Estes Cosmic Interceptor Build, Part 11, Cutting The Intake Tube

Draw a centerline down the "K" tube.

The template is cut from the instructions and taped to the tube.

Line up the centerlines. Trace with pencil.

TIP: If you set the wide, rounded end of the template very close to the tube end - there is just enough to make a second intake fairing if you screw up the first attempt. 

The sidelines are straight and you can use a straightedge to cut them. Tape a metal ruler down the side pencil lines.

Or you can cut the lines freehand.

Don't cut through on a single pass! Use a new blade, cut slow and controlled. 

The edges are cleaned up with sandpaper on a block.

On the top is the rough cut,

Below is after sanding the edges flat an rounding the front and rear curves.

Estes USS Enterprise #1275, Part 9, Pylon Supports & Dowels

I fitted the pylon into the pylon brace, then set it next to the body tube. The pencil line is the masking area to keep the filler/primer off the gluing areas. 

On the right - the notched end of the pylon is dry fitted in the bulkhead and marked, again for a mask. 

Here's the pylon masked for a shot of filler/primer.

After the filler primer was sanded -

The cut out is revised to fit the pylon, rounded dowel on the back side.

Estes USS Enterprise #1275, Part 6, Internal Support Ring

The internal support ring  (RT-99D, 3.7" diameter)

has to fit over the "hump" in the primary hull bottom disk. 

Cut the template using a straightedge on the straight lines an scissors on the curves. 

The template doesn't go all the way around the support ring. 

Mark the cutaway crescents with pencil.

Cut the crescents out with a sharp knife.

Here's how the cuts are placed on the ring, directly on opposite sides.

A dry fit in the lower hull disk. Note they do not contact the hump when centered on the disk.

I'm not gluing the ring in place yet.

Wolverine Phoenix AIM-54A, Fix!, Part 4, Peeling & Squaring Up

This is the 4" extension glued 2" over the coupler.

If I cut through just the tube I can still use the original coupler.

On the left, the outside layer of the tube is carefully peeled off.

On the right, the coupler is starting to show. I was surprised how most of the coupler didn't have much glue. On the original build - after sliding the tube segments together, the glue was pushed towards the bottom.

The coupler was 4" long, 2" extend out the bottom.

Little bits of glue still remain towards the low end. This was sanded clean with 220 grit on a block.

The lower cut above the fins was sanded flat using a block.

This low end can be squared up - the upper part can't with the coupler in place. I tried to get as straight a cut as I could.

Wolverine Phoenix AIM-54A, Fix!, Part 3, Tube Cuts

At the pencil lines - 

A straight piece of 110 lb. cardstock was wrapped around the tube and taped closed.

Tape was also added to the bottom edge to keep the cardstock guide still while cutting.

I started with a razor blade but switched over to my X-Acto knife with a new #11 blade.

The cardstock guide edge made the cut pretty easy to do.

As always, don't try to cut through a tube with a single pass. Ease up on the knife. It should take a few rotations of the tube to cut completely through.

TIP: Turn the tube under the blade. Keep the knife blade still. 

This was a pretty clean cut. 

With the upper tube removed, repeat the second cut at the line 4" above this lower cut.

Wolverine Phoenix AIM-54A, Fix!, Part 2, Measure & Mark

The only decals that will be lost when removing the 4" of body tube is this small one.

I took a picture with a ruler reference so I can home print something later at the correct size.

The upper launch lug will be cut off and replaced later. 

Slice off most of the lug just above the glue fillets, then remove the fillet areas.

The Estes kit had two 1" long, 3/16" diameter launch lugs.

This Wolverine kit included two, 2" long 3/16" diameter lugs.

I marked the tube at the body tube joint (right side pencil mark) -

then 4" below that. These will be the two cut lines.

The inside coupler is 4" tall. After the cuts, there should be 2" of coupler (half) extended down out of the top tube. 

Estes EAC VIPER #0820, BT-55 Upscale, Part 4, Cutting the Main Tube

I know - Some of you already know how to do many of the steps on a simpler build like this. There are new builders joining the blog everyday. If you are like me, you need to be reminded a few times to drive a point home. Just ask my ex-wife.

The original kit had a BT-50 tube that was 9 1/2" long. Multiply 9.5" by the scale factor of 1.36 and the upscale BT-55 tube should be cut at 12.92" long.

It's not difficult to cut a body tube and it should be part of your skillset.

Wrap a piece of cardstock around the tube at the 12.92" mark. trace around the top edge with a pencil.

Trace around that pencil line with a new, sharp knife blade. 

DON'T TRY TO CUT WITH A SINGLE PASS OF THE BLADE!

Using moderate pressure on the blade, you may have to go around the tube three times to cut through.

Chances are, the cut line will be a bit rough.

Simply square up the tube end with a sanding block with 220 grit sandpaper.

Check the edge by sliding in a nose cone. Look close at the tube end and the shoulder lip of the nose cone. Turn the nose cone, making sure the tube end is square.

Estes Odyssey #7235 Build, Part 12, Tube Edges & Interior Seams

On the BT-50 tube (Part L) -

The cut tube edges are also sealed and smooth.

I squeezed out a drop of medium CA glue on some scrap cardboard. A Q-tip was dipped in and the CA glue wiped around the cut tube end.

This hardens up the fibers and allows them to be sanded off cleanly. It also seals the tube edge and will look smoother when painted.

Wrap some 400 grit around an empty engine casing. It is about the right size to smooth out the cut curve.

You may have to do the CA glue / sand operation twice to get a good edge.

The cut BT-80 tube is wide open and the interior seam could be seen on the finished model.

I used a knife blade to apply some CWF on all the seams that are close to the ends of the tube.

Sand smooth with 400 grit. If you decide to use filler/primer on the inside of the tube - the filler/primer will smooth out the rough surface to an extent - be sure to mask the glue line where it will contact the main BT-55 tube.

Estes Odyssey #7235 Build, Part 11, Cleaning Up The End Cut Tubes

I used a sandpaper roll to clean up the rough cut edges on the big tube. You can also wrap some 220 grit sandpaper around a small bottle, something around an inch and a half in diameter.

Even after following up with some 400 grit sandpaper there was still some paper fuzz on the edge.

Some medium CA glue was wiped on with a Q-tip. This hardens the edge for a smoother surface sanding with 400 grit.

The smaller tube wrap almost matched up when wrapped around the BT-50 tube. It really doesn't matter on this - just connect the gap with a pencil line.

Here's the other end of the same tube after cutting in the taper.

Notice the rough edge at the bottom of the curve. Wrap sandpaper around a dowel or engine casing to even up the edge.

Follow with a CA glue wipe and smoothing with 400 grit sandpaper.

Estes Solar Sailer II, Kit # 2044, Step 3, Parts Prep

Cutting tubes isn't difficult and should be part of your rocketry skillset.

Sometimes I use a few wraps of masking tape for a cutting edge guide.

Clean up and square the tube against some 220 grit sand paper on a block.

There are some exposed centering ring faces where the BT-50 top and bottom tubes overlap the interior BT-20 central tube.

TIP: You can smooth out the exposed face for a cleaner finished model.

On the left, a light coat of wood glue is smeared on the flat face of the centering ring. Let dry.

Sand the dried glue and the face will end up smooth and flat. You might have to do a second glue/sand treatment.

The top ring shown is before, rough with the layered wraps showing.

The bottom ring is after the glue - sanding treatment. 

It looks larger than the upper ring, but it is the same size.

I only treat one side of the ring, the side that will be seen on the finished model.

I draw arrows on the sides pointing to the smooth side for reference when gluing up the assembly later on.

Estes Blackhawk #2053 Build, Part 6, A Third Vent Tube!

This instruction drawing better shows the assembly.

The ejection charge goes up, makes left turn then goes up again. Remeber, there's a bulkhead in the larger tube that directs the ejection charge up. 

That Centuri rear eject would have been easier.

Here's the final vertical tube, a BT-50.

This one also gets a reinforcement coupler and another cut hole.

I'm marking the dowel to apply glue inside the tube. The tubes above give me a height reference.

The yellow tube pushes in the coupler.

The yellow tube also sets the cardstock bulkhead. 

The final circle cut!

Tape and mark with the guide wrap. Pencil trace and another new #11 blade!

Odd'l Rockets F-18 Hornet Development & Build, Part 4, Engine Mount & Jet Engines

The engine mount is standard with the Kevlar line retained under the top bend of the engine hook.

The engine tube is an Odd'l Rockets heavy wall BT-20H, stronger than a standard BT-20.

A tube marking and cutting template is supplied with the kit. You will be removing a long rectangle piece so the BT-5 tube can overhang the end of the BT-50H main airframe tube.

Wrap and tape the paper template around the BT-5 tube. Punch small holes with a pin down the cut lines. Remove the template and connect the punched dots with a pencil line.

With a new, sharp blade -
Cut the end first.

Then cut the long side lines. You'll find it easier to cut a straight line using a aluminum angle for a knife guide.

Here's what you should end up with.

Notice there is some rough edges.

Careful sanding with a block will clean up and straighten out the cut lines.

Estes Skylab #001973, Build, Part 18, Cut, Smooth & Fill

I usually use a break-off blade knife for most of the builds. This is one of those times where a more expensive X-Acto style blade is needed,

In the side cuts, my (new #11) blade was set at an angle almost laying down on the fairing sides.

The top line against the tape goes straight in at a 90 degree angle.

GO SLOW! 

Don't try to cut through with a single cut. 

After the piece is removed the cuts look pretty rough.

Notice the side cuts aren't right against the fairings. I tend to cut wide and trim down to fit. 

I ended up doing a lot of small trim cuts to clean everything up.

First, CWF fill was used in the joints and sanding with 400 grit.

Filler/Primer was sprayed in a small cup then dabbed onto the joints to fill any remaining gaps.

Estes Skylab #001973, Build, Part 17, Cutout Between The Fairings

Here's where some measurements don't add up.

The instructions say 5 1/2" from the body tube cut (coming up below) to the bottom of the second wrap.

After this next step the tube cuts left just 5 3/16" for the height of the vertical black bands.

I checked Peter Always Rocket of the World for a second reference drawing.

I penciled in the cut lines straight out to the horizontal taper line on the fins. This is the same line as in the Estes instructions.

If I were to cut as high as the horizontal fin taper line, the vertical black bands would end up short of the 5 1/2" height in the instructions.

Cutting at the horizontal taper line, you would cut right into the corrugations.

Estes doesn't say how tall the cuts should be.

I made a guess and a compromise.

Earlier, the instructions have you cut the wraps with a 1/16" border edge just outside the end of the corrugations. I did the same 1/16" edge here at the bottom of the lowest wrap. This made my cut just at the bottom of the center, tall embossed detail.

I marked the cut line with a pencil.

A piece of tape followed to (visually) make sure the line was horizontal. 

Get ready - Change out your knife with a new blade.

More in the next post.

Sanded & Square Body Tube Ends TIP

From TRF, Hooked On Rockets Posted his tip for sanding the ends flat on a cut tube.

"So if you are talking about making true edges to match up with each other, you could do this:

Glue up some sandpaper to a FACTORY EDGE body tube with CA and then cut out the sand paper inside the tube with an exacto...
Then use a body tube coupler inserted in the rig to true up the cut edge.
And of course, since it looks like you have cut a BT shorter than factory, you should have a factory edge on your "cutoff"....that's the edge you wanna glue up to the sand paper."
______________________________________________________

Neil W got to work and put together this series of pictures to better explain the process:

OK, here we go.
I glued the tube to 220 grit sandpaper (seemed like a good choice for this) by applying a nice bead of medium CA around the joint. Pro tip: give it plenty of time to fully cure.





I then carved the hole out with a #11 Xacto. Turned out to be pretty easy job, only took a minute. The hardening of the tube/paper joint from the CA made it pretty easy to remove only sandpaper and not damage the tube (not that small nicks will make any difference).

Of course I had to test it out. Insert coupler halfway...





Then insert tube to be sanded...

Then twist the two tubes against each other. Worked great! Will need to knock the lip off the edge of the tube when finished, but that's super easy.

I made a BT55 and BT60 so far, with a BT50 in progress. Bonus: they nest nicely for storage!

I rate this as an A+ tip.

Now if only I had ordered a BT-70 coupler in my last order ...

Neil adds:
I have two followups:
1) It does really produce a lip on the tube that must be sanded off afterwards. I'm going to experiment further and see if wrapping the tube can prevent that.
2) It's *really* good for squaring off the shoulders of nose cones. When applying CWF to a balsa nose, it takes but a second to clean up the edge after it's dry, no need to do the tube twist while it's still wet.

Thanks to Hooked On Rockets and Neil W - 

I'll have to give this a try -