Pat Sparks BOMARC Build

[MikeMaben]

[LSP_Kevin]

So it appears that my BOMARC project has literally gone sideways:

 

 

It seems that the slight lean has been putting pressure on the cradle, which has let go of the bottom of the missile, allowing it to twist even further away from vertical. This in turn has caused some slight deformation in the structure around the pivot.

 

I've managed to remove the missile from the launch rail, though not without plenty of paint damage. I'm going to have to (attempt to) drill out the vertical rail at the pivot and reprint those parts, basically starting that section from scratch. I'll then (attempt to) use some brass tube or rod to replace the pivot pin. If that doesn't work, I'll either have to (attempt to) remove the launch assembly completely and reprint the entire thing, or push the whole thing aside as a failure.

 

 

Kev

[Martinnfb]

This is way too epic to scrap it Kev. Would it be possible to support the arm itself by drilling into it in order to install a rod protruding down through the base for support ? 

 

Cheers

 

Martin

[LSP_Kevin]

1 hour ago, Martinnfb said:

This is way too epic to scrap it Kev. Would it be possible to support the arm itself by drilling into it in order to install a rod protruding down through the base for support ? 

 

Cheers

 

Martin

 

Not any more! But I'll post an update soon showing why.

Kev

[Dandiego]

I too have had a similar problem with the Moonbat. Any weight bearing resin part will deform over time.

 

Live and learn.

 

Dan

[LSP_Kevin]

While the simplest thing to do would be to re-print the vertical rail section, I'd still need to remove the old one, so I figured if I could extract it in one piece, I'd have a go at straightening it. After some careful work with a photo-etched razor saw, I managed to separate all the relevant bits. After a bit of testing, it seemed that there was enough flex in the vertical rail assembly to allow it to be straightened, so I started by clamping it to a suitable piece of ceramic tile:

 

 

I think filled the sink with hot water, set the timer for 5 minutes, and dunked it in.

 

So, did it work?

 

Well, yes. I'm pretty sure it's straight now.

 

 

 

Kev

[Derek B]

I don't know...you let your BOMARC go on holiday to Pisa in Italy and it comes back with its own ideas! lol 

 

I am almost hesitant to say that this has been a steep learning curve (or angle) for you Kev, but I have absolute faith in your determination to prevail in this matter, so, with true Aussie grit, I am certain that you shall overcome this problem (you are most likely already 3D printing a replacement part as we speak!).

 

Good luck with this Kev, we are all with you.

 

Derek

[jenshb]

Just caught up on this, and it has been  very interesting to see the failures and successes.  This really highlightes the fact that it is not as easy as clicking "Print", and then a perfect specimen comes out.  As with any technology, it requires the willingness to learn to build experience so you know what works and what doesn't.

 

Regarding the launch tower, would it be better to make the basic structure from plasticard cut on the Silhouette rather than relying on the resin?  Alternatively, a firmer, more robust resin may be the answer?

[Landrotten Highlander]

10 minutes ago, jenshb said:

Regarding the launch tower, would it be better to make the basic structure from plasticard cut on the Silhouette rather than relying on the resin?  Alternatively, a firmer, more robust resin may be the answer?

I think it is a bit more complicated than just trying a harder resin.  I am sure the printing direction has an influence as well.  Remember, you are literaly printing a thin layer of resin on top of another layer, and the strength comes from the bonding between these 2 layers.

 

As in any industry, 3D printing has to be a production tool amongst all the others, complimenting the other production tools, but never completely replacing it (at leas I think not in our lifetime).

Given the fact that a reletively heavy rocket is hung onto this component, a more traditional production method may indeed be the answer to this.  Perhaps build the framework in a traditional manner, and 'hang on' the details with 3D printed parts?

[dennismcc]

Gosh I did not have a clue what a Boeing BOMARC was before I read this, and what an epic and amazing journey it has been, I think it looks great.

Reading about it they were supposed to be stored in a horizontal position in as storage shelter with a removeable roof, could you not show it in this horizontal position?

 

Cheers

 

Dennis

[LSP_Kevin]

Thanks for your input, fellas. I'm re-printing the vertical rail parts as I type, so fingers crossed for that. It's not worth trying to scratch-build the thing, as it's not likely to be any stronger, and it's also beyond my level of interest in this project. I do intend to try to reinforce the assembly with some brass stock, however, so hopefully that will help. When everything is positioned correctly, there's actually hardly any weight on the vertical assembly that isn't already supported at the base, so it's just a matter of achieving the correct alignment.

 

12 hours ago, dennismcc said:

Reading about it they were supposed to be stored in a horizontal position in as storage shelter with a removeable roof, could you not show it in this horizontal position?

 

I did briefly consider this, but the missile extends way out over the base to a comical extent, so I think it'll have to remain upright.

 

Kev

[patricksparks]

Hi Kevin, sorry about the mess !!! I was thinking that if you are going to keep the airframe vertical permanently, what if you were to put a brass rod into the launch tower vertically and go down through the pivot point into the base ??? Just thinking out load... 

All the best,

 

Pat

[dennismcc]

Glad to hear that you have a solution Kev, it would be a real shame not have a successful outcome after all your work.

 

Cheers

 

Dennis

[LSP_Kevin]

Thanks again, fellas. I've re-printed the vertical rail pieces now, and they've come out rather well. More importantly, they're straight! So as long as I don't screw things up while joining them together, I'm in with a chance. I've ordered some brass angle stock to assist with reinforcing the structure, but my gut tells me it won't be stiff enough. I'm hoping it'll be here before Christmas, but not the best week to order something and want it quickly!

 

Kev

[LSP_Kevin]

8 hours ago, patricksparks said:

Hi Kevin, sorry about the mess !!! I was thinking that if you are going to keep the airframe vertical permanently, what if you were to put a brass rod into the launch tower vertically and go down through the pivot point into the base ??? Just thinking out load... 

All the best,

 

Pat

 

Not your fault, Pat! Though I might suggest making the walls a little thicker for the vertical rail parts, just for added stiffness. As for the brass rod, I reckon I'd only screw that up too! We'll see how Plan A goes first...

 

Kev