1/16 British Saladin Armoured Car project

[airdave]

hahaha I keep a lot of reference sheets around my work station.
The Bulletin board above my monitor has a small sheet with all the dowel sizes I use.
I collect dowels of all different sizes.




Yup...wooden toothpick is on that list!!

Although, I found that while toothpicks are all about 2mm diameter
they are never consistent, or smooth, or straight...

so, I sand them until they are, which makes them about 1.8mm.
Thats the reference size I use when I am definitely incorporating a toothpick as a center shaft or or as a support.





...
Yes, I am painfully aware that rolling a 6" by 3mm tube is difficult.

Funny thing is, I need a 12" tube.
LOL

The model will use two tubes, about 6" each, joined at the middle with a sleeve tube.

...
For everyone's benefit, a little explanation...



The Saladin has Torsion Bar/Rod suspension.
The solid rods are held in tubes and brackets along the side of the vehicle.
The entire assembly looks like one long rod although it varies in diameters between
tubes, solid torsion bar rods, aswell as various sleeves and brackets.

The scale model needs a supporting rod/tube that can't be any thicker than 3mm diameter.
Keeping it as one long tube means it aligns everything that attaches to it.
There are many scale objects that will connect with it.
This is another reason why I cannot enlarge the diameter.

Rolling a 3mm tube is not an easy thing to do and right off the bat I am tempted to just use a long dowel (3mm thick).
But it has to have the same finish as the rest of the kit, it has to have a printed paper exterior.
Easiest option there is to use a slightly smaller dowel, and wrap a printed layer around it...getting it to 3mm.

Problem, as always is, I am designing a retail kit.
So, I can't just say "use this" or "go buy this".
I can't suggest "painting" or demand the use of other materials (in a cardmodel)
I have to first design a paper part to put into the kit.
Something that the builder can print and use.
I also have to give instructions on how to use the part(s).

Now, if the part is very difficult to use, I can offer suggestions for assembly
and suggestions for alternate methods of assembly.
I can even suggest the use of other materials.

I don't think its fair to assume that everyone who buys the model
can handle whatever assembly method I suggest.
Its not fair to assume that everyone can buy and use the same materials.
And so I am looking for ideas, for alternative design methods.

But rather than have people suggest things for the kit,
I just wanted to challenge everyone to create the part and show me how you did it
...or show me how you would prefer to do it (if it was in a kit).
Maybe, from that, I can come up with more ideas.

[thorst]

What also came to my mind was my father telling me once that old Wilhelmshafen ship card models used an approximation for the thin gun muzzles, they did it as n-sided prisms or frustums. I think they had about 6 to 8 sides each. He mentioned that this was much superior to rolling tiny tubes and didn't look worse at such small radia. Perhaps that's an alternative. Even a 4-sided prism may be enough to get the impression right.

[airdave]

There are some objects that must swivel on this tube.
There are also some objects that butt up to the tube, and may well rely on meeting a rounded surface so they can swivel slightly into position.

The idea of a an octagon(8) sided tube isn't a bad one.
I don't think 3mm diameter is too small to do it.
But it still presents a problem with the items that need to swivel..

Although it wouldn't be that hard to smooth out the tube after it is assembled.
A scored and folded tube sounds easier than rolling a tube.
I'm going to give this one a try...just to see what the tube itself looks like.

[Vermin_King]

I know it seems crazy, but half tubes always seem easier to build than tubes. Would it be feasible to use a half tube for the mostly hidden areas, and shorter full tubes where they are more visible?

[airdave]

Half tubes? only half the work, right?
Is that why its easier? lol

Joking aside...a half tube might be okay if you were mounting it against a flat surface.
But this set of Torsion Rods is mounted out from the surface.
And I have to wrap some extra layers at certain locations and then attach
the three Adjusters, three Upper Control Arms, and Hull mounting brackets.

I agree, it might not be that visible, hidden under the Hull sides and behind the Wheels
but I think it needs to be a full round tube because of all the attaching parts.



................

I tried the scored tube approach to rolling some tubes.

First I printed up a pair of tubes...this is what I need for either side.
I decided to go with two wrap sections, resulting in two layers of tube.
The 3mm diameter is too small to deal with a joiner strip.




I divided the tube into eight parts...that gives me 1.2mm spacing.
Any smaller than that, and it will become very hard to score all the lines.
My scoring tool is more than .5mm thick!

With a straight edge, I carefully scored all lines on the outer and inner wraps.

I thought about this...and realized that scoring on the outside of the part is best.
As you press the scoring tool into the paper,
you are stretching one side of the material more than the other side
....in this case, the outside of the tube.




So, then I started "rolling"...actually, folding the creases.

At first it was easy...the part seemed to fold over at the creases on its own.
But only half the creases were working.
It was difficult to fold each crease and do it cleanly, because the spacing is so narrow.
It took some time, and I had to keep repairing small buckles and bends...
but eventually I got all 16 creases folded and the "tube" started to take shape.



This is where it got tricky.
Just like any rolled tube, the gluing part is tricky and messy.
I don't see any other way than applying glue along the full length of the tube.
But you have to take your time not get glue everywhere...
and the longer you take, the more the glue starts to set up in places.

Your time to make adjustments (while joining the part) vanishes as the glue sets up.
You've got to work fast and try to keep it all in line and straight.




Eventually I got two tubes "rolled" and glued.
They are only slightly better than what I can do with a normal rolled tube.




But, I will admit, forming the "tube" is a lot easier and quicker with the creased approach.
Its definitely a suggested method for rolling tubes.
All I have to do is add reference marks, at each end of the paper part,
to use for making all the score lines.

But I am still unsure as to whether this is the printed paper part solution
that I am looking for.

Any other ideas?

[rjm]

Not what you asked for, but I just measured some bamboo skewers
from the grocery store. They are 23mm or 28mm long. The diameter
is 2.98mm. Just a thought.
Cheers, Bob

[papermate]

Hey, Dave, my 2-cent method. What I did was start with cutting out a 6 by 2 inches rectangle from a newspaper which is handy to find and easier to start rolling. I used a knitting pin of 2-3/4 mm (again easy to find) and roll the said newspaper around it. Repeat rolling until the newspaper is tight around the knitting pin. Take away the knitting pin and use both palms to apply pressure on the roll until it is about the same diameter or thickness of the knitting pin. Glue the rolled tube by starting with both ends and the middle outwards until you are satisfied. No? Start all over, it's costless!!!

Then comes the printed part of the tube that I call it the skin and the attached pics are self-explanatory. If you need the tube thicker at various sections, you can add printed "skin" appropriately.

There are many ways to Rome and this may help without incurring extra hard-to-find materials in your coming kit. Hope it helps.

Papermate

[papermate]

One more thing, "skin" paper used is 80 gsm weight. Is that your 20 lbs? Good for rolling tubes.

Papermate

[airdave]

rjm...

I use bamboo stuff too, but those skewers are too short for this application.
The problem I have with bamboo sticks and skewers is that they are much harder to sand.
(if you need to sand down to a smaller diameter)

I have found, at local craft stores, discount and surplus stores, and at "dollar" stores,
various packages of wooden dowels and craft sticks.
Theres a lot available if we just look for them.
I collect whatever I come across (for future use).

As you can see in the photo I posted earlier, I have various diameters of longer dowels already to use.
Including some that are not on my list.
So, there are many options in this regard.


papermate...

this is the obvious method I have already alluded to.
I will be using this method myself and recommending it in the kit.

I can provide a part that can be printed on lighter weight paper
(70-80gsm / 20-24lb paper)
and then the part can be "wrapped" around a wooden dowel.
The builder will need to measure the dowel and adjust its size as necessary.
As long as the final thickness (3mm) is achieved.

But I believe I still have to provide a "paper part" within the kit,
that can be printed and used with no outside materials.
I believe this is my responsibility with a digital paper model.
No matter how difficult or easy it is to assemble.

Using the aircraft Cockpit Canopy as an example...a kit always has a paper canopy included.
Some kits also have a template to cut a clear plastic canopy from acetate.
But it would be wrong to provide no canopy...and just suggest the builder buy a vacuformed canopy.

I was hoping I might get a "this is how I want to assemble this part" suggestion.
Or a better part than I have already come up with.
I think this idea has been discussed before. (the rolling of narrow tubes)
Its always been a difficult assembly to deal with.
There's obviously no simple solution.

I'll continue with what I have and make a report soon.
Thanks for the input guys.

[nando]

I don't know if this can help or it is out of theme, but this discussion remembered me a way to do tiny ( very tiny ) tubes described in this thread ( Saturn V Launch Escape System ).
You can find the description of the process in the instructions for the Apollo LES lattice in this site.

Here below you can see an extract from the instructions.


But it could be difficult to insert this kind of process in your model.
However compliment for your designs.

Best, Nando