How to cut the driveshaft on a Mashima motor?

[VonRyan]

I bought a 12x20 Mashima motor at Timonium (for only $12) and I want to use it in my brass PRR BS10, but the driveshafts need to be cut.

How do I go about doing that? I figured I'd ask before I ruined what few tools I have.


Thanks all!

[Loren Perry]

One way is to loosely wrap the motor body with something soft like Kleenex tissue paper and then apply power to the motor from a power pack. The tissue should allow the motor to turn freely. The tissue keeps debris from entering the motor.

Now use a Dremel moto-tool with a cut-off disk and gently apply the spinning edge of the disk to the spinning motor shaft. Make sure the two rotating parts (Dremel disk and motor shaft) are rotating opposite to each other to get the best cutting action. Use minimal force to avoid damage or overheating the shaft. You don't have to do it all at once - you can cut a small amount at first to create a notch around the circumference of the shaft, back off to steady yourself, and then cut some more until done.

You can do this by hand or you can carefully and gently (VERY gently!) clamp the motor in a vise to steady your task.

And yes, I've successfully cut motor shafts this way. Worked fine for me.

[Chris333]

Never did it with the motor running, but use cut off wheels as well. Go slow so it doesn't get real hot and keep shavings/dust from getting inside.

[mmagliaro]

+1 on the Dremel
Wrap a strip of masking tape around the shaft so that it forms a sort of "cone" with open end of the
cone facing the motor.  So... it is only stuck to the shaft, not the motor.  That keeps all chance
of any metal dust getting into the bearing to a minimum.  When you are done, brush it all away really good
before you take the tape off.   

I never run the motor when I do it.  I just run the Dremel with the cut-off disk in it.  That will cause the motor shaft
to spin.   Just go slow and you'll be fine.  When you are done, DO run the motor on clip leads and hold a file against
the tip of the shaft to file a 45 degree chamfer on the edge.  That will make it easier to push on a worm or
flywheel. 

Oh.. and if you have diamond cutoff disks instead of the just the normal ones, use one of those.  They can cut
that hardened drill rod that the motor shaft is made of much more easily.

That's a darn good price on a 12x20 Mashima.  Congrats!

[Cajonpassfan]

Like Chris, I just cut them with a new disk. I clamp the shaft and hold the wrapped motor. But Loren's technique sure puts a new "spin" on the task 
Otto K.

[peteski]

I also use masking tape to prevent steel shavings from entering the open-frame motor and sticking to the magnets.  I start with a piece of masking tape which is impaled on the drive shaft being cut.  I then wrap that piece over the motor and use additional pieces of tape to wrap the motor completely.  Once it is protected I use cutoff disk in a Dremel tool (on medium speed) to cut through the shaft.  I usually hold the motor either in my hand or against some surface (like the workbench) while I'm cutting through the shaft.  I never found it necessary to clamp it in a vise.  Eye protection is a must!  Careful - the piece that gets cut off will be rather warm.

Once cut through, I use the cutoff disk as a grinding wheel to gently dress the cut end.  Then I unwrap the masking tape making sure that none of the shavings get inside of the motor. In certain cases I pick up the shavings using another piece of masking tape's sticky side before unwrapping the motor.

I have never found it necessary to have the shaft (motor) running while cutting, but that is an interesting idea.

[VonRyan]

Oh. No Dremel here.

How do I do it without a Dremel?

[u18b]

To be honest, I would suggest you buy a dremel.  And ceramic cut off wheel.

A motor tool was one of the best investments in my hobby I made about the 3rd year I started modeling.

I wore one out.  Now on my second, and I'll be replacing it some day.

[C855B]

To be honest, I would suggest you buy a dremel.  And ceramic cut off wheel.

A motor tool was one of the best investments in my hobby I made about the 3rd year I started modeling.

I wore one out.  Now on my second, and I'll be replacing it some day.

Ditto. They are soooooo inexpensive now, relative to what I paid for my first one in 1970. I bought it at Fedco... if any of you older Californians remember Fedco.

Like Ron, I wear them out. I'm on my fourth one, although we ought to discount the early battery version I had which couldn't cut/grind/drill its way out of a paper bag.

[Cajonpassfan]

Cody, you gotta have a Dremel. I actually use my 4.8V Cordless; for the light jobs we all do it is so light and convenient I hardly ever get the big brother out. Paid like $23 bucks for it, and its battery is always charging, ready to go....
Otto K.

[Kisatchie]

To be honest, I would suggest you buy a dremel.  And ceramic cut off wheel....

Hmm... one whack with
an ax... um... oops...

[Lemosteam]

I have on you can have Cody, if ya pay for shipping.  it is a bit finicky and needs some kind of repair that makes better contact with the brush springs and motor contacts under them. I have not had time to work on it...

.

[JMaurer1]

I remember FedCo! We had one not too far away from where I grew up (closest store to the house). It was right next to the White Front. Memories!

Dremel is a MUST HAVE tool. I have three and have had to replace the brushes on two of them when they wore out. 

[wazzou]

I was raised in Sacramento and remember GEMCO, but not FedCo.

[mmagliaro]

Cody,
That motor shaft is hardened steel, like drill rod.  Trying to cut it with anything but a Dremel
will most likely result in failure.  At best, you just won't cut it and whatever tool you use to try it
will be wrecked, and at worst, you'll slightly bend the shaft or distort the housing or bearing,
in which case, the motor goes in the garbage.

Diagonal cutters, hacksaw... any other crazy ideas you may be pondering, forget it.
One time in my life, I cut one with a huge pair of electricians pliers.  That was 20 years ago
when I didn't know what I was doing.   It worked, but I wouldn't do it ever again.