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Re: [Homebrew_PCBs] Re: laptop drill press (foot switch safety)

2003-07-25 by Ron Amundson

----- Original Message -----
From: starsnstripes_2003
To: Homebrew_PCBs@yahoogroups.com
Sent: Friday, July 25, 2003 3:14 PM
Subject: [Homebrew_PCBs] Re: laptop drill press

Thanks for the ideas, Dave ;-)

I already had thought about a simple footswitch, But it would only
turn on the Dremel.
MCM? or Mouser? has a footswitch with phono plug for about $7.00.
I can mount a phono jack in a cheap power strip and plug the
footswitch into it to enable foot operation for the whole power
strip. I think Dremel gets about $45 for their footswitch...Ouch!

You don't need the spring to pull down on the Dremel. You might need
it to provide counter-balance for a true-gravity feed, though.
Gravity does the job fine. (Adjust the pivot bolt just snug enough
to remove "play" in the arm). I used a little melted candle-wax to
lubricate the pivot points.
The feed arm on mine has the feel of a regular drill press with just
about 80 deg. arc providing the full 1/4" travel. Works just fine
for my purposes :-)

I chuckled with your suggestion of an auto-tool changer! I came from
a CNC production environment with over 500 various CNC machine tools.
Most had tool changers. They are a pain in the A$$...(I was CNC
Maintenance Leader there.)
My Dremel set came with Hex and Knurled collet nuts.
The knurled collet nut allows pretty fast changes just using "finger-
tight" if you stick to the Carbide drills with 1/8" shanks. They are
only about $4.25 for a pack of 5 (resharpened) at Drill Bit City.

As for auto-feed and retract, I suppose if you were really serious,
you could mount a stepper motor w/controller to a modified feed arm,
and provide a limit / microswitch to do the retract.

Not sure if the solenoid would work, but it might if you let the arm
free-fall and the solenoid do the lift.

I'm not THAT serious, though!

Well, maybe if I find an old printer that I can scrap...Hmmm...So
much fun in such a small Yahoo Group!
Next up: X/Y Table ?

--- In Homebrew_PCBs@yahoogroups.com, "Dave Mucha" <dave_mucha@y...>
wrote:
> --- In Homebrew_PCBs@yahoogroups.com, "starsnstripes_2003"
> <bwatson@a...> wrote:
> > I was so impressed with your Laptop Drill that I made a tabletop
> > version. (I told ya I liked it!)
> > Elegant simplicity...
>
> Nice pic, and it looks good.
>
> I thought about the unit and if I were to modify it, I would add
an
> articulating arm magnifying light to see the hole locations
better,
>
> AND....
>
> I would add a foot operated lever. spring load the lever so when
you
> stepped on it, the drilling arm drilled the hole and only the
spring
> pulled the dremel, not the power of your foot.
>
> alternatly, mount a solenoid and a foot switch.
>
> now, to design a fast change chuck for a Dremel.......

If you do use a phono plug, make sure you put a relay and transformer with it to avoid running the mains current on a phonoplug.

In the US, it seems about 20% of residential buildings are wired backwords, and as such you could end up with 120V on the phonoplug shell, so I'd make sure that a low voltage signal was running through the footswitch which would enable a relay to turn on the dremel. Make sure to use a decent relay, as the inductive kickback from the dremel can fry contacts pretty easily if you don't have the proper snubber.

Another solution is a foot switch designed for mains operation such that there are no safety concerns. Sometimes you can find them surplus for under $10.

Thanks
Ron

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

Re: laptop drill press (foot switch safety)

2003-07-25 by starsnstripes_2003

YES! Ron has a VERY GOOD point!
I wasn't going to get into wiring basics, but for this you should be
aware of safety! Ron's idea is the best, but I'll use the phono plug
for mine.

I use stereo 3 conductor phono plugs/jacks for one of my projets, so
using the tip conductor for "Hot" and the center conductor
for "Neutral" would be one solution. If Hot is connected to the
center or shell conductors, You would get a JOLT when you plugged it
in under power!

Use the plastic insulated plugs. (Or use a proper Heat-shrink tubing
to insulate the metal ones.
Also, you should use a 3 conductor wire so that you
can carry the ground to the switch housing.
Connect the Green ground wire inside the power strip to the outer
shell and one conductor (shield if it has one) of the cable. At the
other end, connect this ground wire to the housing of the metal
footswitch.

You don't want the hot wire connected to the outer shell or switch
housing at any time!

The footswitch I mentioned only has a 2 conductor plug.
You would need to replace it and the cable with a 3 conductor rated
for the job, or as Ron suggested, use a low voltage relay rated well
over the current of your drill.

> If you do use a phono plug, make sure you put a relay and

transformer with it to avoid running the mains current on a
phonoplug.

>
> In the US, it seems about 20% of residential buildings are

wired backwords, and as such you could end up with 120V on the
phonoplug shell, so I'd make sure that a low voltage signal was
running through the footswitch which would enable a relay to turn on
the dremel. Make sure to use a decent relay, as the inductive
kickback from the dremel can fry contacts pretty easily if you don't
have the proper snubber.

>
> Another solution is a foot switch designed for mains operation

such that there are no safety concerns. Sometimes you can find them
surplus for under $10.

>
> Thanks
> Ron

Re: laptop drill press (foot switch safety)

2003-07-26 by Dave Mucha

>
> Well, maybe if I find an old printer that I can scrap...Hmmm...So
> much fun in such a small Yahoo Group!
> Next up: X/Y Table ?

I've got a couple 7550 HP plotters.....
gotta be able to use a couple sections from the gantry to move
something as light as a PC board.....

My T-tech routing/drilling machine uses a DC motor for the spindle
and a solenoid to drill. not much more travel than a plotter pen up
and down....

and the 7550 has a carosel... maybe it could hold a half dozen drill
bits.... a small DC motor with a drill bit as the tool holder. no
need to change the bit, change the whole motor....

I think it's too late and I'm getting too far afield.

Dave

Re: [Homebrew_PCBs] Re: laptop drill press (foot switch safety)

2003-07-26 by Ron Amundson

From: starsnstripes_2003
To: Homebrew_PCBs@yahoogroups.com
Sent: Friday, July 25, 2003 5:08 PM
Subject: [Homebrew_PCBs] Re: laptop drill press (foot switch safety)

YES! Ron has a VERY GOOD point!
I wasn't going to get into wiring basics, but for this you should be
aware of safety!

I use stereo 3 conductor phono plugs/jacks for one of my projets, so
using the tip and center conductors to carry the current would be a
good solution. Also, you should use a 3 conductor wire so that you
can carry the ground to the switch housing.
Connect the Green ground wire inside the power strip to the outer
shell and one conductor of the cable. At the other end, connect this
ground wire to the housing of the metal footswitch.
<b>You don't want the hot or neutral sides connected to the outer
shell or switch housing!</b>

Ron respondes....
I wasn't planning on jumping in, but I learned about mains voltage too many times the hard way in my younger days.

I would be careful with even the phone plug, UL and CE have standards for spacing and insulation and the phoneplug insulator is probably not rated nor is the spacing adeqaute(but on the other hand probably works just fine and is much less $$$$ than a UL or CE approved power connector. Just be careful, in commercial gear one does a lot of safety testing and validation to use non-approved connectors and it works, but it takes a great deal of time and money. Safety is key, UL is more fire protection and CE is more along the shock hazard issue, but both overlap.

I'm learning a great deal from this list, I ordered some plans from one of the members the other day for a pcb mill, and hope to use it for drilling and may add some of the cool ideas discussed here. Amazing stuff!!!!
Thanks
Ron

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

Re: laptop drill press (foot switch safety)

2003-07-26 by Dave Mucha

--- In Homebrew_PCBs@yahoogroups.com, "Ron Amundson"
<ron_amundson@h...> wrote:

> From: starsnstripes_2003
> To: Homebrew_PCBs@yahoogroups.com
> Sent: Friday, July 25, 2003 5:08 PM
> Subject: [Homebrew_PCBs] Re: laptop drill press (foot switch

safety)

>
>
> YES! Ron has a VERY GOOD point!
> I wasn't going to get into wiring basics, but for this you should

> aware of safety!

I use a simple foot switch on my drill press. it is just an
electrical box with a wire on one side and a recpticle on the other.
I think they call it a deep switch box.

anyway, a momentary pushbutton on it as the only contorl.

The cord pugs in to the wall, and the drill plugs into the
recpticle. the momentary makes contact as long as my foot is on the
button.

When taping holes, I need a hand on the part and a hand on the
spindle feed. the foot switch allows me to control the motor.

I was thinking of using relays and a reversable motor, but then I got
a taping head and that is all moot.

Dave

Re: laptop drill press - foot operated drilling

2003-07-26 by Dave Mucha

--- In Homebrew_PCBs@yahoogroups.com, "Ron Amundson"
<ron_amundson@h...> wrote:

>
> ----- Original Message -----
> From: starsnstripes_2003
> To: Homebrew_PCBs@yahoogroups.com
> Sent: Friday, July 25, 2003 3:14 PM
> Subject: [Homebrew_PCBs] Re: laptop drill press
>
>
> Thanks for the ideas, Dave ;-)
>
>
> I already had thought about a simple footswitch, But it would

only

> turn on the Dremel.

For the PCB drilling, which when done manually is boringly
repetitive, I was thinking that if one used a solenoid to peck the
drill into the board, it would leave your hands free to move the
board.

Being one of those that thinks about different solutions, I would
also considder a lever to do the drilling.
putting on a lever like a brake pedal in a car, the pedal could be as
simple as a lever with a spring to transfer the force. I think the
power of a foot pedal would snap drills in a heartbeat.

But, then I think a full CNC unit would be the most fun to make.

Dave

Re: [Homebrew_PCBs] Re: laptop drill press (foot switch safety)

2003-07-26 by Stefan Trethan

i would never ever use a phono plug (3.5mm, even 6mm i would not use) for
mains current.
this are definitly low voltage connectors, you can't tell when and where
the pins are touching each other
when inserting. also they are for very small currents designed. nothing to
use a drill..

if you buy a footswitch with a "microswitch" in it, which is capable of
switching enough amps and volts then i would
cut off the cable, install proper connectors if needed (or hardwire it).

but if i had to go for the little current, little voltage phono plug
version (or the switch in the foot pedal is too weak) i would
use a relais (or a conductor) which has low voltage coil.
but this requires a second sorce of this low voltage so i would surely use
other connectors if this is not available
for other purposes already.

so guys, please if you really are making pc boards you can get a bit more
serious
and install this properly... mains voltage is lower where you live, i know,
but phone plugs are not suited.

maybe get a suitable plug (maybe with cable attached from other dead
machine) and the plug socket (cable mount version)
abd wire it up with a footswitch. this would be useable for other machines
too...

at least where i live you can buy a plug which has a socket on his back.
this would be perfect for this application.

good luck....

regards
stefan