Table Alignment, Using Dual Dial Indicators

[dusty]

After completing my modifications to two dial indicator setups, I was faced with the challenge of table alignment using a method not previously used or discussed (at least not by me).

With the headstock and carriage pushed together to meet the rubber bumper, I secured all of the locks. With all of the trunnion bolts loose and the quill fully retracted and the standard table insert removed, I installed a new home made setup block to the left of the blade in place of the normal table insert.

This setup block measures 11 1/2"x 1 31/64". The length is not critical while the width was calculated so as to "center" the blade in the cutout. It was cut carefully to ensure that the long sides are parallel.

The main table was then moved into position so that the setup block was positioned between the table cutout and the blade. Theoretically, this centers the blade and positions it so that the miter tracks are parallel to the blade.

The two trunnion bolts that are accessible were secured, making certain not to allow the main table to shift.

The table is now properly aligned (and if done correctly needs no further alignment). Secure the other two trunnion bolts and the task is complete.

To satisfy myself that this was successful, I used two dial indicators to check 1) infeed edge of blade, 2) center of blade and three outfeed edge of blade. The dial indicators were zeroed together as shown at the infeed edge of the blade.

1 Opposing Gauges Zeroed.jpg (1.88 MiB) Viewed 11129 times

2 Centered on Blade.jpg (1.7 MiB) Viewed 11129 times

3 Outfeed Side.jpg (2.08 MiB) Viewed 11129 times

The dial indications, I believe, indicate a successful alignment. However, as I compare the numbers on the two dial indicators at each of the three locations, I cannot explain the variations. This is the first time I observed dual indicators and they confuse me a bit.

I did rotate the blade to three other locations and took similar readings. This was done to satisfy myself that the two-tooth method previously used was not necessary and could be abandoned as part of table alignment. The saw blade is from Shopsmith and is relatively new so I am confident that it is as flat as any Shopsmith saw blade will be.

[algale]

Sitting home with the flu, I'm having a hard time visualizing how this set up block works. At first I thought it might be riding in the miter slot, but re-reading, that's clearly not the case. How about a picture?

Also (and I know I sound like a broken record), I suspect that the confusing readings of the twin indicators are the result of using the insert as a reference surface for the tips of the dial indicators.

Now that you have the table aligned to your satisfaction and have documented measurements using this dual dial indicator method, it would be interesting to see what measurements you would get by using your old dial indicator jig, which I take it fit in the miter slot and held the tip of the indicator above the table/insert at a constant height/angle.

My suspicion is that your method is more than good enough, which I define for my own purposes as anything less than or equal to .005".

[reible]

What I'd like to hear would be what are the results of using the shopsmith miter gauge with stop rod and a feeler gauge and the tip of one tooth rotated from front to back. Since you have it where you want it this would be a good time to see what numbers that produces.

I used this method for years and had found it to be pretty good. Then came the era of the dial indicator and after finding that frustration for doing the settings I went back to the old method of doing the setting and then using the dial indicator to check things only.

Yes I have done some things differently like using a master plate and the like but I still think the old way works pretty good and would take a lot of effort to improve upon.

The problem with using a saw blade is that you never know how flat it is. This was especially bad on cheap stamped blades but even now with the laser cut ones I think a couple of thousand is not out of the question. Using the same tooth takes that out of the equation. Any error on the flatness and any error in the arbor can either add or cancel but you never know which.

I may pick up a woodpecker version this coming year. I see them on sale now and then, just $10 off but still some savings. I'd like to see how well it works seeing as how they have what I think to be a superior design. The rod in the miter slot means you are getting a center of the miter slot be it a bit wider or not, and you are well into the slot rather then the top edge that could and is a bit more uneven(at least mine seems that way).

Ed

[dusty]

What I'd like to hear would be what are the results of using the shopsmith miter gauge with stop rod and a feeler gauge and the tip of one tooth rotated from front to back. Since you have it where you want it this would be a good time to see what numbers that produces.

I used this method for years and had found it to be pretty good. Then came the era of the dial indicator and after finding that frustration for doing the settings I went back to the old method of doing the setting and then using the dial indicator to check things only.

Yes I have done some things differently like using a master plate and the like but I still think the old way works pretty good and would take a lot of effort to improve upon.

The problem with using a saw blade is that you never know how flat it is. This was especially bad on cheap stamped blades but even now with the laser cut ones I think a couple of thousand is not out of the question. Using the same tooth takes that out of the equation. Any error on the flatness and any error in the arbor can either add or cancel but you never know which.

I may pick up a woodpecker version this coming year. I see them on sale now and then, just $10 off but still some savings. I'd like to see how well it works seeing as how they have what I think to be a superior design. The rod in the miter slot means you are getting a center of the miter slot be it a bit wider or not, and you are well into the slot rather then the top edge that could and is a bit more uneven(at least mine seems that way).

Ed

I always aim to please (though that does not always happen). Using the left hand miter track, shopsmith miter gauge and stop rod:

The tooth was closest at the outfeed side. I adjusted the stop rod so as to touch that tooth and locked it in place. Rotated the blade to bring that tooth to the infeed side and relocated the miter gauge and stop rod. I was able to feel a .005 feeler gauge but could not pass it past the tooth. Using .004" feeler, the feeler sides through with some slight drag. I would call it at .004".

Stop Rod and Feeler Gauge 003.jpg (1.74 MiB) Viewed 11093 times

Stop Rod and Feeler Gauge 005.jpg (1.76 MiB) Viewed 11093 times

[dusty]

Sitting home with the flu, I'm having a hard time visualizing how this set up block works. At first I thought it might be riding in the miter slot, but re-reading, that's clearly not the case. How about a picture?

Also (and I know I sound like a broken record), I suspect that the confusing readings of the twin indicators are the result of using the insert as a reference surface for the tips of the dial indicators.

Now that you have the table aligned to your satisfaction and have documented measurements using this dual dial indicator method, it would be interesting to see what measurements you would get by using your old dial indicator jig, which I take it fit in the miter slot and held the tip of the indicator above the table/insert at a constant height/angle.

My suspicion is that your method is more than good enough, which I define for my own purposes as anything less than or equal to .005".

I will attach a picture later to help explain. In the meantime, I simply removed the ZCI, unlocked the quill feed, located the setup block between the blade and the table cutout and secured the quill feed with the setup block trapped in between. This was done with the trunnion bolts loose. This allows the table to position itself against the setup block. Theory being that the table is now the correctly positioned and centered in the cutout.

I do not believe the insert is causing any issue at all. I don't know how to prove that. The only thing I might say is that moving the dial indicator in across the blade shows no irratic movement.

[algale]

Well, I'd say that the proves your method works since the difference is < 0.005 inches.

[ecom1]

Is the main table locked to the accessory table when you make these tests? I remember seeing a Sawdust Session showing a little play in the main table that could be limited by locking it to the extension - I ask because I could see myself leaning against the machine while making the reading and possibly "twisting" the table.

[dusty]

Sitting home with the flu, I'm having a hard time visualizing how this set up block works. At first I thought it might be riding in the miter slot, but re-reading, that's clearly not the case. How about a picture?

Also (and I know I sound like a broken record), I suspect that the confusing readings of the twin indicators are the result of using the insert as a reference surface for the tips of the dial indicators.

Now that you have the table aligned to your satisfaction and have documented measurements using this dual dial indicator method, it would be interesting to see what measurements you would get by using your old dial indicator jig, which I take it fit in the miter slot and held the tip of the indicator above the table/insert at a constant height/angle.

My suspicion is that your method is more than good enough, which I define for my own purposes as anything less than or equal to .005".

Picture attached. Not a well composed picture but I think it answers your question. If not - just say so.

[dusty]

Is the main table locked to the accessory table when you make these tests? I remember seeing a Sawdust Session showing a little play in the main table that could be limited by locking it to the extension - I ask because I could see myself leaning against the machine while making the reading and possibly "twisting" the table.

NO, I did not lock the tables together but it would be a good idea.

PS No, it would not be a good idea, as JPG pointed out later in this thread. The extension table would most likely not be properly aligned at that time and tying the two together would hinder main table alignment. Remember. the trunnion bolts are loose and the main table can be moved all around. You might be successful, tying them together, but only if by some chance the extension table was where it should be.

Even with the extension locked to the main table you want to avoid lending on the main table. It does move. Set up in the saw table mose and mount a dial indicator and see jsu how much it moves. Especially bad if the locks are not secured.

[algale]

Yes, thanks Dusty, I see. I like the idea a lot.

I may make something similar, only with a tight fitting miter bar of its own. A properly sized plywood board would be screwed/glued to the miter bar and extend over the table and half way across the table insert.