Parallel Extension Tables

[algale]

JPG, It might be interesting to know what all those pre-510/520 adjustment procedures were to get the M5/500 main table/extension table parallel and coplanar. The only adjustment I recall reading about from the old M5 manual to try to get twist out had to do with squaring the headstock. I think I read about that in one of your posts. Were there others?

I partially agree with you that those old adjustment techniques are less important with the 510/520 system, but only to the extent we are talking about a legless "floating" table. Since that kind of table takes its position by the rails/tubes, twist doesn't matter. But getting rid of twist still matters with the 510/520 when using an extension table AND trying to tie the extension and main table together with the tubes to create a more rigid platform. Nick's video proves just how significant that twist becomes.

Regarding "purity" and the "secret" adjustment screw: I also noticed Nick mentioning how he had taken the machine out of adjustment prior to filming, but my guess is he first monkeyed around to get it into adjustment, then did the 1/4 turn to take it out of adjustment, so he knew how much he needed to turn the "secret" screw to get it properly adjusted quickly for filming purposes. And I'm still miffed he didn't prove the table could be swapped back to the other end and that the adjustments would hold. All he proved was that you could take one extension table, adjust it perfectly for one end, then swap it and get it into alignment in a particular location using the "secret" set screw. Even if the table could be swapped back, would that alignment and "swapability" hold as the Shopsmith is moved around to some other location?

Which brings me to a question that reible's posts got me thinking about. I have questions about twist being induced unintentionally after things are set up t. It seems to me like you could set things up nice and square and perpendicular on a nice flat surface, like a work bench, or even a studio floor, compensating things perfectly and possibly achieving the holy grail of perfect "swapability" without ever having to make adjustments again if the machine is only used on flat, even surfaces. But let's face it, the surfaces of most basements/garages/driveways where we use our Shopsmiths are not flat and have some uneven spots. I see this in my own basement when I move my jointer around and try to use infeed and outfeed tables. The floor may look flat, but it isn't remotely flat.

But still, wherever I move my Shopsmith on my uneven basement floor -- and I move it around a lot -- whenever I go to lower it down, it miraculously sits on all four of its feet. If that's the case, my machine has got to be twisting in some direction to accomplish this, right? And I can't see how the Shopsmith can accomodate the twist of sitting with all four legs flat on an uneven surface without that twist being translated to the orientation of the extension table leg bore holes in the headrest relative to those bore holes in the base arm assembly. Nick's 1/4 turn of the "secret" adjusting set screw shows just how much even a little twist can impact whether a swapped extension table remains sufficiently co-planar to the main table to tie that tables together using the tubes that run through the fence rails.

If I am correct about all this, it suggests to me that I (and I suspect most of us who don't work on essentially perfectly flat floors) can never achieve any kind of permanent swapability that will travel with the Shopsmith as you move it around your work area.

So here's what I want to know from folks who own a 510/520 and have purchased an extra extension table to dedicate it to the left side while using a separate extension table dedicated to the right side and who have a set of the extra long rail tubes:

• Do you find you can consistently tie the left extension table to the main table with the fence rail tubes and that you can tie the right extension table to the main table through the fence rail tubes?

• If so, can any of you tie all three tables together using the extra long rail tubes?

• If you can do one and two, what kind of area do you work in and how flat is the floor your Shopsmith sits on?

• Do you move your Shopsmith around your work area or does it remain in a fixed location?

Sorry for the too long post. -Al

[dusty]

I have not viewed that video in a long time but maybe I need to. But until I do, I have a question. The "secret screw". When you adjust the secret screw to take out the twist, are the set screws that secret the Way Tubes (Base Arm and Tie Bar) loose? If not, I doubt what I have heard about that screw doing anything other than lift one end (the Tie Bar).

I just had the Base Arm, Way Tubes and Tie Bar off. The Headstock has been off for a couple days now. I pulled the hinge pin and lifted that sub-assemby of parts off to do some measurements. I might have to regress and go back to that configuration but I did not sense any twist.

No, I don't have to regress. I can just unlock the tie bar and twist (with the other end secured in the Headrest). This is what the "secret screw" would do. I expect it to be quite rigid.

[algale]

I have not viewed that video in a long time but maybe I need to. But until I do, I have a question. The "secret screw". When you adjust the secret screw to take out the twist, are the set screws that secret the Way Tubes (Base Arm and Tie Bar) loose? If not, I doubt what I have heard about that screw doing anything other than lift one end (the Tie Bar).

He does not loosen any of the set screws that hold the way tubes into the castings and, yes, the "secret" adjustment screw is only lifting up one side of the tie bar.

[JPG]

JPG, It might be interesting to know what all those pre-510/520 adjustment procedures were to get the M5/500 main table/extension table parallel and coplanar. The only adjustment I recall reading about from the old M5 manual to try to get twist out had to do with squaring the headstock. I think I read about that in one of your posts. Were there others?

I partially agree with you that those old adjustment techniques are less important with the 510/520 system, but only to the extent we are talking about a legless "floating" table. Since that kind of table takes its position by the rails/tubes, twist doesn't matter. But getting rid of twist still matters with the 510/520 when using an extension table AND trying to tie the extension and main table together with the tubes to create a more rigid platform. Nick's video proves just how significant that twist becomes.

. . .

I do not recall ANY SS mention of the secret screw other than to align the idler shaft to the jointer shaft and to align the 'left' aux table in one video. I did create a post where I used a laser line to adjust that secret screw to place the headstock and both aux table mounts on a straight line(thus eliminating way tube twist). My purist position stems from realizing that secret screw is there for alignment during original assembly at the factory to adjust out twist and to move it for other purposes will upset that alignment.

My point re Nick's video with a 520 is that with the main table/aux table connection with tubes and the adjustableity of the aux table mount with double nuts, alignment is achieved in two of the three orthogonal planes (in retrospect I realize it does so in all three planes) so the way tube twist is indeed the only thing that still varies and the secret setscrew does remove that variation.

[JPG]

I have not viewed that video in a long time but maybe I need to. But until I do, I have a question. The "secret screw". When you adjust the secret screw to take out the twist, are the set screws that secret the Way Tubes (Base Arm and Tie Bar) loose? If not, I doubt what I have heard about that screw doing anything other than lift one end (the Tie Bar).

He does not loosen any of the set screws that hold the way tubes into the castings and, yes, the "secret" adjustment screw is only lifting up one side of the tie bar.

And when the clamp is tightened the waytubes will be twisted from whatever at rest condition they are in and force the assembly into alignment. That at rest condition can/will be affected by floor variation etc.

Now one thing I think we are ignoring is the effective beam structure the the two way tubes and bench tubes create when it is all clamped tight.

All this is moot if the clamp is not 'tight'.

[DLB]

Regarding the video:

The method Nick uses to align the extension table with the main is completely different than the one in the manual. I'm intrigued and will try it soon. The question: Does it produce as coplanar a table system as the method in the manual? Important step that he did not mention: Main and Extension rails must first be confirmed with alignment gauge. Can this methodology be applied to a 510, if so how?

Same on the Main table. If I'm aligning or confirming the Main is correctly aligned to the plane of rotation, I use a square rather than a Wixie or equivalent. In the video he read 0.1 degrees, and says it's close enough. Knowing the Wixie, that means 0.1 +/- 0.2 degrees. What number would not have been close enough? Open question: Is that as close as I'd get it with a square?

Most important: What preconditions need to exist before adjusting the anti-twist setscrew? I gave measurements in the data-collection thread for this subject that indicate my Headrest example is out of alignment with Base in two axes by measuring the diagonals and by measuring the angles of the planes represented by each pair of extension table tubes. So if I follow the method in this video, am I likely to correct the alignment of this Mark? I have pretty strong doubts about that and therefore think the video is misleading. Certainly it will work if that setscrew is the only thing out of adjustment, but what about the real world?

The only thing I got out of this that seems certain is that when Dusty develops his alignment procedure it will have to include getting the base setscrew right and do that in the correct sequence relative to other adjustments that may be necessary.

Since I have a machine that is not aligned anyway, I'll try to answer these questions myself and report back with my findings (but not the 510 one).

- David

[algale]

Now one thing I think we are ignoring is the effective beam structure the the two way tubes and bench tubes create when it is all clamped tight.

Even with the clamps tight, and despite the uneveness of my floor, my experience is that, like a cat, the Shopsmith always lands on its four feet. Flex is occurring somewhere and since the headrest and base arm casting are attached to the feet/legs (much like in the song "the leg bone is connected to the hip bone") I cannot see how that can happen without the headrest and base arm bore holes no longer being perfectly aligned with one another.

[dusty]

I have not viewed that video in a long time but maybe I need to. But until I do, I have a question. The "secret screw". When you adjust the secret screw to take out the twist, are the set screws that secret the Way Tubes (Base Arm and Tie Bar) loose? If not, I doubt what I have heard about that screw doing anything other than lift one end (the Tie Bar).

He does not loosen any of the set screws that hold the way tubes into the castings and, yes, the "secret" adjustment screw is only lifting up one side of the tie bar.

And when the clamp is tightened the waytubes will be twisted from whatever at rest condition they are in and force the assembly into alignment. That at rest condition can/will be affected by floor variation etc.

Now one thing I think we are ignoring is the effective beam structure the the two way tubes and bench tubes create when it is all clamped tight.

All this is moot if the clamp is not 'tight'.

I'm a bit confused about what happens when the lock handle is secured. The lock does not pull downward on Tie Bar. It tnds to pull the Tie Bar laterally away from the Headrest thus pulling the Way Tubes into position. What applied force produces the twisting action?

This is not a significant question for me. The tip of the "secret screw" is flush with the surface of the casting. I set it that way for storage. I have never used it.

[dusty]

Trying to impart a twisting action on the end of the Way Tubes. No evidence of twist.

20201213_062730.jpg (440.88 KiB) Viewed 2768 times

This picture was taken this morning after I read the posts here about twisting the Way Tubes. I felt very, very little (if any) indication of twisting when I attempted to impose that twist action on the tie bar. I don't employ the "screw screw". Never have.

[JPG]

He does not loosen any of the set screws that hold the way tubes into the castings and, yes, the "secret" adjustment screw is only lifting up one side of the tie bar.

And when the clamp is tightened the waytubes will be twisted from whatever at rest condition they are in and force the assembly into alignment. That at rest condition can/will be affected by floor variation etc.

Now one thing I think we are ignoring is the effective beam structure the the two way tubes and bench tubes create when it is all clamped tight.

All this is moot if the clamp is not 'tight'.

I'm a bit confused about what happens when the lock handle is secured. The lock does not pull downward on Tie Bar. It tnds to pull the Tie Bar laterally away from the Headrest thus pulling the Way Tubes into position. What applied force produces the twisting action?

This is not a significant question for me. The tip of the "secret screw" is flush with the surface of the casting. I set it that way for storage. I have never used it.

Regarding the action of the clamp. The beveled end of the clamp 'head' and the beveled socket into which it tightens does indeed exert force to rotate the tiebar(and tubes etc.) down onto the headrest including the set screw. The force is originated by the 'bottom' of the two beveled surfaces pulling the tiebar down. So thee has the equivalent of a greenie headerest(no secret thingie).