Thursday, January 21, 2021

Semroc Laser X, KV-33 Build, Part 13, Comparing Old & New

It's always interesting to look back on an older build and evaluate your work over time.
Throughout this post - On the left is the older build, the right side the new build.

Here you can see the difference in the decal opacity. I really don't like that pink look next to the full red color on the fins.
Also notice the thicker fins on the right side or newer build.

On the lower body - 

I like the wider fin spikes which better fit the thicker fins.
On the left you can see some fin grain and seams in the launch lug. I was probably using sanding sealer then.

My fit and finish of the engine vanes is much better. This time I centered the engine hook in line with the launch lug. The Semroc instructions place the lug and hook as shown on the left.

The shroud is smoother and the paint gloss better. 

On the left side is the original build. It looks like I used super glue to adhere the fins. This time I scraped off a line of paint and used white glue.

This was interesting.
I now attach the Kevlar to the elastic shock cord inside the lip of the body tube edge. I probably wouldn't get a zipper on this model, but why take the chance!

Wednesday, January 20, 2021

Semroc Laser X, KV-33 Build, Part 12, Decals!

The vertical body decals are centered between the fins and upper roll pattern wrap decal.

TIPS: Make a light pencil line at the center point on the body and the center point of the decal. Simply line up the center pencil marks and the decal will be centered.

The decals didn't have a deep opaque color like my earlier Semroc Laser X kit did. The decals were also very brittle.

The larger roll pattern wrap cracked!
I figured I would simply slide it up and trim off the broken up area.

Notice the darker red vertical band on the right center side. This is the decal overlap. It has a richer red from being two layers of ink.  
Here's another example of centering marks.

Mark the body tube at the center point. Mark the decal at the center.
If the pencil marks are in line, your decal is centered! This is how I would center headlines when doing paste-up at the print shop.

The UNITED STATES decal (set on bright white paint) looks pink next to the rich red color of the fins.

The upper body adapter did need some masking tape to get a good fit.
TIP: Roll the tape over the edge of the low end of the adapter so the tape edge won't lift up when slid into the body tube.

Tuesday, January 19, 2021

Semroc Laser X, KV-33 Build, Part 11, Red Paint & Spikes

Here's the mask for the larger red fins - 
Marked Scotch tape went into the root edges,
Brown masking tape filled the areas between the fins,
A plastic grocery bag was taped over the top.
After the tape mask was pulled - 
The outside edges of the fins were sanded down to the bare balsa.

The spike sides are a rounded surface, some of the exposed bare balsa might show through on the sides.
TIP: This was one of the rare instances where I could use a Sharpie for touchup that wasn't black ink. The red Sharpie was a good match - that doesn't usually happen with other colors.
Just the edges of the bare balsa got some red.

The black spikes were also scraped for gluing.

Set the spike beside the outside edge of the fin. I used a small wrap of masking tape to make a border edge.

The gluing line was scraped using my knife, ending just inside the tape borders.

Here's the spike glued on.
Again - Use white glue for this visible glue fillet. It dries clear.

Note the spikes aren't centered on the outside edge of the fin.

Monday, January 18, 2021

Semroc Laser X, KV-33 Build, Part 10, Small Red Fin Gluing

I'm doing the red masks in two separate sections, the upper body first.
The upper fins were stuck down on masking tape on some cardboard. These photographed an orange color - the real red is shown below.

On the right are the fin spikes, sprayed gloss black.
Even though the upper fins were set root edge to root edge, some red paint still got into the crack.

On the left is the before,
On the right is the bare balsa after sanding the paint off with a block.

These upper fins will be only "end glued" with no fillets so you need a rough, bare surface for the glue to be absorbed. Why no fillets? White glue dries with a flat finish. To gloss it up would require a clear coat, something I'd rather avoid. 

You can still see the roughed up root edge line under the paint.

I carefully scraped away the paint down the line not getting any wider than the 1/16" thickness of the fins.

TIPS: Use white glue for a visible joint like this. The white glue will dry clear and not be noticed. Yellow glue will dry yellow and be unsightly. 
After the glue dried, I applied a drop of medium super glue with a toothpick at the base of the fins. 

With this drop of glue at the rear of the fins it won't be noticeable. Hopefully it will strengthen the joint a bit.

Sunday, January 17, 2021

Semroc Laser X, KV-33 Build, Part 9, White & Black Paint

I couldn't see a good way to mask the smaller red fins with the cardstock black shroud right below it. I knew I had to paint these fins off the model and glue them on after the adapter was painted black. 

Normally I wouldn't recommend gluing fins on after painting, but these fins are small and not subjected to hard landings.

In the upper picture you can still see the roughened root edge line even after the white paint was shot. 

On of the upper fins broke along the glue line. It had to be glued back, shot with filler/primer and sanded smooth.

Here's the upper body mask for the black nose cone and adapter.

I got a much better gloss on the shroud this time by lightly sanding between coats.

The lower body was hit with an overall gloss white. 
Notice the paper towel keeping any overspray out of the upper tube end.

The engine mount isn't glued in yet so a piece of 65 lb. cardstock was rolled and set in the back end for something to hold on to.

Saturday, January 16, 2021

Semroc Laser X, KV-33 Build, Part 8, Masking & Gluing The Vanes

Here's a weird paint mask to give your a better glue bond on the root edges of the vanes.
The engine mount is not glued in place yet. Slide it in and you can use the fins to place four of the tape strips. The other strips are simply centered between those.

The mount is taped into the tube. The tube is masked and the engine mount tube sprayed black.

On the right - The masking strips are removed.
This mask doesn't have to be very clean, the vanes will cover up any rough edges.

I wasn't getting a good fit of the root edge against the mount. I realized the glue fillet was in the way! I slightly rounded off the corner and got a better fit. 

I glued on every other vane and centered the remaining pieces.

Notice the masking tape wrap around the black coupler. The fit in the main tube was pretty loose.

Friday, January 15, 2021

Semroc Laser X, KV-33 Build, Part 7, Fitting The Shroud

The scanned shroud was loaded into Corel Draw.
Four slightly different sized were copied. Out of these four I should have one that will fit. Always dry fit shrouds before using any glue.

Normally I'd go to and make a shroud, but the website was down the day I needed to print one up. is back now, go to the site, and go to the "Tools" section. 

The upper adapter is glued to the low end of the BT-5 size tube.

On the right side, notice how little glue is used on the upper position contact ring of the shroud.
A line of glue was also applied to the edge of the upper centering ring on the adapter.

Finally the right sized shroud! 
A good, sliding fit and a good match to the outside diameter of the lower body tube.

While the glue is still wet,
You can shape and mold the glued joint. Coax the upper joint for a better, even fit.

This is an overlapping tab shroud.
Sometime I fill the raised seam with some CWF.