Truing, As Best You Can, Shopsmith Table Tops

[jsburger]

Closing Comment: I was very disappointed at how few users contributed. I was disappointed because I know that many of you experience this same issue but never said a word.

Sorry, Dusty. I've been less active than usual on the forum lately as I've been consumed with trying to get the Slow Boat done before things freeze over here.

I do find maintenance and alignment issues interesting and I will surely come back to this thread over the winter.

I was using my extension table today on the right side and, once again, used two levels across the main and extension table to get it all coplanar.

I align the extension table using Nick's method but I find there's a lot of slop in my bores on the right side and if I remove and reinsert the extension table it can easily be made to pitch and yaw before the locks are applied and it will not necessarily lock coplanar to the main table if I am not vigilant with the levels.

I do wonder whether inconsistency in the bores from the left and right side contribute to the error.

I seriously doubt that but I have only three sets of bores to judge from. I don't sense any slop in any of mine.

I totally agree Dusty.

[rjent]

To be honest Dusty, I am in awe that this kind of precision is possible, much less required for cutting wood. I was fascinated by what you guys were talking about (and I did ask one question ) but felt inadequate with my still (but growing) limited experience with these machines ....

After following this from the beginning, it makes me wonder how a high end cabinet saw would live up to this kind of scrutiny ... like a Grizzly or even a lesser Steel City. It would be interesting to compare .....

Well, this discussion is about aligning two or three separate tables to each other. A cabinet saw does not have that problem. Yes, my Powermatic PM2000 has two bolt on cast iron wings but once you bolt them on they don't move. On the other hand, my Powermatic 14" band saw has an aux table on the left side that is separate from the main tilting table. It was a real pain to get aligned with the main table. IMO, mostly due to the way it is mounted and adjusted. However, once aligned it will never be moved.

That is kind of my thought process here John. We KNOW these machines change/convert/adjust and it is why many woodworkers don't like them and think of them as amateurish, BUT you guys, justifiably so, are talking precision that is equal to your Powermatic, it just takes longer and takes more effort to achieve. I knew that when going in to this game, and I don't mind, but I am also amazed that this kind of precision is needed in wood working.

[jsburger]

OK, I WILL ask the question.

Let's take a saw like the Grizzly G1000 series table saw.

grizzly cabinet saw.jpg

To my eye, which I admit is still noob, looks similar to a 520 ProFence system on a Mark V or 7. This unit has less rip capacity but more HP and costs 1500 dollars or so......



Would this "table" live up to one thousandth tolerance like is expected on our machines (I understand you can "align" the extension tables and achieve that, but when swapping them you find they are "off".

Would the grizzly be held to that much of a standard?

Secondly, it this kind of tolerance necessary for woodworking? I work with less tolerance when building a 350 horsepower small block chevy or Ford engine.

I am just amazed that we are even talking these kinds of measurements. Are they necessary?

Trust me, I am not arguing, I am just having to rethink my approach to making wood projects if this kind of tolerance is needed or desirable .....

The cabinet saw fences are not the same as the 520 but they are equal in precision. As far as rip capacity cabinet saws in that configuration have a 52" rip capacity. True the SS can be configured for more than that but when you ever need that?

As for the table, the 4' wide cast iron table on my Powermatic PM2000 does not deviate more than 0.002 using a straight edge and a feeler gauge. There are no tables to swap so there is no issue.

Look at the pictures I posted when I swapped my extension tables after aligning and swapping end for end. They are off left to right about 1/16 or 3/32. That is not very precision.

A thou tolerance is not necessary in wood working but a 1/64+ is.

[jsburger]

OK, I WILL ask the question.

Let's take a saw like the Grizzly G1000 series table saw.

grizzly cabinet saw.jpg

To my eye, which I admit is still noob, looks similar to a 520 ProFence system on a Mark V or 7. This unit has less rip capacity but more HP and costs 1500 dollars or so......



Would this "table" live up to one thousandth tolerance like is expected on our machines (I understand you can "align" the extension tables and achieve that, but when swapping them you find they are "off".

Would the grizzly be held to that much of a standard?

Secondly, it this kind of tolerance necessary for woodworking? I work with less tolerance when building a 350 horsepower small block chevy or Ford engine.

I am just amazed that we are even talking these kinds of measurements. Are they necessary?

Trust me, I am not arguing, I am just having to rethink my approach to making wood projects if this kind of tolerance is needed or desirable .....

I can't speak to the tolerances of this specific machine but I will make a couple general comments regarding this type of machine. If I had the shop space, I would have one. But mine would look like this:

http://www.tylertool.com/delta-36-l336- ... wwn36-l336

The tight precision that has been discussed on this forum is generally not required in wood working and especially not in the type of wood working most of us do. But if you are building something that is going to cover the expanse of a family room wall tiny errors make for big problems before you are done. Charlese has built several pieces of fine furniture that we have seen here on the forum. He says he is not into precision measuring but if he was not making precision cuts his furniture would not be so impression. Yes, precision is possible using a Shopsmith.

The big difference between my Shopsmith and my dream Delta Unisaw is the precision of the tables with respect to the blade. The Unisaw is a direct opposite arrangement. The tables move on the Shopsmith. Once that Unisaw is setup properly, one would not want to move that arrangement at all. The table is the reference surface. The arbor moves with respect to the table and the arbor is one fine piece of machinery.

The Unisaw is capable of handling large work pieces with the same degree of accuracy as it does smaller work pieces. This is a major factor in anything other than a home workshop. From my 400 sq ft garage shop, the Shopsmith makes it possible for me to get the precision I want and the versatility. The Unisaw cannot do that

You ask about tolerances. What are tolerances? Tolerances are limits that have been imposed upon a project. Imposed by whom? Imposed by the person who is finely going to accept and us the finished item. If a 1/6th of an inch (.062") gap is acceptable, then it meets the requirements. However, a slightly smaller gap at say 1/32" (.030") might look better. I shot for still tighter control. I look for 1/64" (.015") and almost always accept a lot less.

Glue lines not wider than .015" sounds more impressive than glue lines 1/64" wide.

Right on Dusty.

[JPG]

Thank you for the Wixey details. I now see everything is perpendicilar to the blade within .1 degrees(.3[or .2] degrees off level low right from the operator position. That is within the tolerance of the wixey itself.

That .1 degree tolerance represents more than 1/16" over the 50" between the tables.


My conclusion is that a digital angle gauge with a .1 degree accuracy/repeatability/resolution is inferior to using a known straight edge and feeler gauges(shims)or optical(laser).

The wixey however provides a quick check method.

[jsburger]

Ok, I get that. I have two observations from here.

One is that all of you guys have mentioned that you can get repeatability by using a said extension table on the same end every time. If I am wrong about that, then correct me LOL. If that is true, then mark your two extension tables "L" and "R" and you are done .

And second, that is a 3000 dollar retail machine that only does one thing. Seems like a lot of money for a tool that if the kind of precision that you are talking about is needed, but achievable with the SS, but just not convenient. And believe me, I totally understand your point about the tolerance that is needed to cover a wall, Pretty high precision is needed for that kind of job. But it could be argued that you could set up a SS 520 in a configuration similar to your "dream machine" and leave it set that way and have the same capability. Am i wrong? LOL Am I just not seeing the big picture. Once that "big" job is done, you then "take down" the SS "precision" setup and go back to the magic that is SS.

I need to think about this brother. You have bumfuggeled my perception ....

Dick,

Yes you are right. This discussion is about swapping extension tables from end to end. If you have one extension table and align it on what ever end and then swap ends it is not aligned. Not by a few thou but 1/64 or more. That is a lot. Not everyone has two extension tables.

I have two extension tables since long before I upgraded to a MK 7. They are marked Left and Right and I never had a problem since I never changed ends. Then I upgraded to a MK 7 and realigned the tables and no problem.

Then someone said if you have a MK 7 double tilt that problem goes away since both end castings are the same. So I decided to check. It was not true on my machine hence the discussion.

[jsburger]

Hear me now. This is very important. THERE IS NO BIG PICTURE! At least not one that is pleasing to every one. Your shop is YOUR SHOP. It does for you what you want it to.

Furthermore, you are right about the left and right wings being calibrated and marked exclusively for that use. I already do essentially that except that I typically don't have a left wig. My jointer occupies that slot.

So why all of the discussion??? Because it is a phenomena that "bugs me". The way the Shopsmith is constructed, those tables should swap back and forth with "no deviation" but they don't. You tell me why.

I totally agree Dusty. It bugs me too. I spent most of my career trying to figure out these kinds of problems both mechanical and electrical. I had an electrical engineer that I worked with as an AF civilian call me at home about 6 months age (I have been retired for 3 1/2 years). He had an anomalous inductance measurement on an F-16 component that they were testing as a first article certification from a new manufacture. He wanted my opinion but the measurement made no sense. They had the component retested and sure enough it was operator error.

[JPG]

Well not willing to leavewell enough alone, I continued exploring aligning using that laser. First I dug out 7" aux table and added the 8 nut and washer height adjusting stuff. I used 3/8 x 2 1/2" screws with continuous threads(left the heads on).

After getting it 'close' using 'historical' method I then got out the laser.

No pix tonight, but the first step was to cast that laser in vertical mode and project a line from the right end to the left end. The laser was positioned so that the line passed through the quill shaft center and aligned with the modified table mount(center marked). The laser remained there.

After flipping the laser to horizontal mode, the table was adjusted for equal height of the beam, near the 4 ends of the way tubes. A tricky process that required minute adjustments of the table mount nuts.

Having done that, the main table was checked using a 4' level, but not altered(close enough for roadwork ) The aux table was moved to the left end and it looks like the one in Utah!

Checked the spt posts at both ends, and neither are 'normal' to the way tubes. Less than a degree according to the i-Gauge(wixey look alike).

So %&(*^&E$%! Now what? Split the difference?

At least the way tube set screw tweak etc. will resolve rip fence aligning using a single aux table mounted at either end and table height parallel front to rear..

[dusty]

Well not willing to leavewell enough alone, I continued exploring aligning using that laser. First I dug out 7" aux table and added the 8 nut and washer height adjusting stuff. I used 3/8 x 2 1/2" screws with continuous threads(left the heads on).

After getting it 'close' using 'historical' method I then got out the laser.

No pix tonight, but the first step was to cast that laser in vertical mode and project a line from the right end to the left end. The laser was positioned so that the line passed through the quill shaft center and aligned with the modified table mount(center marked). The laser remained there.

After flipping the laser to horizontal mode, the table was adjusted for equal height of the beam, near the 4 ends of the way tubes. A tricky process that required minute adjustments of the table mount nuts.

Having done that, the main table was checked using a 4' level, but not altered(close enough for roadwork ) The aux table was moved to the left end and it looks like the one in Utah!

Checked the spt posts at both ends, and neither are 'normal' to the way tubes. Less than a degree according to the i-Gauge(wixey look alike).

So %&(*^&E$%! Now what? Split the difference?

At least the way tube set screw tweak etc. will resolve rip fence aligning using a single aux table mounted at either end and table height parallel front to rear..

cast that laser in vertical mode and project a line from the right end to the left end ???

[JPG]

Well not willing to leavewell enough alone, I continued exploring aligning using that laser. First I dug out 7" aux table and added the 8 nut and washer height adjusting stuff. I used 3/8 x 2 1/2" screws with continuous threads(left the heads on).

After getting it 'close' using 'historical' method I then got out the laser.

No pix tonight, but the first step was to cast that laser in vertical mode and project a line from the right end to the left end. The laser was positioned so that the line passed through the quill shaft center and aligned with the modified table mount(center marked). The laser remained there.

After flipping the laser to horizontal mode, the table was adjusted for equal height of the beam, near the 4 ends of the way tubes. A tricky process that required minute adjustments of the table mount nuts.

Having done that, the main table was checked using a 4' level, but not altered(close enough for roadwork ) The aux table was moved to the left end and it looks like the one in Utah!

Checked the spt posts at both ends, and neither are 'normal' to the way tubes. Less than a degree according to the i-Gauge(wixey look alike).

So %&(*^&E$%! Now what? Split the difference?

At least the way tube set screw tweak etc. will resolve rip fence aligning using a single aux table mounted at either end and table height parallel front to rear..

cast that laser in vertical mode and project a line from the right end to the left end ???

Crude but hopefully effective.

Vertical laser.jpg (113.33 KiB) Viewed 1877 times