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TBM Avenger radio mast

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  • Member since
    July 2019
  • From: Vancouver, British Columbia
Posted by Bobstamp on Friday, May 12, 2023 9:04 PM

TBM radio mast/canopy problem solved! (I think). I gave up on using the parts of my TBM model and made my own radio mast from sprue, following the advice sprovided by various Finescale members. 

I drilled a small hole through the bottom of the new mast, inserted a short piece of stiff brass wire, and affixed it with super-thin cyanoacrylate glue. I also drilled a hole through another short piece of sprue, sanded it to the same diameter as the radio mast, and cut it to a length of three or four millimetres. It would serve as a collar to keep the mast from wobbling too much. 

After inserting the brass wire through the hole in the canopy, I slid the collar over the wire and carefully applied Testor’s Window Maker (white glue) around the collar. I haven't attached the radio antenna yet, but the mast seems very secure. It's not an elegant solution. It's a kludge. But it works. 

One problem I encountered was that the bulkhead behind the pilot’s seat forced the mast to lean forward. It was even worse with the collar in place. Ideally, I should have reversed course and drilled a holethrough the bulkhead for the brass wire. Instead, I filed and sanded the back of the bulkhead to make room for the collar. I hope that this diagram does a better job of explaining this than my words!

When I attached the canopy/radio mast to the cockpit, using Testor’s Window Maker, I made sure to put a small glob of glue on the front of the collar so it would adhere to the bulkhead. I probably removed 20% of the bulkhead through filing and sanding, but with the canopy in place it looks fine. Next time, if there is a next time, I'll just drill through the bulkhead. There would never have been a problem if Hobby 2000 had provided a larger attachment tenon/peg on the antenna and a sufficiently large hole in the canopy. 

Bob

 

On the bench: A diorama to illustrate the crash of a Beech T-34B Mentor which I survived in 1962 (I'm using Minicraft's 1/48 model of the Mentor), and a Pegasus model of the submarine Nautilus of 20,000 Leagues Under the Seas fame. 

  • Member since
    March 2005
  • From: West Virginia, USA
Posted by mfsob on Monday, May 1, 2023 6:55 AM

Another idea, at least it worked for me in 1/144 - make the mast one solid piece and affix the "inside" portion ot the rear of the pilot's seat and rollover headrest. I was doing a diorama with the Minicraft kit, and the kit radio antenna was basically part of the sprue. I took a piece of brass rod (0.025-inch, I think), pounded the "top" part flat, filed it to shape, and then drilled a hole through the canopy and glued the base of the rod to the cockpit floor. Painted in the interior colors, it isn't even noticeable.

And I second the idea of stretched sprue for the rigging. It's all I use because it's cheap, and very easy to tension - you just light a match, blow it out, and then pass it underneath the sprue after you glue the ends in place. It'll tighten right up with minimal strain on fragile parts. This pic doesn't show it clearly, but you can see the how the radio mast and aerial wires turned out:

 

  • Member since
    July 2019
  • From: Vancouver, British Columbia
Posted by Bobstamp on Friday, April 28, 2023 10:32 PM

gregbale

The reinforcing piece underneath is also a good solution. I forget for the Avenger specifically, but in most such real-world installations there's a junction box or relay inside cockpits where antenna masts attach, so a quick toddle for photos online should guide you for possible shape and color. The wire reinforcement is also pretty much always a good idea, if you've got bits and a steady hand to drill it out.

Good advice, Gregbale! I didn't have to google anything. I just looked through the photos I've previously downloaded from a variety of websites, and found this one:

 

There is clearly a "junction box or relay inside cockpits where antenna masts attach". I'm on it, almost finished the scratchbuilt antenna mast, and working on the "junction box or relay".

 

Bob

 

On the bench: A diorama to illustrate the crash of a Beech T-34B Mentor which I survived in 1962 (I'm using Minicraft's 1/48 model of the Mentor), and a Pegasus model of the submarine Nautilus of 20,000 Leagues Under the Seas fame. 

  • Member since
    July 2019
  • From: Vancouver, British Columbia
Posted by Bobstamp on Friday, April 28, 2023 2:45 PM

@ everybody, especially the Baron:

Thank you all for your assistance. I'm moving ahead with a scratchbuilt radio mast, with a short, stiff wire for additional support. I'm going to try to glue a small block of styrene under the canopy to provide some additional lateral stability.

The Baron has given me credit I don't deserve. The photo I uploaded in my original post is not mine, as I mentiooned, and neither does it show my TBM model! I'll replace it with an image of the box art for my model, which clearly shows the radio mast and antenna. I hope that I don't embarrass myself when I do post a photo of my model. It's the best-looking model I've yet made, but I've sure made a lot of mistakes. But if you look at the model from 10 feet away, it looks great!

Bob

On the bench: A diorama to illustrate the crash of a Beech T-34B Mentor which I survived in 1962 (I'm using Minicraft's 1/48 model of the Mentor), and a Pegasus model of the submarine Nautilus of 20,000 Leagues Under the Seas fame. 

  • Member since
    September 2006
  • From: Bethlehem PA
Posted by the Baron on Friday, April 28, 2023 8:00 AM

Yeah, I'm with Greg, especially on using styrene cement to attach the mast to the greenhouse.  Personally, I don't use CA glue to attach styrene to styrene.  I want the chemical weld bond between those pieces, that styrene cement creates.

And I agree with him about minimum tension on the antenna line.  When I read your original post, that's the first thing I thought, when you described attaching the line-it was too tight.  I do use CA glue for this application, of unlike materials, but for antennas like this, I will sometimes make a tiny nick in the tip of the mast, to rest the end of the line in.  But yeah, just the barest tension necessary.

That's a beautiful model, too! When I first saw your photos, I thought it was a larger scale than 1/72, from the level of detail you have there.

The bigger the government, the smaller the citizen.

 

 

  • Member since
    March 2003
  • From: Towson MD
Posted by gregbale on Thursday, April 27, 2023 4:36 PM

Bobstamp
I'm having a somewhat troubled relationship with CA. I've tried to avoid getting it anywhere near clear parts, which will become clouded if they're in contact with the vapour, or so I understand.

Just as an FYI, CA frosting on clear parts -- as long as it's fumes alone, and not the actual adhesive -- cleans up pretty easily with denatured alcohol on a Q-tip or micro brush.

Again, good luck. Look forward to seeing your 'turkey' when it's done! YesYesYes

Greg

George Lewis:

"Every time you correct me on my grammar I love you a little fewer."
 
  • Member since
    July 2019
  • From: Vancouver, British Columbia
Posted by Bobstamp on Thursday, April 27, 2023 4:06 PM

Thank you for your thoughts, gregbale.

Yes, "peg" works fine, as does tenon, which I wouldn't have thought of. They wouldn't let me take shop courses in high school, because my grade average was too high, not that I had a chance of getting into National Honor Society.

I've tried stretching sprue with minimal success, which is to say no sucess? Longer pieces just seem to be beyond my ability. 

I think that between a reinforcing piece underneath the canopy and a scratchbuilt radio mast, I should be able to accomplish the task. Maybe. I've started making one already.The only real challenge is getting enough adjoining surface area to literally seal the deal. 

I'm having a somewhat troubled relationship with CA. I've tried to avoid getting it anywhere near clear parts, which will become clouded if they're in contact with the vapour, or so I understand. One thing is clear: less is more when you're using CA. Too much, and it will remain in a liquid state, it seems. 

Bob

 

 

On the bench: A diorama to illustrate the crash of a Beech T-34B Mentor which I survived in 1962 (I'm using Minicraft's 1/48 model of the Mentor), and a Pegasus model of the submarine Nautilus of 20,000 Leagues Under the Seas fame. 

  • Member since
    March 2003
  • From: Towson MD
Posted by gregbale on Thursday, April 27, 2023 2:20 PM

'Male nipple'...um...'peg?' (Or 'tenon,' if you wants to get fancy.... Big Smile)

Anyway, I feel your pain. Though I am a diehard EZ-line fan...I must confess that the situation you describe is usually where I end up using stretched sprue. If there's not enough frame area to solidly attach the base of the mast -- with CA, or regular solvent glue where applicable -- a 'no (or minimal) tension' solution seems the best bet. Stretched sprue attached with white glue is surprisingly strong...and easy to cleanly replace, should one of those unfortunate 'oopsies' occur.

The reinforcing piece underneath is also a good solution. I forget for the Avenger specifically, but in most such real-world installations there's a junction box or relay inside cockpits where antenna masts attach, so a quick toddle for photos online should guide you for possible shape and color. The wire reinforcement is also pretty much always a good idea, if you've got bits and a steady hand to drill it out.

Just my 2 cents. And it's really good to have you back. Good luck, with whatever fix you decide to go with! Yes

 

 

 

Greg

George Lewis:

"Every time you correct me on my grammar I love you a little fewer."
 
  • Member since
    July 2019
  • From: Vancouver, British Columbia
TBM Avenger radio mast
Posted by Bobstamp on Thursday, April 27, 2023 1:41 PM

Just two or three hours away from completing my Hobby 2000 1/72 model of a Grumman TBM-3E Avenger, I hit a snag with the model's canopy-mounted radio mast. This image of the model's box art shows the location of the mast:

The mast that came with the model is too tall, and the "rectangular male nipple" at the base is too large for the hole in the canopy that it's supposed to fit into. (Is there an actual term for the little projecting bits of plastic parts that are supposed to fit into small holes in opposite parts?)

I tried carving the "male nipple" thing smaller, and enlarged the hold it's supposed to go into but, the the tiny area of contact is too small to solidly attach the antenna. When I tried to string the elastic EZ Line antenna between the mast and the planes' tail fin, the mast just collapsed, leaving behind an ugly white hole in the top of the canopy. 

I had an extra model, so I grabbed its radio mast and its canopy, which is now masked and ready for paint. But now what?

Hobby 2000 obviously had second thoughts about that radio mast, because in the second kit the mast is about half the size of the one in the first kit I bought. But that not an improvement, bevause the second mast  would be even harder to attach solidly to the canopy. 

One possibility is would be to attach a thin brass wire to a scratchbuilt radio mast to reinforce the bond between the mast and the canopy, but that could very difficult to pull off, considering the small size of the mast.

Another possible workaround: Glue a small piece of clear plastic to the inside of the canopy beneath the hole for the mast, then drill a hole through that to deepen the anchor point. 

Any other suggestions would be appreciated.

Bob

P.S. I haven't visited you guys in a long time, mainly due to Covid (I only thought I was dying for three days, back in November), and have had some lingering problems with a lingering cough abnd general lack of initiative and fatigue.)

 

 

 

On the bench: A diorama to illustrate the crash of a Beech T-34B Mentor which I survived in 1962 (I'm using Minicraft's 1/48 model of the Mentor), and a Pegasus model of the submarine Nautilus of 20,000 Leagues Under the Seas fame. 

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