Table Alignment, Using Dual Dial Indicators

[algale]

That would be a way to align the accessory table after the main table is aligned.

I was actually just going to ask this question.

I did routine maintenance and alignment on my 520 a couple of months ago, and aligning the accessory table was a huge PITA. I've been thinking about how to simplify the process, and thought that I could perhaps loosen the bolts under the accessory table, then lock it to to the main table (while keeping a square against the disc sander), and then tighten everything down. I can't see why this wouldn't work.

Is this what everyone else does?

I follow Nick's procedure from this video.

[youtube]https://www.youtube.com/watch?v=EpuDalMsoag[/youtube]

[ecom1]

I just re-wathched the Sawdust Session on that, and what Nick did was loosen the extension table bolts, then adjust them to match the table rods (i.e. so the table rods slide smoothly between the main and extension). I guess if the guides are aligned properly, and the table is flat, this should work.

[ecom1]

That would be a way to align the accessory table after the main table is aligned.

What I meant was if you leaned/put pressure on the table while taking the reading, you could twist the table out of alignment with the quill - locking the main the the extension would lessen any "twist"factor"

[JPG]

Any time when alignment adjusting is being performed, all external forces should be eliminated. That includes 'leaning' on that which is being aligned.

[dusty]

When the trunnion bolts are loose, by all means you can not lean on the table(s). With the trunnion bolts secured, the Mark V is not all that susceptible. I see .003" - .005" of movement when external forces are applied to the tables, headstock, etc. These same measurements change that much as you simply lock down the table, carriage and headstock.

[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 am still not certain about the deviation in numbers that I get when using the dual dial indicators. I have checked and double checked the alignment, however, and it is as good as I have ever had.

I think that most of my confusion has been brought about by the fact that the indicators are not identical in appearance as I move them around. If I pay attention only to the numbers and disregard the physical position of the indicator needles - everything checks out.

If I hold the dial indicators in my hands and zero them both, they look alike. Manually activating the plunger and allowing it to return, they both function alike, time after time.

If I zero the indicators in the same location, they read zero but the indicators are at different locations on the dial. Duh!!

The tips, though they look alike, are not exactly the same length. Thus, the degree of rotation of theindicators is not identical. I came to realize this when I had the two meters setup opposing one another at the same location. A .005" change in one was the same in the other but in the opposite direction (as you would expect). Swapping tips on the indicators and doin the same thing over and over is what finally clued me in.

This has been a learning experience just riddled with "cock pit errors".

Final conclusion: The dual indicator procedure works well and is, in my opinion, a bit easier and quicker. It is not anymore accurate. In fact, by double checking using the alternate procedures that we all know about, there is not a great deal of difference in the accuracy that is available.

Using the miter gauge with a stop rod and a set of feeler gauges can get you to the same level of accuracy as dual dial indicators but is a bit more of a tedious process.

I ordered a second set of indicator tips so that I can have identical tips on both indicators. I just hope that when they arrive, I am not disillusioned.

[JPG]

I hope the 'new' set of tips matches one of the 'current' sets.

[dusty]

I hope the 'new' set of tips matches one of the 'current' sets.

yeah, I do too. The original set came from Shopsmith. The replacement set was purchased on-line and looks identical. If there isn't a match, I'll have to try again. The new tip set was $9.00 with free shipping.