Servo hacking...
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I recall seeing a tutorial for hacking a servo to allow it to travel to
270 degrees or a bit more. Does anyone have a link to this mod or
advice on how to do it?
Thanks!
g.
270 degrees or a bit more. Does anyone have a link to this mod or
advice on how to do it?
Thanks!
g.
Comments
> 270 degrees or a bit more. Does anyone have a link to this mod or
> advice on how to do it?
There is a full photo tutorial on our website for modifying a Futaba servo for
full rotation:
http://www.hvwtech.com/servos_mod_fut.htm
Mark Hillier
President, HVW Technologies Inc.
Mark@H...
Tel[noparse]:([/noparse]403)730-8603 Fax[noparse]:([/noparse]403)730-8903
http://www.HVWTech.com
See our NEW BASIC Stamp Prototyping tools !
for continuous rotation. We are currently using pre-modified servos so the
text has changed, but you can find that information all over the Internet.
A good place to start is the Dallas Personal Robotics Group (www.dprg.org) or
the Seattle Robotics Society (www.seattlerobotics.org).
-- Jon Williams
-- Parallax
In a message dated 4/10/02 3:32:12 PM Central Daylight Time,
geneb@d... writes:
> I recall seeing a tutorial for hacking a servo to allow it to travel to
> 270 degrees or a bit more. Does anyone have a link to this mod or
>
[noparse][[/noparse]Non-text portions of this message have been removed]
The easiest standard-size servo I have found to modify is the Futaba S-148.
I believe these are discontinued and replaced by the 3003. The 3003 is
almost as easy to modify, but not quite. If you are not handy, the
pre-modified servos from Parallax will save you some grief.
Here is one page for modifying servos:
http://www.rdrop.com/~marvin/explore/servhack.htm
Original Message
> Early versions of our Robotics text described hacking the Futaba S-148
servo
> for continuous rotation. We are currently using pre-modified servos so
the
> text has changed, but you can find that information all over the Internet.
>
> A good place to start is the Dallas Personal Robotics Group (www.dprg.org)
or
> the Seattle Robotics Society (www.seattlerobotics.org).
> > I recall seeing a tutorial for hacking a servo to allow it to travel to
> > 270 degrees or a bit more. Does anyone have a link to this mod or
> for continuous rotation. We are currently using pre-modified servos so the
> text has changed, but you can find that information all over the Internet.
>
Continuous rotation is not what I'm after. I need to command it to a
certain point and have it stop - the pot is needed for that kind of
feedback.
> A good place to start is the Dallas Personal Robotics Group (www.dprg.org) or
> the Seattle Robotics Society (www.seattlerobotics.org).
>
>
Thanks for the links!
g.
> > for continuous rotation. We are currently using pre-modified servos so the
> > text has changed, but you can find that information all over the Internet.
> >
> Continuous rotation is not what I'm after. I need to command it to a
> certain point and have it stop - the pot is needed for that kind of
> feedback.
In that case, you would need to replace the exisiting pot with a physically-
identical part who's resistance at 270° was the same as the original pot's
resistance at 90°. Doing this would cause a corresponding degradation of
resolution as well.
Certainly not impossible, but definately a tall order !
Mark Hillier
President, HVW Technologies Inc.
Mark@H...
Tel[noparse]:([/noparse]403)730-8603 Fax[noparse]:([/noparse]403)730-8903
http://www.HVWTech.com
See our NEW BASIC Stamp Prototyping tools !
Assuming the pot will turn 270 degrees, you could probably modify the stop
and get the motion you are looking for. Keep in mind many of the mini /
micro servos can't be modified.
Original Message
> > Early versions of our Robotics text described hacking the Futaba S-148
servo
> > for continuous rotation. We are currently using pre-modified servos so
the
> > text has changed, but you can find that information all over the
Internet.
> >
> Continuous rotation is not what I'm after. I need to command it to a
> certain point and have it stop - the pot is needed for that kind of
> feedback.
easy to modify, but not quite." Do you have instructions on how to
do it. I took it apart expecting to look like the old S-148, but it
is obviously quite different. I used the instructions from the older
version of the ROBOTICS! Stamps In Class for modifying the S-148. It
was quite easy to do. How do I do it for a 3003 servo?
Thanks,
Steve
Charles E. Fromage says:
The easiest standard-size servo I have found to modify is the Futaba
S-148. I believe these are discontinued and replaced by the 3003.
The 3003 is almost as easy to modify, but not quite. If you are not
handy, the pre-modified servos from Parallax will save you some
grief. Here is one page for modifying servos:
http://www.rdrop.com/~marvin/explore/servhack.htm
g.
and replacing it with fixed resistors. I want to keep the thing mostly
as-is, so I can unmodify it if necessary. In this case you would only have
to buy a replacement gear.
Lets see -- If I remember right, there is no removable slotted piece in the
output gear. The slots are actually molded into the bottom of the gear
itself. I used a drill slightly bigger than the pot shaft to cut away that
part of the gear. Just be careful not to drill too deep.
The gear should have a little ridge on top that keeps it from rotating all
the way around. Carefully cut this ridge away just like is shown for the
S-148.
Before you reassemble, center the pot shaft -- i.e. adjust it to the center
of its travel. After assembly, install the servo horn and carefully rotate
the servo by hand. If you feel any binding, stop immediately. Chances are
the pot is probably still being turned and you need to cut away the slots on
the gear a bit more. When you disassemble the servo can tell because the pot
shaft will no longer be centered.
Assuming you are going to use two servos for drive motors, you may want to
reverse one motor so that the servos react the same way to the same PULSOUT
values. Otherwise you would need to make the value larger on one servo and
smaller on the other to change speeds. The motor swap is a bit more work
than I will discuss right now.
Once you find the neutral or stopped PULSOUT value for one servo, you can
quickly pop the top off the other one and adjust the pot so that it uses the
same value.
**********
> I just bought the new 3003 model. You indicate that "it is almost as
> easy to modify, but not quite." Do you have instructions on how to
> do it. I took it apart expecting to look like the old S-148, but it
> is obviously quite different. I used the instructions from the older
> version of the ROBOTICS! Stamps In Class for modifying the S-148. It
> was quite easy to do. How do I do it for a 3003 servo?
> The easiest standard-size servo I have found to modify is the Futaba
> S-148. I believe these are discontinued and replaced by the 3003.
> The 3003 is almost as easy to modify, but not quite. If you are not
> handy, the pre-modified servos from Parallax will save you some
> grief. Here is one page for modifying servos:
> http://www.rdrop.com/~marvin/explore/servhack.htm