[BBC-Micro] BBC Master SCSI

Ian Wolstenholme bbcmailinglist at beebmaster.co.uk
Mon Jun 1 21:42:50 BST 2009


In the past I've sent off the entire board or unit to be duplicated and
they've done everything, artwork, tooling, manufacturing the PCB, sourcing
the components, fitting the components, sourcing the box, cutting holes in
the box in the right places, fitting the PCB to the box & screwing the lid
on - everything.

Obviously this approach (due to my technical don't-know-how) increases
the overall cost by a good way.

If a few of us who are interested in the SCSI interface collaborate and we
can do some of the leg-work, I'm sure we could get some boards produced
for a much lower cost.  If somebody else can produce the CAD files then I
should be able to get the ICs for a reasonable cost, lower than you would
from the likes of Farnell.  I might be willing to fund the production costs
if there is a reasonable prospect of shifting a good percentage of the finished
boards at the end of it.

Best wishes,



Ian


----- Original Message -----
From: Mark Haysman [mailto:jumbos.bazzar at btopenworld.com]
To: bbc-micro at lists.cloud9.co.uk
Sent: Mon, 1 Jun 2009 16:31:38 +0100
Subject: Re: [BBC-Micro] BBC Master SCSI

Hi.

I presume you're referring to the Tooling charge, where you send the CAD 
files to them and they make the board from that? You're not sending them a 
blank PCB to copy are you?

The PCB houses I've worked with have always done their own in-house Tooling, 
and usually costs around the £60 mark for smallish boards, and is a one-off. 
The economy of scale dicatates that they will make a certain amount of PCBs 
per "run", so if you only order 20, they may end up making 50, and charging 
you a lot more per board for those 20 than they would if you took the full 
50, as they're not wasting any.

There are PCB houses in China which are cheap and cheerful, but it's always 
a case of "you get what you pay for", and they take longer too.

Mark.


----- Original Message ----- 
From: "Ian Wolstenholme" <bbcmailinglist at beebmaster.co.uk>
To: <bbc-micro at lists.cloud9.co.uk>
Sent: Monday, June 01, 2009 2:20 PM
Subject: Re: [BBC-Micro] BBC Master SCSI


There's one just ended on E-Bay!!!

I've had duplicate boards made in the past (eg. the Econet module and
SJ Econet clock with slight modifications) and although the cost is fairly
prohibitive (hence the selling price of these items) I'm sure it could be
done if there is any demand.

It's almost certainly not economic to do anything less than 50 and I don't
think I could ever shift that many.

One of the major components of the cost in the past has been the PCB
artwork, they said that this cost would not arise if I ever needed a second
run (!!!) of anthing, so if somebody else could do this work, it might bring
down the overall cost a bit.

There are several people on the list who are selling items with manufactured
PCBs, somebody might be able to produce a board a lot cheaper than my
method of sending one off to somebody and saying "Make me this".

One obvious area of improvement (apart from the resistor which seems to
run ridiculously hot) is the SCSI connector which would benefit from a
more solid set of pins going into the BBC motherboard connector.

Best wishes,


Ian
----- Original Message -----
From: Darren Grant [mailto:darren.grant at adslnation.com]
To: bbc-micro at lists.cloud9.co.uk
Sent: Mon, 01 Jun 2009 13:21:52 +0100
Subject: [BBC-Micro] BBC Master SCSI

Would anyone have a BBC Master AIV SCSI Interface they would like to sell me
by any chance ?

Thanks
Darren


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