Enerjet by Aerotech Strong Arm Build, Part 17, Adapting A Painting Wand

I use painting wands to hold my rockets horizontally when spray painting.

The wand is a 1/2" dowel shoved into a used 18mm engine casing. 

This is too small a diameter to fit this larger rocket engine mount.

I wrapped some corrugated cardboard around the casing and closed it up with tape. To fit the 29mm diameter mount, the cardboard is just over a full wrap around the casing. This wider diameter gives a good friction fit. 

With the dowel wand slid into the mount,

Some masking tape is placed sticky side out inside the main body tube.

A rolled up paper towel is press into the area around the mount and up against the inside wall of the main tube.

Any open areas are covered with additional pieces of masking tape.

Now the rocket can be spray painted without getting any paint inside the low end.

Enerjet by Aerotech Strong Arm Build, Part 16, Setting The Lowest Centering Ring

I'm back from vacation, hoping to paint the lower body assemblies - but, it's been raining! So, onto other steps.

 

Check both sides of the centering ring, pick the smoothest side to be exposed out the bottom.

On one side, there was a chip. I marked this side with "X's". This side will be facing up, not seen. 

The low edge of the body tube is slightly "squared", out of a perfect round. The four fins are locked into the rings and pull in the body tube. 

It would be very difficult to "slide" the ring in with the tube slightly out of round. 

On the left, I sanded an angle into the edge to make the insertion easier.

Notice the laser charred edge has been sanded.

The center of the ring also got a taper to slide over the engine mount tube.

The ring is slid in and rests against the root edge tabs of the fins.

Here I've applied a wood glue fillet around the ring/tube joint.

Enerjet by Aerotech Strong Arm Build, Part 15, Nose Cone Re-Paint & White Paint

The nose cone color was picked to closely match the upper roll bar on the sticker sheet.

An earlier post showed bubbles as the nose cone paint dried. 

I usually don't use Rusto spray paint but this gray was the closest.  This time, the spray coat was even and glossy.

The rest of the body is painted a gloss white with no masking.

Here's the body after a light first coat. Sanding followed with 400 grit.

Enerjet by Aerotech Strong Arm Build, Part 14, Launch Lug Fit & Fillets

While the fit of the vane sides were pretty good, the edges could still use a fillet.

I used Titebond Quick and Thick with a smaller Elmer's glue bottle nozzle. 

TIP: On a long fillet like this, it's easier to glue and smooth about half of the length, then do the upper half. Too much excess glue can pool under your finger when smoothing out a long fillet. 

GOTCHA: The coupler end inside the upper slot prevents the front of the launch lug from fully seating.

I filed down the front half of the positioning tab to fit over the coupler.

Beacon Fabri-Tac was used to glue the launch lugs in position.

A piece of masking tape held it down while the glue sets up.

I'll be on vacation for the next five days, there may not be posts while I'm away.

Enerjet by Aerotech Strong Arm Build, Part 13, Gluing The Vanes

 

With the low end tip of the vane set at the tape wrap, 

the vane is pressed in place down the pencil line.

Hold the vanes in place with tape as the glue sets up.

Go back and check the alignment to be sure there wasn't any movement. Epoxy is slippery!

Check the edges for any glue that may have squeezed out.

You can pick it up with a Q-tip.

I'm building three of the Strong Arm kits, you might notice one build with no seam fill or filler primer.

On one build, I glued the vanes on using Fabri-Tac with good results. Fabri-tac takes a while to dry, the bond felt as strong as the epoxy joints.

I had a few vane tips that ended up raised.

In the top picture, you can see the open end.

Here, I've used a wood glue fillet to fill the gap.

Enerjet by Aerotech Strong Arm Build, Part 12, Setting The Vanes

The rear of the vanes are 2" from the front tip of the fins.

Instead of using the wrap around guide, I got out my aluminum angle.

It's pretty easy to draw a pencil line, extending from the front leading edge tip of the fins.

I made a 2" mark on the angle and transferred that onto the body.

For position consistency, 

I pencil marked an even wrap of masking tape.

The low end of the vane will be set just above the tape wrap. The picture shows a dry fit.

I tried using CA glue on the back of the vane to adhere it, but there wasn't enough surface contact for a good bond. I've got to use epoxy. It'll flow and fill some voids.

15 minute epoxy was spread on the underside of the vane using a Q-tip stick with the cotton end removed. 

To even out the epoxy bead and prevent squeeze out beyond the edges - 

I wiped off the sides with a folded paper towel. This evens out the bead over the entire length of the vane. 

The even center bead result is shown on the right.

Enerjet by Aerotech Strong Arm Build, Part 11, Fin Fitting

Earlier - 

The lower lock ring (on the engine mount) had to be moved forward 1/2" to be in the correct position for the rings to sit just outside the end s of the fin slots. This also set the engine mount to be flush with the main airframe tube.

Try as I might, the low end of the TTW tab would not click into place.

To fit into the new position of the lower lock ring, the inside notch had to be cut 1/2" up from the bottom. On the left, the notch to be cut is marked with pencil.

On the right, the notch was cut with a razor saw.

A  CA glue bead is applied to all contact points along the root edge. 

 

These fins take a little bit of effort to snap them into place.

Experience has taught me - 

Snap in the front first, then snap the rear tab into the rear ring.

TIP: Place your thumb into the engine mount tube for support while pushing down on the fin until it clicks.

Enerjet by Aerotech Strong Arm Build, Part 10, You're Not Alone!

I see paint problems on the Facebook rocketry pages. It happens to all of us!

    

I usually have better luck at spray painting once the weather cools and the humidity drops.

No fancy masks on this one, the nose cone is sprayed a medium gray.

I did mask off the shoulder.

The initial two coats are sprayed on light, the third coat is sprayed on a bit wetter for a good, smooth gloss.

I checked them an hour later. Most of the nose cone was fine, the tip was not. The paint didn't craze or wrinkle, but there were bubbles!

I'll wait a day and sand smooth. After 48 hours I'll try again!

Enerjet by Aerotech Strong Arm Build, Part 9, Filling The Tube Joint

Here's the tubes together, the coupler inside glued together using 15 minute epoxy.

The pencil lines are lined up before the glue sets up.

 

Most of the joint gap was first filled with CWF, the excess smoothed out using a single edge razor blade.

The picture shows the joint after the CWF was sanded to surface.

The high spots end up fuzzy after sanding.

I wipe on some medium CA Super Glue using a Q-tip applicator.

After it dries, sand using 400 grit on a block.

A final fill is a shot of filler/primer and sanding with 400 grit.

Taking these extra steps, you shouldn't see the tube joint seam on the finished model.

Enerjet by Aerotech Strong Arm Build, Part 8, Gluing In The Engine Mount

This may seem like a lot of pre-glue fitting, but everything must be in the correct position so I double check the fit of all parts. 

The engine mount is glued in.

I applied a ring of 15 minute epoxy from the low end, just above the top of the fin slots.

Why use epoxy? You'll have more working time. You can slide and turn the engine mount into the correct position without it locking up in the wrong place.

As you slide in the mount - 

Keep your eyes on the fin slots making sure the centering rings remain visible, just above and below the top and bottom of the slots.

As the mount is slid into position, TURN the mount to even out the epoxy making a more even internal fillet.

With the centering rings just above and just below the ends of the fins slots -

Slide in the fin tabs without clicking them into the lock rings.

Epoxy is slippery, the TTW fin tabs will keep the mount in the correct position as the glue dries. 

TIP: If you haven't used epoxy before, wear gloves. You might be allergic or could develop a epoxy allergy over time.

Enerjet by Aerotech Strong Arm Build, Part 7, Engine Mount Fit & Coupler Gluing

Before setting the engine mount, 

the TTW fin slots are removed. 

You'll want to see the centering rings position through the slots.

Remove the launch lug slots, too.

Slide in the engine mount. 

Slide in the fins, don't fully snap them in place yet. You are just checking that the centering rings are above and below the top and bottom of the fin slots.

The end of the engine mount tube should be even with the end of the main airframe tube.

I set my sanding block onto the end to make sure both tubes were even.

The mount will be locked in place once the TTW tin tabs are snapped into the locking rings inside.

On the left, 

The upper tube is flipped over for the coupler to be glued up to the 3" halfway pencil mark.

The shock cord is draped over the end.

TIP: To keep any epoxy glue off the shock cord, I applied some tape and slid it down the cord to where it might contact any squeezed out epoxy.
 

Enerjet by Aerotech Strong Arm Build, Part 6, Fit & Joining Two Tubes

On the left are the two tubes slid together using the coupler inside. No glue yet.

On the right is after sanding the tube ends square, the sanding shown below in the left side picture. Again, no glue yet.

Square up both tubes with a sanding block with 220 grit.

Slide the tubes together using no glue over the inside coupler.

Rotate the upper tube until you get the best, tightest join of the two tube ends.

Mark that best joint with a pencil line. When glue is applied, line up the pencil lines.

Having a tighter joint of the two tube ends will make it easier to fill the seam. 

The seam fill is coming in a few posts.

Enerjet by Aerotech Strong Arm Build, Part 5, Tube Seams

   

Back to the Enerjet by Aerotech Strong Arm build. 

To see the first four posts: CLICK HERE

I had to go back and do a little more CWF fill where it fell out of the seam. This happens on occasion. I mark them as I find them using pencil.

After sanding the CWF to surface,

The tubes got a shot of filler/primer.

Notice the masking tape set inside the tube end to keep the interior surfaces clean.

On the right is the same tube after sanding. Filler/Primer fills what seam lines were left after the first CWF pass. Only this two-step fill is necessary.

The edges of the tubes got a wipe of CA glue using a Q-tip.

Use your fingers as a depth gauge keeping the CA line even.

The centering ring glue fillets are up inside the tube, not near the CA'd edge. Wood glue or epoxy won't soak into the tube if the CA glue has sealed it off.

The tube ends are sanded after the CA glue dries. 

This gives you a hard, stronger edge tube.

Newbie TIPS, Part 2

More TIPS for new builders:

 9. Don't "tack" on fins using super glues. 

        Super glues will seal the root edge of the fin. 

        Your wood glue fillets cannot soak into a CA sealed root edge.

10. Use less glue to initially tack on fins and launch lugs.

        Less glue will grab and set quicker. You can always add glue fillets later.

11. Cut out chutes using a metal straightedge and a sharp knife. 

        Don't use scissors as shown on the sheet.

12. PAINTING: 

        Read the directions on the spray can!

        Most brands recommend: Re-spray within one hour or after 48 hours.

        Plastic nose cones take MUCH longer to dry before recoating.

        Spray when humidity is lowest, usually around 2:30 in the afternoon.

13. STICKERS: Don't touch the adhesive on the backs of peel and stick decals. Your fingerprints can show under the clear borders.

        After peeling off the backing paper, hold and place the decal while stuck to a clean knife blade. Wipe off the blade before using it to place stickers.

14. Dip the sticker in water to allow repositioning on the rocket.

        Apply water to the area on the model and leave the surface wet before setting down the sticker.

        Work out air and excess water from the sticker from the center out to the edges.

15. WATER SLIDE DECALS:

        Practice using the vendor name decal (the Estes logo decal or kit number) to get an idea of the soak times before transfer.

        Like the stickers, wet the final decal position on the rocket body before laying down the decal. The water under the decal allows it to be moved around until into final position.

Newbie LPR TIPS, Part 1

For all the new blog readers - 

Some of these TIPS aren't always mentioned in kit instructions. 

1. READ THE DIRECTIONS BEFORE ASSEMBLY. 

        There is a reason why most instructions suggest this.

        You might want to plan your paint patterns before gluing things together. 

2. Start each build with a new blade in your knife and new sandpaper in your sanding blocks. 

3. DRY FIT EVERYTHING before using any glue.

4. DON'T USE INK to mark fin position lines.

         Use pencil to mark body tubes.

         Ink can and will bleed through lighter colors of spray paint.

5. Don't trust kit supplied fin marking guides. 

        To test a kit supplied marking guide - 

        Wrap and mark the fin lines, then rotate the marking guide to the next pencil mark.

        If the new marking guide position and pencil marks don't align, the marking guide is incorrect.

        Go to: payloadbay.com. Go to "Tools", then "Fin Wrap Tool".

        Enter in your body tube size and number of fins and print out.

            

6. Sand body tube ends flat using a sanding block.

        Many tubes (especially larger diameter body tubes) many not have a clean, straight end cut.

7. Change out a wide wood glue nozzle with the nozzle  from a white glue bottle. The size of the threads on the base of the white glue bottle nozzle will fit the wood glue bottle.

        You'll have a better control of glue flow.

8. Don't "set" knots with Super Glue. 

        Super glues (CA glues) will harden shroud lines and shock cords. It makes them brittle and prone to breaking.