to looking more closely at them, and it became obvious that there was only one way to attach them.  The two motors each have three mounting points arranged in a triangle, and a "freewheel" lever that disengages the wheels from the motors (if both are toggled).  I wanted that level accessible and I needed to attach two of the three mounting points to flat, steel tubing.

I drove out to Metal Supermarkets in Kent, Washington and picked up around 20 feet of hot-rolled square steel tubing, and 10 feet of flat steel (1" x 0.125").  The latter I did not use in today's adventures, but I will be using it on the top of the fender to reinforce what I did today.  I also swung by my neighborhood Lowe's (many, many times today, as it turned out) to get a new metal-cutting blade for the miter saw, and metal-drilling bits for the drill press.

After cutting off a portion of steel tubing based on the length of the fender interior, I drilled it to match the two mounting points I had selected.  I also cut a hole to accommodate a portion of the tire and motor.  It became glaringly obvious that my plan of bolting the square tubing directly to the fender wouldn't work—the wheels were much too small.  I stacked and stacked 1/2" offcuts of wood to get it to the height it needed to be for a good 2" of clearance from the fender base.  The stack was roughly 3.5 inches, bringing the length of tubing just about level to the fender base.

Back to Lowe's I went, this time for some (inaccurately named) 2x4s.  These beams of wood are actually about 1.5" by 3.5", but it was the same height as my stack.  I had the friendly store employee cut me up some three-foot lengths, and I also selected washers, nuts, and some hex-bolts of various lengths.

I got back home, and, since it was a beautiful day yet again, I took everything outside.  I placed the offcuts of the beams inside and placed the wheel assemblies on top to see if my madcap plan would work.  I was pretty happy with the result, but I still wanted to strengthen the fender with a framework of steel beams.

I cut, drilled, and attached three lengths of steel to the center, left, and right side of the fender.  Then, to get the best of both worlds, I made dado (housing) cuts in each of the wooden beams using the table saw to fit over the steel beams.  Next, I aligned my hand drill to the holes already cut in the steel beams, and continued drilling the rest of the way into the wood.  Then I took 5-inch long hex-bolts and secured them to the frame.  I make is all sound so simple; however, this part of the assembly took me awhile, from inception to execution.

This was all ad-hoc thinking on my part.  No plan.

I debated whether or not to trim the long lengths of steel tubing from the wheels since the two wooden beams I had attached weren't that far apart.  In the end, however, I decided to go overkill.  I repeated the above process and attached two more wooden beams: one closer to the front, and the other closer to the rear.  I figured that this way, the weight placed on the fender from the rest of the Dalek—including the batteries, skirt, shoulders, neck, head, extra bits, and, of course, me—would be more evenly distributed along the fender frame.

(The "L" brackets that can be seen in the pictures are right now just for show, but I plan on further securing the wooden beams to the fender with them next time.  I also plan on adding four more lengths of steel bar—one on either side of the two center wooden beams—then bolting them to the wood beams and steel beams attached to the wheels.  This will give added strength to, and further secure, the wheel assemblies.)

With all the gubbins that I attached underneath, I was very pleased at how clean everything was up on top.  When I took it back to the garage for the evening (man, that things weighs a lot more now), I placed it in its normal position flat on the floor and stood on it.  Then I walked all over it.  There wasn't a creak to be heard, and it felt very solid.  This was also with the wheel assemblies removed, so it will be another story altogether when I add those, along with appropriately-sized caster wheels in the front and back.

Now, I'm not an engineer by any stretch of the imagination.  This was a very ad-hoc approach to solving the problem of how to mount small wheels with bizarre mounting points.  I've tried to over-engineer my ideas as they came to me, but if anyone can see any problems that are glaringly obvious, I would be much obliged.

Saturday, June 7, 2014

Day 82 - Fender and shoulder re-enforcement, and some wheelchair time

Today was an absolute gorgeous day, so I decided to cross a few of the unappealing yet necessary tasks off my to-do list.  Chief among these was laying fiberglass tape on the interior of the fender.  I carefully un-stacked Rainier and carried the fender outside.  I sealed off the exterior seams of the fender with painter's tape, flipped it over, and cut out sections of fiberglass for each panel.

I mixed up some resin, using much less catalyst than I had during the colder months (even so, one batch gelled and cooked sooner than I had wanted), and applied a strip of fiberglass each to the upper and lower seams.  I let that cure for a couple hours, then returned and flipped the fender over.  After taking off the painter's tape, I mixed up a couple batches of Bondo and filled the gaps on the exterior.

Since there was still plenty of sunshine left, I took a wee break and then decided to do the same thing with the shoulder section.  I carefully took off the slats and carried the shoulder section outside as well.  I positioned more fiberglass tape into place on each of the four interior beams, slathering resin onto each as I went.  I let that cure for while, and then added more Bondo to the underside of the shoulders for the heck of it.  People will likely never see that part, but if I attach the shoulders to the skirt with a hinge, it will be visible.  Overkill?  Probably.

By this time, the sunlight was fading, so I went into the garage and started tearing apart the wheelchair.  Before doing so, I downloaded the operators manual for the model (a Jazzy Select Elite) and read it thoroughly, seeing how it was all put together and whether or not I was going to blow myself up.  Eventually, I got the drive motors completely removed.  This was very encouraging to me, as I am eager to try Variable's non-welding method of attaching them to the fender.

At Lowe's, I saw perforated square steel tubing that I might be able to bolt the motors into.  I need to measure to be sure.  If not, I'll get non-perforated stock, and drill the bolt holes myself.  The only other question I have is whether or not I need to keep the wheels the same distance apart as they were when the wheelchair was assembled.  Specifically, would crazy things happen when I am trying to turn, as the fender top is much wider than the wheelchair (75cm vs 58cm).  Something tells me it will be fine, but I would like to make sure.

Thursday, June 5, 2014

Day 81 - Cowl assembly

I decided to tackle the cowl assembly next.  I think it's the last great pain-in-the-neck part to build, so I might as well get it out of the way!  I'm heartened by reading that the actual prop cowls (when observed up close) look like they were made out of bread dough.  Mine will look better (one hopes).

So, first, I gave Rainier a haircut by trimming off the excess fiberglass from under the dome.  Now he's properly bald.  I also added the slats temporarily, just for kicks, as they make him look even more Dalek-y.

I removed the dome and took it upstairs to work in a dust-free area.  Taking my painter's tape, I masked off the approximate area on the dome where the cowl will be positioned.

Like ccain before me, I used my old MacBook Pro box (as well as a Wii U box) for the cowl parts.  It took me hours to extrapolate the dimensions from the NSD plans.  Two of the measurements had both straight line and arc values specified (very handy), but the rest didn't, so I wasn't sure what they were actually measuring.  I took my best guesses at these—looking at lots of reference photos while doing so—and figured I would just pad it with Bondo later on if the cowl wasn't aesthetically pleasing to the eye.

Why the role-playing dice?  Well, the small plastic box they came in proved convenient to make an exact 90° angle for the cowl front and cowl top.  Once I figured out where to position this part of the assembly on the dome, I wondered how I was going to make the side pieces conform to the curvature.  Then I remembered that I have the exact thing I needed: my old dome former.  I traced out that curve and cut out the pieces.

Then it was just a matter of assembling and securing everything to the dome with tape.  Like AdamSt, I attached duct tape face-up on the dome, taped it down with painter's tape, then added strips of cardboard along the sticky surface.  Because of the tension of the cardboard strips, some of the tape lifted up slightly from the underlying dome.  I will need to add extra painter's tape over the top of the cardboard to hold it down.

I had some trouble getting the nameplate section attached, which looks flat on all the cowls I've seen.  On mine, it needed to curve along the chamfer of the dome; otherwise, big gaps would exist on either side, which I haven't seen on any other cowls.  So that part was confusing.

Now that the major shape of the cowl is defined and attached, I can cover it with Bondo and see how it will all look after sanding.  Like the dome, this will be a three-part process of cowl plug, then cowl mold, then casting the eventual fiberglass cowl from the mold.

Tuesday, June 3, 2014

Day 80 - Filling slats and attaching hemis

I allowed the Bondo to cure on the slats overnight.  I then detached all of them from the shoulders, trimmed and sanded the excess Bondo off of them, and peeled off the masking tape from the shoulders.

While the other slats were still curing, I worked on the wide center slat.  This was the most difficult slat to position and secure.  In other diaries, I've seen people flatten the front of the shoulder section to get it to fit, but I didn't want to risk damaging that section.  So, instead, I very deliberately sanded and thinned down the underside of the slat with a combination of the belt sander and Dremel.

I ran into trouble, however, when I very nearly sanded off the bottom of the holes I drilled with the forstner bit.  They were paper-thin when I caught what I had done.  Since I was busy Bondo-ing the other slats, I slathered a bit of filler onto the backs of these thin sections to reinforce them.  After that had cured, I finally managed to fit the center slat, and added the rest of the Bondo to fill in the gaps.

The next step was to make the slats a bit more water-resistant, so I mixed up a batch of Titebond wood glue and water and sprayed it onto the front, sides, and backs of the slats, and allowed them to dry outside.

While they were drying, I decided to finally position all of the hemis onto the skirt section.  I hadn't messed with that section since July of last year, so I wanted to make damned sure my drill holes were positioned correctly.  Adhering to the NSD guide, I marked up all the panels.  For the side and back panels (4a, 4b, 5a, 5b, and 6), I needed to compensate by adding a millimeter or two to get everything looking aligned visually.

I shaved off the tags from all of the hemis with my Dremel, and removed all the springs included in my oil seals.  With the springs, I found that the hemis didn't quite fit.

Finally, all 56 were attached.  And now, this thing is starting to look like a freakin' Dalek.  Wow.

Sunday, June 1, 2014

Day 77 through 79 - Shoulder slat fitting and positioning

It's been quite a while since my last entry, mainly because I just spent a week in beautiful Puerto Vallarta!  My first time spending more than just a few hours in Mexico.  Had the best margaritas of my life, brought back many bottles of tequila.

Alright, what have I been doing that would be of interest to this diary?  Oh, yes.  I was in the middle of making slats.

I cut out a single prototype slat and slid it all the way round the shoulders so that I could find the widest area between the beveled sections.  The reasoning for this was that I wanted to make all of the slats follow this template, and then I could trim each one down as necessary (easier to trim off than to add on).  I used the scroll saw to cut them all out of my HDF board, running each one alone a clamped piece of HDF to keep the lines as straight as possible.  After awhile, the task was complete, and I had 36 slat sides cut out.

Next task was to glue them all onto the slats I had previously cut out.  I hadn't used the router to make a rebate cut like I had done with my gunbox assembly; instead, I just slapped them directly onto each of the slats' sides using a good amount of Liquid Nails.  This process took a little more than a day since I ran out of clamps.  To hide the seam on the slat fronts, I'll just skim some Bondo on there and sand it down.

Once they were all assembled and dry, I trimmed the excess lengths of HDF using the chop saw.  I positioned some of the slats against the shoulders to see how everything lined up and what the eventual trimming would have to be.  Using a combination of the Dremel tool and my bandsaw (mounted upside-down on my stool), I trimmed and sawed a few of the slats.

I decided that I wanted to attach the center back slat first, so that I would have a reference point relative to where the other slats would be located.  I temporarily taped the rest of the slats onto the shoulders using my best guess as to their position.

Using a calculator, I added up the distance between each slat (from the two small ones in the front all the way to the back center slat) and divided that number by 8 (the number of gaps).  The answer was 4.015cm, so I re-taped all the slats so that they were 4cm from each other.

I drilled a hole into the shoulders for each slat's top bolt, and temporarily held them into place with a loose machine screw.  The tape I then recycled to make a barrier between the slat edges and the shoulders for when I would later apply Bondo to fill in the gaps.  I proceeded to take each of the positioned slats off one-at-a-time, and trimmed it with the Dremel and belt sander to make sure it fit into its own unique place on the bend of the shoulders.  As I re-attached each slat, I drilled the lower hole, and then bolted them securely into place, placing a nut on the inside of the shoulders.

Next up was to mix up some batches of Bondo and fill in the gaps, and that's currently curing as I type.

Oh, also over the last few days, I've been gluing a few of the hemis at a time, and I FINALLY got them all completed.  What a menial part of this build!  I should probably drill some holes in the skirt to position these puppies, soon.