Semroc Apollo Capsule/Tower tips thread

[chanstevens]

OK, I know there have been a number of Saturn 1b/Little Joe II build threads posted here (and on TRF), but I figured we owe ourselves and those that follow in our footsteps a simple collection of tips related to the most difficult and vexing aspect of the construction--that [insert expletive here] tower...

Having spent the better part of this past weekend building one capsule (that's my 4th), I'm getting better at it, but still haven't found a way to lessen the PITA factor. Let's toss around tips/tricks.

1) Jeweler's plate? Tried a decent one found on E-bay, hardened steel. Nice for rounding sloppy sanding job, but doesn't actually "shave" down a dowel, instead sort of trying to smoosh it into smaller diameter.

2) Stick dowel in a drill, sand while it spins. Not too bad, though a little tricky to get a consistent diameter. Coupled with the jewler's plate, though, it can be effective, but still takes (me, YMMV) a good 30-45 minutes per set of 4 dowels. Also, especially when working down the smaller (0.041" dia) dowel, the little suckers get fragile and are prone to snapping if sanding too aggressively.

3) Replace wood dowels with styrene--I'll be trying this cheat method next. Found some decent 0.040 made by Evergreen for $1.89 per 10-pack (14" long each) at Hobbylinc. Only downside is closest match to 0.058" larger diameter is 1/16" (0.0625), so still looking at draw plate/sanding to get that one down.

And those are just addressing the dowel diameter fun--how about getting the sizing/orientation of the upper & lower struts right? Again, I'm getting better but still always seem to struggle with either a ring that slants a bit or struts that don't quite line up nice and centered. I'll post a few pics of this weekend's effort later.

So...who else besides me is incredibly anal-retentive and detail oriented, obsessing about how to make a capsule tower that doesn't look like a popsicle stick science fair project? What did you do to get a satisfactory result?

--Chan Stevens

[Bob H]

1) Jeweler's plate? Tried a decent one found on E-bay, hardened steel. Nice for rounding sloppy sanding job, but doesn't actually "shave" down a dowel, instead sort of trying to smoosh it into smaller diameter.

After you run the dowel through the tapered side of the hole to smooth it, pull it through the hole from the opposite way and it will shave off a little of the dowel. Pull it through a few times until it come through easily and then go to the next smaller hole. You will need to taper the end of the dowel to get it started. I can get a dowel down to the correct size in about 5 minutes.

A good source for extra dowels is the stick from the "glue applicator" that Semroc supplies in a lot of their kits. The dowels are the same size. I buy those for use in the shop but usually they are not stocked on the shelves. The pharmacist at CVS ordered them for me. They are 6" wooden handled swabs and come in a box with 10 bags of swabs with 100 in each bag. I cut off the sticks after using so I have a big bag full of spare dowels.

I have the tower built but haven't built the "V" struts yet. I built the first tower, didn't like how it came out, and then built a second tower that I like much better. I'm going to use that tower on the LJ II and build a new tower for the Saturn 1B.

[sandman]

So...who else besides me is incredibly anal-retentive and detail oriented, obsessing about how to make a capsule tower that doesn't look like a popsicle stick science fair project? What did you do to get a satisfactory result?

--Chan Stevens

Me! :D

OK, maybe not quite to your level yet. :rolleyes: But I did turn the 25.5" diameter upper ring on the lathe! That may have been a bit "over the edge". :o

I use the Dremel/drill sanding method and I think it's quite effective.

I use the kit dowel stock for the larger uprights and lower cross pieces.

For the smaller dowels I've started with round toothpicks. Not quite as much material to remove.

You can screw up a whole lot of toothpick and still not waste much money.

The correct scale sizes should be 0.05" for the 3.5" diameter cross pieces and 0.036" for the 2.5" cross pieces.

[foose4string]

Chan, I tried the Styrene rod method first and wasn't entirely impressed. I completed the tower but wasn't satisfied. The legs weren't exactly even, the bottom ring titled slightly, and the rod had lots of rough spots from the glue.

The rod diameter is consistent and well within acceptable specs, but gluing was a PIA. I used Ambroid Pro Weld, which is a good product for this, but like any glue for plastic, it "melts" and fuses the plastic. So, I ended up having rough spots on the plastic that didn't look so hot. And the plastic is so small, you risk melting away some of the plastic, changing not only the diameter, but the length. My other concern was attaching the plastic strut to a balsa capsule. What to use? CA? I tried a plastic safe CA with no luck. Epoxy? Nah....overkill.

Just wasn't sure what to do here, so I started building another tower with the supplied dowels. I felt much better about a wood to wood glue joint, than a plastic to wood joint. I borrowed a tip from Sandman and chucked the dowels in my Dremel and sanded away. Not a bad method at all. I did manage to snap off a small portion of the first dowel while getting the hang of it. The dowels needed a small wrap of tape around one end in order for the chuck to grab tightly. After cutting the dowels to length, I used Titebond wood glue to glue the dowel sections together, using a round toothpick to apply a very tiny drop on each joint. The toothpick was a very nice tool for this, much more precise than using the brush applicator of the plastic weld. The wood glue grabbed quickly, but was still pliable enough to make minor adjustments over several minutes. After each joint was dry, I again used the toothpick to reinforce the joints with another tiny dab of glue, carefully using the point to work glue in the tiny crevices, but also scraping away any extra glue as I went.

Making the flat tower assemblies was actually fairly easy using the template, wax paper, corkboard, and straight pins, just like the instruction called for. Tweezers are a must! The jig even proved useful for gluing those sections together. The biggest headache was gluing the rings and V-struts together. I used a ton of straight pins to hold this assembly together while the glue dried. Too bad there isn't a jig for this step, only a cardboard template to position the feet.

After a total of SEVERAL hours and a migraine later, I had what resembled a pretty good looking tower. Not perfect by any stretch, but much better than my first attempt. I chose to fill and prime the capsule before attaching the tower, and afterward, was very happy with my decision to do this. Attaching the tower to the capsule is the easiest part and the most gratifying, because you know it's done!

I'm attaching a pic of the V-strut assembly. You can see the amount of pins it took to hold everything in place! Anybody who has built this, knows what a tight space this is, not more than a centimeter or two. Next time, I may try to fashion a balsa or cardstock jig that supports the assembly from the underneath. I think that's what Tony V. said he did on his, and it seems like a good idea. Before I came up with the pin idea, I was going to ask Tony if he still had his jig, and would be willing to mail it to me! I was getting pretty frustrated at that point. But luckily, this method worked out ok.

[chanstevens]

Me! :D
The correct scale sizes should be 0.05" for the 3.5" diameter cross pieces and 0.036" for the 2.5" cross pieces.

I thought the wood dowels looked non-scale at 0.058 and 0.040, especially when compared to the Apogee tower that's about the same scale and can be assembled in maybe 15 minutes. Given the time and money that Tim put into his design, I figured it was more accurate scale.

All that work to sand them down, and we're not even doing it to scale? Man are we nuts...

[foose4string]

Heck, I ain't that anal ! :D Looks *almost* like an Apollo Tower...close enough for me. I know I should have sanded even more off the dowels than what I did, even to the kit specs. I'm sure they could have stood a few more rotations in the Dremel. But I didn't want to compromise strength for scale accuracy, and I plan on flying it eventually! It looks and feels pretty sturdy, I think it will hold up well.

[ghrocketman]

I cheated to the nth degree for the capsules on my Semroc S1B and LJII !
I bought the 1/70 plastic capsules and towers from Apogee !
A little pricey at about $20 each shipped, but well worth the reduction in PITA factor of all those wooden dowels to sand.
I would build the Semroc capsules if it was not for sanding the danged dowels to the proper diameter....are correct diameter wood dowels not available ?
I don't remember sanding dowels when I built my original Estes K-30 LJII....maybe I just cut them and left the diameter wrong.
I still have that capsule somewhere.

[foose4string]

1/16" is the smallest dowel size that is readily available, and even that size can be tough to find. However, I noticed while using a round toothpick as a glue tool, that it was the same 1/16" diameter that is included with the kit. So, if you run short on dowels, you can always pick up a box of toothpicks and you'll have enough lumber for 50 towers or so. :D Sanding the dowels with the Dremel wasn't that bad at all, just took a little while. Sat on the porch , lifeguarded the kids while they were in the pool, and let the Dremel do the work. I don't think I spent more than an hour doing it.

[sandman]

1/16" is the smallest dowel size that is readily available, and even that size can be tough to find. However, I noticed while using a round toothpick as a glue tool, that it was the same 1/16" diameter that is included with the kit. So, if you run short on dowels, you can always pick up a box of toothpicks and you'll have enough lumber for 50 towers or so. :D Sanding the dowels with the Dremel wasn't that bad at all, just took a little while. Sat on the porch , lifeguarded the kids while they were in the pool, and let the Dremel do the work. I don't think I spent more than an hour doing it.

Exactly! :D

I doubt I could even work on a model if I didn't have a box of round toothpick handy. :rolleyes: