Author Topic: Table saw rebuild  (Read 5591 times)

Spork

  • Walrus Stache
  • *******
  • Posts: 5753
    • Spork In The Eye
Table saw rebuild
« on: December 14, 2013, 12:08:18 PM »

About a year ago a widow friend of my father gave me her late husband's table saw.  It is an old Rockwell 34-440 contractor's saw.  It is heavy as hell (compared to contractor saws I see today).  When I got it, it was not in the best of shape.  There was a lot of minor surface rust.  The fence required a rubber mallet to move it.   Mechanisms to raise/lower/tilt the blade were difficult to move (understatement).  The wiring looked like a portable electric fire.  Add to this: every square inch of this thing was covered in mud dauber nests.

I am by no means a woodworker.... but I'd like to be.  I'd really like a nice saw one day... but until I have a little skill and can justify the expense, I'm not ready to buy one.  With that in mind, this saw finally reached the top of my "do it" queue recently.  I tore the saw portion down completely, cleaned it up, lubed it with dry lubricant.  It looks much better.   I threw out all of the wiring and replaced it up to the motor (but did not dig into the motor itself).

The motor has no markings on it whatsoever.  It was wired for 120v, so that is how I rewired it.  There is no plate with voltage/amperage on it.  The motor appeared clean from the outside, so I did not tear into it at all. According to his widow, this was the one thing this guy was protective of when it came to mud daubers.  He had screening on it to keep them out of the motor internals.

The lead hot wire on the motor was huge... like probably 10ga or maybe 8ga wire.  Google tells me this would be either a 13amp or 15 amp motor.  Once it was all put together, I plugged it in and turned it on.  The damn thing only pulls 4amps.

The blade is old and needs to be replaced... but with the old blade, it will do a mediocre job going through 1/2in material.  Bigger than that... and the blade slows to unusable.

I'm thinking the motor is either shot... or needs work.   When it comes to electrical motors: I'm fine as a partswapper... but I really don't know what I am doing.  Would replacing brushes (or something?) be a reasonable course of action?  Or is this a bit of a lost cause? 

_JT

  • Stubble
  • **
  • Posts: 229
Re: Table saw rebuild
« Reply #1 on: December 14, 2013, 04:31:09 PM »
Table saws are typically equipped with AC induction motors, also know as 'asynchronous',  or 'squirrel cage' motors, if you've heard any of those terms.

First things first: induction motors are magical devices. One of their many magical properties is they draw a variable amperage based on the load you place on them. They also have upper and lower bounds, call 'unloaded'  amp draw and 'full load' amp draw. The plate rating is going to be your FLA (full load amp draw), or what the motor would draw if it was loaded to its maximum rated horsepower. When you started your motor, it drew 4 amps. That's unloaded. At that point in time, the only power the motor is using is the minimum amount needed to keep its stator field from collapsing. Typically, unless it's a huge industrial motor, this is just a few amps. Your unloaded amperage is higher than I'd expect for a single phase 3/4 or 1hp tablesaw motor, which is probably an indication of motor windings in subpar shape. It is possible to have motors rewound, although that's not really cost effective for a motor that small.

Second thing: ac motors don't have brushes (which is why they're so quiet), so there aren't any easy parts to swap out.

I'd put a new blade on it and see how it does, and it if still struggles to cut through greater than 1/2" material look into replacing the motor. Depending on the age, there may be a dedicated online community that are experts and refurbishing/repairing that exact saw.

Good luck!
« Last Edit: December 14, 2013, 09:23:40 PM by _JT »

Spork

  • Walrus Stache
  • *******
  • Posts: 5753
    • Spork In The Eye
Re: Table saw rebuild
« Reply #2 on: December 14, 2013, 05:15:52 PM »
First things first: induction motors are magical devices. One of their many magical properties is they draw a variable amperage based on the load you place on them. They also have upper and lower bounds, call 'unloaded'  amp draw and 'full load' amp draw.

AH!  Ok, that at least makes me feel somewhat better.  And that makes sense.  I'm a computer nerd and the same thing is true of computer power supplies.

A new blade was my next guess.  I would say this blade not only doesn't look very high tech... it looks as if it has seen better days.

I was mostly worried that if a thin kerf blade wouldn't go through a 2x2... that a wide dado was going to be impossible.... but... I have seen new saw blades make huge differences.

ArcticaMT6

  • Stubble
  • **
  • Posts: 167
Re: Table saw rebuild
« Reply #3 on: December 14, 2013, 11:39:41 PM »
Definitely put a new blade on. I'm pretty partial to the Freud Diablo blades, Home depot carries them. Great quality for cheap prices.

Woodshark

  • 5 O'Clock Shadow
  • *
  • Posts: 78
Re: Table saw rebuild
« Reply #4 on: December 15, 2013, 04:08:18 PM »
Clean it up. Smack a new blade on it and enjoy using a tool that is affectionately known on the net as "old iron".  Now you got some braggin' rights.

Spork

  • Walrus Stache
  • *******
  • Posts: 5753
    • Spork In The Eye
Re: Table saw rebuild
« Reply #5 on: December 15, 2013, 05:10:13 PM »
Clean it up. Smack a new blade on it and enjoy using a tool that is affectionately known on the net as "old iron".  Now you got some braggin' rights.

I've been fishing for an "old iron" Powermatic 66 (at a reasonable price) for almost 10 years...   

This will hopefully get me over the hump until that find shows up.

Woodshark

  • 5 O'Clock Shadow
  • *
  • Posts: 78
Re: Table saw rebuild
« Reply #6 on: December 17, 2013, 03:43:26 PM »


You and me both brother. You and me both.

Exflyboy

  • Walrus Stache
  • *******
  • Posts: 5992
  • Age: 57
  • Location: Corvallis, Oregon
  • Expat Brit living in the New World..:)
Re: Table saw rebuild
« Reply #7 on: December 17, 2013, 05:07:40 PM »
Buy a 10" blade with carbide teeth from Harbor Freight... Good blades and the cheapest anywhere. 40T blades cheap and good for rough cutting.. 60Ttooth spendier (still cheap thought) for finish work.

It is possible your belt or squish plates (friction connection to the blade) are slipping.

Simple mechanical stuff.. take a look at these items.

As long as the motor spins freely its good to go.

Frank

Spork

  • Walrus Stache
  • *******
  • Posts: 5753
    • Spork In The Eye
Re: Table saw rebuild
« Reply #8 on: December 22, 2013, 04:08:21 PM »
I finally got around to getting a new blade... that seems to have fixed the issue.  Thanks!

It still isn't quite equivalent to a big ass powerful cabinet saw (but I guess that would be an unreasonable expectation)... but it will definitely rip 2 inch materials.   It will definitely be enough to get me started.