Shopsmith Forums

The short stub is roughly 2 1/4 " on all the eccentrics. I did some digging and found the original straight tubes with the stop collars. You are right, no side to side adjustment. It is a bit of a bear to get the vertical adjustment. I guess the power coupler takes up the difference. Why the design change anyway? Were users taking out bearings or breaking couplers with the straight tubes?

I checked my Band Saw with eccentric posts I have that is aligned to my Mark 7. I did not measure the posts but they sit at the same position as yours do in the picture in your second post.

As to the change from the straight posts to the eccentric posts I do not know the reason. My 1956 Greenie Band Saw has the original straight posts and it aligns fine.

Check to make sure you did not install the band saw eccentric tubes upside down. Per page 8, figure 1, of the band saw manual, "THE LONG END GOES UP."


https://www.shopsmith.com/ownersite/manuals/845539.pdf

My two cents: If you don't need the horizontal offset (error of 1/32 or less IMO, but the old book said 1/16") and you have straight tubes I would use them. Straight tubes are inherently more stable because: 1) slightly larger diameter is a better fit in the BS and in the SS; 2) longer length fully engages the upper BS collar, the BS stop, and the full depth of the Headrest or double tilt base; 3) stop collars engage more surface area of the Headrest or double tilt base. Of those I think the diameter is the biggest "improvement" factor but it's kind of hard to isolate the features. The only thing straight tubes aren't better at is horizontal alignment. I only have two other SPTs, I need and use eccentrics in both. But if I ever needed them for the bandsaw I would want to know why.

I'm not saying there is anything wrong with eccentrics, though I think they could be better. Thousands of users are happy with them. And the mothership hasn't changed them since they introduced them as far as I know (other than those swell offset versions). Clearly they are good enough.

- David

The question is how do you align the BS to the SS using the old long tubes?

I have never had straight tubes so I really don't know but if the hubs can truly be aligned (without using eccentrics) I believe that the process has to be a very tedious assembly process right from the retractable casters on up.

In my experience it is a matter of having an aligned Base. There are some very detailed threads on that subject. There are also some threads with specific instructions for the bandsaw alignment, but not everyone will agree that they should be followed: https://www.shopsmith.com/ss_forum/view ... 32#p244532 Review the whole thread, but that specific post has the old Shopsmith instructions. In my case (two machines) I went through the Base alignment process on this forum, which I attribute to JPG and Dusty as they were the primary contributors. To me, centered drive hubs was a natural result of that process but I know Dusty's results differed. My experience also suggests that bandsaw drive position does not vary from one BS to the next, but that is limited to the two samples I used straight tubes on.

- David

"Simple" adjustment! Loosen two bolts securing the bench tubes at the headrest end. Insert 2x4 and rotate the headrest as required. Tighten the bench screw bolts. Should work for ALL SPTs since they are ALL centered the same. Only the idler shaft is variable(belt tension adjustment).***


I do NOT recommend the big set screw adjustment(bench tube twist) for this!


*** That means the jointer may not be consistent with other SPTs that connect to the upper shaft.

I think splitting the difference is viable. Let the connector do it's thing then.

Alternatively, I think straight tubes make sense for SPTs that connect to the upper shaft and eccentric tubes for things(jointer/compressor/???) that connect to the lower(varying location) shaft. The eccentric tubes are only required to compensate for the idler shaft variability and need to be readjusted when belt tension is adjusted.

I can also confirm that the straight tubes work well with Double Tilts (DT). My main machine is a DT Upgrade and my shorty is a home brewed DT (base only), both upgraded earlier this year. I can move an aligned bandsaw on straight tubes between the two without re-alignment. (I'm sure it would work with eccentrics as well.) This is upper aux shaft only, as JPG pointed out.

- David

DLB wrote:I can also confirm that the straight tubes work well with Double Tilts (DT). My main machine is a DT Upgrade and my shorty is a home brewed DT (base only), both upgraded earlier this year. I can move an aligned bandsaw on straight tubes between the two without re-alignment. (I'm sure it would work with eccentrics as well.) This is upper aux shaft only, as JPG pointed out.

- David

This is neither surprising or enlightening since with DT castings there are minimal if not minuscule differences in hole spacing from one casting to the next. With just reasonable care while assembling the base units and bench tubes nearly precision measurements should occur. I was truly impressed when I assembled my first DT. I have done three since and the first was no accident.