Replies

1. 
   forestgirl | Apr 09, 2002 08:45am | #1

   I'm no expert in this effort, but I just completed a major struggle with my Jet contractor's saw (without a master plate), and can pass on how I did the measuring part, FWIW!

   First, I installed the absolute best blade I had with regard to flatness.  I found the tooth that was closest to the miter slot I was measuring to and marked that tooth with a Sharpie pen.  Then I pulled the rule out of my Stanley combination square, and clamped it to the miter gauge (upright, not flat on the table).  I positioned The Tooth at the very front of the blade's arc, and butted the rule up against the body of the saw blade, right next to that tooth.  I started at the front of the arc, because I knew that the blade was closer to the miter slot at the front than at the back.

   Then I rotated the saw blade so that The Tooth was at the very back of the arc, and slid the miter gauge, along with the rule, back to that place.  It was easy to see the gap between the edge of the rule and the saw blade.

   Now, I wasn't able to get with .001, but that was because my saw's screwed up!  When I get a new one, I won't be able to afford a Masterplate ;-) so I'm sure I'll use the same method.  The main difference being, I'll probably use my Incra 1000 miter gauge to clamp the rule to, rather than the dumb Jet miter gauge.

   Good Luck!

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl!

2. 
   RickL | Apr 09, 2002 12:58pm | #2

   Those are pretty tight tolerances you are asking for a tablesaw. I was adjusting saws long before those products came out. We had a $30,000 Giben beam type panelsaw that you couldn't get a gauge in so we used a piece of MDF to read the cut. If both edges of the MDF had front and back saw marks from the blade this meant the saw was cutting straight and true. If the left edge of the MDF cut edge had the front saw marks from the right edge of the MDF had the back marks from the saw blade you knew the saw carriage was cocked at an angle. You could also get an inexpensive dial indicator gauge from a place like http://www.use-enco for about $16 and mount it on a piece of wood on your miter gauge and mark a tooth and indicate off that tooth with the blade in forward and back positions. Make sure you use the same tooth. Not sure how clear I made that point. There's a lot more to say about how to go about this. I'm sure there are some books and articles on this. With subjects like this a picture is worth a thousand words and more than can be conveyed in a short post. A feeler gauge will also work. I'm sure someone else will chime in with a few other ways. Gotta run. Good luck!

3. 
   HowardAcheson | Apr 09, 2002 06:00pm | #3

   Here is the low tech, low cost way to align a tablesaw that I learned maybe forty years ago and teach to my students now.

   Make 3/4 x 3/4 x 12" hardwood stick. Drill a hole somewhat centered in one end and insert a brass #8 x 1" round head wood screw about half way. Raise the blade completely up. Clamp this board in your miter gauge (if you determine that there is some slop in your slot to miter gauge, use a playing card to take up the slop) so the screw head just about touches the blade at the front. Now rotate the blade by hand (BTW, unplug the saw) and determine which tooth is the closest. Adjust the screw in or out until it just touches this tooth. Mark this tooth. Rotate the blade so the tooth is now at the back of the table and move the miter gauge/stick assembly to the back and see if it touches the marked tooth to the same extent. If it doesn't, adjust the trunnion until it does. The blade does not move directly around the center so you will need to repeatedly go back to the front of the blade, readjust the screw, and then again measure the back. Be sure to check after tightening the trunnion as the trunnion frequently moves when being tightened.

   The same adjustment gauge can be used to set the fence parallel to the miter slot. Slide the miter gauge to the front of the table and move the fence over to the screw head and insert a playing card between the screw head and the fence just so you can move the card as it touches both the fence and the screw head. Now move the miter gauge to the back of the table and see if you have the same feel when you insert the card. I like my fence absolutely parallel--if you want to have a slight opening to the fence, you can easily estimate the opening by adding a thickness of paper to the card.

   I always show my students with a dial gauge that their adjustments are within .001 - .002.

   You can also use the same gauge to measure blade runout by using a $5.00 feeler gauge.

   Bottom line, there is no need to spend more than the $0.05 for the brass screw.

4. 
   HowardAcheson | Apr 09, 2002 06:04pm | #4

   Here is the low tech, low cost way to align a tablesaw that I learned maybe forty years ago and teach to my students now.

   Make 3/4 x 3/4 x 12" hardwood stick. Drill a hole somewhat centered in one end and insert a brass #8 x 1" round head wood screw about half way. Raise the blade completely up. Clamp this board in your miter gauge (if you determine that there is some slop in your slot to miter gauge, use a playing card to take up the slop) so the screw head just about touches the blade at the front. Now rotate the blade by hand (BTW, unplug the saw) and determine which tooth is the closest. Adjust the screw in or out until it just touches this tooth. Mark this tooth. Rotate the blade so the tooth is now at the back of the table and move the miter gauge/stick assembly to the back and see if it touches the marked tooth to the same extent. If it doesn't, adjust the trunnion until it does. The blade does not move directly around the center so you will need to repeatedly go back to the front of the blade, readjust the screw, and then again measure the back. Be sure to check after tightening the trunnion as the trunnion frequently moves when being tightened.

   The same adjustment gauge can be used to set the fence parallel to the miter slot. Slide the miter gauge to the front of the table and move the fence over to the screw head and insert a playing card between the screw head and the fence just so you can move the card as it touches both the fence and the screw head. Now move the miter gauge to the back of the table and see if you have the same feel when you insert the card. I like my fence absolutely parallel--if you want to have a slight opening to the fence, you can easily estimate the opening by adding a thickness of paper to the card.

   I always show my students with a dial gauge that their adjustments are within .001 - .002.

   You can also use the same gauge to measure blade runout by using a $5.00 feeler gauge.

   Bottom line, there is no need to spend more than the $0.05 for the brass screw.

5. 
   sschefer | Apr 10, 2002 07:34am | #5

   Well, I think I am somewhat of an expert in this field. Jeeze, I know I've done it enough for sure. First off, the framing square is probably the last thing you want to use. I've yet to find one that is accurate within .001. The stick with a brass screw method works excellent. My high school shop teacher taught me the same trick. That will get you within about .002 but that's only if the blade you are checking against is flat, your arbor runout isn't excessive and you remember to hold the miter gauge up against the slot. All of these later things are what will get you all confused when you put a dial gauge on it. One minute it will be dead on, then without realizing you've moved the blade, a second check will show it to be out again. The next time you can't seem to remember which side of the miter slot you held against, etc, etc. Do you really need accuracy beyond .002 ? It all depends on what type of work your doing. If you rip with a rip blade and don't expect to get glue line ready cuts then no. On the other hand if you rip with a 50 tooth combo blade like me and don't have a jointer then the quality of the cut is very important and therefore so is the blade alignment. I have the plate and the dial gauge that rides in the miter slot. It's all I use anymore and it's not that big of an investment. I'll continue to use it until I can afford a jointer and then I'll stop all of this anal blade alignment stuff. LOL Obviously I'm kidding about it being anal. Proper blade and fence parallelism is an extremely important safety factor. Let it get out of hand and you risk some serious kickback problems.

   Steve - in Northern California

   
   

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   Edited 4/10/2002 12:38:04 AM ET by Steve Schefer

   
   

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   Edited 4/10/2002 12:40:17 AM ET by Steve Schefer

1. 
   DaveArbuckle | Apr 10, 2002 09:04pm | #6

   Steve, as Howie mentioned, you should be using only one tooth of your tablesaw, and it should be marked (I use a Sharpie, but I'm sure other brands of markers work well also ;-)). This eliminates the concern regarding blade or arbor runout.

   Dave

1. 
   sschefer | Apr 10, 2002 09:41pm | #7

   Dave, you are correct I made the mistake of making an assumption.

   The way to check for runout it is to rotate the blade and mark the point at which max runout is seen. Then rotate the blade 90 degrees from the mark and draw a line across the the lowest point of the fully raised blade. Rotate the blade another 90 degrees, mark it and you will have the min. Now rotate the blade measuring the difference between the minimum and maximum and divide that in half. You now have the average difference and you can place the blade back to where the line accross the blade that you created before is now parallel to the table. In this manner you will be checking against the average arbor/blade runnout rather then the max or min. When your conduct your checks and adjust your trunion, the average difference can be used to determine your true alignment. If it works right, you should be able to set your trunion to give you a .000 corrected difference from front to rear. Remember to check across the exact center of the blade.

   Did I remember to tell you that I'm anal about blade alignment

   Steve - in Northern California

   Edited 4/10/2002 2:42:32 PM ET by Steve Schefer