screwgun triggers

M

Michael Robinson

Guest
I have a cordless impact driver and drill set I use all the time. How does
the speed control in the trigger work, is it just a rheostat? It's been a
long time since I took a drill apart, but I don't remember seeing any active
circuitry.
 
On 8/15/2013 8:32 PM, Michael Robinson wrote:
I have a cordless impact driver and drill set I use all the time. How does
the speed control in the trigger work, is it just a rheostat? It's been a
long time since I took a drill apart, but I don't remember seeing any active
circuitry.
Click to expand...
I haven't taken one apart for a while but the last time I did it was a
little PWM circuit.

Tom
 
On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How does
the speed control in the trigger work, is it just a rheostat? It's been a
long time since I took a drill apart, but I don't remember seeing any active
circuitry.
Click to expand...
I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.

Michael
 
Michael Black wrote:
On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How does
the speed control in the trigger work, is it just a rheostat? It's been a
long time since I took a drill apart, but I don't remember seeing any active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.
Click to expand...

SCR speed control, all in the trigger housing. I've had to replace
several in the last few decades, but I still have plenty of new spares.
I stocked up when the BD surplus store had them for 25 cents each. I
bought all 62 they had in stock. The first two I used to convert single
speed drills to variable paid for all of them. :)


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
 
Michael Robinson wrote:
I have a cordless impact driver and drill set I use all the time. How does
the speed control in the trigger work, is it just a rheostat? It's been a
long time since I took a drill apart, but I don't remember seeing any active
circuitry.
Click to expand...

PWM. A Rheostat would give poor torque, and dump a lot of energy as
waste heat under your finger.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
 
On Thu, 15 Aug 2013, Michael A. Terrell wrote:

Michael Black wrote:

On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How does
the speed control in the trigger work, is it just a rheostat? It's been a
long time since I took a drill apart, but I don't remember seeing any active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.


SCR speed control, all in the trigger housing. I've had to replace
several in the last few decades, but I still have plenty of new spares.
I stocked up when the BD surplus store had them for 25 cents each. I
bought all 62 they had in stock. The first two I used to convert single
speed drills to variable paid for all of them. :)
Click to expand...
I think that occurred to me at one point. I think I paid $25 Canadian for
this drill in 1975, and the only thing I've had to do to it was replace
the brushes about 20 years ago.

About five years back, I found another Black & Decker drill about the same
vintage (still a metal case) for $3 at a garage sale, bought it as backup.
And then found another one of the same vintage in the garbage when the
students moved out. One of the others at least has the reversing switch.
But now, I have one to leav in my drill press adapter.

Michael
 
Michael Black wrote:
On Thu, 15 Aug 2013, Michael A. Terrell wrote:


Michael Black wrote:

On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How does
the speed control in the trigger work, is it just a rheostat? It's been a
long time since I took a drill apart, but I don't remember seeing any active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.


SCR speed control, all in the trigger housing. I've had to replace
several in the last few decades, but I still have plenty of new spares.
I stocked up when the BD surplus store had them for 25 cents each. I
bought all 62 they had in stock. The first two I used to convert single
speed drills to variable paid for all of them. :)

I think that occurred to me at one point. I think I paid $25 Canadian for
this drill in 1975, and the only thing I've had to do to it was replace
the brushes about 20 years ago.

About five years back, I found another Black & Decker drill about the same
vintage (still a metal case) for $3 at a garage sale, bought it as backup.
And then found another one of the same vintage in the garbage when the
students moved out. One of the others at least has the reversing switch.
But now, I have one to leave in my drill press adapter.

Michael
Click to expand...

Those adapters are OK for some work, but they won't do what a full
drill press, or a Cameron precision drill will. :(

The floor mounted full height drill press will let me lower the table
at least 24" and can have alignment fixtures and/or toggle clamps bolted
to the table's slots to get more accurate holes. It also has 12 speeds,
selected by moving a pair of belts.

The precision drill only takes bits /8" or smaller. It is intended
for a model shop, or watch making/repair. If you ever get the chance to
own either, you'll be pleased with the additional capabilities in your
workshop. :)


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
 
"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:M86dndUvl4IYBJDPnZ2dnUVZ_hIAAAAA@earthlink.com...
Michael Black wrote:

On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How
does
the speed control in the trigger work, is it just a rheostat? It's
been a
long time since I took a drill apart, but I don't remember seeing any
active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.


SCR speed control, all in the trigger housing. I've had to replace
several in the last few decades, but I still have plenty of new spares.
I stocked up when the BD surplus store had them for 25 cents each. I
bought all 62 they had in stock. The first two I used to convert single
speed drills to variable paid for all of them. :)


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
Click to expand...

This is cordless (DC) equipment I'm inquiring about. I can see putting an
SCR in a drill that runs on AC. What circuit do _cordless_ drills or impact
drivers use?
 
On Sat, 17 Aug 2013 15:39:44 -0400, "Michael Robinson"
<kellrobinson@yahoo.com.no_spam> wrote:

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:M86dndUvl4IYBJDPnZ2dnUVZ_hIAAAAA@earthlink.com...

Michael Black wrote:

On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How
does
the speed control in the trigger work, is it just a rheostat? It's
been a
long time since I took a drill apart, but I don't remember seeing any
active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.


SCR speed control, all in the trigger housing. I've had to replace
several in the last few decades, but I still have plenty of new spares.
I stocked up when the BD surplus store had them for 25 cents each. I
bought all 62 they had in stock. The first two I used to convert single
speed drills to variable paid for all of them. :)


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

This is cordless (DC) equipment I'm inquiring about. I can see putting an
SCR in a drill that runs on AC. What circuit do _cordless_ drills or impact
drivers use?
Click to expand...
The two I have taken apart used PWM. But not infinitely variable.
There were steps to the speeds. They were Harbor Freight tools that I
bought specifically to take apart because I needed the variable speed
motor and driver for something else. And on one of my cordless tools
you can hear some sort of oscillator changing pitch as the trigger is
pulled.
Eric
 
SCR speed control, all in the trigger housing. I've had to replace
several in the last few decades, but I still have plenty of new spares.
I stocked up when the BD surplus store had them for 25 cents each. I
bought all 62 they had in stock. The first two I used to convert single
speed drills to variable paid for all of them. :)
Click to expand...

I did something similar with Milwaukee battery sockets (on the bottom of the
18V drills). I've epoxied these adapters in Bosch and other 18V drills & saws
that someone is throwing away. Now all take the M 18V battery pack.
 
On 8/17/2013 3:39 PM, Michael Robinson wrote:
"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:M86dndUvl4IYBJDPnZ2dnUVZ_hIAAAAA@earthlink.com...

Michael Black wrote:

On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How
does
the speed control in the trigger work, is it just a rheostat? It's
been a
long time since I took a drill apart, but I don't remember seeing any
active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.


SCR speed control, all in the trigger housing. I've had to replace
several in the last few decades, but I still have plenty of new spares.
I stocked up when the BD surplus store had them for 25 cents each. I
bought all 62 they had in stock. The first two I used to convert single
speed drills to variable paid for all of them. :)


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

This is cordless (DC) equipment I'm inquiring about. I can see putting an
SCR in a drill that runs on AC. What circuit do _cordless_ drills or impact
drivers use?
Click to expand...

PWM, as Tom stated in the first reply.

Mike Terrell was replying to Mike Black about his 1975 B&D drill,
which is was not cordless. In Mike Terrell's reply to you, his
answer was PWM.

Ed
 
"Michael Black" <et472@ncf.ca> wrote in message
news:alpine.LNX.2.02.1308152211580.9756@darkstar.example.org...
On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How
does
the speed control in the trigger work, is it just a rheostat? It's been
a
long time since I took a drill apart, but I don't remember seeing any
active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.
Click to expand...

A more recent B&D I took apart (a replacement battery cost more than a new
drill) had nothing more than a MOSFET and a slider pot linked to the
trigger, the heatsink was custom made (cast aluminium) to fit as much fins
as possible in the space behind the brushes.
 
"Michael Robinson" <kellrobinson@yahoo.com.no_spam> wrote in message
news:520fd180$0$49427$862e30e2@ngroups.net...
"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:M86dndUvl4IYBJDPnZ2dnUVZ_hIAAAAA@earthlink.com...

Michael Black wrote:

On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How
does
the speed control in the trigger work, is it just a rheostat? It's
been a
long time since I took a drill apart, but I don't remember seeing any
active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it
has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.


SCR speed control, all in the trigger housing. I've had to replace
several in the last few decades, but I still have plenty of new spares.
I stocked up when the BD surplus store had them for 25 cents each. I
bought all 62 they had in stock. The first two I used to convert single
speed drills to variable paid for all of them. :)


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

This is cordless (DC) equipment I'm inquiring about. I can see putting an
SCR in a drill that runs on AC. What circuit do _cordless_ drills or
impact drivers use?
Click to expand...

In theory - the motor causes back-emf, that could possibly commutate an
SCR - but a loaded motor produces less back emf so operation could be
unpredictable!
 
On Mon, 19 Aug 2013, Ian Field wrote:

"Michael Black" <et472@ncf.ca> wrote in message
news:alpine.LNX.2.02.1308152211580.9756@darkstar.example.org...
On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How
does
the speed control in the trigger work, is it just a rheostat? It's been a
long time since I took a drill apart, but I don't remember seeing any
active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it has
variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.

A more recent B&D I took apart (a replacement battery cost more than a new
drill) had nothing more than a MOSFET and a slider pot linked to the trigger,
the heatsink was custom made (cast aluminium) to fit as much fins as possible
in the space behind the brushes.

That might be, though back in 1975, I don't recall power mosfets.
Click to expand...

And while the variable speed isn't perfect, I think it's too smooth to be
a rheosstat (or a mosfet or transistor acting as a variable resistor).

Michael
 
"Michael Black" <et472@ncf.ca> wrote in message
news:alpine.LNX.2.02.1308191700120.17736@darkstar.example.org...
On Mon, 19 Aug 2013, Ian Field wrote:



"Michael Black" <et472@ncf.ca> wrote in message
news:alpine.LNX.2.02.1308152211580.9756@darkstar.example.org...
On Thu, 15 Aug 2013, Michael Robinson wrote:

I have a cordless impact driver and drill set I use all the time. How
does
the speed control in the trigger work, is it just a rheostat? It's
been a
long time since I took a drill apart, but I don't remember seeing any
active
circuitry.



I've always wondered. I bought my Black & Decker drill in 1975 and it
has variable speed (but doesnt' reverse). It's trigger is a very small
package, and I don't see anything elsewhere, but it can't be a rheostat,
too small for that too.

A more recent B&D I took apart (a replacement battery cost more than a
new drill) had nothing more than a MOSFET and a slider pot linked to the
trigger, the heatsink was custom made (cast aluminium) to fit as much
fins as possible in the space behind the brushes.
That might be, though back in 1975, I don't recall power mosfets.

And while the variable speed isn't perfect, I think it's too smooth to be
a rheosstat (or a mosfet or transistor acting as a variable resistor).
Click to expand...

In field controlled dynamos; the field current is much less than the rotor
winding - perhaps the same can be true of the field current in a motor.

The rheostat wouldn't have to be so big - but you'd probably burn out the
armature with prolonged low speed!
 
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