shaft extension

[Mike Amick]

How do you guys usually extend a shaft when you need to. I have to
change out a motor on a mill I am working on, and the shaft on the bad
motor is like 6" long to go through the very thick step pulley. The shaft on
all the motors I am considering is much shorter.

Im thinking I am going to have to conical shape the ends a bit, weld it up,
then turn it down. Am worried about the hardness of the weld though.

Suggestions ?

[digr]

I did the same thing with 2 ton electric hoist that had a 3 phase motor on it and I put a single phase on it without a problem. Check to see if you can press the shaft out of the armature on the new motor and make a new one. I did a 100% weld on the shaft.

[dalee100]

Hi,

Depends on how much of a load is placed on the motor. I have welded a few up with extentions and done shrink fits. But I mostly prefer a simple key and set screw if possible.

Dalee

[KiddZimaHater]

Drill a hole in one end of shaft A, then turn shaft B to fit snuggly into the hole of shaft A.
Next, mill a slot across Shaft A, to centerline.
On Shaft B, mill it down to centerline as well.
They will now slide together and 'Lock'.
A little weld will make it permanent.
It might not be feasible with a short motor shaft, but it might give you an idea.
This is a trick I was shown by an old-timer to make drills longer.
I apologize for my awful drawing.
-

[Mike Amick]

Oh yea .. I have heard about pressing the shaft out of an armature, I have a good press
so I might check that out. But I like Haters idea too .. it has that thinking outside the
box feel.

Also I forgot to mention that I have to go from a 5/8 shaft to a 3/4 shaft ..

On a shaft that has a sleeve on the end to go from 5/8 to 3/4, is there enough meat
to have structural integrity ?

Thanks
Mike

[darryl]

Any chance of boring at least part way through the step pulley to allow a larger shaft at that point- would give the option of pressing that end of the shaft over the existing shaft. Should be enough meat there.

[Jaakko Fagerlund]

If the shaft is plain old S355 and not some highly alloyed, the welding isn't going to harden it. Every weld I've machined has been soft as peanut butter in the lathe, the only issue being some interrupted cutting as the weld is not symmetrical or round.

[malbenbut]

John Stevenson has repaired many motor shafts by building uo with weld, I don't know if he extended any but I'm sure his expertise on this matter would be very helpful to you.
MBB

[jlevie]

Also I forgot to mention that I have to go from a 5/8 shaft to a 3/4 shaft ..

Reduce the diameter of the 5/8 part, bore the 3/4 part, and heat shrink the two together.

[EVguru]

John Stevenson has repaired many motor shafts by building uo with weld, I don't know if he extended any but I'm sure his expertise on this matter would be very helpful to you.
MBB

Two for me so far. One for the BP clone, the other for a Denford Easymill.

[Doozer]

KiddZima,
The method you have illustrated is creative and pretty cool
but for all the effort and really not having much strength
I am not sure I would do it. You do not want to take away
any "meat" from the origional shaft if possible. I believe a
plain old way of turning a generous chamfer (weld prep)
on both the motor and the extension shafts, and welding
them makes the most sense. Use a extension shaft that
is 1/8 to 1/4 inch larger than the motor shaft for cleanup
room of course.
The method you have shown might be good if you are wanting
to use silver solder or braze. In that it might be the hot ticket.

--Dooer

[bruto]

Another method worth considering if you can do it well:

Many years ago the 2 horse motor on my Sears compressor broke. The stress on the serpentine-style belt sheared the shaft off just to the inside of the bearing. It was an expensive motor, so I took it to a local old fellow who did stuff, and he machined a very tight sleeve to go over the stub, then pressed a new piece of shaft into it. It came loose the first time, so I took it back and he did it again, and the repair this time has lasted for about 20 years.

The old fellow celebrated his 90th birthday recently. He's still fixing stuff.

[The Artful Bodger]

..so I took it to a local old fellow who did stuff............

Ha ha! I hope someone says that about me one day!

[Paul Alciatore]

If your new motor has the shaft extending out of both ends, perhaps you can just use the press to move it so more sticks out the end for your pulley.

[Mike Amick]

If the shaft is plain old S355 and not some highly alloyed, the welding isn't going to harden it. Every weld I've machined has been soft as peanut butter in the lathe, the only issue being some interrupted cutting as the weld is not symmetrical or round.

Ok .. interesting. I welded up an old vice and tried to mill the weld smooth. Broke a bunch
of EM's I always thought it was the weld it self that was hard (mig welding) I am way not
afraid to give it a try on the shaft though ..

Reduce the diameter of the 5/8 part, bore the 3/4 part, and heat shrink the two together.

Thats why I come here .. lol Can't believe that thought didn't come to me. Just steal a
little meat from the smaller shaft help the integrity.

Ok .. I think I am going to go what appears to be the traditional route. I'll weld prep the
shafts and weld. Also .. as per the great suggestion, I will use a shaft that is larger than
needed so I can straighten and smooth.

Thanks
Mike