RE: RE: [CAD_CAM_EDM_DRO] Adding a Tail shaft to servo's with no tail shaft

All motors are different.

Most have a set of bolts that hold some end plates onto a tube with the
field or permanent magnets mounted to that.

Mark the end plates and tube so the go back in the same place, I just
scratch them with a scribe and realign the scribed line.

If the brushes will come out, from the external casing remove them.

Now gently pull ends off very gently, if the brushes are internal, watch out
for them, they could fly off, or some motors have the field wires soldered/
crimped to the far end and this can catch and break the brushes. Also watch
to see how you are going to get them back in, there are often little holes
you drop a piece of rod into to hold the brushes retracted until the motor
is reassembled.

After this its all gently pull the ends off the bearings, most just have a
plane ball race at each end, sometimes these will be spherical.

If the motor was designed to run into a pinion then it may have a thrust
race on one end, this is normally just a single ball the end of the shaft
mates up against. If this is to be removed for the tail shaft, make sure the
motor cannot slide up and down in its body and damage itself. Most are held
by the ball races up against flanges and pinched by the end caps.

I prefer a bolted on extension, this can sleeve down over or into the main
motor shaft, but the bolted option seems a lot tougher. If you don't bolt,
try and turn for a press fit, and ensure you break the shoulder where you
turn the spigot to reduce stress. Again the bolt option has no stress.

The flexible coupling to the encoder is because it doesn't matter how good
you can machine, or what kit you have, perfect alignment will never exist
and encoders fall apart at the slightest stress. Most flexible couplings are
just a piece of alloy, brass or plastic, drilled at the ends with grub
screws to grip the shafts, and cross cut so they flex. Don't worry about
making them, they aren't that expensive to buy.

You'll also need to turn up an extension casing to go between the motor and
encoder which houses the coupling with holes to get to the grub screws. And
off course drill the end of the motor casing, or knock out a blanking plug.

That should just about do it.



Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

RSGB DRM111(Cornwall)

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of H & J Johnson
Sent: 26 April 2007 22:57
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: RE: [CAD_CAM_EDM_DRO] Adding a Tail shaft to servo's with no
tail shaft



Thanks Mark, how tough is it to pull the armature out of the motor to
machine the shaft? I've got a machinist who I think would gladly tackle it
but I don't want to wreck the motor by pulling it appart or something. Also,
what is the reasoning behind the flex coupling to the encoder? I could see
it if the tail wasn't running true but.. if it is..??

My game plan was to simply face off the end of the existing shaft.. d&T for
a male stud type stub shaft and lock-tite it in there.. and be done.. I like
the idea of chucking the drive end and using the body on the steady so you
can true the end if need be.. like you say.. it might be hard on bearings
depending how its set up..

any "got ya's" to watch for while pulling these appart? They are an MCG
motor...

Jarrett

----- Original Message -----
From: Mark Vaughan <mark@.... <mailto:mark%40vil.uk.com> com>
Date: Thursday, April 26, 2007 3:47 pm
Subject: RE: [CAD_CAM_EDM_DRO] Adding a Tail shaft to servo's with no tail
shaft

> I have popped the motors in a lathe before, drilled and taped the
> end, then
> bolted a stub on with some locktight.
>
> You can normally get it pretty true if your careful with your
> turning, you
> can run the motor and hand work the stub afterwards with a graver
> if there's
> any slight error, or spin the motor on a lathe with the body held
> in the
> steady so it runs tru in the motor bearings to finish it off. Make
> sure you
> use a flex coupling to the encoder, even on motors with tail shaft
> stubsfrom new.
>
> I have seen others join the stub in with a V, or filled slot to
> stop it
> turning, but locktight and hi tensile socket cap head seems to
> work, glues
> it all to the screw.
>
> Make sure you motor doesn't have a thrust bearing on the end, if
> it's a
> roller bearing your OK, but some motors have a single ball thrust
> bearingwhich might cause an issue.
>
>
>
> Regs Mark
>
>
>
> Dr. Mark Vaughan Ph'D. B.Eng. M0VAU
>
> Managing Director
>
> Vaughan Industries Ltd, reg in UK no 2561068
>
> Water Care Technology Ltd, reg in UK no 4129351
>
> Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
> Phone/Fax 44 1872 561288
>
> RSGB DRM111(Cornwall)
>
> _____
>
> From: CAD_CAM_EDM_ <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
DRO@yahoogroups.com
> [CAD_CAM_EDM_ <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
DRO@yahoogroups.com] On Behalf Of jerryflyguy
> Sent: 26 April 2007 22:08
> To: CAD_CAM_EDM_ <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Adding a Tail shaft to servo's with no
> tail shaft
>
>
>
> I remember someone posting a process they went through to add a
> tail
> shaft to a DC motor, thus making it possible to put an encoder on
> it. I
> can't find the site in my huge pile of favorites, anyone ever done
> this
> or remember the site I'm thinking of?? I've got my hands on some
> great
> DC motor's but they don't have the tail shaft..
>
> Thanks guy's
>
> Jarrett
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
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