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Pat Sparks BOMARC Build


LSP_Kevin

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1 hour ago, LSP_Kevin said:

 

Thanks, dutik - but it was already glued in place before! All the bonds became unstuck due to the stresses applied by the gradually worsening lean. This is not about trying make everything move, but just to get it all straight again, so that it doesn't fall apart again. So far, I'm not having much luck!

 

Kev

 

This is all good learning stuff Kev - I have faith in you prevailing; don't give in!

 

Merry Christmas.

 

Derek

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  • 2 weeks later...

Just a quick, photo-free update on this one. I managed to grab the drill bit I was after, but it turns out it's too large for the standard Dremel collets and chuck. I reluctantly tried it in a pin vise, but this did more damage than anything else, so I had to abandon that. I'm awaiting the arrival of a third-party chuck that allegedly fits the Dremel, but will take the 4mm drill shank I need to use. I appreciate that my descriptions haven't really been adequate in explaining what I'm trying to achieve here, but I'm hoping my plan will bear fruit, and it will all make sense then.

 

Stay tuned!

 

Kev

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  • 2 weeks later...

And finally, we're back to this one! The third-party chuck I ordered arrived yesterday, but contrary to its advertised capabilities, it does in fact not take a 4mm drill bit. Super frustrated by that, but that's Temu for you! It was cheap, so I'm not out a ton of money.

 

At this point I figured I had nothing to lose by trying to drill the required holes by hand again, since the necessary drill bits easily fit into the superb David Union pin vise. And by some miracle, I seemed to have been successful this time.

 

axjZyy.jpg

 

4mm brass tubing inserted through 5 separate 4mm holes. Much more stable than before, with only the tiniest hint of wobble. This isn't quite my original plan, but still puts me where I want to be, so I should be able to finish this one off now. Again.

 

Kev

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OK, nearly there! The launch tower has now been painted and reassembled, ready for action:

 

g5J1FE.jpg

 

Since taking these photos, I've added styrene caps to the holes I had to drill for the brass tube axle:

 

teQ72R.jpg

 

Just some paint repairs to do on the missile itself to do now.

 

Kev

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I'm happy to report that the BOMARC saga is finally at an end. The launch tower has been (largely) fixed, and the hinge mechanism rebuilt using brass tubing. There's still a slight list to starboard, but as long as it stays together, I really don't care at this point!

 

CXOxPz.jpg

 

s127ZF.jpg

 

Kev

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Congratulations Kev. Your perseverence is admirable and inspirational.

 

Knowing what you know now, how would you change things to avoid this problem?

 

Do you see a way to re-engineer the design to avoid this issue without losing the scale/ accurate appearance of the model?

 

 

Cheers,

Guy

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15 hours ago, geedubelyer said:

Congratulations Kev. Your perseverence is admirable and inspirational.

 

Knowing what you know now, how would you change things to avoid this problem?

 

Do you see a way to re-engineer the design to avoid this issue without losing the scale/ accurate appearance of the model?

 

 

Cheers,

Guy

 

Good questions, Guy, but I'm afraid I don't really have good answers for them! Part of my initial problem stems from some minor flaws in the printing of some of the parts - in particular, the two 'pins' that form the central axle for the launch rail were malformed. I figured at the time that it didn't matter, but in retrospect, I should have made plans to replace them with brass at the outset. Even had I reprinted those parts, I suspect the pins wouldn't really have been strong enough to take the load for the long term. If I were Pat, I'd reconfigure the design to allow for brass tubing to be used here without having to modify anything.

 

But also, the 'knuckle' at the bottom of the launch rail that connects to the piston printed with a slight twist, which exacerbated the bent look of the original rendition. I took care when reprinting this part to make sure it came out straight! I just wasn't fully cognisant the first time around of just how important it was to have everything straight and true for final assembly on this one. Slight deviations, or areas of slight play between the parts, end up being magnified later, and put undue strain on key areas.

 

Kev

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On 12/23/2023 at 4:16 AM, dutik said:

If nothing solves the issue there is just one last solution: Skip the "moving" option, align it in the straight position and glue everything in place :tumble:

 

Good luck, and Merry Xmas to you!

 

Regards

- dutik

 

My personal option in such cases is the rock wall right outside my modeling room.  I don't have near the fastball pitch as in my youth but it is still enough to make a recalcitrant model pay the ultimate price.  :fight:

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