Table Saw Alignment

Before diving into the project, it’s good to review a couple of helpful reminders:

It’s really easy to lose parts

• There aren’t a lot of different parts but keeping them in one place is important. 
• I used magnetic parts tray but a jar or small cup will work too. 

It’s easy to forget how things go together

• I reassemble as much as I can as soon as I can.  Even if I know it will need to come apart again this will help me to keep track of the parts and gives me practice on how they go back together.
• I take photos or video showing how things go back together whenever I think something will give me trouble later on.
• I might get unexpectedly interrupted during disassembly.  The interruption might take me away from the project for hours, days, or even weeks.  So, leaving things as assembled as possible and keeping photos of stuff might just save the project.

Disassembly

• I removed the blade, blade guard, and the throat plate.
• I removed the fence, guide rails, mounting hardware, and table extensions.
• After that, I removed the belt.  This is easily done by lifting up the motor and taking the belt off of the pulleys.
• Then I removed the motor.  On some saws the motor is bolted to the frame.  For this saw the motor can be removed by pressing in two spring loaded pins at the hinge point.
• Finally, I removed the switch.  For the most part, removing the switch allows me to take away the motor and all of its wiring.

At this point I’m ready to unbolt the saw from the legs and place saw upside down on the floor.  Normally it would be prudent to put down some wood or a piece of carpet to protect the table surface from damage.  But, in this case it just doesn’t matter.  I don’t think that the concrete is going to cause any harm.

I continued by removing the hand wheels.

Both the blade tilt and blade elevation shafts have these roll pins that need to be removed.  A pin punch is needed to push the pins out of their holes.  I support the shaft with a block of wood before trying to tap out the pins.  If I don’t do this the shaft will flex with every tap on the punch and the pin won’t move.

Then I removed the screw that holds the blade tilt angle pointer.

Finally, the sheet metal shroud is ready to be removed.  There are four bolts that hold the shroud to the table.

Somehow, two of the bolt holes in the shroud were damaged on this saw.  The shroud will need to be repaired before reassembly.

Here is the other damaged bolt hole.  Once the bolts are removed the shroud can be taken off with the shafts passing through their respective holes.

Doesn’t look like much without the shroud!  I’ve put the hand wheels back on temporarily so that I can keep track of the parts. 

The blade carriage will come free from the trunnions when the trunnion bolts are removed. 

I took this photo so that I could remember how the blade tilt shaft went back together. 

The shaft is held in place with collars which are held in place with set screws.  Here’s a close-up photo showing how the set screw slipped and gouged the surface of the shaft.  Gouges like this will need to be smoothed over with a file before the shaft can be pulled through the bushing.  Attempting to pull it through without filing the gouges smooth will cause damage to the inside of the bushing.

The shaft was also bent.  It must be straightened before it can be pulled through the bushing.

I marked the inside of the bend with a felt tip pen so that I could remember which way the bend went.  Then I placed the shaft in a milling vise with three aluminum blocks.  These will provide the pressure I need to straighten out the shaft.  I use aluminum because it is soft and won’t cause dents in the shaft.  A plain old bench vise can be used to do this just as well.  I carefully bend it back a little at a time, checking periodically to make sure that I don’t over do it.

With the shaft removed, it becomes obvious that the bushing wasn’t drilled on center.  This is done on purpose to allow for adjustment.  We’ll see this again when the saw is reassembled.

I wanted to polish the surface of the shaft in the lathe to remove rust, scratches, and dings.  But, it would be dangerous turn such a thin rod supported on only one end.  So, I center drill the end of the shaft, allowing it to be supported by the tail stock center.

Here’s the setup I used to polish the shaft.  There is no reason to remove the worm gear so I left it on.

To prevent gouges in the future, I filed flats in the shaft where the setscrews go.  I will reassemble the collars onto the shaft with thread locker so that it will not loosen.

Inspection

Before taking any measurements, I cleaned and scraped all the important surfaces. 

I put the front trunnion on one inch gauge blocks on the surface plate to measure it’s height at top-dead-center.

Then I compared that measurement to the top-dead-center of the rear trunnion on the same gauge blocks.  The trunnions were within 0.0023″ of each other.  This is excellent.  I pretty much expect them to match to within 0.005″.

Then I put the table into the machining center to measure the height of each boss.  The difference between the lowest point on the lowest boss to the highest point on the highest boss was 0.0329″.  This is not so excellent.  In the next installment I will be machining the table.  The first step will be to make sure that all of the bosses are at the same height.  They will be used to fixture the table when I machine the top.  If they are not all at the same level then the table will not come out flat.

The last thing I wanted to do was check arbor/flange runout and the condition of the bearings.  Unfortunately, the arbor is threaded all the way up to the flange so I wasn’t able to obtain an accurate measurement.  However, I did measure the flange runout using the setup shown above.  This is a 0.0001″/div test indicator and I have it mounted with a small magnetic base.  Anything under 0.001″ of runout is acceptable and I measured a total indicated reading of 0.0006″ - which is very good. 

Pushing and pulling on the arbor didn’t reveal any measurable axial play.  As I mentioned in the article on table saw diagnostics, bearing play should be less than 0.001″.  It can affect the accuracy and reliability of measurements needed to align the blade.  Vibration from axial play will produce a poor quality cut which will need further work (jointing) before glue-up.  If the play is more than 0.005″ then the bearings are worn out and need to be replaced.  

Finally, I rotate the arbor by hand to see how it feels.  If it rotates with a rough and gritty feel then the bearings are damaged and need to be replaced.  The bearings on this saw rotate freely and smoothly and appear to be in pretty good condition.

Comments and questions are most welcome.  Let me know if I missed something!

Ed Bennett
ejb@tablesawalignment.com