My boid, semroc kit #KA-6

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bradycros

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My Boid


SemrocKit #KA-6​


This kit caught my eye and I thought I'd have a go at it.

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Go to www.semroc.com/Store/scripts/RocketKits.asp?SKU=KA-6 and read the specs. You'll see that the nose cones, fins amd BT lengths are variable.

That means what's advertised on the cover art for the kit ain't necessarily what your gonna get. Hope you like suprises!

Semroc uses something like twenty four different nose cones and a bunch of different fins that go on a series 8 body tube. That makes alot of combinations for the "My Boid" kit.

The "My Boid" I got is closer to looking like the drawing inside the instructions with a stubby'r cone (pic 1), close but still different. It does not resemble the cover art (pic 2).

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Here's the parts for the "My Boid" I received laid out.

You can clearly see the difference between the art and the kit, SUPRISE!

I had already started filling the nose cone before I decided to take pictures of the build.

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A conformal sanding block needs to be made to aid in the task of smoothing out the surfaces of the nose cone and body tube.

The OD of a #8 body tube is .908" and I don't have any extra or scrap #8 tube. I do have an extra BT-50 tube with a OD of .970", which is close enough for a rounded sanding block. It will do, and do just what I want it to do.

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A suprising number of items (each serving its own purpose) were used to fabricate simple rounded sanding blocks.

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After running the rounded sanding block up and down the entire length of the body tube the high spots get knocked down some and the low spots show up as still shining spots.

Look closely at the photo or expand it. The most visible spots on this tube are locate are near the middle.

Taking the steps and time to elimiate these spots now will aid greatly in getting the desired smoothness on the finish paint.

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A highly specialized bio/mechcanical tool was used to apply just the right amount of the filler.

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Thin out the filler with water until it's got the thickness of sour cream. Get a dab on the end of your bio tool and smear it into and around the spiral that runs the length of the tube.

Only apply enough filler that will cover about 1" at a time, rub it around and smooth it out, remember, you have more then one bio tool at your disposal for smoothing out the filler. Your trying to build up low areas, not create new high areas.

You'll develope a feel for it in a short time.

Keep a damp towel handy to wipe your tools off on because the filler will cake up on them faster then you might think.

Sometimes you'll run into a spot on the tube where the filler doesn't want to stick. Just come back to the spot after the filler residue has dried. You'll find the filler will now stick and be spreadable at that spot.

Picture two shows the filler after the bio tool treatment.

Sand with rounded sanding block.

Repeat filling and sanding as needed.

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Use same technique on the nose cone.

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Interesting that the My Boid kit has TTW fins now....must be a recent change. The Boid was my first Semroc kit when I came back to rocketry about 2 1/2 years ago. By luck or intent, mine looked just like the art.

I have had many more kits from Carl and company since. :)
 
The grain of the balsa fins was very open and soft. But they are lazer cut and TTW, both features are a plus.

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Use the same highly specialized bio/mechcanical tool to apply just the right amount of the filler to the fins. Sand, repeat as needed.

A smooth, wood grain free paint job starts here.

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Before filling and after filling. The TTW tabs were left bare for the glue to grab on to when the fins are mounted.

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Scrubed the shine off the outside of the motor tube and centering ring until bare paper started to show itself. This will promote better glue adhesion.

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The motor tube comes with a slit in it for the motor hook. After the motor hook is pushed into place and then removed, a large burr is made and left in the inside of the tube. I want that booger removed.

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A Q-tip is used to coat the inside of the tube with thin CA. The CA will harden up the card board fibers, reducing wear from installing and removing motors.

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After the booger hardens up it can be filed smooth with a rat tail file.

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The motor hook was laid inside the centering ring and a line was traced along both sides.
 
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Ran an X-acto along the lines and removed a few layers of the paper.

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The motor hook now fits between the motor tube and the centering ring very nicely. Before it was jamming up everything and causeing the centering ring to bulge. That bulge would have been transferd to the body tube.

So... bulging, jamming and boogers eliminated.

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A loop is made in one end of the kevlar, then placed under the forward end of the motor hook.

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The kits motor block went AWOL or there never was one since there is no mention of it in the instructions. The booger the motor hook made in the motor tube was removed so the motor block could sit directly on the motor hook.

With only the thin card board of the motor tube to stop any fore or aft movement of the motor hook, perhapes a motor block should be made and placed on top of the motor hook.

A strip of rolled up card stock will do the job.

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The strip of card stock was rolled up to fit the I.D. of the motor tube, then soaked with CA.

After the CA dried a notch was cut into the motor stop to fit over the top of the motor hook. Now the entire top of the motor will be in contact with the motor stop, not just the top of the motor hook.

Motor stop was glue in.

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Both ends of the body tubes I.D. need to be toughend up with thin CA.

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After the CA dried a notch was cut into the motor stop to fit over the top of the motor hook. Now the entire top of the motor will be in contact with the motor stop, not just the top of the motor hook.

That's a great idea about notching the engine block to better fit against the bend in the engine hook. Sometimes the engine block (or motor stop, or thrust ring or whatever you want to call it) sits at an angle when glued in place against the hook end.

I see you are reinforcing the body tube ends with CA.
That Q-tip applicator seems to work the best for control and an even coat.
I usually have to sand down the CA coat a bit for a smoother slide in when gluing in the engine mount. At about a penny apiece, the Q-tip style applicators are cheaper than anything else like a micro brush.
 
I flew my Boid at the Alamo Open last month. Unexpectedly, it took 2nd place in the A altitude event.

One of these days I'll have a chance to update my threads...
 
That's a great idea about notching the engine block to better fit against the bend in the engine hook. Sometimes the engine block (or motor stop, or thrust ring or whatever you want to call it) sits at an angle when glued in place against the hook end.

I see you are reinforcing the body tube ends with CA.
That Q-tip applicator seems to work the best for control and an even coat.
I usually have to sand down the CA coat a bit for a smoother slide in when gluing in the engine mount. At about a penny apiece, the Q-tip style applicators are cheaper than anything else like a micro brush.


Well ... I think it's a practical idea, don't know about it being great... but thanks!

I sand down and smooth out the CA coating with this sanding block. It was made at the same time as the sanding block in the beging of this thread. It can be seen in the lower middle of the first picture.

But, you are absolutly right that it's something that should be done.

Seen any other good sanding ideas lately?

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I use a highly specialized bio/mechcanical tool to apply just the right amount of the filler.

I was reviewing a software design document once that contained a sentence that started with "The program responds to asynchronous tactile input ...."

It took me a while to realize that the author meant "typing."

Back on topic, sort of ...

What do you think (or any others think) of the My Boid as a build for groups of kids? We've been recommending it under the assumption that kids would appreciate the variability in the kits. Each kid's rocket would be unique. But, I'm not sure that's true since we haven't actually used them for a group build yet.

-- Roger





 
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