Thursday, November 22, 2012

T2-21 Build-Series #4

Transom stiffener, rear cowl rests & servomounts etc. Interesting stuff... ;)


KEP's T2 .21 Presentation
KEP's T2 .21 Freebie
KEP's T2 .21 Build Series #1
KEP's T2 .21 Build Series #2
KEP's T2 .21 Build Series #3
KEP's T2 .21 "Inspirational" Article

Even if you have used a laminate made of two 3 mm (1/8") thick airplane birch plywood the transom still can be upgraded and made stiffer with some added flat sheets of carbon. I use 0.7 mm. ZAP-a-gap medium CA glued in place with plenty of glue. That will take a while to stick so use some gloves and press down until the plate doesn't move around any longer. Then use CA kicker.

The cowl rests are made of scrap pieces of 6 mm plywood. They are glued 1 mm below the tub deck with CA glue.

This is what I start out with when making the servo mounts for all three servos. Its 6 mm thick gaboon plywood scrap pieces where the top part is glued at the end so its easier to drill and tap the holes (instead of doing it in end grain). CA glued of course. Sand the top piece flush with the sides.

Steering servo mounts for Futaba S9551 or BLS551. Note the hole for the servo wires. See the PDF's for measurements. Note, they should be slightly too high as that will be trimmed down later. That means they will also be glued to the tub bottom of course.

This steering servo alignment/angle template was the one I used when doing the T2-21 prototypes. In the 2of2 PDF I have included some cut-out templates that you can use instead. See below.

Note, this picture is not to scale. Use the paper-copy of the PDF freebie you have already downloaded and printed out in 1:1 scale (2of2 file). The lower one in the illustration is used to get the angle right for the steering servo - see here below.

Steering servo attached with Futaba original rubbers & eyelets with Du-Bro #4 screws and aluminum #4 washers. The angle of the rails are sanded while attached to the servo. Just put it over the paper template to view if you have got the angle right... Align the complete servo set-up in the tub and tack booth mounts to the inside of the tub with ZAP-a-gap medium CA. Then carefully remove the servo and add more glue to the outside of all glue joints. Let set for 5 minutes and use a little kicker to get it to finally set (and build glue fillets).

The protruding servo mounts are cut-away roughly with the band-saw and then sanded flush with the Great planes bar-sander and you guessed it right - 80-grip sand paper. :)

It's the same process with the CH2 & CH3 servos. Note, here the mounts are just plain 6 mm plywood (gaboon). No added fancy stuff. :) See the PDF's for measurements.

This side-view template is also included in the 2of2 PDF (this picture is not to scale). Cut it out to help with the alignment for gluing the CH2 & CH3 servo mounts.

The CH2 & CH3 combo servo mounts are glued in place at 90 deg vs the tub side and then sanded smooth with the tub side bottoms.

Additional pics taken from building the prototypes (note the soft 4 mm gaboon tub sides etc). Nope, there is not a lot of room so stick with the specified servos. :)

First clear the threads with a M4 or 8-32 tap if you haven't already done that. Then make 1 or 1.5 mm thick pieces of scrap plywood to cover them up. The numberplate covers are glued with epoxy. Make sure no epoxy is dripping down into the threads...

All for now! :)

Next: KEP's T2 .21 Build-Series #5

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