Tuesday, December 30, 2014

Day 104 and 105 - Recasting the plungers and making cowl 2.0

I got my Polytek A70 rubber in the mail, and set to work on recasting the plunger.  This stuff is so much different than the A30!  It's still a two-parts-in-equal-measure substance, but the pour time is only five minutes (as opposed to 30), and the demolding time is only an hour (instead of 18 hours)!

Once the first one had been released from the mold, I turned around and made five more that day.  I've got six plungers in all, and a whole lot more of the stuff left!  I'm debating on using it all, and that would net me about—at rough guess—18 plungers or so, since
I've only gone through about a third of the two bottles.

(I've since discovered that two of them have one small air bubble each in the cup portion, but they're hardly noticeable, and I will probably just cover them with a few permanent marker penstrokes.)

In the meantime, the A30 plunger has all but fallen completely apart.  Poor thing.

Then I set to work on my second attempt at the dome cowl.  I had again pre-cut my fiberglass pieces for the first layer (to make sure all the angles were shape to mitigate air bubbles), and then planned on using surfacing veil for the second layer, and thicker ripped-up chop mat for the third and potential fourth layer.

I got out the dome cowl mold and washed it.  Having neglected to add the name tag indentation on my first attempt with the cowl, I corrected that this time.  I took an old plastic convention entry badge (PAX, for those who are curious), cut two 7.5cm x 3cm rectangles out of it, and cementing them together with carpet adhesive, clamped for a nice amount of time.  Then, I sprayed a lesser-grade adhesive (the one I used for the rubber dome inserts) onto one side, let that get tacky, and clamped it onto the cowl mold for about an hour.

I coated the mold with a sponged-on layer of PVA (left to dry), and then a few passes of silicone release agent spray.  No wax this time.  My leftover can of gel-coat had set in its tin since the time I had last cast a cowl, so I needed to go get another one, grumble, mutter.

With the fresh tin in hand, I stirred it all up so that it wasn't all settled and separated.  Then I poured myself five ounces or so in a separate pot, added the catalyst, and stirred, stirred, stirred.  I sponged all that on (with about an ounce left over), and let it sit for two hours with the heater on in the garage.

Once it was mostly dry, I placed the pre-cut pieces into position and mixed up about four ounces of resin.  Once those pieces were in place, I added a layer of surfacing veil glass over the top, ensuring that I had taken care of any visible air bubbles.  I took about an hour break, and then tackled the next layers of chop mat, mixing up six more ounces of resin for that.

All in all, I think this one will turn out much better than the first.  I'm still going to need to do a lot of repair work on it to smooth it all out due to the rough, ripply texture of the mold, but hey, that's what Bondo and sandpaper are for.

I'll get this Dalek done if it kills me!  (Or rather, unless it kills me!)

Monday, December 15, 2014

Day 101 through 103: Floppy plunger time!

This will hopefully be an informative yet amusing post.  So, where did we leave off?  Oh yes, I had made a plunger master mold out of ABS plastic and PVC pipe.  Let's show the kiddies what I did with it!

I was very inspired by chrisosborne's post about making a two-part silicone mold for the plunger, but I didn't want to build a mold box out of acrylic sheets.  I looked around on the web for alternatives, and after perusing a few YouTube videos on the subject, I decided to build one out of Lego bricks.

Keeping this mold exactly centered was very important to me, as I wanted the final rubber plunger to have a uniform wall thickness (the thinnest part of the plunger only being 1/8" thick).  The main advantage of having a Lego mold box, according to my thinking, was that all the Lego studs would keep everything very much in center.  I used a forstner bit to drill a hole in one of my sacrificial Lego bricks (*gasp!*) to center the PVC portion of the plunger.

For the bottom of the mold box, I made an extra reservoir space with a grilled floor.  This would force the cured bottom mold to be perfectly in place and not move around, again ensuring the centering of the final piece.

To keep the plunger master mold in place, and to prevent silicone from seeping into the inner cup, I filled the plunger bowl with plasticine putty.  When I placed the master mold back into the mold box and centered it, it stayed put.

(Not pictured is the event known as the "cup overfloweth", where I lost about $75 worth of leaked silicone when I tried to mold the bottom part first without making sure things were sealed.  Lego like to come apart when weight is placed on them.  Who knew?)

Next up was to mix up a batch of the silicone (I used something called a Squirrel mixer, which caused me no end of amusement, ah, the visuals) and whipped up a bunch of blue goop in no time.  It has a nice 30-minute pour time, too.  I placed the mold box on the floor, and from about three feet up, I poured the silicone in a very thin bead to reduce air bubbles.  After a few long minutes, I was done and the mold was filled.  Now I just had to let it set for 24 hours.

A day later, I checked on the mold and the silicone was nice and firm.  I took the bottom part off and cleaned out all the putty, wiping off any remaining smudges of it with paper towels and a microfiber cloth.  I placed the bottom of the mold box back on, prepare more liquid silicone, and fill in the bottom part of the mold.  And then wait another 24 hours.

When the other half of the mold was ready, I removed the whole lego enclosure and looked at my handiwork.  I had two wonderful halves of the plunger mold, complete with alignment keys and perfectly centered.  The man at TAP Plastics told me that nothing sticks to silicone like more silicone, so I used some release wax and an oil-based agent (called Pam cooking spray) on the mold interior.  I was thrilled to mix up a batch of black rubber and get to work!

I modified the Lego box a bit by only using a few rows of bricks around where the two mold pieces meet, to prevent leakage.  In the center of each side, I built pillars all the way to the top of the mold to lay a jig, which would be used to suspend and center a bolt within the plunger stem.  This would then screw in the plunger to its arm bushing.  I destroyed another sacrificial lego by drilling a centered 1/4" hole for the bolt.  I then mixed up some of the two-part rubber and added the black pigment to it (note that it says "shore A-30" on the bottles, this will be important).  This mixed very thinly, so I needed to slap a bit of the plasticine clay onto the Lego to prevent leakage.

After about 18 hours or so, it was time to demold the plunger.  I was very excited!  The bottom mold popped off easily enough, and before too long I managed to get the top part off, too!  And then I held my plunger to the light, and it ... started ... to ... droop.  And there were weird and bumps on its surface.  The drooping, I later found, was due to the shore number (remember A-30?).  A-30 is softer than a pencil eraser (which is A-40).  A-70 is about the strength of a car tire.  A-85 is a wheel on an inline skate.  TAP Plastics doesn't carry anything beyond A-30, since they're selling mold-making materials.

So, again, I referred to chrisosborne's post, and saw that he ordered A-70 rubber, which I promptly went online and ordered, too, from the very same store!  It hasn't come in yet, but when it does, you'll be the first to know how it goes!  (Well, after me, obviously.)

As far as the pits and blemishes, I can only assume that the TAP Plastics guy was wrong about the vegetable oil.  I think it reacted to the liquid rubber and made things kinda weird, chemically.  The plunger is still a bit tacky (bits of rubber fall off when a finger rubs it) even after several days, now.  ChristmasDalek expressed a potential interest in it, but I'm not sure its ability to survive in our harsh world.


Thursday, December 4, 2014

Day 100 - Eyestalk pivot and plunder plug assembly

Although I've been working on Rainier since July of 2013, this marks day 100 of active work on him!  So, I wanted to post something iconic: the completed eyestalk and the plunger!

My previous attempt at making the eyestalk pivot wasn't too successful, as I had neglected to make sure that the circular pieces of MDF and HDF were all lined up perfectly when I glued them together.  I found, after sanding them, that there was a slight angular tilt instead of a perfect cylindrical piece.  Because of this unevenness (and the fact that it was already cut in a circular shape), it was very difficult to drill a shallow hole where the eyestalk tube would be inset.

I mulled over in my mind how else I wanted to approach this.  What I decided to do was to take larger rectangular pieces of MDF and HDF—cut to the same size and squared on the table saw—and glue those together as before.  Once the glue had set, I marked off the square I wanted to work with, found center, and drilled the shallow where the eyestalk rod would be inset.  I also took the opportunity to drill the centered 3/8" hole for the lamp rod to pass through.  Then I took the 4" circular saw blade to it, and cut out the circle.

To solve the issue of how the lamp rod and axle rod would meet, I decided I would use my leftover 1" aluminum tubing for the axle.  Using the same 1" forstner bit, I drilled a hole all the way through the center of the pivot on its side, then test-fitted the tubing.  When I get ready to fit the lamp rod, I will simply use the eyestalk pivot itself as a jig to drill the 3/8" holes through the aluminum tube.

The outside diameter of the saw is 4", which means that the resulting piece is shy of that by about an 1/8".  Using some of the 4" Plastruct ABS tube I bought for the eyeball, I measured and sliced off a section and clamped it on with a two-part epoxy glue.  Once that had set, I carefully drilled (starting small and working my way up with larger and larger bits) the eyestalk tube hole.

A nice advantage of having the ABS plastic on the outside was that I could now adhere the pivot strips.  I took a tip from Jon Place's build diary and used zip ties.  I couldn't find ones that were flat; the only ones I could find had a texture on them, but I actually quite like it.  It compliments the more industrial look of the NSD-type daleks in my opinion.  One problem with the plastic these ties were made from, however: it basically ignores my acrylic cement.  So, what I used instead was simple super glue.  To space the strips evenly, I used a blade from my jigsaw.  Afterward, just for kicks, I ran a bead of acrylic cement along each space, let that set for a bit, and then took an X-acto knife to trim off the excess.

I carefully trimmed the zip ties along the inset hole and test-fitted the eyestalk tubing.  It was a very nice fit, so I assembled the eyestalk with the new pivot, and am very pleased with the result.  It is now set aside for eventual sanding and painting, not to mention the electronics.

Moving onto the plunger, I followed lochsloy's method of measuring out and cutting the inner and outer Plastruct cup parts.  For removing these sections, I used my Dremel tool for the major work and some 80-grit sandpaper for fine-tuning.  I switched to finer and finer grits to polish it off.

The part of the plunger that had me confused the most was the outer flare.  In lochsloy's diary, he leaves the part as-is, only sawing away the hole for attaching it to the plunger.  In screenshots and prop photos that I've seen, the outer flare seems to be trimmed quite a bit.  My decision was to leave it as-is, and when I cast the eventual rubber plungers, either trim it down with an X-acto knife or just leave it alone.  What I did have to do, however, was cut back the four outer ribs by about an 1/8" so that I could attach the flared rim to the outer bottom part of the middle plunger cup.

Attaching everything together was done by using the same acrylic cement I used for assembling the light cages.  I didn't need to use melted ABS glue as I did for the eyeball, since this is intended to just be a plug for an eventual silicon mold.  I also took some two-part epoxy glue and attached a measured length of 3/4" PVC pipe for the stem.  This will then fit in nicely with my 1" tubing I will be making the "hard" back section of the plunger out of.

And there we have it!  Next up: making the silicon mold of the plunger!

Sunday, November 16, 2014

Day 99 - Neck bin mesh

The cold weather is preventing me from working on dome cowl 2.0, so I decided to return to work on Rainier by crafting the mesh segments for the neck section.  This was very exciting for me, as I've had the material components for this for quite some time, just sitting in their boxes.

First thing first, I needed a template to account for the curvature of the interior of the neck section.  Taking some leftover scrap cardstock from when I measured out the shoulder section cladding, I placed it inside the neck and traced out and cut a few quick lines.  I checked this single template on each of the eight interior sections of the neck, just to make sure the measurements were accurate all the way round, in case the neck was a little lopsided.

The template was a good fit for each section, so I used it to trace an outline on the eight aluminum BBQ grills I had stored away.  I took my Dremel tool and carefully cut out each of the aluminum sections with a metal cutting blade.  The speed of the blade coupled with the delicate nature of the grills meant that a few of the aluminum "tines" were a little bent, so I took some pliers and straightened them back into their "V" positions.

Taking the black voile cloth out of its box, I cut out several oversized square pieces with scissors.  The cloth was a bit wrinkly from being stored away for so long, so I stacked the squares on top of each other, placed them between two towels, and ironed them out. (I didn't place the iron on them directly, as they are polyester and I didn't want the iron to burn them.)

At Lowe's, I found that Loctite made an aerosol carpet adhesive (stronger than the other adhesive I used for placing the rubber inserts into my dome mold), so I procured some and used it on the BBQ grills.  The instructions on the tin said that for a stronger hold, spray one layer and let it sit for 2-5 minutes, and then spray another layer on top of that.  I did just that, and then placed the black voile carefully onto each grill, gently smoothing it on with my hand.  I took a large spare board and covered the freshly-sprayed sections, applying some hefty weight to them (a combination of myself and my electric wheelchair batteries, somewhere around 200 pounds).  Then I played Bejeweled on my phone for 5 minutes.

After that, I took the board off.  I noticed that, similar to AdamSt's diary, the adhesive sprays in a spiderweb-like pattern, which would need to be cleaned up.  Rubbing the grill with the abrasive side of a standard kitchen sponge did the trick on that front.

I then trimmed off all the excess voile with scissors, and for an extra measure, very carefully burned off any frayed bits with a cigarette lighter.  All eight sections were finally complete!  I also had my Heronrib nearby, still in its box, so I cut out eight sections of that for eventual trimming.  I will trim them to shape once I'm ready to attach them to the neck section, which won't yet happen until it's sanded, primed, and painted.

Looking through the mesh, I finally have my first hint of what my obscured vision will be like inside Rainier!

Sunday, October 19, 2014

Day 98 - Eyestalk

I got inspired to work on the Plastruct disks that I had bought, and to see what kind of further progress I could make on the eye and eyestalk.  First, I needed to make a simple jig with each of the disks measured out on it and four flat nails to dissuade the disk from wandering while being drilled.  This way I could make sure I drilled in the center each time.  I decided to use a 3/8" forstner bit for cutting the disks after practicing first on a spare bit of acrylic.  Even with the jig, there was a small amount of eye-balling I needed to do make sure that the bit didn't wander too far off-center while tapping.

After the largest of the disks was done, I hammered in another set of nails for the next size down.  After drilling those, I repeated that for the smallest of the disks.  After all six disks were drilled, I also drilled the same sized hole into the back of the eye I had made previously.

I cut a small length off of my 3/8" threaded lamp rod and secured a disk onto it using two nuts above and one below.  I made sure that these were very snug (worrying a bit that I might crack the plastic) so that nothing came loose while the drill was spinning.  I put the lamp rod into the chuck of my drill press and proceeded to use a variety of methods to trim off the excess plastic that I didn't need.

Gently pressing down on a sheet of 80-grit sandpaper worked for a bit, but soon the plastic heated up and got somewhat soft.  I turned off the drill and waited for the disk to cool.  After that, I tried a hacksaw blade, and that seemed to work much better.  While the disk was spinning, I placed the hacksaw blade under it teeth upwards, and gently scraped it along the bottom of the disk, frequently checking the diameter with my calipers to make sure I was adhering to the plans.  After several minutes, I had trimmed off all that I needed.  I repeated this for the remaining disks, getting faster with each one.

After that, each disk was scuffed using steel wool and a 320-grit sandpaper sponge to get a nice frosted effect.  A quick spacing check using the aluminum I had previously cut seemed pretty satisfactory to me.  I then set these aside for a bit.

Back when I was making the inner gunbox assemblies, I kept the two 1/2" thick MDF circle offcuts my hole saw had made.  These, along with two circles of my thinner HDF board, were the 3.6cm thickness I needed for the eyestalk pivot.  I glued and clamped these together, and they're curing as I type.  Later, I will sand it smooth and drill a hole to accommodate the lamp rod.  It's just shy of the 10cm diameter needed, but the outer ribbed detailing I'll add to it should make it just the right size.

In order to make the optical illusion that the eyestalk consists of a single piece of metal, I needed to think outside the box a bit.  I have 3/8" threaded lamp rod to run the eventual wires through, but the thickness of the actual eyestalk is one inch.  This means I need to have layers built up around the rod.  Several weeks ago, I looked and looked for anything that would let me make nice, snug layers for the eyestalk, but the only thing I could find was some 3/4" PVC pipe.  It fit fairly well inside the 1" aluminum tubing that I have, but it still rattled around a bit.  Further, the threaded rod was much smaller than the PVC's inside diameter.

One day while looking for the very nuts that I used above to secure the disks onto the threaded rod, a thought struck me.  These nuts looked about the same size at the inner diameter of the PVC pipe.  A quick experiment showed me that I could fit the PVC over the nuts quite snugly, and that the whole assembly was nice and centered.

I made sections of PVC that were slightly shorter than the aluminum that will surround them (to accommodate the curvature of the eye disks once assembled).  To make the aluminum fit more snugly, I added a layer of trimmed duct tape to the PVC.

Then, I took two of the nuts and spun them way down the threaded lamp rod.  The longest piece of PVC covered them, one at each end to keep it centered.  Then I surrounded it with its aluminum part, slid an eyestalk disk down on top of that, then another nut/PVC/aluminum bit, another eyestalk disk, etc, etc, etc.

Before too long, I had finished it all off by placing the eye onto the rod, and securing it in place with a wide washer and a nut.  I was particularly pleased with how even and centered the eye disks were, keeping the illusion of one solid piece of tubing.

Now I just need to wait for my LED to arrive so that I can start with all the inner eye pieces, and get this bad boy lit up!

Monday, October 13, 2014

Day 96 and 97 - Dome cowl

I finally decided to stop being afraid of the dome cowl and actually finally make it.  I set out and bought a few more fiberglass supplies from TAP Plastic, then began cutting up pieces of cloth for the angled sections inside the mold.

I waxed the interior of the mold several times and let that sit for a bit. Then I applied a layer of PVA and let that dry.  Finally, I dusted a few coats of silicon mold release.  I wanted to make sure I had plenty of release layers between the mold and the final part!

After a little more time, I mixed up about 3oz of gel-coat and spread that on with a brush.  As it is getting colder, I added the maximum recommended amount for the catalyst.  I let the gel-coat sit for about three hours until it was only just slightly tacky, mostly dry.

I took some fiberglass strands that I pulled off of some woven cloth and placed that in the small trench in the top of the mold.  I was really afraid of having air bubbles in this little section, so I made sure to reinforce it as much as I could.

Then I placed the rest of the cur pieces in their positions, mixed up about 4oz of resin, and started brushing it on.  These cut sections didn't really overlap each other, so I then took some thin torn-up surfacing veil and applied some overlap.  Then I applied a heavy layer of overlapping chop mat on top of all that, with another 5oz of resin sealing it into place.  I rolled the mold all around in my hands while the resin started to set.  Once I no longer saw movement of the liquid, I sat it down and waited for it to cure.

The next day, I attempted to separate the part from the mold.  I have read many stories on how difficult it is to remove a cowl, but I didn't want to resort to cutting the mold into two pieces.  I placed putty wedges in similar to how I separated the dome from its mold.  On the bottom of the mold, however, I placed too many, and the cowl started to crack and split slightly.  Panicked, I removed all the wedges and decided upon a different strategy.

All around the mold, I put in one wedge, and then a second on top of it.  I then hammered in a wooden stir-stick in between the two wedges.  The stick always went in quite a bit further, so they were clearing the beveled edge of the cowl.  I repeated this this all around the cowl.

I poured in some boiling-hot water between the cowl and the mold, and eventually the two parts separated!  I quickly washed off the cowl and took a closer look at it.

The split in the middle was the most obvious.  It's going to need to be Bondo'd up a bit to conceal that.  But that's okay, because I also noticed that I had totally forgotten to place an indent in the mold for the recessed ID tag area!  When I Bondo this part, I'll be sure to include the ID tag indentation.  There was also an air pocket in one of the four corners; again, totally repairable.

I was especially happy with how well the detailing turned out on the top of the cowl!  This was the part I thought would be the most mangled.  But it's great!

I took my Dremel tool and cut/ground the hole in the cowl where the eventual eyestalk will be, and temporarily attached the cowl to the dome for a quick photo op!

Next steps: Repair the cowl and put the ID tag indentation in place, then sand the whole thing because all the ripply roughness of the mold transferred to the cowl.