Aluminum extrusion for blade radio board

[s vernon]

There is obviously a particular aluminum tee extrusion that can be used to make a very nice blade radio board. Can you tell me about it? Size (height, flange width and thickness), material, and where it is available. And I think you know for whom this question is meant.

Such aluminum tees are not easy to find locally nor on the net.

The finished board, in case anyone is curious, has the jib trim servo laying on its side aft of the mast support. The vertical blade is cut out for the servo. The RMG winch is aft of that. The rudder servo is aft of the winch and is standing on end with the axis of the arm running side to side. This allows the end of the rudder servo arm to be very high without the rudder servo being mounted high. A hole is cut in the vertical blade for the rudder servo. The ears of the 2 servos are on the right side of the blade. The winch is mounted on the right side of the blade. That balances the weight, with the RMG on the right and the servo cases on the left.


Scott

[kahle67]

Scott,

I know where to get one of those. It comes already screwed to a ballast with a boat around it. An expensive radio board indeed!![;)]

No, just kidding! The t-bar I have used on a few came from aluminum scrap that I found in one of my fellow club member's(pack rat) back yard. I have no idea what the extrusion used to be before I butchered it up. It can be made from angle as well which might be easier to find with the proper vertical height. As a matter of fact, I used an aluminum breaker box door once. When searching, I try to find something thick enough to tap 4-40 threads(for mounting servos) but not too heavy. Of course it lightens up when all of the cutouts are made plus it is on top of the ballast as low as possible.

Go visit a metal scrap yard with a sharp hacksaw.


Reichard

[philair]

Check out "http://www.onlinemetals.com/".

They have a variety of angles, tube, etc. in smaller quantities & are reasonable.

[Gene Rosson]

You can improvise a tee section by cutting an I beam down the web to suit your required dimension. I beam is more likely to be available than tees. As a matter of semantics; I beam has tapered flanges, wheras "wide flange" has flat flanges. I'd expect that the WF is more suited for the job. There are some architectural sections with the desired cross section. Also there are some rectangular tubes that have a dividing web down the center. Architectural shapes are usually extruded from a slightly different alloy such as 5052. Its a little softer than convential 6061 but the radio gear won't know the difference.

My radio board, and its' layout, is similar to the description posted. Tee section was not required. I used a flat piece of aluminum bolted directly into the ballast. The ballast slopes downward aft, so some different length spacers were used under the board to make it level. Spacers are half inch round aluminum shaft with quarter inch holes down the centerline. Ballast is drilled and tapped for quarter-20 threads in four places. Three bolts would do just as well. The RMG is mounted with the sheet metal bracket described in the RMG instructions. Jib trim servo is laying on its' side, flat against the board. Rudder servo is standing up and held in place by some aluminum spacers made from bits of 5/16 flat bar. The board is tapped, under the spacer holes, for 3-48 screws. The rudder post bellcrank resembles a C clamp with a 3/16 hole in the top to accept the rudder shaft. The bottom extends downward about an inch and a half where the arm is attached. The bottom is offset so as to clear the lower part of the rudder shaft housing. The rudder push rod is almost horizontal with that arrangement. I am including all that detail to suggest that you can have a very low set board without having to resort to hard to find extrusion shapes. My board with all the hardware including quarter inch stainless cap screws weighs 14.5 ounces. It is set well below the water line and probably below the center of bouyancy.

[bogordoug]

In my office building I have been watching them build walls in an open area. It appears that some of the aluminium extrusions used to support the walls (tracks which are attached to the floor) and inserts to hold in the door and windows will serve this purpose. So check out some commercial building sites, talk to the contractors and you may be able to get some useful scraps.

Doug Hale

[Pink66]

Scott,

I get all my aluminum assemblies from "H" shaped aluminum reinforcing used inside vinyl deck handrail assemblies. Check out your local residential construction jobsite. You might find some.

Mark

[s vernon]

Mark,

Thank you, but I live in the land of cedar decks and handrails. At worst they make some expensive fake cedar-looking ones. I will look around tho just in case. (I think it must be against the law to build a house around here - north of Atlanta - without a deck. humor)

Scott

[Gene Rosson]

Recently I received a catalogue from A firm called Micro-Mark, (WWW Micromark.com) It seems that they have model building tools and materials of all kinds. The catalogue is like a candy store. They list a tool that they call a cutting guide. It is an aluminum tee bar 2" wide with 3/4" fin. Eleven inches long $4.95, 22 inches long $6.50.

Micro Mark seems to cater to the model RR hobbyist but they have a whole gaggle of items that will gladden the hearts and flatten the wallets of we boat nuts.

[E Artz]

I got something similar called a T-Bar sander by Applied Design
from my local hobby shop for $3 and change.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LX0454&P=7



Earl