Homebrew PCBs

Hi,

Is very difficult to find a pcb spindle. Drilling a pcb hole of 0.5mm in 
a FR4 laminate needs carbide tools and 50.000rpm spindle.  This things 
cost more than all other things to make a good CNC router.
I have found a away, but still didn't make/test the thing. From this 
great sites (and thanks to them)
http://www.cnconabudget.com/dan_d.JPG
http://www.buildyouridea.com/cnc/spindle_05/spindle_05.html
http://www.cncathome.com/spindles.html
http://www.students.tut.fi/~kontkant/jv2.php.html
http://members.home.nl/zoltar/CNC/classicsystem/10%20euro%20frase.pdf

I think to have found a way to do my 50.000rpm or more (i think i can 
get 80.000rpm) pcb spindle.
Using this tool from ebay seller (he made the tool from my request!!)
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=110329201156

And high speed skate bearing or better like this
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=400000902567

And a AC brushed (universal) motor from a electric wood plane. It has a 
30.000rpm motor and a 2:1 or similar reduction that can be inverted to 
give 60.000rpm, using the same timing belt and pulleys.

Do you think it will work nice? I have made a circuit to pwm control the 
motor speed. And i think if i give DC to the motor it will run in lot 
more than 30.000rpm.

I want to post the circuit online, but which cnzone forum pcb spindles 
should go?

Simao

Personally i think a direct drive brushless motor is the way to go for
these speeds.

Also i think you need to pre-load the bearings to reduce runout. And i
would select oil lubricated bearings over grease lubricated ones.

I may be wrong i am not a mechanical engineer.

ST


On Mon, Jan 19, 2009 at 9:32 PM, Simão Pedro Cardoso
<simaocardoso@...> wrote:

> Hi,
>
> Is very difficult to find a pcb spindle. Drilling a pcb hole of 0.5mm in
> a FR4 laminate needs carbide tools and 50.000rpm spindle.  This things
> cost more than all other things to make a good CNC router.
> I have found a away, but still didn't make/test the thing. From this
> great sites (and thanks to them)
> http://www.cnconabudget.com/dan_d.JPG
> http://www.buildyouridea.com/cnc/spindle_05/spindle_05.html
> http://www.cncathome.com/spindles.html
> http://www.students.tut.fi/~kontkant/jv2.php.html
> http://members.home.nl/zoltar/CNC/classicsystem/10%20euro%20frase.pdf
>
> I think to have found a way to do my 50.000rpm or more (i think i can
> get 80.000rpm) pcb spindle.
> Using this tool from ebay seller (he made the tool from my request!!)
> http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=110329201156
>
> And high speed skate bearing or better like this
> http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=400000902567
>
> And a AC brushed (universal) motor from a electric wood plane. It has a
> 30.000rpm motor and a 2:1 or similar reduction that can be inverted to
> give 60.000rpm, using the same timing belt and pulleys.
>
> Do you think it will work nice? I have made a circuit to pwm control the
> motor speed. And i think if i give DC to the motor it will run in lot
> more than 30.000rpm.
>
> I want to post the circuit online, but which cnzone forum pcb spindles
> should go?
>
> Simao
>

There are 40.000rpm brushless motors with water cooling and controllers 
at less than 100eur from any RC store. But these small motors need 
30-40A and so they can only run few minutes because they really heat.

Other brushless motors just give >1000eur and need an 1KHz 3 phase 
controller.

Or modify and RC motor with more windings to work at 100V or more. 
Wood plane seems nice for now. I don't mind to exchange the motor once a 
year to make some boards...

But i am just someone with electric tools at home... not an engineer...


Stefan Trethan wrote:

>
> Personally i think a direct drive brushless motor is the way to go for
> these speeds.
>
> Also i think you need to pre-load the bearings to reduce runout. And i
> would select oil lubricated bearings over grease lubricated ones.
>
> I may be wrong i am not a mechanical engineer.
>
> ST
>
> On Mon, Jan 19, 2009 at 9:32 PM, Sim\ufffdo Pedro Cardoso
> <simaocardoso@... <mailto:simaocardoso%40gmail.com>> wrote:
> > Hi,
> >
> > Is very difficult to find a pcb spindle. Drilling a pcb hole of 0.5mm in
> > a FR4 laminate needs carbide tools and 50.000rpm spindle. This things
> > cost more than all other things to make a good CNC router.
> > I have found a away, but still didn't make/test the thing. From this
> > great sites (and thanks to them)
> > http://www.cnconabudget.com/dan_d.JPG 
> <http://www.cnconabudget.com/dan_d.JPG>
> > http://www.buildyouridea.com/cnc/spindle_05/spindle_05.html 
> <http://www.buildyouridea.com/cnc/spindle_05/spindle_05.html>
> > http://www.cncathome.com/spindles.html 
> <http://www.cncathome.com/spindles.html>
> > http://www.students.tut.fi/~kontkant/jv2.php.html 
> <http://www.students.tut.fi/%7Ekontkant/jv2.php.html>
> > 
> http://members.home.nl/zoltar/CNC/classicsystem/10%20euro%20frase.pdf 
> <http://members.home.nl/zoltar/CNC/classicsystem/10%20euro%20frase.pdf>
> >
> > I think to have found a way to do my 50.000rpm or more (i think i can
> > get 80.000rpm) pcb spindle.
> > Using this tool from ebay seller (he made the tool from my request!!)
> > 
> http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=110329201156 
> <http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=110329201156>
> >
> > And high speed skate bearing or better like this
> > 
> http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=400000902567 
> <http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=400000902567>
> >
> > And a AC brushed (universal) motor from a electric wood plane. It has a
> > 30.000rpm motor and a 2:1 or similar reduction that can be inverted to
> > give 60.000rpm, using the same timing belt and pulleys.
> >
> > Do you think it will work nice? I have made a circuit to pwm control the
> > motor speed. And i think if i give DC to the motor it will run in lot
> > more than 30.000rpm.
> >
> > I want to post the circuit online, but which cnzone forum pcb spindles
> > should go?
> >
> > Simao
> >
>
> __._,_.

Find a suitable-size/torque "400 Hz. 3-phase motor".  Re-do the  "output end" 
with a suitable precision angular-contact ball-bearing rated for  30,000 RPM, 
and install a tiny collet-chuck.  This takes some machining  skill and 
experience.
 
Wire up a 400 Hz inverter.  This will require either a LUCKY source of  the 
needed transformer, or the ability to "roll your own" for the specific  
application.
 
The 400 Hz. "instrument motor" I found at my local "surplus outlet" is a  
quasi-3-phase design which requires 400 Hz. single-phase plus a specific  
capacitor/resistor to provide a "third leg".  A one-of-a-kind application,  but it 
works!  Spins 24000 RPM and drills FR-4 nicely.  
**************Inauguration '09: Get complete coverage from the nation's 
capital.(http://www.aol.com?ncid=emlcntaolcom00000027)


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

I can understand and appreciate your desire for speed, however, there 
are many drawbacks to this speed as well.  Heat is going to be a 
problem - keeping the bearings from getting too hot will be a problem.   
Making sure that the spindle and tool all run perfectly true - within 
1 to 2 microns at worst is key.  Any run-out at the tool will 
eventually cause the bit to wobble and that leads to breakage.  Power 
is generally not an issue with these small drill bits, but if you are 
overdriving, you have to account for that in your power requirements.

I have probably drilled a couple thousand holes in PCB stock using a 
large woodworking drill press.  I believe the speed I am running at is 
around 2500 RPM.  The most common size drill I have been using is .75 
MM (.030") and I go up or down from there for various components.  
From what I have observed over time, the drills don't break or dull 
due to slow spindle speed, they break due to operator error - 

feeding too fast
not having the bit aligned on center of where to drill
moving the part sideways while drilling or retracting

Speed helps, but attention to method will save more bits in the long 
run.  

Chris

Isn't a desire of my own, from pcb laminates datasheets you can read 
recommended drill bit speeds.
It is about 100.000rpm for an 0.25mm to 10.000rpm for 4mm. To drill a 
0.5mm drill hole on FR4 is recommended 60.000rpm with infeed of 37mm/s. 
But this is just to give a longer live to the drill bits. Lower rpm just 
need lower infeed ( i guess).
On westwind http://www.westwind-airbearings.com/pcb/index.html you can 
see 80.000 to 210.000rpm spindles (in a price range like cars i guess), 
they have air bearings, water cool and need a lot of equipment to 
operate. Also the cheapest (but still expensive pcb cnc's) use cheaper 
spindles like 
http://www.centerline-inc.com/partners/kavo/kavo_product_documents.php 
of 60.000rpm.

You are right when say i should look at tool cost more than just speed. 
Making a speedy machine but with big run-out will result in damage tools 
anyway. And more than a carbide bit price, is a good bearing, which 
should also live longer.

My only wish is to run between 30.000rpm and 40.000rpm all tool bits 
bellow 1mm. But never bellow 30.000rpm for these. And i hope to make a 
machine capable of this.

Simao

lcdpublishing wrote:

 >
 > I can understand and appreciate your desire for speed, however, there
 > are many drawbacks to this speed as well. Heat is going to be a
 > problem - keeping the bearings from getting too hot will be a problem.
 > Making sure that the spindle and tool all run perfectly true - within
 > 1 to 2 microns at worst is key. Any run-out at the tool will
 > eventually cause the bit to wobble and that leads to breakage. Power
 > is generally not an issue with these small drill bits, but if you are
 > overdriving, you have to account for that in your power requirements.
 >
 > I have probably drilled a couple thousand holes in PCB stock using a
 > large woodworking drill press. I believe the speed I am running at is
 > around 2500 RPM. The most common size drill I have been using is .75
 > MM (.030") and I go up or down from there for various components.
 > >From what I have observed over time, the drills don't break or dull
 > due to slow spindle speed, they break due to operator error -
 >
 > feeding too fast
 > not having the bit aligned on center of where to drill
 > moving the part sideways while drilling or retracting
 >
 > Speed helps, but attention to method will save more bits in the long
 > run.
 >
 > Chris
 >

Would be curious how you balance the assembly?  At 60k-100k rpm, this will be critical for smooth operation and prevent tools from breaking, bearings from seizing, etc.


      

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

http://www.irdbalancing.com/balancing.asp

--- On Wed, 1/21/09, Mike Henry <mikeh_dhr@...> wrote:

From: Mike Henry <mikeh_dhr@...>
Subject: [Homebrew_PCBs] Re:50.00rpm pcb spindle idea
To: Homebrew_PCBs@yahoogroups.com
Date: Wednesday, January 21, 2009, 12:32 PM










    
            Would be curious how you balance the assembly?  At 60k-100k rpm, this will be critical for smooth operation and prevent tools from breaking, bearings from seizing, etc.



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




      

    
    
	
	 
	
	








	


	
	


      

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

It's a good thing but, I am surprised by quantity of professional, and 
experienced reply on a Homebrew named list...

If would buy a already made machine if wish a really good one. It's just 
an hobby thing.
And as i said my wish is a 30-40.000rpm spindle. I can test if it handle 
above that but it stops there.  This is a cheaper dremel like tool, but 
it can go faster or make less noise for the same rpm and have 
replaceable bearings (they came in a box of 10), and maybe a better tool 
chuck.

My questions related to use of DC with pwm on and AC brushed motor, or 
where to post it on cnczone, didn't deserve answer like a balance 
machine did.


 > on Wed, 1/21/09, Mike Henry <mikeh_dhr@...> wrote:
 >
 > Would be curious how you balance the assembly?  At 60k-100k rpm, this 
will be critical for smooth operation and prevent tools from breaking, 
bearings from seizing, etc.

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

Of course you could use a DC or AC universal motor. Both will run just
fine with PWM.
AC universal motors will also run just fine with phase angle control
(like a light dimmer). That's what's in variable speed power drills.

But they have brushes, so get some earplugs ;-)

I have no idea how well any type of gearing will hold up at that
speed. That's why i suggested direct drive.

You can make your own brushless motors if you like, or buy one and
operate it mucht below it's design power output (like 10 times), then
it should not overheat.

PCB drilling, especially small drills, requires virtually no torque.
Friction with the bearings and air will probably exceed it by far.

Maybe you can also drive it with compressed air. There are air
grinders that run pretty fast, if you add a small turbine on the top
of your spindle that may work, but will be very loud.

ST

On Wed, Jan 21, 2009 at 9:05 PM, Simao Cardoso <simaocardoso@...> wrote:
>
> It's a good thing but, I am surprised by quantity of professional, and
> experienced reply on a Homebrew named list...
>
> If would buy a already made machine if wish a really good one. It's just
> an hobby thing.
> And as i said my wish is a 30-40.000rpm spindle. I can test if it handle
> above that but it stops there.  This is a cheaper dremel like tool, but
> it can go faster or make less noise for the same rpm and have
> replaceable bearings (they came in a box of 10), and maybe a better tool
> chuck.
>
> My questions related to use of DC with pwm on and AC brushed motor, or
> where to post it on cnczone, didn't deserve answer like a balance
> machine did.
>

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@...> wrote:
>
> Of course you could use a DC or AC universal motor. Both will run just
> fine with PWM.
> AC universal motors will also run just fine with phase angle control
> (like a light dimmer). That's what's in variable speed power drills.
> 
> But they have brushes, so get some earplugs ;-)
> 
> I have no idea how well any type of gearing will hold up at that
> speed. That's why i suggested direct drive.
> 
> You can make your own brushless motors if you like, or buy one and
> operate it mucht below it's design power output (like 10 times), then
> it should not overheat.
> 
> PCB drilling, especially small drills, requires virtually no torque.
> Friction with the bearings and air will probably exceed it by far.
> 
> Maybe you can also drive it with compressed air. There are air
> grinders that run pretty fast, if you add a small turbine on the top
> of your spindle that may work, but will be very loud.

Here's an inexpensive one:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?itemnumber=47869&Submit=Go

Walt.

> 
> ST
> 
> 
> On Wed, Jan 21, 2009 at 9:05 PM, Simao Cardoso <simaocardoso@...> wrote:
> >
> > It's a good thing but, I am surprised by quantity of professional, and
> > experienced reply on a Homebrew named list...
> >
> > If would buy a already made machine if wish a really good one.
It's just
> > an hobby thing.
> > And as i said my wish is a 30-40.000rpm spindle. I can test if it
handle
> > above that but it stops there.  This is a cheaper dremel like
tool, but
> > it can go faster or make less noise for the same rpm and have
> > replaceable bearings (they came in a box of 10), and maybe a
better tool

> > chuck.
> >
> > My questions related to use of DC with pwm on and AC brushed motor, or
> > where to post it on cnczone, didn't deserve answer like a balance
> > machine did.
> >
>