Homebrew PCBs

Today's project was to see if I could cut v-scoring with a table saw.
I found an old steel plywood blade (no carbide to break off, lots of
teeth) and reground it to a V point:

* mount the blade backwards to avoid cutting your grinding wheels

* run the saw

* initial grind with an angle grinder

* use a 30-60-90 triangle to position a ginding stone for final grind.

GENTLE pressure is all that's needed, and very little actual grinding
time.

The result snapped cleanly and showed no signs of burning.  Obvious
drawback is that plain steel will need sharpening more often, but it's
better than trying to resharpen a router bit or scrollsaw blade.

(yes, I know about metal shears, but I don't own one of those - yet)

On Wed, 1 Apr 2009 15:30:42 -0400, you wrote:

If you do get a metal shear, wait until the big one is on sale, if
that's what you want.

Overpriced otherwise.  Be wary, that sucker is very heavy, so you need
a good place to put it, a way to get it up there, and a good light.
You should also adjust the clearance between the blade and bed so it's
relatively tight.

Mine works ok for me (30 inch model, but I also do metalwork).

Harvey

>
>Today's project was to see if I could cut v-scoring with a table saw.
>I found an old steel plywood blade (no carbide to break off, lots of
>teeth) and reground it to a V point:
>
>* mount the blade backwards to avoid cutting your grinding wheels
>
>* run the saw
>
>* initial grind with an angle grinder
>
>* use a 30-60-90 triangle to position a ginding stone for final grind.
>
>GENTLE pressure is all that's needed, and very little actual grinding
>time.
>
>The result snapped cleanly and showed no signs of burning.  Obvious
>drawback is that plain steel will need sharpening more often, but it's
>better than trying to resharpen a router bit or scrollsaw blade.
>
>(yes, I know about metal shears, but I don't own one of those - yet)

Harvey White <madyn@...> writes:

> Be wary, that sucker is very heavy, so you need a good place to put
> it, a way to get it up there, and a good light.

I've got a full woodshop already, including an 8" long bed jointer, so
I'm already prepared for those types of issues.

I was thinking of this model: http://www.grizzly.com/products/g6089

It's halfway between the tiny HF model and the big 30" model.  My
blank PCB stock is at most 9x12.

Is the purpose of the shear to cut PCB's?

It's instruction manual says it will shear up to 20ga metal, which is 
0.035in. Seems that if I were to get a shear (and I have thought about 
it), I'd want to cut 0.062in PCB material, which the model referenced 
below will not do . . . unless I'm missing something?

Steve

DJ Delorie wrote:

> Harvey White <madyn@...> writes:
>
>   
>> Be wary, that sucker is very heavy, so you need a good place to put
>> it, a way to get it up there, and a good light.
>>     
>
> I've got a full woodshop already, including an 8" long bed jointer, so
> I'm already prepared for those types of issues.
>
> I was thinking of this model: http://www.grizzly.com/products/g6089
>
> It's halfway between the tiny HF model and the big 30" model.  My
> blank PCB stock is at most 9x12.
>

What thickness of board are you talking about?

I have great success cutting 1/32 board with a carbide scoring tool from Home DEpot ($7)!

I use a good quality combination square I bought at Harbor freight on sale ($25).

I use a carbide scriber (Home Depot $5) to scratch the where the edge of the board is on both sides.
Then I hold the combination square next to the scoring tool blade after the point of the blade is set in the scribed mark.
Then I score each side 4 to 5 times then I snap it off on the edge of a board . After It is snapped off a couple of strokes with a file and the edge is smooth. This method works on 1/16 board also but the scoring needs more strokes.!

On rthe question of the combo brake/shear machine plastics etc. can be somewhat thicker than the metal specs ,as stell sheeting is harder to shear off!

73

Mike




________________________________

From: DJ Delorie <dj@...>
To: Homebrew_PCBs@yahoogroups.com
Sent: Wednesday, April 1, 2009 7:30:42 PM
Subject: [Homebrew_PCBs] v-scoring



Today's project was to see if I could cut v-scoring with a table saw.
I found an old steel plywood blade (no carbide to break off, lots of
teeth) and reground it to a V point:

* mount the blade backwards to avoid cutting your grinding wheels

* run the saw

* initial grind with an angle grinder

* use a 30-60-90 triangle to position a ginding stone for final grind.

GENTLE pressure is all that's needed, and very little actual grinding
time.

The result snapped cleanly and showed no signs of burning. Obvious
drawback is that plain steel will need sharpening more often, but it's
better than trying to resharpen a router bit or scrollsaw blade.

(yes, I know about metal shears, but I don't own one of those - yet)



[Non-text portions of this message have been removed]

> Is the purpose of the shear to cut PCB's?

Yes.

> It's instruction manual says it will shear up to 20ga metal, which
> is 0.035in. Seems that if I were to get a shear (and I have thought
> about it), I'd want to cut 0.062in PCB material, which the model
> referenced below will not do . . . unless I'm missing something?

On other shears, they break the max thickness down by type - steel,
copper, aluminum.  Softer metals allow a thicker piece.  One would
assume that something as "soft" as FR4 could easily be cut with such a
tool, even if twice as thick as steel.

> What thickness of board are you talking about?

1/16" (0.062") as these are commercial boards. For my own boards, I
use two layers of 0.010" prepreg clad, which I can cut on a regular
paper cutter before adhering together.  Between those, the tape, and
the copper, it works out to be about 0.31" thick.

On Wed, 01 Apr 2009 21:14:15 -0400, you wrote:

>Is the purpose of the shear to cut PCB's?
>
>It's instruction manual says it will shear up to 20ga metal, which is 
>0.035in. Seems that if I were to get a shear (and I have thought about 
>it), I'd want to cut 0.062in PCB material, which the model referenced 
>below will not do . . . unless I'm missing something?

Fiberglass is softer than metal, but you do have to be careful since
the glass fibers are tough to cut through.  I do know that mine (the
30 inch model) is good for 0.062 inch PC board material.  A little
sanding on the edge to get rid of the odd fiber, and it's good to go.
Not sure on that little one, though.  

Harvey

>
>Steve
>
>DJ Delorie wrote:
>> Harvey White <madyn@...> writes:
>>
>>   
>>> Be wary, that sucker is very heavy, so you need a good place to put
>>> it, a way to get it up there, and a good light.
>>>     
>>
>> I've got a full woodshop already, including an 8" long bed jointer, so
>> I'm already prepared for those types of issues.
>>
>> I was thinking of this model: http://www.grizzly.com/products/g6089
>>
>> It's halfway between the tiny HF model and the big 30" model.  My
>> blank PCB stock is at most 9x12.
>>

--- In Homebrew_PCBs@yahoogroups.com, michael tenore <wb2lcw@...> wrote:
>
> What thickness of board are you talking about?
> 
> I have great success cutting 1/32 board with a carbide scoring tool from Home DEpot ($7)!
> 
> I use a good quality combination square I bought at Harbor freight on sale ($25).
> 
> I use a carbide scriber (Home Depot $5) to scratch the where the edge of the board is on both sides.
> Then I hold the combination square next to the scoring tool blade after the point of the blade is set in the scribed mark.
> Then I score each side 4 to 5 times then I snap it off on the edge of a board . After It is snapped off a couple of strokes with a file and the edge is smooth. This method works on 1/16 board also but the scoring needs more strokes.!
> 
> On rthe question of the combo brake/shear machine plastics etc. can be somewhat thicker than the metal specs ,as stell sheeting is harder to shear off!
> 
> 73
> 
> Mike
> 
> 
> 
> 
> ________________________________
> From: DJ Delorie <dj@...>
> To: Homebrew_PCBs@yahoogroups.com
> Sent: Wednesday, April 1, 2009 7:30:42 PM
> Subject: [Homebrew_PCBs] v-scoring
> 
> 
> 
> Today's project was to see if I could cut v-scoring with a table saw.
> I found an old steel plywood blade (no carbide to break off, lots of
> teeth) and reground it to a V point:
> 
> * mount the blade backwards to avoid cutting your grinding wheels
> 
> * run the saw
> 
> * initial grind with an angle grinder
> 
> * use a 30-60-90 triangle to position a ginding stone for final grind.
> 
> GENTLE pressure is all that's needed, and very little actual grinding
> time.
> 
> The result snapped cleanly and showed no signs of burning. Obvious
> drawback is that plain steel will need sharpening more often, but it's
> better than trying to resharpen a router bit or scrollsaw blade.
> 
> (yes, I know about metal shears, but I don't own one of those - yet)
> 
> 
> 
> [Non-text portions of this message have been removed]
>
Sheet metal shears are the only way to go! I tried scoring, hacksaws, drilling perf holes, even heavy paper guillotines (which despite what I read on various blogs, were absolutely useless on FR4). Finally, I bought the $79 8" sheet metal shear from Grizzly -- 100's of PCBs later, it still cuts like a knife through butter, and board edges are surprisingly clean and straight.

Ristone64

I agree. Any type of shear (even handheld tinsnips) have worked better
for me than most saws. A fine toothed carbide blade in a circular saw
will make the better cut (square perfectly clean edge) but is not
worth the noise and dust. Strangely enough the glass fibers don't seem
to dull the blades of shears too badly.

As someone already mentioned you get a better egde by aligning the
blades closer together than you would for sheetmetal.


ST

On Thu, Apr 2, 2009 at 5:23 AM, thebrit49 <ristone64@...> wrote:

> Sheet metal shears are the only way to go! I tried scoring, hacksaws, drilling perf holes, even heavy paper guillotines (which despite what I read on various blogs, were absolutely useless on FR4). Finally, I bought the $79 8" sheet metal shear from Grizzly -- 100's of PCBs later, it still cuts like a knife through butter, and board edges are surprisingly clean and straight.
>
> Ristone64
>
>

At 10:23 PM 4/1/2009, you wrote:
> > I have great success cutting 1/32 board with a carbide scoring 
> tool from Home DEpot ($7)!

in the tile department of Home Depot, there is a carbide scoring tool 
for scoring and breaking tile backer-board. it's about 6-7$ if that's 
the one you're talking about. good tool also for removing grout if 
you need to redo your tile shower.


William Alford

GI Motility Medical Research Page
http://alford.grimtrojan.com/  

[Non-text portions of this message have been removed]

Yes thats the one! Mine has a red handle1
73
Mike




________________________________

From: William Alford <walford@...>
To: Homebrew_PCBs@yahoogroups.com
Sent: Friday, April 3, 2009 9:09:32 PM
Subject: Re: [Homebrew_PCBs] Re: v-scoring/tool


At 10:23 PM 4/1/2009, you wrote:
> > I have great success cutting 1/32 board with a carbide scoring 
> tool from Home DEpot ($7)!

in the tile department of Home Depot, there is a carbide scoring tool 
for scoring and breaking tile backer-board. it's about 6-7$ if that's 
the one you're talking about. good tool also for removing grout if 
you need to redo your tile shower.

William Alford

GI Motility Medical Research Page
http://alford. grimtrojan. com/ 

[Non-text portions of this message have been removed]




[Non-text portions of this message have been removed]