Making a lightwight box - foamboard?

[NoSpam]

I need to make a lightweight case to carry a strangely shaped guitar
around, is foamboard any good for this? If not, is there anything else -
or am I back to using plywood as usual?

[Owain]

fibreglass sheet?

Owain

[NoSpam]

I'll investigate, but I'm not sure that it would be any lighter than 4mm
plywood.
Is there anywhere to buy honeycomb board (like the stuff Ikea use, but 6
or 10mm?)

[Nightjar]

I don't know where you would buy it, but this is the stuff to make
really lightweight items from, particularly if you laminate aramid or
carbon fibre sheet on either side:

http://www.plascore.com/pn1-nomex-aramid-fiber-honeycomb.php

It is used for racing boat hulls and, in PN2 grade, aircraft, so a boat
builder (or Airbus Industries) might be able to help.

Personally, I would use aluminium to make the case.

Colin Bignell

[Peter Parry]

On Thu, 15 Mar 2012 23:59:36 +0000, NoSpam <nom...@hursley.ibm.com>
wrote:

>I need to make a lightweight case to carry a strangely shaped guitar
>around, is foamboard any good for this? If not, is there anything else -
>or am I back to using plywood as usual?

Get a lump of Cellotex/Kingspan and carve to shape. Clad in
lightweight 3 ply to give abrasion/impact protection by cutting the 3
ply to shape and attaching it to the Kingspan using Polyurethane glue.
Before gluing strip the aluminium foil from the outer surface of the
board. If you spray the board and kingspan lightly with water the PU
glue foams up and fills all the voids between plywood and core giving
you a very strong and stable box.

[NT]

On Mar 16, 9:06 am, Nightjar <c...@insert.my.surname.here.me.uk>
wrote:

And the more curves you can get in the case design, the better the
strength to weight ratio is.


NT

[NoSpam]

Thanks Colin, this looks priocey but I'll investigate

[NoSpam]

Thanks for an intersting idea

[fred]

In article <9sgrfe...@mid.individual.net>, NoSpam
<nom...@hursley.ibm.com> writes

I'd be worried about the celotex shedding dust, also it's rigid so wont
absorb shock too well (might be important if this is to be used as a
shipping case.

A balance might be to use one of the common packing packing foams such
as Plastazote. This stuff does give a bit so absorbs shock but think it
would be stuff enough for Peter's hard shell idea to work.

The idea is to build it up thickness in layers but you can pre-cut the
shape first which makes the sculpting much easier.

This is 20mm sheet, quite expensive but you might just get the full case
out of one sheet:

http://www.bluearan.co.uk/index.php?id=ADH019320

No connection, first hit, may be cheaper elsewhere.
--
fred
it's a ba-na-na . . . .

[The Natural Philosopher]

actually a way that may work for you iof you have te patiemce is once
again culled from the model aicraft knowledge repostiry.

Glue slabs of high density extruded polystyrene foam (floor insulation -
generally blue mauve or pink) together (use epoxy) and use knife, wire
brush and sandpaper to make whatever shape you want and then cover it
all in epoxy resin and glass cloth. If teh epoxy resin is too expensive
use a water based acrylic varnish - anything that bonds the cloth to the
foam is good.

interior finish from crushed velvet of coirse :-) exteriors? its your
choice but if the acrylic or epoxy is 100% sound then for sure you can
use body putty and car spray .

a cheaper (heavier) alternative to the glass/epoxy/acrylic is to use
papier mache over the foam. Wall paper paste and strips of newspaper or
brown paper built up to about 3mm or so should suffice. That will then
also take a spray paint finish.


Never forget that hand moulding is actually quite easy a thing to do.

If you decide that e,g, the papier mache is all you need, the foam can
be washed out entirely with cellulose thinner post moulding.

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

[NoSpam]

My thoughts were starting to drift the same way. I used to own a share
in an aircraft called a Rutan Long-Ez that was built using moldless
composite techniques.

Papier mâché is an interesting idea - I haven't played with that since I
was a kid. I've no idea how thick it needs to be for reasonable strenth,
but I think it may be tough to get a decent flat surface finish. More
food for thought!

[Nightjar]

I'd more or less forgotten it. It will be a lot cheaper than aramid
honeycomb.

Colin Bignell

[The Natural Philosopher]

It is slightly tougher than MDF.. finish is no problem since it sands
easily enough. and if you uses strips torn edged they can be layered
fairly well. I did a plane like that - problem was a pinhole and the
paint ate the foam through it.

but that was a single paper layer - if you use about 1/8" plus it is
essentially a sort of wood and any way you finish wood will work.

[The Natural Philosopher]

I've sort of used the brown paper over foam a couple of times and it is
a good finish ..the thought came partly from laterally thinking about
laminating glass and partly out of thinking of all those moulded fibre
cases one has over the years.

> Colin Bignell

[Andy Dingley]

On Mar 16, 2:31 pm, NoSpam <nom...@hursley.ibm.com> wrote:
> Papier mâché is an interesting idea

Friend of mine did it for a musket case. Considerable waste of time
and effort. Loads of layers to make it strong enough, and it's a long
time drying between layers and an even longer time afterwards.

Fibreglass would have been quicker and easier.

The mould was expanded polystyrene blocks, stuck together with copydex
and shaped with a rasp. Take it out afterwards with some acetone.

[Thomas Prufer]

On Thu, 15 Mar 2012 23:59:36 +0000, NoSpam <nom...@hursley.ibm.com> wrote:

I made a form-fitted toolbox insert using polyurethane foam, see below.

Worked well...


Thomas Prufer



>First, I placed the tools in pleasing arrangement, turned so that the less
>undercut side is up. Photographed arrangement. Wrapped tools in clingfilm in
>case foam gets through to them. This also reduces the detail somewhat -- I
>didn't want foam to mold to every loop and crevice, just to the general outline.
>Placed tools on cardboard face down, mirroring arrangement, referring to
>photograph.
>
>Taped tools in place on a piece of cardboard, using masking tape to reduce
>undercuts. (I decided to leave out some small boxy bits, and just cut holes for
>those later.) Covered tools with a thin bit of jersey fabric, to provide
>protection from foam, and a little overall clearance between foam and tools --
>there will be fabric over the foam in the final inset. This also softens any
>sharp edges that may cut the plastic bin liner. Placed a bin liner over the lot:
>tools, cardboard, fabric. I used a polyethylene bin liner so that the foam will
>not stick to the liner -- PE is one of the things listed on the can that PU foam
>won't adhere to. Now, I sucked the air from bin liner. I used an injector pump
>and a bit garden hosepipe attached with a cable tie. Fiddled with the plastic to
>get it to conform well to the tools, and get the folds and wrinkles to lie flat.
>(This was the part that had me really worried: I wanted a vacuum to get the
>plastic foil good an close, but any tiny hole would result in foam being sucked
>all over all the tools.)
>
>Built four cardboard sides, a bit smaller than the box it will fit in. Fold out
>bottom edge, and attach over the cardboard/tools/bin liner using binder clips.
>Taped gaps on the inside to keep foam inside. Dampened the foil and cardboard --
>the foam wants a bit of moisture to cure.
>
>Put on old clothes, rubber gloves, shook can and foamed away, squirting the
>stuff in the undercuts first. As the final foam block was to be about 30 liters,
>I ignored the "maximum thickness of 30 mm per layer" and emptied the can. (I
>have had half-used cans sitting in the corner harmlessly at first to find that
>they had oozed their guts out the moment I turned my back. So out with it.) This
>thick layer may have contributed to the large pores near some of the tools.
>
>It looked as if it were far too little for a while, but then expanded slowly and
>continuously. From previous experience with the stuff, it always does, and still
>I put in too much. So I'd left the cardboard sides very high, so no worries. (No
>canoes here!)
>
>I let the injector pump run for about two hours, and then turned it off. The
>lightly moistened top layer had started to cure and was no longer tacky or soft
>by then, so I assumed the bottom with the tools would also have started to cure.
>This foam block cured overnight.
>
>The tools came out easily this morning: I cut open the bin liner from
>underneath, pulled the tools out, pulled the fabric off, and peeling off the
>plastic sheet from the foam without any trouble. No leaks. There are large
>pores, gaps, and holes under the tools, but overall, details molded well. The
>pores tend to be at flat surfaces. Some narrow gasp of 1.5 cm wide an 2 deep
>have filled in well, with a fine-grained foam. Perhaps the moisture keeps the
>pore size down? The bin liner rounded out the edges nicely.
>
>The next step will be to cut the remaining holes with a cutter knife and a
>scalpel, reduce some of the undercutting, and maybe provide some clearance holes
>to make it easier to grip and remove tools.
>
>Yellow foam with large pores is not pretty - this would do for packing, but not
>for use or display. I have bought some crushed velvet to cover the foam. This is
>a synthetic fabric and very elastic, so placing it over the foam and inserting
>the tools one by one, from the middle out, pulls it into the cutouts nicely. The
>crushed look makes the inevitable folds and wrinkles much less noticeable and
>unobjectionable. Hot-melt or double-sided carpet tape should hold the fabric
>down nicely, perhaps aided by the odd pin; I have yet try this.
>
>Should you think crushed red velvet a bit too much -- it was cheaper than felt
>by about half, and felt would have required a lot of cutting, joining and
>gluing!

[Nospam]

Thanks Thomas.
Did you find that the foam caused the cardboard sides to bulge outwards?
Was much heat generated while the foam cured?

[Nospam]

On 20/03/2012 07:06, Thomas Prufer wrote:

[NT]

On Mar 20, 7:06 am, Thomas Prufer <prufer.pub...@mnet-

Nice one. Could we put that on the wiki? I don't know if you've got
any pictures.


NT

[Nospam]

On 20/03/2012 07:06, Thomas Prufer wrote:

Sorry about the earlier multiple messages, this is what I intended to write:

Thanks Thomas!
A couple of questions:

Did you find that the foam caused the cardboard sides to bulge outwards?
Was much heat generated while the foam cured?

What is an "injector pump" in this context?

[Thomas Prufer]

On Tue, 20 Mar 2012 09:02:00 +0000, Nospam <Nom...@hursley.ibm.com> wrote:

>Did you find that the foam caused the cardboard sides to bulge outwards?

Not much, not more than the weight of the foam. The box was open on the top, so
the foam could expand freely, without building up pressure. Also, I moistened
the box.

>Was much heat generated while the foam cured?

I'd say no, but I didn't test the middle. I foamed and left, because of a) the
urge to touch and feel and fiddle and b) because the damn stuff won't come off,
ever, short of using an angle grinder, unless you catch it immediately with
acetone...


Thomas Prufer

[Thomas Prufer]

On Tue, 20 Mar 2012 02:16:33 -0700 (PDT), NT <meow...@care2.com> wrote:

>Nice one. Could we put that on the wiki? I don't know if you've got
>any pictures.

Putting it up on the Wiki is fine.

I may be able to find the pictures -- where should I mail them, if they turn up?

And it wasn't really a toolbox, but a sample suitcase for a travelling salesman
in vampire killing weapons: oak stake, silver knife, gun, holy water, garlic
extract, tables of sunset & sunrise...


Thomas Prufer

[The Natural Philosopher]

Thomas Prufer wrote:
> On Tue, 20 Mar 2012 09:02:00 +0000, Nospam <Nom...@hursley.ibm.com> wrote:
>
>> Did you find that the foam caused the cardboard sides to bulge outwards?
>
> Not much, not more than the weight of the foam. The box was open on the top, so
> the foam could expand freely, without building up pressure. Also, I moistened
> the box.

leaving a bit open is the key - the pressure is great but et foam is
almost fluid long after the expansion stops and the thing sets.

>
>> Was much heat generated while the foam cured?
>
> I'd say no, but I didn't test the middle. I foamed and left, because of a) the
> urge to touch and feel and fiddle and b) because the damn stuff won't come off,
> ever, short of using an angle grinder, unless you catch it immediately with
> acetone...
>
>
> Thomas Prufer

From the small amount of foam I have done yes, it gets warm, but
nothing like as warm as some catalysed polyeters get.

[NT]

On Mar 20, 3:47 pm, Thomas Prufer <prufer.pub...@mnet-
online.de.invalid> wrote:

> On Tue, 20 Mar 2012 02:16:33 -0700 (PDT), NT <meow2...@care2.com> wrote:
> >Nice one. Could we put that on the wiki? I don't know if you've got
> >any pictures.
>
> Putting it up on the Wiki is fine.

Done:
http://wiki.diyfaq.org.uk/index.php?title=Foam_toolbox_moulding

> I may be able to find the pictures -- where should I mail them, if they turn up?

A good option is to put them on tinypic or similar sites, and say you
release them into the public domain.

> And it wasn't really a toolbox, but a sample suitcase for a travelling salesman
> in vampire killing weapons: oak stake, silver knife, gun, holy water, garlic
> extract, tables of sunset & sunrise...
>
> Thomas Prufer

thanks, NT


NT

[Nospam]

Please can you explain what sort of "injector pump" you used to suck the
air out of the bin liner?

[Thomas Prufer]

On Tue, 20 Mar 2012 17:17:25 +0000, Nospam <Nom...@hursley.ibm.com> wrote:

>Please can you explain what sort of "injector pump" you used to suck the
>air out of the bin liner?

http://en.wikipedia.org/wiki/Aspirator_%28pump%29

which is a widget that attaches to mains water one end, sucks air in the other,
and a water/air mix comes out the third.

I though the vacuum cleaner might not like running for long with very little air
moving through it, and I have the pump thing, so I used it.

I don't think you'd need it for a guitar, it being large and fine detail not
being necessary. Stick a vaccuum cleaner on it for a few seconds, if at all.


Thomas Prufer

[Thomas Prufer]

On Tue, 20 Mar 2012 09:59:27 -0700 (PDT), NT <meow...@care2.com> wrote:

>A good option is to put them on tinypic or similar sites, and say you
>release them into the public domain.

I have found the pictures of making the molding, but I need to make some of the
finished box.

What is a suitable size to upload? 640x480?


Thomas Prufer

[Nospam]

Thanks, that's something else I've learned about, although possibly it's
not the best thing to use for very long with a water meter (and shortage!)

[NT]

On Mar 20, 6:08 pm, Thomas Prufer <prufer.pub...@mnet-
online.de.invalid> wrote:

> On Tue, 20 Mar 2012 09:59:27 -0700 (PDT), NT <meow2...@care2.com> wrote:
> >A good option is to put them on tinypic or similar sites, and say you
> >release them into the public domain.
>
> I have found the pictures of making the molding, but I need to make some of the
> finished box.
>
> What is a suitable size to upload? 640x480?
>
> Thomas Prufer

Excellent. 640's fine, 1000 is too. I forget the current limit, but
200k is accepted on the wiki.


NT

[Rod Speed]

Nospam wrote
> Thomas Prufer wrote

>> Nospam<Nom...@hursley.ibm.com> wrote

>>> Please can you explain what sort of "injector pump" you used to suck the air out of the bin liner?

>> http://en.wikipedia.org/wiki/Aspirator_%28pump%29

>> which is a widget that attaches to mains water one end, sucks air in the other, and a water/air mix comes out the
>> third.

>> I though the vacuum cleaner might not like running for long with very little air moving through it, and I have the
>> pump thing, so I used it.

>> I don't think you'd need it for a guitar, it being large and fine detail not being necessary. Stick a vaccuum cleaner
>> on it for a few seconds, if at all.

> Thanks, that's something else I've learned about, although possibly it's not the best thing to use for very long with
> a water meter (and shortage!)

You dont have to use it for long with the sort of box being discussed.