Pat Sparks BOMARC Build

[Gazzas]

Wow!  Those look great!  I would like to make some 200mm figures some day from drawing to painting.  But I don't know if I will ever find the dedication.

 

[LSP_Kevin]

Just now, Gazzas said:

Wow!  Those look great!  I would like to make some 200mm figures some day from drawing to painting.  But I don't know if I will ever find the dedication.

 

 

I do have to clarify that these are all files I found online, and not my own designs. I'm not sure that's something I'll ever have the time to get into.

 

Kev

[LSP_Kevin]

So, back to the BOMARC, and here it is (almost) fully assembled:

 

 

Still some work to do to tidy up the joins, and I still have to assemble the engine tail cones. I'm a bit unsure about the optimum sequence here, though, as test-fitting shows that I'll need to work on those joins too. This suggests adding them now so that I can take care of all that before priming and painting. But they're large, and once they're on, they'll be in the way for priming and paint. Catch 22!

 

I did sharpen the nose cone however, as Pat's design is a little blunt:

 

 

Speaking of painting, I've decided to go with the black and white scheme, mostly because I can leverage the painting guide that comes with the ancient Revell 1/46 kit:

 

 

It's actually a relatively complicated paint scheme, but should look quite striking when done. I'll either have to cut my own masks or make my own decals for the markings, and most likely a combination of both - though the stars-and-bars can come the Fantasy Printshop set I have.

 

Right, I'm off to contemplate the order of operations, and maybe print out some more launch tower parts!

 

Kev

[Dandiego]

Looks awesome Kev. Kudos to you and Pat.

 

Will be following. 

 

Dan

[LSP_Kevin]

2 hours ago, Dandiego said:

Looks awesome Kev. Kudos to you and Pat.

 

Will be following. 

 

Dan

 

Thanks, Dan. Still a way to go, as I suspect painting this thing will trip me up in a few places. I've also got to finish printing the launch tower, but all I have from Pat is the files, and no idea about what most of them are, or how they go together!

 

Kev

[Dandiego]

Well I know what you mean. When I got the files from Chad I just started printing and gluing. I had the front end of the F-103 all glued up with filler and primer before I printed up the back half. Got myself into a pickle or two by being too excited. Only after building it did I understand what the build sequence should be.

 

I think everyone here only kinda read the instructions with a kit. We know what we are doing! I've done this before!

 

Sounds good until you have a collection of parts but no instructions. Makes for an interesting build. I am sure you will figure it out. My suggestion, print out all of the parts before you start gluing. Wish someone had told me that.

 

Dan

[LSP_Kevin]

26 minutes ago, Dandiego said:

My suggestion, print out all of the parts before you start gluing. Wish someone had told me that.

 

That's certainly my intention for the launch tower! I've test-fitted the bits I've done so far, but am not convinced I've got it right! Once I have all the parts to hand, I can study some photos and hopefully figure it out.

 

Kev

[amurray]

On 7/23/2023 at 6:24 AM, LSP_Kevin said:

I'm pleased to report that the engine parts were (mostly) a great success!

 

 

It wasn't until I'd removed all the supports that I realised the central cone thingies came out a little warped:

 

 

I'm hoping that I might still be able to use them, since the warped sections are hidden inside the engine nacelles anyway. But lots of clean up work to do to find out!

 

I'm so glad Pat posted this image in his own thread, though:

 

 

Otherwise, I'd have no idea how these parts were supposed to go together!

 

Right, I'm off to do some sanding...

 

Kev

 

Looks great!  Any thoughts on why your quick success with the engines and their thin, delicate exhausts vs. the hard time you had with the wing and tail trailing edges?

[Troy Molitor]

Love it Kev.  Keep them coming.  

[LSP_Kevin]

1 hour ago, amurray said:

 

Looks great!  Any thoughts on why your quick success with the engines and their thin, delicate exhausts vs. the hard time you had with the wing and tail trailing edges?

 

Well, for one, it's a matter of relatively simple shapes versus relatively complex ones. With complex shapes, it can be difficult to lay out the supports so that all elements are guaranteed to print successfully. It's about finding the right combination of orientation and support layout. I'm facing that issue now with the launch tower blast shield.

 

The other major stumbling block with the wing and tail sections was that the outer tips on these pieces are all but separate parts, and most of my failures were in those areas. I just wasn't supporting them well enough. Right now I'm solving most of these issues with brute force, and probably over-supporting in some areas, so this is something I'll need to improve upon with experience.

 

Kev

[amurray]

3 hours ago, LSP_Kevin said:

 

Well, for one, it's a matter of relatively simple shapes versus relatively complex ones. With complex shapes, it can be difficult to lay out the supports so that all elements are guaranteed to print successfully. It's about finding the right combination of orientation and support layout. I'm facing that issue now with the launch tower blast shield.

 

The other major stumbling block with the wing and tail sections was that the outer tips on these pieces are all but separate parts, and most of my failures were in those areas. I just wasn't supporting them well enough. Right now I'm solving most of these issues with brute force, and probably over-supporting in some areas, so this is something I'll need to improve upon with experience.

 

Kev

 

Obligatory Disclaimer:  I know squat about 3D printing.  But I have built 3 Revell BOMARC kits and modified them according to extensive online research (makes me an "expert," right? ).

 

In the world of 3D printing how can the straight wing trailing edges be a more complex shape than the circular engine exhausts that are even thinner than the wing leading edges?  And the number of supports for the trailing wing edges far exceeds the number of supports for the engine exhausts?  

 

This a fascinating article!  Please understand that my questions are not criticism.  I am over my head trying to grasp a new technology come to our hobby and how you are manipulating it.  I am in "learning mode." 

Edited July 30, 2023 by amurray

[LSP_Kevin]

6 minutes ago, amurray said:

In the world of 3D printing how can the straight wing trailing edges be a more complex shape than the circular engine exhausts that are even thinner than the wing leading edges?  And the number of supports for the trailing wing edges far exceeds the number of supports for the engine exhausts?

 

All good, Art. It's not that the trailing edges are a complicated shape, but a delicate one that doesn't take well to being asked to support the weight of the entire print as it grows. Bear in mind that resin printing happens upside-down, so the print grows downwards from the base, with the effects of gravity increasing as it does. It may look like the supports are there to 'hold up' the print, but they don't work that way at all. They actually have a twofold job: one is to stop gravity from distorting the print and pulling it out of shape, and the other is to provide connection points across the print so that all pixels in a layer are attached to something, and not trying to print in 'mid-air', so to speak. If that happens, that element just floats away in the pool of resin in the vat, and then that part of your print (or perhaps all of it) has failed. Anything that has to print parallel to the build plate is already a problem, as you then need to support it its entire length (like the trailing edges), or the bits between the supports will become 'islands', not attached to anything, and fail to print properly.

 

It's hard to explain all this in words, but if you have a look at this image from earlier in the thread, you can see that the trailing edge is not in good shape at all:

 

But this is how it actually prints:

 

 

Layer by layer, from the top of the image all the way down. Each layer gets printed in its entirety in one pass. Angled surfaces tend to 'grow' naturally from each previous layer, extending out just a little bit, like a set of stairs. Wherever you think the process is going to run out of road, so to speak, you need to add a support.

 

It's complicated! I recommend watching a few explainer videos, as they'll probably make more sense than anything I've just written.

Kev

[amurray]

Kevin,

 

I sincerely appreciate your attempt to educate the uninitiated but I still look at the pix of the leading edges vs. the pix of the exhaust nozzles - and I can't grasp the distinction.

 

IMO this a "sign from above" that Art should not personally engage in 3D printing!  Instead I will follow the posts of others such as yourself and (try to ) learn but not make the mistake of attempting the craft.  

Edited July 30, 2023 by amurray

[LSP_Kevin]

It's a complicated business, for sure, Art. And one with a mountain of shifting variables to contend with! But the short version is that you want to print things at an angle if you can, keep supports away from delicate bits if possible, and delicate bits pointed away from the build plate. Check out this explainer video for the basics, which might help make anything I've said make a bit more sense!

 

 

Kev

[LSP_Kevin]

More 3D printing! This time I'm having another go at printing the blast shield for the launch tower, and keeping the high probability of failure in mind, have basically conceived of them as test prints. I put supports under two examples using opposing orientations, and no tilt in the z-axis:

 

 

While I now feel comfortable with the basic mechanics of adding supports manually in Chitubox, I've got a long way to go before I can claim any sense of expertise, everything is just "best guess" right now.

 

That said, they both turned out better than I expected, and much better than the first one:

 

 

However, I'm sure the keen-eyed among you will have spotted some problems already. There's some layer delamination on both pieces (evident on the one on the right in the photo above), and the plate facing the floor on the left piece has anything but a straight length-wise edge:

 

 

It's fair to say that in these photos, they both look usable. Sadly, a side-on view reveals the wave-like distortions in the main blast shield on both pieces:

 

 

So while these are close, they're not close enough, and it's back to the drawing board. Pat sent me some screenshots of a suggested support layout for this piece, and ironically it's similar to what I used for the first one. What I did learn from this latest test print, however, is that as far as possible, it's best to avoid printing flat surfaces paralell to the build plate.

 

Until next time!

 

Kev