wrote:
Tim,

Would the following cover most of my entry level needs for sheet metal
fab, for getting sheet metal in small enough shapes for my taig? I'll
'punch' holes by using the mill.

The Eternal Squire
----------------------

18'' SHEET METAL FABRICATION TOOL KIT CUTTER ROLLER

That tools claims 18gauge capacity, and probably is thinking of steel
and could do some operations on thicker aluminum.

Not sure what kind of aluminum sheet you have, but 18gauge aluminum is
a bit wimpy for many electronic enclosures. It's OK for a small
mini-box, but very much less than ideal for anything larger.

That tool you point out is OK for a lot of work, but IMHO you'd also
need a "real" shear and a brake to do any sort of box fabrication. Some
of the bending can be done with a homebrew brake made out of 2x4's and
hinges but you'll get tired of this real quick.

If you think you can cut arbitrary shaped holes in large sheet metal
boxes with a milling machine, you have skills I do not have. But I
think it's more likely that you've never done much sheet metal
fabrication. A mill is not the best tool for cutting holes in sheet
metal (although clamping to sacrificial flat pieces of wood does help.)

Tim.

If you think you can cut arbitrary shaped holes in large sheet metal
boxes with a milling machine, you have skills I do not have.

Not planning on large sheets anyway. But thanks for your comments,
they're helping me abandon overly expensive possibilities.

I'm thinking my best niche would be to custom mill boxes up to 2X2X1
with walls at least 1/4 inch thick, with top panel either 1/4 or 1/8
plate up to 2X2. That's plenty for QRP, subsystems, microcontroller
boxes, and some scientific apps.

The Eternal Squire

wrote:
If you think you can cut arbitrary shaped holes in large sheet metal
boxes with a milling machine, you have skills I do not have.

Not planning on large sheets anyway. But thanks for your comments,
they're helping me abandon overly expensive possibilities.

If you think it's do-able, don't stop just because I said that I tried
it and it didn't work for me :-).

Working sheet metal in a mill or a drill press has caused some, um,
near-disasters in many amateur shops. Poor clamping resulting in
spinning sheets with sharp edges are the most common but I've
personally put one dent in a cement wall with some thick sheet in a
belt sander :-).

I'm thinking my best niche would be to custom mill boxes up to 2X2X1
with walls at least 1/4 inch thick, with top panel either 1/4 or 1/8
plate up to 2X2. That's plenty for QRP, subsystems, microcontroller
boxes, and some scientific apps.

For sizes that small I think you ought to price out some common
aluminum extrusions.

2"x2"x1" is really tiny for any experimenting. Not so bad for a small
already-known-quantity project with a tiny tiny circuit board. But too
small for most homebrew projects and it just barely accomodates a
connector or switch or two on each side. And at that size you're
smaller than most existing die-cast and miniboxes. Heck, you're smaller
than an altoids box :-).

Or maybe you mean 2feet x 2feet x 1 feet? Even then you might want to
see what standard size extrusions are around. Quarter inch walls will
make a box that large be pretty heavy (not as heavy as the solid
aluminum block that big though! By my calculation that'll be 700 pounds
of aluminum as a solid block...)

Take a look at some of your competition:


http://www.globalspec.com/FeaturedPr...ildABox/9443/0

I think you could one-up them by making a web tool for
design/spec/order submittal. Having a selection of common extrusions to
start with and then specifying the customizations (mostly holes!, maybe
something about end panels, heck in my wish list I'd put painting and
anodizing and lettering), punch in my credit card number, hit "order
now", and a couple days later the UPS guy brings a finished box. Seems
feasible and a step beyond "fax us your diagram and we'll send you a
quote". expresspcb.com and frontpanelexpress.com show that there is a
real market for this sort of stuff, both "professional" and "amateur"
customers buy from each.

The goal is not to be cheaper than the mass-producers are, but to offer
true value in customization and ease of specifying/ordering.

Tim.

On 20 Mar 2006 08:30:07 -0800 in rec.radio.amateur.homebrew, "Tim
Shoppa" wrote,
Working sheet metal in a mill or a drill press has caused some, um,
near-disasters in many amateur shops. Poor clamping resulting in
spinning sheets with sharp edges are the most common

That is deadly true; but I would think if you are going to make a
business of it that you would set up some _good_ clamping fixture
that would hold your sheet with no slipping. How is PC Board
milling done?

To elaborate a little bit about my typical needs and wants:

NEEDS:

3" x 4" x 5" box. Not too picky if it's die-cast or sheet metal or
milled out of ingot. Front cover needs a rectangular hole about 2" x
3/4" to let a LCD show through. A couple of square buttons stick
through the front panel. A couple of toggle switches stick through the
front panel. A PCB is attached behind the front panel (where all these
LCD's and switches are mounted).

Internally maybe a transformer. Two D-sub connectors on the sides, so I
need nice D-sub holes.

Back panel has several BNC's and other stuff mounted in D-shape holes.
Also a IEC line input connector (rectangular hole).

I'd happily pay $50 and maybe $100 for something like this fabbed in
single quantities. I might make 2 or 3 orders a year. I'd expect a web
or PC-based tool (for free) to help me specify the order, and a web
order form that'd let me submit an order at 3AM on Saturday night when
the kids are asleep and I have an hour to spec what I want. I'd expect
delivery in a week or so. I'd expect the resulting box to be flawless
and everything within tolerance and all the holes to be "clean".

WANTS:

Painted (powder-coated?) or anodized cabinet and/or panels.

Lettering on front/back/sides.

Internal threaded bosses or maybe slots for mounting PCB's and stuff.

These could add another $30-$100 to what I'd pay.

My standards about what I'd be willing to pay have little to do with
retail prices of existing boxes or what I could hack out with a file
and a nibbler but more to do with what typical prototyping services
(expresspcb, frontpanelexpress) charge per job and a perceived value in
a really finished custom box.
(And a little bit in the cost of specialty punches. I actually have a
couple of D-subs and D cutters that I've picked up over the years.)

Some people will tell you that what I'm willing to pay is too high by a
factor of ten. These are not your potential customers (and I don't
think you'd ever make money by selling to them. No disrespect, I
understand those who don't want to pay any money to have other people
do work for them.) At the same time what I'm saying that I'm willing to
pay is a fraction (maybe 1/4 or 1/8th) what a local machine shop would
charge for a one-off job. I'm not paying because I'm incapable of doing
a shoddy job at putting all these holes in an off-the-shelf box, I'm
paying because I want a really professionally customized box with nice
holes made using punches I don't already own :-).

Tim.

Tim,

Thank you for making your wants and need crystal clear. You've
been a great help!

The Eternal Squire

Tim Shoppa wrote:
To elaborate a little bit about my typical needs and wants:

NEEDS:

3" x 4" x 5" box. Not too picky if it's die-cast or sheet metal or
milled out of ingot. Front cover needs a rectangular hole about 2" x
3/4" to let a LCD show through. A couple of square buttons stick
through the front panel. A couple of toggle switches stick through the
front panel. A PCB is attached behind the front panel (where all these
LCD's and switches are mounted).

Internally maybe a transformer. Two D-sub connectors on the sides, so I
need nice D-sub holes.

Back panel has several BNC's and other stuff mounted in D-shape holes.
Also a IEC line input connector (rectangular hole).

I'd happily pay $50 and maybe $100 for something like this fabbed in
single quantities. I might make 2 or 3 orders a year. I'd expect a web
or PC-based tool (for free) to help me specify the order, and a web
order form that'd let me submit an order at 3AM on Saturday night when
the kids are asleep and I have an hour to spec what I want. I'd expect
delivery in a week or so. I'd expect the resulting box to be flawless
and everything within tolerance and all the holes to be "clean".

WANTS:

Painted (powder-coated?) or anodized cabinet and/or panels.

Lettering on front/back/sides.

Internal threaded bosses or maybe slots for mounting PCB's and stuff.

These could add another $30-$100 to what I'd pay.

My standards about what I'd be willing to pay have little to do with
retail prices of existing boxes or what I could hack out with a file
and a nibbler but more to do with what typical prototyping services
(expresspcb, frontpanelexpress) charge per job and a perceived value in
a really finished custom box.
(And a little bit in the cost of specialty punches. I actually have a
couple of D-subs and D cutters that I've picked up over the years.)

Some people will tell you that what I'm willing to pay is too high by a
factor of ten. These are not your potential customers (and I don't
think you'd ever make money by selling to them. No disrespect, I
understand those who don't want to pay any money to have other people
do work for them.) At the same time what I'm saying that I'm willing to
pay is a fraction (maybe 1/4 or 1/8th) what a local machine shop would
charge for a one-off job. I'm not paying because I'm incapable of doing
a shoddy job at putting all these holes in an off-the-shelf box, I'm
paying because I want a really professionally customized box with nice
holes made using punches I don't already own :-).

Tim.