1/18 Scale Blue Box F4U-1A Corsair Modification

[JayW]

1 hour ago, RLWP said:

@JayW  - you seem to have got yourself a bit lost at the moment.

 

It's true you can construct wonderful things in CAD, I used to do that for a living. Will you see most of that detail? And if you are going to have to pay to get it printed it's going out of your control, and it's going to cost

 

So far in this thread you've demonstrated that you are good at making parts - excellent in fact. Can I suggest you take a break and decided what it is you want to do? To me, you are more than capable of finishing this 'plane with the tools you already have.

 

Richard (who is quite familiar with losing himself down fascinating rabbit holes)

I here 'ya.  Getting back to why I considered 3D print, recall I was struggling mightily with machining the wheel halves.  I think the last failure on the lathe was just a bridge too far and I was no longer willing to invest so much time and effort into another machined part living in fear all along that it might self-destruct at any moment.  To watch that nearly finished part, after hours of careful turning and milling, jam and fling itself across my garage was soul destroying.  I still desire to 3D print the wheel details.  I await a couple of test parts that are in the mail, to see how successfully they duplicate the details I created. 

 

One of the test parts, BTW, is the tire itself where in order for me to create the diamond tread I want on a lathe-turned tire, I must fashion a complicated jig that allows me to make saw cuts with a razor saw at the proper angles and intervals to produce the diamond pattern.  Did this for my P-47 and although gratifying it was a monstrous PITA.  

 

So mission creep is the problem here!  You see it.  I see it.  And I need to protect against it.  The Corsair landing gear components appear to be singularly complicated, more so than any other LG I have created so far.  So you can see the lure.  At the very least, in addition to the wheel halves and tire, I would like to get a 3D print solution for that elbow on the lower strut.  I have no confidence in my ability to "hog out" a good part from a block of material which is what it would take to make a convincing looking part.   

And cost - I think the cost alone is going to send me packing.  We'll see.

 

And thanks for your faith in me building this thing by other means. 

Edited May 17, 2021 by JayW

[RLWP]

I'd say you were really close with the machining of the wheel, I was expecting to be congratulating you on your next attempt

 

You don't have to 'hog out' stuff from solid, I'd be fabricating the leg from tube. For instance, the shallow bend is a thin wedge cut out and the tube closed up. The more acute bend is the same with a bigger wedge, or cut the tube through. file the ends and rejoin at an angle.

 

I'd do that in brass tube and solder the joints - because I can solder*. If you can't, bend up a bit of steel rod, put that in the inside and fill the tube with epoxy

 

There's always a way

 

Richard

 

*silver solder, probably leaving me the option of soldering on the lugs and other lumps

 

[spartacus2000]

No problem.

If you need I will always be available even for a conceptual input

[JayW]

I got some 3D print test parts in the mail a couple days ago, from a fellow LSP guy - a tire and an inner wheel half.  You have seen the pictures of the digital models, but here they are again:

 

 

 

The intent of the test parts was to see if the process reproduces the level of detail I want, how accurate it does holes, and to see how it handles thin gages.  

 

Here:

 

 

 

Lotsa clean-up required as you can see.  But not as bad as it looks.  Provided was a one-piece tire, and a two-piece tire - I will decide which I like best (probably the one-piece).  And of course the complex inner wheel.

 

Here are the parts cleaned up and painted:

 

 

 

I have to tell you, I was impressed.  It's cool to machine parts on the lathe / end mill.  And I have had success.  But I cannot come within a mile of this kind of detail.  These parts are not perfect, mostly due to my own digital modelling.  Nothing like seeing the parts for real to make a final determination.  I am going to widen the tread pattern a bit on the tire, and increase the gage a bit of the internal ribs on the wheel (they are too fragile to even work on at the moment). 

 

Now I know what you might be thinking - there is an honor associated with scratch building, and this is not scratch building.  But know that I am going to limit the 3D print parts to details that I would do a miserable job at scratch building, or which are just too difficult or painful.  Depending on cost, I will have at least half a dozen details mostly landing gear parts.  Man - I'll bet a 3D printed R-2800 cylinder would look great!  

 

I hope to provide a cockpit update next (RH side).  Stay tuned!    

 

 

Edited May 24, 2021 by JayW

[chuck540z3]

Wow Jay, those wheels/tires are beautiful!  So nice!

 

Cheers,

Chuck

[Citadelgrad]

4 hours ago, JayW said:

I got some 3D print test parts in the mail a couple days ago, from a fellow LSP guy - a tire and an inner wheel half.  You have seen the pictures of the digital models, but here they are again:

 

 

 

The intent of the test parts was to see if the process reproduces the level of detail I want, how accurate it does holes, and to see how it handles thin gages.  

 

Here:

 

 

 

Lotsa clean-up required as you can see.  But not as bad as it looks.  Provided was a one-piece tire, and a two-piece tire - I will decide which I like best (probably the one-piece).  And of course the complex inner wheel.

 

Here are the parts cleaned up and painted:

 

 

 

I have to tell you, I was impressed.  It's cool to machine parts on the lathe / end mill.  And I have had success.  But I cannot come within a mile of this kind of detail.  These parts are not perfect, mostly due to my own digital modelling.  Nothing like seeing the parts for real to make a final determination.  I am going to widen the tread pattern a bit on the tire, and increase the gage a bit of the internal ribs on the wheel (they are too fragile to even work on at the moment). 

 

Now I know what you might be thinking - there is an honor associated with scratch building, and this is not scratch building.  But know that I am going to limit the 3D print parts to details that I would do a miserable job at scratch building, or which are just too difficult or painful.  Depending on cost, I will have at least half a dozen details mostly landing gear parts.  Man - I'll bet a 3D printed R-2800 cylinder would look great!  

 

I hope to provide a cockpit update next (RH side).  Stay tuned!    

 

 

No, i dont think a single person thinks “this isn't scratch building,” Jay.   I think those wheels were created using a design/modeling you created, and they look amazing. 

[RLWP]

9 hours ago, JayW said:

Now I know what you might be thinking - there is an honor associated with scratch building, and this is not scratch building.

 

It's all about getting the job done, and the 3D printing has done that beautifully

 

I can make engines for the scratchbuilds I do, if I can find a kit one I will usually use that - otherwise there's a danger I'll get distracted chasing ideas down rabbit holes. You paused, made a decision and moved forward - and that's a skill

 

Nice work, Jay. One step closer to finishing!

 

Richard

[dodgem37]

Great show.

 

'Now I know what you might be thinking - there is an honor associated with scratch building, and this is not scratch building.'

I must apologize, Jay.  I disagree.  It's a new tool in the scratchbuilders' vocabulary.

 

Sincerely,

Mark

[airscale]

3 hours ago, dodgem37 said:

Great show.

 

'Now I know what you might be thinking - there is an honor associated with scratch building, and this is not scratch building.'

I must apologize, Jay.  I disagree.  It's a new tool in the scratchbuilders' vocabulary.

 

Sincerely,

Mark

 

 

100% agree...

 

there is no code of ethics for scratchbuilding where you are cheating Jay - this is a tool, you are using the best tool for the job and 3D modelling is an evolution of our toolset..

 

much as in the same way I could cut a brass rod by rubbing it very hard with a pebble until I have two parts - 10,000 years ago that might have been appropriate, now I get the tool for the problem I am trying to solve and do it in seconds accurately with a dremel..

 

you have proven other-wordly skills at scratchbuilding - there is not a viewer here who thinks - 'oh, look at that, Jay cheated, he has gone right down in my estimations, he is a fake scratchbuilder....'

 

free yourself of that burden my friend

 

..this is just stunning creativity and that is what it is all about

 

Peter

 

 

[JayW]

17 hours ago, chuck540z3 said:

Wow Jay, those wheels/tires are beautiful!  So nice!

 

Chuck - you ain't seen nothin' yet!  

 

7 hours ago, airscale said:

free yourself of that burden my friend

 

Thanks Peter.  You know, I am in the process of 3D modelling the P-51B/C/D/K nose and cowl and chin intake surfaces using points data from the original loft drawings (these loft drawings are not available at Aircorps Library BTW - I obtained years ago with help from the P-51 SIG people).  Almost no modelling manufacturer get's this 100% right.  21st Century Toys got it approximately 100% wrong in 1/18.  Your Lope's Hope looks about right on I think.  This in the unlikely event I take a crack at another 1/18 Mustang (if I do it will be my late uncle's P-51D-20NA "Sissy Mana").   A second try would be much better than the first, which is many years old, and I have learned a thing or two since then.  It occurs to me that one could 3D print just about the entire airplane!   Would that be scratch building?? 

12 hours ago, RLWP said:

You paused, made a decision and moved forward - and that's a skill

 

Richard - yes I did.  And there are more decisions to make!  That lower strut that a few of us are fretting about (ha!) - gotta decide how to do that one.  Test part coming, which will be taken to failure. 

 

12 hours ago, RLWP said:

One step closer to finishing!

 

Technically true - the Corsair project may outlive a few of us!  If I try to do the wing folds, I might be done this decade.  BTW - why would I do that if not just for the challenge?  The land-base bound Corsairs (mine will be one of them), I believe, didn't even use their wing folds; may well have de-activated the system and saved some weight.      

[D.B. Andrus]

Great work Jay. I wouldn't be concerned about being "correct" in your approach....as others have stated it's all about accomplishing the task.

 

Maybe some variation on this technique might help with the L/G:

 

 

Keep up the fascinating work!

 

HTH,

 

Damian

[JayW]

9 hours ago, D.B. Andrus said:

Maybe some variation on this technique might help with the L/G:

 

yeah Damian - definitely an option.  Are those printed parts there?

[D.B. Andrus]

1 hour ago, JayW said:

yeah Damian - definitely an option.  Are those printed parts there?

 

No, they're resin cast. Here's a link to my products:

 

https://forum.largescaleplanes.com/index.php?/forum/103-synthetic-ordnance-works/

 

I'd be happy to answer any questions.

 

Cheers,

Damian

[JayW]

Today I received my lower strut test part, 3D printed out of grey resin.  The goal here is to try to determine if this part can be used as is, or does it need an internal strengthening member like a stiff wire.  Previous posts have discussed this.  In which case, the lower strut would have to be made in two halves split down the middle, and hollowed to accept the bent up wire.

 

Recall the lower strut looks like this:

 

  

 

The part of interest is labelled "I worry about this part". 

 

Here is the lower strut detail test part fresh from Tim:

 

  

 

It is a gorgeous part.  Wonderful detail.

 

OK, this Corsair is going to weight roughly the same as my 1/18 P-47D.  So to determine approximately how much dead weight the lower strut must carry, I measured same on the P-47:

 

 

0.972 pounds.  

 

I assembled the lower strut by adding aluminum tubes for the oleo and the axle, and added the tire and wheel to it.  Then I put together a crude test stand of sorts:

 

 

Now to put weight directly above the strut.  I have a can full of civil war style lead slugs which weight 0.062 lbs each.  So I started to load it up and see if/when the strut breaks.....

 

1 pound:

 

 

No appreciable bending either .  Good.  This is how it's going to be on display.

 

2 pounds:

 

 

Messed up the three pound photo....

 

Four pounds:

 

 

 

Got some bending going on!  But no fracture yet.

 

Five pounds plus:

 

 

Wow!  I ran out of slugs.  Look at that bending.  I guess I could have tossed in some other things, but I had seen enough.  When I relieved the strut of weight it sprang back to its original shape - no permanent set.

 

I also did an engineering analysis at the critical section just below the oleo, determining the bending moment for one pound dead weight, and using the advertised ultimate strength of the material (5076 PSI).  My calcs suggest the part fractures at around 5 pounds.  So the part beat my prediction.

 

I have concluded that the single piece lower strut will be strong enough and stiff enough to adequately support the model.  So relax folks!  It's gonna be OK!

 

I have been working on the cockpit.  But not quite ready to show progress.  Next post, I promise.  

 

 

 

 

 

 

 

 

 

 

 

Edited June 8, 2021 by JayW

[brahman104]

Some impressive torture testing there Jay! I was thinking the same; I thought the resin would snap without much weight on it, let alone 5lbs!!! Pretty darn impressive!

 

Now that you have that worry over with, I'm keen to see the printed leg in all its glory

 

Craig