Worn Shaft Repair - Machining JB Weld

Well, my new (vintage) table saw has a few problems.  That's always expected, but how extensive are those problems is the real concern.  Can they be repaired for cheap?

I wired up my 220V circuit, complete with new plug and new outlet, and new switch, and the 1HP motor roared to life.  And boy did it roar.  It was much louder than I expected it should be, so I started troubleshooting.  Let's split the dictionary in half (you know that thought process, eh?).

I took off the belt from the pulley of the motor to the arbor shaft of the saw blade, and turned on the electric motor.  Either the problem will stay, or go away, and I can continue troubleshooting from there.  Well, the motor roared to life again, but this time it shuttered itself to a quick stop. 

I unplugged the motor and looked closely at the motor shaft.  I was a bit taken than I could move that shaft side to side quite a bit.  Much more slop than there should be.  It was obvious a bearing has gone bad.

Tearing things apart, the bearing was quite fine.  The shaft, on the other hand, was not.  The hard bearing whittled quite a bit of material off the shaft.  The bearing bore is 0.670, and the shaft measured at 0.630.  That is 0.040 of wobble, and that is a whole bunch.

My simple and cheap thought was to build up the worn area with JB Weld, and grind it back down to its proper diameter.  Well, I can be a little more precise than "grinding down" surely.  Let's see some pictures already!

Here's the motor armature with shaft.  

The bearing and area of interest is on the right.

This is where the bearing sits.

 This is the wear in the shaft.

 

This center silvery area is where the bearing sits:  0.040 undersized.

 

I chucked it up in the lathe, and I could see with my indicator that the wear was not even concentric.  There was a definite high and low spot.

I turned it down back to concentric.  While I don't think this was necessary, I wanted to leave a rough surface.  Better for my JB Weld to adhere to.

Applying the JB Weld to the worn area of the shaft was a piece of cake.  I noticed that the epoxy would droop over time, so I let the lathe spin as it set up.  A slow speed of 30 rpm kept the epoxy very concentric and smooth:

 

A day later, after the epoxy fully cured, I turned it down to the proper size.  JB Weld machines beautifully with a sharp insert.

The bearing fit on perfectly snug.  I thought I would see how well I did and find the high a low spots with my dial indicator.  Here's the low spot:

And the high spot...  The difference is 0.0002 or so.  That's 2 tenths of a thou.  Much improved over what it had been.

Installed it all back together tonight during a thunderstorm, and the motor sure spins smooth.  I think I'll let it sit without a belt on the pulley so as to not produce any significant loading on the bearing and new epoxy.  Perhaps a few more days will allow it to fully cure and harden.  But initial results look very promising.  Time will tell....

Wednesday Night Adventure Trip

My el-cheapo table saw just bit the dust. 

 
It's only 5 years old or so, but it is truly falling apart.  I don't use it much, and I certainly haven't abused this table saw, but you can see how it is failing.  First off, the cheap aluminum table is so thin, the bolts holding the mechanism underneath are breaking out.

Where this el-cheapo aluminum table top mounts to the base, the plastic is falling off in chunks.  Two of the 4 corners are having this problem.  

What a hunk of junk - look at that big crack:

Thank God for Craigslist.  Last night, I loaded up the family and we headed off to Monticello for the Craigslist deal of the century.  I bought an old Craftsman table saw from a guy looking to reclaim some room in his garage.  This thing is a real tank.  No plastic parts here.

I got a rolling stand, complete with caster wheels that don't roll,
and multiple slides and fences, 

and the saw itself.  It is a Model 100 from Craftsman.  It must weigh 100 pounds.

With a little research, I believe it to be mid 1950s vintage.

That electric motor is huge.  It is a 220V beast, so I will need to add a breaker and outlet to my barn, but that is a quick and easy job.  

I bought all this stuff for less than half of what I bought my junky $99 plastic table saw.  This one should last for my lifetime, I'm sure.  I'm also curious to see if I can clean in up a bit and restore it to it's former glory.  It is a good candidate for a wintertime restoration.

A New Handle Crank

With the purchase of some new steel recently,

I finally made a crank arm for the old Post Drill.

The old Post Drill had been missing this piece for as long as I can remember.  That's probably because it was never hand powered in my lifetime, but driven by an electric motor.  I designed a new crank to work as follows:

The slot is to fit around the 2 "nubbins" on the gear mechanism.

(Ignore the baked enchiladas in the background - it just shows relative size)

I made a little bend in the crank handle to avoid hitting the "advance" mechanism at the top of the post drill.

It fit just right!

Now it's just missing a wooden handle on the long carriage bolt.

 It works pretty smoothly!

Next to do is to make a proper wooden handle for this crank.