In most sheet metal work, the holes are not drilled and the metal is
not sawed. The holes are typically punched out of the sheet metal
(usually a 4 foot x 8 foot sheet) by a large multi-headed numerically
controlled punching machine. The operator programs in all the hole
locations and the type of tool used (round, square, oblong, hex, or
special like a RS-232 connector) and its orientation if needed. The
sheets are programmed to be punched with the highest yield of parts
possible. That is why custom parts are expensive. You have to have a
large part count to make it worth punching. Typically the metal shop
will try to mix jobs from different clients using the same gauge
metal to lower cost otherwise extra metal left over is recycled at a
loss. The edges are punched with a series of long slot punches. You
can see marks along the edge of a panel where the punches overlap
unless a post-process sanding cleanup is done. Also typically the
front face is called out and the job is specified weather the holes
are to be punched from the front or rear surface. If you look closely
at the edges of the holes you can see this as a very sharp edge on
the exiting side and a small rounded edge on the side where the punch
hits the metal. This get more obvious as the punch wears out and
doesn't punch as cleanly.
The type of holes that one can have punched are totally limited by
the sheet metal house. It is limited by what punches they have in
stock. Most houses will have a huge variety of round and square hole
sizes and allot of the common slot sizes (used by rack ear holes for
instance) along with commonly used custom holes like for IEC power
connectors and computer serial connectors. Most odd shapes can be
made by punching combinations of smaller holes too. If a client needs
an odd shape hole that will be used a lot in a job, a custom punch
will often be made to add to the sheet metal house's library.
Doepfer's metal shop may not have the small slot punches mentioned
and they may want way too much to make a custom punch.

I hope that helps. I can tell you from experience that seeing a large
sheet metal machine pound out a piece is very impressive. Here is a
link to a site that shows the whole process: <http://www.industrial-
computer-source.com/white_paper_sheet_metal.html>

James

On Oct 22, 2008, at 12:04 PM, Guy Drieghe D. wrote:

>
> James,
>
> Can you please enlighten the non-metal workers (and non-native English
> speaking) amongst us as to what exactly "hole punch" and "slot punch"
> thingies are
>
> tia !
>
> - Guy
>
>
> On 22 Oct 2008, at 20:41, James Husted wrote:
>
>> Dieter-
>> And thanks for making them! I know they are probably not a hugely
>> selling product either. I have already hacked my AS stuff (and
>> reducing it's resale prices accordingly). Unfortunately for me at the
>> time I would not be willing to let go of 3-hp of panel space (one in
>> each side of a bank of AS). Things are different now. As a old metal
>> work guy I really see changing the hole punch currently used by
>> everyone to a slot punch instead as a much better solution (Cwejman
>> seems to be the only one doing this). That way any module can be used
>> in any system. Changing punches should cost nothing more than a
>> programming fee for older modules already in production and nothing
>> for newer modules.
>>
>> -James
>>
>> On Oct 22, 2008, at 11:06 AM, yahoo@... wrote:
>>
>>>> The only other concern is the 1/2 a hp hole spacing difference from
>>>> Doepfer and AS modules. Expect a gap or break out the drill press!
>>>>
>>>> -James
>>>
>>> As mentioned several times we have 1.5 HP blind panels available to
>>> avoid
>>> these gaps !
>>>
>>> Best wishes
>>> Dieter Doepfer
>
>
> [Non-text portions of this message have been removed]
>
>
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