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+-- Thread: Set the cursor on a T-Square fence (/showthread.php?tid=7344816)
Set the cursor on a T-Square fence - Paul K. Murphy - 12-05-2018
How to calibrate the cursor. No instruments, accuracy better than your perceptions or ability to use it.
We’ll assume you have a piece of MDF or very stable plywood lying around; say, two pieces 12” X 15”.
Decide how you’d like to view the cursor, where your line of sight will be. Take this step and really make that choice. You’ll need to view the saw this way in the future. You have to like it, to be satisfied.
Set the saw to 4” and rip three 4” pieces from your two pieces of panel stock. Do not release the cam lever. Leave that fence locked. Place the six pieces of 4” stock edge to edge, cram them into the fence with a little force. Pushing them with your hand will be enough. Measure the six pieces. 4 X 6 = 24. The six pieces will probably not be exactly 24”. Whatever error has occurred will be manifested as error X 6. If you are off 1/64”, you’re over by 1/64”, the group will measure 6/64” greater than 24”. That’s a whopping 3/32”. Since you have not moved the cam lever, this is the known result of this setting. Loosen the screws that fix the cursor and make the adjustments. Now set the saw to 3 3/4” and repeat the process. The math will be the same, only with new numbers. Now you’re working with multiples of 3 3/4 instead of 4. You may have to do this three or four times until you get it right on the money. I’ve never had to tinker with it past two times. Incidentally, I actually just use five 4” pieces. It’s just a common sense way to multiply the error on initial setups so they can be easily seen. Like I said, you’ve got to decide how you like to view the cursor, and you’ve got to stick to it. If you don’t, parallax will ruin everything.
Do this when you change blades.
RE: Set the cursor on a T-Square fence - CARYinWA - 12-05-2018
(12-05-2018, 12:49 AM)Paul K. Murphy Wrote: How to calibrate the cursor. No instruments, accuracy better than your perceptions or ability to use it.
We’ll assume you have a piece of MDF or very stable plywood lying around; say, two pieces 12” X 15”.
Decide how you’d like to view the cursor, where your line of sight will be. Take this step and really make that choice. You’ll need to view the saw this way in the future. You have to like it, to be satisfied.
Set the saw to 4” and rip three 4” pieces from your two pieces of panel stock. Do not release the cam lever. Leave that fence locked. Place the six pieces of 4” stock edge to edge, cram them into the fence with a little force. Pushing them with your hand will be enough. Measure the six pieces. 4 X 6 = 24. The six pieces will probably not be exactly 24”. Whatever error has occurred will be manifested as error X 6. If you are off 1/64”, you’re over by 1/64”, the group will measure 6/64” greater than 24”. That’s a whopping 3/32”. Since you have not moved the cam lever, this is the known result of this setting. Loosen the screws that fix the cursor and make the adjustments. Now set the saw to 3 3/4” and repeat the process. The math will be the same, only with new numbers. Now you’re working with multiples of 3 3/4 instead of 4. You may have to do this three or four times until you get it right on the money. I’ve never had to tinker with it past two times. Incidentally, I actually just use five 4” pieces. It’s just a common sense way to multiply the error on initial setups so they can be easily seen. Like I said, you’ve got to decide how you like to view the cursor, and you’ve got to stick to it. If you don’t, parallax will ruin everything.
Do this when you change blades.
I guess I am a little confused. How can I measure if I don't have any instruments? If I have a tape then I just cut, measure, and set the cursor. I usually measure with a HF caliper but a tape is close enough.
RE: Set the cursor on a T-Square fence - Phil Thien - 12-05-2018
(12-05-2018, 10:34 AM)CARYinWA Wrote: I guess I am a little confused. How can I measure if I don't have any instruments? If I have a tape then I just cut, measure, and set the cursor. I usually measure with a HF caliper but a tape is close enough.
I think he is just saying no instruments like a caliper.
I think this method is actually a very good way to calibrate to a tape measure, though.
RE: Set the cursor on a T-Square fence - Stwood_ - 12-05-2018
That's quite a task....
RE: Set the cursor on a T-Square fence - Phil Thien - 12-05-2018
It is really just like the five-cut method often used for checking a sled's fence.
Rip several pieces of MDF without moving your table saw's fence.
Use whatever measuring device you tend to use for working on projects, to measure the combined width of the pieces you just cut.
Divide that # by the number of pieces, which will give you a true picture of the exact position of your fence.
Without unlocking the fence, set the scale of your fence to match this number, and you should be in very good shape going forward.
Rinse, repeat for a try at even greater accuracy.
RE: Set the cursor on a T-Square fence - Paul K. Murphy - 12-05-2018
Phil’s got it.
Yes, you will need a tape.