Slightly [OT] Low volume PCB cutting methods

[Rob]

I run a small workshop in which we manufacture our own prototype PCBs.

In the past presensitised board has been cut with a bandsaw. The saw blades
life is very poor and the blades break frequently. We have also tried an
electric coping saw with even worse blade life and a small bench guillotine
which tends to lift the presensitised layer from the copper.

I was toying with the idea of using a diamond rod/wire blade fitted to the
coping saw.
Can anyone please offer me some guidance in the best methods they have found
for cutting F/G board in this environment.

Thanks
Rob

 

[DJ Delorie]

"Rob" <rds2665@yahoo.com.au> writes:

In the past presensitised board has been cut with a bandsaw. The saw
blades life is very poor and the blades break frequently. We have
also tried an electric coping saw with even worse blade life and a
small bench guillotine which tends to lift the presensitised layer
from the copper.

Sounds like poor blades; my bandsaw can cut through soft metals, 6"
thick hardwoods, and nearly all plastics, and I've never broken a
blade on it. One of my scroll saws can take bimetal hacksaw blades
for steel cutting, and my bandsaw has carbide-toothed bands in it.

What, exactly, are you using for tools and blades?

 

[Bill Jenkins]

Check around for a small foot operated shear . I bought a 36" wide
one, made in the 40's for $700 Cdn. It cuts all the board I need.
Since I bought it, I cut 1000's sq feet of FR4 and have not needed to
have the blade sharpened. There are some 27" wide shears that can be
had for a good price as most shops want the 36" one so they can make a
cut across the full size sheet. The last one I saw was sold for $250
Cdn. Try sheet metal shops/suppliers.
I make step and repeat panels and place the patterns .025" apart. One
cut in each direction shears the boards for use.

Hope this give you some ideas. Oh and no nasty fiberglass dust to
contend with.

Bill

On Wed, 8 Oct 2003 11:36:37 +0800, "Rob" <rds2665@yahoo.com.au> wrote:

I run a small workshop in which we manufacture our own prototype PCBs.

In the past presensitised board has been cut with a bandsaw. The saw blades
life is very poor and the blades break frequently. We have also tried an
electric coping saw with even worse blade life and a small bench guillotine
which tends to lift the presensitised layer from the copper.

I was toying with the idea of using a diamond rod/wire blade fitted to the
coping saw.
Can anyone please offer me some guidance in the best methods they have found
for cutting F/G board in this environment.

Thanks
Rob

 

[Rob]

"DJ Delorie" <dj@delorie.com> wrote in message
news:xnfzi4jrj8.fsf@delorie.com...

"Rob" <rds2665@yahoo.com.au> writes:
In the past presensitised board has been cut with a bandsaw. The saw
blades life is very poor and the blades break frequently. We have
also tried an electric coping saw with even worse blade life and a
small bench guillotine which tends to lift the presensitised layer
from the copper.

Sounds like poor blades; my bandsaw can cut through soft metals, 6"
thick hardwoods, and nearly all plastics, and I've never broken a
blade on it. One of my scroll saws can take bimetal hacksaw blades
for steel cutting, and my bandsaw has carbide-toothed bands in it.

What, exactly, are you using for tools and blades?

I'm using Ryobi blades - off the shelf types from our local hardware chain
Bunnings. (I'm in Oz - I guess Walmart may be their equivalent).

I wonder if it would be worth while getting a blade made up by one of the
specialist saw companies. They may be able to provide better quality. When I
fit a new blade the side 'offset' on the teeth seems to disappear in the
first 12" of cutting. It appears as sparks below the cutting table.

Could excess blade speed be a factor ?

Thanks
rob

 

[Rob]

"Bill Jenkins" <bjenkins@direct.ca> wrote in message
news:3f83978c.2735373@public-news.look.ca...

Check around for a small foot operated shear . I bought a 36" wide
one, made in the 40's for $700 Cdn. It cuts all the board I need.
Since I bought it, I cut 1000's sq feet of FR4 and have not needed to
have the blade sharpened. There are some 27" wide shears that can be
had for a good price as most shops want the 36" one so they can make a
cut across the full size sheet. The last one I saw was sold for $250
Cdn. Try sheet metal shops/suppliers.
I make step and repeat panels and place the patterns .025" apart. One
cut in each direction shears the boards for use.

Hope this give you some ideas. Oh and no nasty fiberglass dust to
contend with.

Bill

On Wed, 8 Oct 2003 11:36:37 +0800, "Rob" <rds2665@yahoo.com.au> wrote:

Hi Bill, a company who does small runs for us sometimes uses a guillo just
like the ones you mention. Unfortunately the budget does not stretch to one
(yet!). It would be nice to do away with the glass dust. I'll keep an eye on
the upcoming auctions.

rob

 

[Chris R. Lee]

Read somewhere that a tile cutter (the usual type with a tungsten carbide
wheel) does the job, but havn't tried it.

Regards


"Rob" <rds2665@yahoo.com.au> a écrit dans le message de news:
newscache$s16fmh$us6$1@phantom.amnet.net.au...

I run a small workshop in which we manufacture our own prototype PCBs.

In the past presensitised board has been cut with a bandsaw. The saw
blades
life is very poor and the blades break frequently. We have also tried an
electric coping saw with even worse blade life and a small bench
guillotine
which tends to lift the presensitised layer from the copper.

I was toying with the idea of using a diamond rod/wire blade fitted to the
coping saw.
Can anyone please offer me some guidance in the best methods they have
found
for cutting F/G board in this environment.

Thanks
Rob

 

[Brad Velander]

Why has nobody suggested the obvious? A high speed router & bits. Seems to
be all the fashion in professional PCB shops. 8^>
Mount it upside down in a table (homemade or bought), add a guide bar
and away you go. Add a shopvac and shield if you don't want to deal with the
dust.

--
Sincerely,
Brad Velander

"Bill Jenkins" <bjenkins@direct.ca> wrote in message
news:3f83978c.2735373@public-news.look.ca...

Check around for a small foot operated shear . I bought a 36" wide
one, made in the 40's for $700 Cdn. It cuts all the board I need.
Since I bought it, I cut 1000's sq feet of FR4 and have not needed to
have the blade sharpened. There are some 27" wide shears that can be
had for a good price as most shops want the 36" one so they can make a
cut across the full size sheet. The last one I saw was sold for $250
Cdn. Try sheet metal shops/suppliers.
I make step and repeat panels and place the patterns .025" apart. One
cut in each direction shears the boards for use.

Hope this give you some ideas. Oh and no nasty fiberglass dust to
contend with.

Bill

 

[Mark]

On Wed, 8 Oct 2003 11:36:37 +0800, "Rob" <rds2665@yahoo.com.au> wrote:

I run a small workshop in which we manufacture our own prototype PCBs.

In the past presensitised board has been cut with a bandsaw. The saw blades
life is very poor and the blades break frequently. We have also tried an
electric coping saw with even worse blade life and a small bench guillotine
which tends to lift the presensitised layer from the copper.

I was toying with the idea of using a diamond rod/wire blade fitted to the
coping saw.
Can anyone please offer me some guidance in the best methods they have found
for cutting F/G board in this environment.

Thanks
Rob



You should use carbide cutting tools in order to get clean cuts and

resonably long tool life. Look into some of the carbide PCB cutting
tools from vendors like Think & Tinker and Drill Technology.

Mark

 

[Rob]

"Chris R. Lee" <chrislee.fedupwithspm@freesurf.fr> wrote in message
news:1065642572.88596.0@demeter.uk.clara.net...

Read somewhere that a tile cutter (the usual type with a tungsten carbide
wheel) does the job, but havn't tried it.

Regards

Thanks Chris - I 'll have a look at the hardware store and see what's
available.
rob

 

[nospam]

"Rob" <rds2665@yahoo.com.au> wrote:

"Chris R. Lee" <chrislee.fedupwithspm@freesurf.fr> wrote in message
news:1065642572.88596.0@demeter.uk.clara.net...
Read somewhere that a tile cutter (the usual type with a tungsten carbide
wheel) does the job, but havn't tried it.

Thanks Chris - I 'll have a look at the hardware store and see what's
available.

I once mentioned using a tile cutter but that was only for scoring PCBs (on
both sides) so they could be snapped.

 

[JeffM]

No, it sounds like folks don't appreciate that just because
fiberglass has polyester resin in it doesn't mean it cuts like plastic.
The glass in it is TOUGH.
(Same thing with epoxy or Kevlar; it may be plastic, but it's TOUGH plastic.)

A tile cutter relies on the brittle nature of tile; of no use here.

The sheer idea is the winner IMO.
Finding one with a useable design is the sticking point.

 

[Mike Cowlishaw]

Can anyone please offer me some guidance in the best methods they
have found for cutting F/G board in this environment.

I have found that a Jigsaw works for me better than bandsaws,
the routers, etc. described here. Mount the jigsaw in a table
(I use the Bosch table which is inexpensive, about 9 GBP
or $15, but a home-made one would do as well.) Pop
in a Tungsten Carbide Grit Coated blade, and PCBs are very easy
to cut.

It helps to have a toggle hold-down to grip the PCB if it is small,
and of course dust extraction is advisable.

(A jigsaw mounted in a table is a nice inexpensive alternative
to a bandsaw, too, for light crosscutting and trimming of
woodwork.)

Mike Cowlishaw

 

[Chuck Harris]

Having worked in a PC manufacturing company, I would like to warn you
about using a router on pc boards. It is extremely easy for any size
router bit to grab the board and toss it...vigorously! We had one kid
in the shop who sailed a stack of PC boards, and their aluminum template
thru a wall in the shop... He did this job 8 hours a day, every day, and
just got a little careless one time.

This is also an extremely dusty and messy operation. It requires solid
carbide bits if you are doing fiberglass of any sort. HSS bits will die
before you even finish one side of the board. And a respirator is a
must because the dust is very harmful to your lungs. And even with all
of this, you will endup itchy all over from the little bit of dust you
missed.

The simplest and easiest way of cutting PC boards is a stomp shear. For
just a couple, use a big pair of tin snips. You will have to bend some
curl out of the board when you are done, but it isn't a big deal. A
quick brush over with a fine file, and you are done.

-Chuck Harris, WA3UQV



Brad Velander wrote:

Why has nobody suggested the obvious? A high speed router & bits. Seems to
be all the fashion in professional PCB shops. 8^
Mount it upside down in a table (homemade or bought), add a guide bar
and away you go. Add a shopvac and shield if you don't want to deal with the
dust.

 

[Mike Cowlishaw]

The simplest and easiest way of cutting PC boards is a stomp shear.

(Yes, but not very cost-effective in space or cost, for small volumes.)

For just a couple, use a big pair of tin snips.

I tried this and tin snips were not a success (on the small boards I'm
making, see http://www.speleogroup.org/attinya.html ... though they
might be OK for larger boards). I found I could get nowhere near
the 1-2mm precision I expected, and traces near the edge were lifted.

Also, all cuts had to be straight lines going all the way across, which
puts unwelcome constraints on fitting a number of small boards on a
larger PCB sheet. (This, presumably, is true for larger shears, too.)

Mike Cowlishaw

 

[Chuck Harris]

Hi Mike,

If that is the board you are making, tinsnips would do just fine.
The traces are sufficiently far from the edges as to be of no
trouble.

If you are making the boards for manufacture, you ought to
get the boards made professionally. Something that small would
be pretty cheap from that Bulgarian PC house. And they will
"de panalize" the boards at no extra cost.

I have done numerous "home brew" etched pc boards in the past,
and they always seem to have acid pockets here and there that
add corrosion at a later date. Not something I would want to
give a customer.

-Chuck

Mike Cowlishaw wrote:

The simplest and easiest way of cutting PC boards is a stomp shear.


(Yes, but not very cost-effective in space or cost, for small volumes.)


For just a couple, use a big pair of tin snips.


I tried this and tin snips were not a success (on the small boards I'm
making, see http://www.speleogroup.org/attinya.html ... though they
might be OK for larger boards). I found I could get nowhere near
the 1-2mm precision I expected, and traces near the edge were lifted.

Also, all cuts had to be straight lines going all the way across, which
puts unwelcome constraints on fitting a number of small boards on a
larger PCB sheet. (This, presumably, is true for larger shears, too.)

Mike Cowlishaw

 

[Mike Cowlishaw]

If that is the board you are making, tinsnips would do just fine.
The traces are sufficiently far from the edges as to be of no
trouble.

Thanks .. I did try it. Maybe you have better tinsnips than I
do, or the board are a different material/thickness

If you are making the boards for manufacture, you ought to
get the boards made professionally. Something that small would
be pretty cheap from that Bulgarian PC house. And they will
"de panalize" the boards at no extra cost.

These are strictly non-commercial. (Small volume, etc.) And the
turn-around time in-home is about an hour...

Mike

 

[nospam]

"Mike Cowlishaw" <mfcowli@attglobal.net> wrote:

If you are making the boards for manufacture, you ought to
get the boards made professionally. Something that small would
be pretty cheap from that Bulgarian PC house. And they will
"de panalize" the boards at no extra cost.

These are strictly non-commercial. (Small volume, etc.) And the
turn-around time in-home is about an hour...

What is the harm getting a couple of quotes from local PCB suppliers?

At some quantity you will decide buying them is a good deal.

 

[Ovidio]

Depending on the size of PCB's your working with this may work. I
purchased a mini-shear/press brake from Harbor Freight a while ago.
They no longer sell this but I found that NorthernTool has a similar
model. The Harbor Freight model was made by Central Machinery in
China. Maybe with a little research the same model can be found at a
lower cost. See the link.

http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=6970&langId=-1&catalogId=4006970&PHOTOS=on&TEST=Y&productId=210804&categoryId=0



On Thu, 9 Oct 2003 18:02:39 +0100, "Mike Cowlishaw"
<mfcowli@attglobal.net> wrote:

The simplest and easiest way of cutting PC boards is a stomp shear.

(Yes, but not very cost-effective in space or cost, for small volumes.)

For just a couple, use a big pair of tin snips.

I tried this and tin snips were not a success (on the small boards I'm
making, see http://www.speleogroup.org/attinya.html ... though they
might be OK for larger boards). I found I could get nowhere near
the 1-2mm precision I expected, and traces near the edge were lifted.

Also, all cuts had to be straight lines going all the way across, which
puts unwelcome constraints on fitting a number of small boards on a
larger PCB sheet. (This, presumably, is true for larger shears, too.)

Mike Cowlishaw

 

[Rob]

"Ovidio" <reply.to@usenet.com> wrote in message
news:b5sdov43rghk76epnhjf3pveto50jt1mob@4ax.com...

Depending on the size of PCB's your working with this may work. I
purchased a mini-shear/press brake from Harbor Freight a while ago.
They no longer sell this but I found that NorthernTool has a similar
model. The Harbor Freight model was made by Central Machinery in
China. Maybe with a little research the same model can be found at a
lower cost. See the link.


http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?storeId

=6970&langId=-1&catalogId=4006970&PHOTOS=on&TEST=Y&productId=210804&category
Id=0
Looks good - price isn't too bad. I'll see what I can locate in Oz.

rob

 

[Rex]

On Thu, 9 Oct 2003 13:04:48 +0800, "Rob" <rds2665@yahoo.com.au> wrote:

"Chris R. Lee" <chrislee.fedupwithspm@freesurf.fr> wrote in message
news:1065642572.88596.0@demeter.uk.clara.net...
Read somewhere that a tile cutter (the usual type with a tungsten carbide
wheel) does the job, but havn't tried it.

Regards



Thanks Chris - I 'll have a look at the hardware store and see what's
available.
rob

I have a table saw and often I will cut fiberglass circuit board with
one of those circular fiber blades made for cutting steel. Works pretty
good and lasts a long time.

Two drawbacks: The kerf is pretty wide (about 1/8 inch) so you waste a
bit of board. The blade tends to burn the fiberglass a bit leaving some
black residue. A quick pass with a coarse file cleans that off, though.