1/35 Gas Mechanical Bash

[danpickard]

Marc,
After seeing the VF process you went through, I better understand what it was you were trying to achieve.  What would have you done previously...butt join edge, add filler and sand to curve? or just heat the styrene and bend across an edge?  Makes brass etch even sound easier!   Glad you got the result you were after in the end.  Certainly looks like a clean finish.

Without being an expert on these loco's I think from a visual perspective, I like the idea of the toolbox seat, and yes, with the diagonal strut underneath.  Nice worn leather cushion on the seat with a bit of a rip, maybe some tape across it as a temporary repair etc etc.  There lies the beauty of this type of loco, they were smaller enough for any manor of modifications to be quite quickly and simply done in the local shops.  If you dont actually have a reference shot to a prototype this is specifically meant to be, almost anything is possible I guess.

Dan

[jacq01]

Marc,

seeing the proportions and shape of your form, it is no wonder the material got torn, deformed and showed holes.
It is like pressing steel. Rounded forms and minimum radii ( depending on material elasticity) are a must
and the depth is important in relation to the thickness of the sheet and the clamping force around the edges.

Jacq

[lab-dad]

Great SBS Marc,
I think we all learned something!

As far as the seat goes "I" think the fold up (and outta da way) seat is more practical, especially on a cab of this size.
BTW- she is looking real sweet!
-Marty

[danpickard]

Thanks for that Marty, that ought to make Marc toss and turn in his sleep for a few nights deciding on that one...seat goes up, seat goes down, seat goes up, seat goes down

Dan

[marc_reusser]

Dan

Yes, previously I would probably have tried butt-joining and then radiusing/easing the outside edge. My issue with that approach was several fold, foremost being structural integrity, as the material was quite thin (.010). When butting there is always a chance of not having a perfectly clean seam, where some filling is required, and beween that and the radiusing, I felt there was not enough strength to withstand the necessary handling involved; also in the long term there is a good chance that these individual sheets would slightly deform, and suffer from normal expansion/contraction, and thus there was a good chance that this seam would open. Yes it could have ben rectified by adding an angle piece on the interior...but that sort of defeated the look .  

IMO bending the styrene across an edge is always a tricky proposition, if you are lucky enough not to have the styrene split/crack, because of the hard bend, there is usually the problem of still having too much tension, and always wanting to spring back a bit...even if the bottom were edges were secured//glued in place....the top of the sides would likely always have at least a slight outward flare.

...and heat bending; though a very realistic solution for such a simple shape, for me it would probably have been about the same amount of work, but with less accuracy, and possibly a bit less crispness to the edges. I would have had to rely in perfectly aligning the two bends, getting the perfect width, and applying equal heat and pressure to both sides...which is doable...but would likely take a few tries also.

The beaty of the VF'd pieces is that they are quite strong and ridged, and the are perfectly square and flat, and I have absolutely no worries about handling them.


Jacq

Yes, Live-and-Learn ....I figured from the onset that this would possibly be a problem....but as I had the VF machine (which is now in the trash) I had to give it a try anyway.


Marty

Thanks.

Yup...still pondering that seat...though if I do a fold-up...I will need to build all the hinge pieces, the stepped/toothed adjustable brace rail, and then a tool box on the cab floor......all of which is not the easy way out



Marc

[marc_reusser]

Thanks for that Marty, that ought to make Marc toss and turn in his sleep for a few nights deciding on that one...seat goes up, seat goes down, seat goes up, seat goes down

Dan

HEY!!!!....Stop encouraging him! You guys are just plain evil!

Marc

[danpickard]

Hang on, I've changed my mind and I like Marty's idea...sounds like it might be harder

Dan

[danpickard]

But hang on, I like my idea with the toolbox seat, more scope for character, and you could still build an "extra" toolbox to put under the seat, along with a few spare rags, oil can, bit of chain, engineers lunchbox, maybe a nice warm jacket hanging over the back of the cab wall...now we thinkin'   

Dan

[Chuck Doan]

Maybe the seat should have your patent Kotex "stuffing" showing too?

[marc_reusser]

Boy...everybody's a comedian! 

What started out as a "quickie" project on which to exeriment some painting techniques, it urely has developed into the "Nightmare on Elm Street"  ......for all the complaining I get about never finishing anything, you guy's aren't exactly helping much .


Marc

[Chuck Doan]

Yeah, and all I was going to do was give that tractor a spritz of Dullcoat and throw on some powders!

[Franck Tavernier]

Nice job Marc!

I like very much your rear bulkhead. I understand now why you want to test vacuum technique...About bending, I had the same problem recently as you on my last model in Gn15, with .010" styrene sheet...if you fold too hard the sheet, you will obtain cracked or fissured part especially when you use very fine sheets...And .010" sheet in 1:35 scale is nearly overscale for a bulkhead...0.006" will be closer to the scale, and with this thickness, the styrene is not appropriate any more on a mechanical point of view! That's why, I used now for a long time (but not for my Gn15 model, it would be entirely built in styrene sheet), .15mm or .2mm phosphorous bronze sheet which makes it possible to respect these various thicknesses of sheets compared to the scale, while remaining mechanically strong and resiliant...

I like the seat, but very often on this type of little gas loco, the seat isn't a metal sheet, but wood, with brackets underneath on the rear bulkhead...The toolbox under it, is a good idea!

Franck

[danpickard]

Marc,
In defence of ourselves, you did ask the question.  I'm with Chuck, dullcoat and powders, leave for 10 minutes to dry

I suppose I should point out that it still will probably look good with or without the seat.  And thanks for the info about working with the styrene/bending etc.  Always thorough with the details. Cheers.

Dan

[Krusty]

Now that the server is responding again....

Marc, I've formed styrene in the past by using a die to push softened sheet through a matching aperture in a piece of wood. It works reasonably well with 0.5mm sheet, but might be a bit too vicious for the 0.25mm stuff.

The hinged seat is rather unlikely. On the real thing the seat was invariably fixed, usually with a wood top to provide some vague semblance of comfort, as Franck has already noted. Jenbachs varied, depending on the size of loco. On the 15 and 20 horsepower locos the seat was usually in one corner, with the handbrake in the other corner. This is a JW15.

[John McGuyer]

Marc
You encountered exactly what I was talking about with the dump tank on the vacuum former. Speed while the plastic is at its max temperature is the name of the game. If you can, put some sort of a chamber between your vacuum former and shop vac. That way when you place the plastic over the mold, the air will be vacated rapidly by the vacuum in the tank and it will pull into those corners better.
John