Do the Way Tubes Have an Effect on Alignment

[dusty]

I do not understand this test set up and how it demonstrates a lack of parallelism between bench and way tubes.

Maybe the pictures are not what I should have included but if the bench tubes were parallel to the way tubes they would, at all locations along the length of the tubes, be separated by exactly the same distance.

The first and second images were intended to show that.

The images are at opposite ends of the tubes on the shorty. In one image they are 1/2" apart and at the other end they are 5/8" apart.

I became aware of this when I moved my caliper jig to the right end of the Mark V. The unit could not be placed in saw mode. The caliper prevents the tubes from going down that far. It is about 1/2" too tall.

This whole affair is a surprise to me because I have always assumed parallelism between the tubes.

I will post a picture tomorrow of the caliper jig mounted on the tubes at the right end. This will show clearly that the tubes are not parallel.

[algale]

Maybe the pictures are not what I should have included but if the bench tubes were parallel to the way tubes they would, at all locations along the length of the tubes, be separated by exactly the same distance.

The first and second images were intended to show that.

The images are at opposite ends of the tubes on the shorty. In one image they are 1/2" apart and at the other end they are 5/8" apart.

I became aware of this when I moved my caliper jig to the right end of the Mark V. The unit could not be placed in saw mode. The caliper prevents the tubes from going down that far. It is about 1/2" too tall.

This whole affair is a surprise to me because I have always assumed parallelism between the tubes.

I will post a picture tomorrow of the caliper jig mounted on the tubes at the right end. This will show clearly that the tubes are not parallel.

The third photo, which you added after my comment, clarifies what the vertical ruler was referencing off of. I know understand what you are saying. What does a Wixey say about the angles along (1) length of the bench and way tubes and (2) the angles across the bench and way tubes (board between them)? Do the angles agree or disagree?

[dusty]

The third photo, which you added after my comment, clarifies what the vertical ruler was referencing off of. I know understand what you are saying. What does a Wixey say about the angles along (1) length of the bench and way tubes and (2) the angles across the bench and way tubes (board between them)? Do the angles agree or disagree?

I can't give you actual numbers without going out to do a check but the wixey is relatively close realizing that the wixey is accurate to only .1 degrees.

That error extended the length of the tubes becomes a respectable number.

[dcottrill]

I've know that the way tubes are crowned and that by rotating them in the Tie-bar and base arm will effect how easy or hard it is to move the head stock.

I also would have assumed that the way and bench tubes would be parallel.

Shortly after I got my shopsmith I attended a SS clinic where the instructor expand that the little hex screw under the tie-bar on the way tube is used to align the centers for turning. It makes sense if you are going to be able to set the accessory tables level.

I can also see that if the crown of one tube is the opposite of the other it would result in the way-tubes ending up skewed or twisted.

How much of a concern is this?

[algale]

I can't give you actual numbers without going out to do a check but the wixey is relatively close realizing that the wixey is accurate to only .1 degrees.

That error extended the length of the tubes becomes a respectable number.

I am interested to hear you say that because I have come to have doubts about the reliability of my Beall tilt box (Wixey clone) for critical measurements. A tube reading zero on the Wixey could be 0.1 to -0.1. Thus two tubes both reading the same zero could in fact be as much as 0.2 different. I believe an angle of 0.1 degrees translates to a slope of 1/32nd inches per foot. And 0.2 to a slope of 1/16th inches per foot. I don't know how long your bench tubes are but over a four foot length, a 0.1 degree error compounds to a 1/8 inch error and a 0.2 degree error compounds to a 1/4 inch error.

[dusty]

I am interested to hear you say that because I have come to have doubts about the reliability of my Beall tilt box (Wixey clone) for critical measurements. A tube reading zero on the Wixey could be 0.1 to -0.1. Thus two tubes both reading the same zero could in fact be as much as 0.2 different. I believe an angle of 0.1 degrees translates to a slope of 1/32nd inches per foot. And 0.2 to a slope of 1/16th inches per foot. I don't know how long your bench tubes are but over a four foot length, a 0.1 degree error compounds to a 1/8 inch error and a 0.2 degree error compounds to a 1/4 inch error.

I've gotten lazy while at the same time loosing my confidence in doing these calculations. But I can use sketchup. When a plot a 48" long line and then alter it by .1 degrees, the distant end of the line moves 1/16".

[charlese]

After getting satisfied with perfect alignment of the way tubes, think about how much headstock movement is caused by tightening the wedges on the tubes. There is often a rise and a slight twist. To offset this maybe one can see if the wedges perfectly flat and on the exact angle? Are the wedges exactly spaced on their threaded bar? Maybe there is a need to re-thread the bar, or to rotate one of the wedges one revolution. Have at it!

How about that for efforts in futility!

Of course one can always go to extremes to achieve naught.

[dusty]

After getting satisfied with perfect alignment of the way tubes, think about how much headstock movement is caused by tightening the wedges on the tubes. There is often a rise and a slight twist. To offset this maybe one can see if the wedges perfectly flat and on the exact angle? Are the wedges exactly spaced on their threaded bar? Maybe there is a need to re-thread the bar, or to rotate one of the wedges one revolution. Have at it!

How about that for efforts in futility!

Of course one can always go to extremes to achieve naught.

If this gives rise to understanding, it is not for naught.

I now know for a fact that the way tubes are not parallel to the bench tubes. Why?

I also know that this was changed in the Mark 7. Since the two ends are the same, this difference cannot exist. Why was this changed?

In the Mark V, there is a set screw that does not exist in the Mark 7. Why?

No! This endeavor will not be for naught.

[JPG]

I am having 'difficulty' confirming the 'slope/ft' of 0.1 degrees.

cos(0.1) = .99999848 x 48" = 47.99992689 - 48 = -0.00007311 which is far from 1/16" over 4'.


Whoops!:o shoulda been sin(0.1) = 0.00174533 x 48" = 0.08377578 which is a little less than 3/32.

[dusty]

On my main machine, the Way Tubes are not parallel to the Bench Tubes.

I took readings a couple times today to ascertain that. In the following I have recorded the distance from the top of the BENCH Tubes to the under side of the WAY Tubes. If they were parallel, these four numbers would be nearly identical.

I took the readings on the four corners where the separation is dictated by the Base Assembly and the Headrest.

The readings are as follows:

................LT Side.......RT Side

INFEED........6 1/64".......5 7/8"

OUTFEED.....6 11/64".....5 5/8"

I am uncertain what this all means except that the assumption that the tubes are all parallel to one another is not a safe assumption.