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Bandsaw Table Installation and Alignment

algale

paulrussell wrote Not mentioned in this thread is that once a back-angled blade is fully engaged into the cut, the cutting load is slightly _more_ than a perpendicular blade. Pythagorean worked that all out for us. Admittedly, that penalty is slight given the shallow angle of the blade.

That's a very good point, Paul, and it adds to the doubts I have always harbored about the official explanation for the angle between the blade and the table. I do not believe for one minute the engineers at Shopsmith decided they needed blade tilt to prevent bogging and therefore went about building a band saw to accomplish this. Rather, I believe the blade tilt is an artifact of other deliberate design choices unique to the Shopsmith bandsaw, specifically how it autotracks by leaning the upper wheel backwards and using the autotrack bearing to prevent the blade from from falling off the back of the wheel. Those are desirable features, that an engineer would think about.

Of course the result of those choices is the blade tilts a small amount relative to the table and I suspect after getting questions about it, they decided to declare this was not only a normal condition from the design but a desirable "feature" and came up with the explanation that it helps prevent bogging down.

RFGuy

algale wrote
paulrussell wrote Not mentioned in this thread is that once a back-angled blade is fully engaged into the cut, the cutting load is slightly _more_ than a perpendicular blade. Pythagorean worked that all out for us. Admittedly, that penalty is slight given the shallow angle of the blade.
That's a very good point, Paul, and it adds to the doubts I have always harbored about the official explanation for the angle between the blade and the table. I do not believe for one minute the engineers at Shopsmith decided they needed blade tilt to prevent bogging and therefore went about building a band saw to accomplish this. Rather, I believe the blade tilt is an artifact of other deliberate design choices unique to the Shopsmith bandsaw, specifically how it autotracks by leaning the upper wheel backwards and using the autotrack bearing to prevent the blade from from falling off the back of the wheel. Those are desirable features, that an engineer would think about.

Of course the result of those choices is the blade tilts a small amount relative to the table and I suspect after getting questions about it, they decided to declare this was not only a normal condition from the design but a desirable "feature" and came up with the explanation that it helps prevent bogging down.

Interesting discussion...now I have to check my bandsaw to see if my blade is angled to the table or not. This explanation above makes the most sense to me for why Shopsmith chose this.

dusty

To get my table square to the blade I had to shim the front (infeed side) of the blade. Without doing that the upper surface of a work piece contacted the blade first. I don't know if this has any impact on the discussion but that is what my situation was.

chapmanruss

Dusty,

You said

To get my table square to the blade I had to shim the front (infeed side) of the blade. Without doing that the upper surface of a work piece contacted the blade first.

I'm not sure if I am reading that correctly or if my understanding of it is off. If you had to shim the infeed side to get the blade to table angle to 90° than how was the upper surface of the work piece contacting the blade first before the adjustment? Wouldn't the bottom of the work piece contact the blade first without the shimming to 90°? That is what is happening with my 2006 Bandsaw without adding shims. I was checking the alignment on it yesterday but I haven't had the table off of it yet which is what I plan to do next. I am not sure it has the shim washers, as discussed before, between the table and the trunnions at all four bolting points.

edma194

Dusty, just checking here, before measuring the angle are you pushing the blade back with a piece of wood at the top until it hits the back bearing?

dusty

No I am not pushing a work piece into the blade. In fact, when doing this test the bandsaw is turned off.

Before I did any shimming

I was checking for square to the blade "on the back side of the blade". When I would bring a block of wood the top edge of the block would contact the blade and the bottom edge of the block was away from the blade. After leveling the table, the entire block would contact the blade simultaneouly.

Should have taken more pictures. :(

chapmanruss

Thanks Dusty,

That is the way I thought it should be but the way you said it in the second sentence and following the first sentence

To get my table square to the blade I had to shim the front (infeed side) of the blade. Without doing that the upper surface of a work piece contacted the blade first.

had me wondering if you were feeding a work piece into the blade not checking the back side of the blade. Glad to have that cleared up.

chapmanruss

Yesterday afternoon I finished up maintenance on the 2006 Bandsaw. I really hadn't gone through it except replacing a couple of parts since I bought it a year ago with a Mark V since it has been an extra. I had the table off and it does have the four shim washers but one was not between the table and the trunnion on the infeed side. It was stacked with the thicker washer against the bolt head. Not sure what the previous owner was going for there but all are now in the proper place. I did not add extra shims to the infeed side to get the blade to table angle to 90° so it does have that slight "factory" angle. It does cut beautifully and made a perfect 90° cut on a piece of wool using the miter. :) It's now set up and ready to work.

I still have not decided if I will keep it or sell it but will wait until I check the alignments on the 1996 and 1956 Bandsaws and see if I want one set with the blade at 90° to the table. The 1956 shouldn't need any adjustments since it has hardly been used since it was restored less than a year ago but it has been 5 years since a full alignment was done on the 1996 Bandsaw when the Main Frame was replaced. My how time flies.

Thanks Dusty for inspiring me to do some alignment checks on my Bandsaws.

dusty

I'm wondering, just wondering if the slight angle allows the saw dust to escape the gullets a little bit better than at 90 degrees.

There has to be a reason why the engineers did this. This is not just a happy coincidence. I find very little, if anything, that happened without justification. The Shopsmith design is well thought out. In my mind there is no room for criticism of the Shopsmith until you begin comparing it to a production or contractor tool.

garys

My bandsaw is 40 years old this year so it has the cast iron table and no shims or washers of any kind under it. That would be the way it was assembled back in 1981.

My blade has a bit of angle as shown in this picture.

I've used it only for resawing so I have not encountered any situations where that angle makes a difference. I don't use it for any scroll type work or cutting around corners. I have a scroll saw for that work. If I ever do any cutting of curves, I probably might shim the table to get it at 90 degrees.

JPG

My how time alters one's memory of things happening earlier. The 2° lean on the back of the blade is the result(as Algale already stated) of the unique SS bandsaw auto track design. Those wheel bevels and canted upper wheel cause the leanback.

That slight(2°) angle is only a problem with non-straight cutting and as Jsburger stated cutting tenon shoulders.

Shimming corrects that, however now the bandsaw table is no longer level front to rear. IF one needs to use the main table etc. for support, the slight angle MIGHT become an issue.

dusty

JPG wrote My how time alters one's memory of things happening earlier. The 2° lean on the back of the blade is the result(as Algale already stated) of the unique SS bandsaw auto track design. Those wheel bevels and canted upper wheel cause the leanback.

That slight(2°) angle is only a problem with non-straight cutting and as Jsburger stated cutting tenon shoulders.

Shimming corrects that, however now the bandsaw table is no longer level front to rear. IF one needs to use the main table etc. for support, the slight angle MIGHT become an issue.

How then do you explain the fact that the back edge of the blade is plumb and the table is tilted with respect to that plumb line.

With that tid bit of information I conclude that the wheel bevel and cant are NOT the cause of the lean back but that table position is.

The disconnect seems to be with the definition of "lean back". Lean back with respect to what? I consider the back edge of the blade (for this discussion) to be the reference line.

Then, with regard to non-straight cuts, I don't understand how this effects the angle of the cut line if one is using the appropriate blade (a narrow blade).

chapmanruss

The angle of the blade to the table on my 2006 Bandsaw I went through the last few days looks the same as shown in Gary's picture. The only difference is mine has the aluminum table.

JPG commented,

Shimming corrects that, however now the bandsaw table is no longer level front to rear. IF one needs to use the main table etc. for support, the slight angle MIGHT become an issue.

JPG,

If one needs the Main Table for extra support does it not tilt? :confused: If someone needed more than just the main table could they not use the extension table edge to add to the support for the original (500) table system or add floating tables for the 510, 520 or Mark 7 which can tilt with the main table?

One of the things I like about the Shopsmith is the versatility. If you can imagine it you can pretty much figure out a way to do it with a Shopsmith.

JPG

Please explain to me how one tilts the main and floating tables front to rear. i.e. raise the front relative to the rear 2°.

Dusty the reference is a level mother earth. The table should be level(before tweakng to the blade). The blade ain't plumb.

dusty

garys wrote
My bandsaw is 40 years old this year so it has the cast iron table and no shims or washers of any kind under it. That would be the way it was assembled back in 1981.

My blade has a bit of angle as shown in this picture.

bansdaw.jpg

I've used it only for resawing so I have not encountered any situations where that angle makes a difference. I don't use it for any scroll type work or cutting around corners. I have a scroll saw for that work. If I ever do any cutting of curves, I probably might shim the table to get it at 90 degrees.

Yours is pretty darn good in comparison to mine but your tilts in the opposite direction.

dusty

JPG wrote
Please explain to me how one tilts the main and floating tables front to rear. i.e. raise the front relative to the rear 2°.

Dusty the reference is a level mother earth. The table should be level(before tweakng to the blade). The blade ain't plumb.

Are you telling me that if I drop a plumb line it won't be parallel to the back edge of the blade as I show it in the first attached image? If you are, I am about to get a lesson in how to use a level and plumb line.

dusty

If I zero the AngleCube off the blade and then check the table top it tilts about 2 degrees.

chapmanruss

JPG you asked,

Please explain to me how one tilts the main and floating tables front to rear. i.e. raise the front relative to the rear 2°.

The answer is you don't need to. I currently have three Magna/Shopsmith Bandsaws and on all three the infeed side of the bandsaw blade and therefore the outfeed side of the bandsaw blade is 90° from the infeed and outfeed of the Mark's Main Table.

Bandsaw on Mark V - arrows.jpg

chapmanruss

In the picture above (on the Mark V from the craigslist ad when I bought them) is my 2006 Bandsaw. It is currently on my Mark 7. Interestingly when I set the Main Table on the Mark 7 as an extra outfeed table I have to tilt it about 2° down on the left side to match the Bandsaw's table. If I was to shim the Bandsaw's table 90° to the blade I may not have to tilt the Mark 7's Main Table at all. I haven't tried it on my Mark V for comparison. Next I may have to try my 1998 & 1956 Bandsaws to see how they compare.

dusty

chapmanruss wrote In the picture above (on the Mark V from the craigslist ad when I bought them) is my 2006 Bandsaw. It is currently on my Mark 7. Interestingly when I set the Main Table on the Mark 7 as an extra outfeed table I have to tilt it about 2° down on the left side to match the Bandsaw's table. If I was to shim the Bandsaw's table 90° to the blade I may not have to tilt the Mark 7's Main Table at all. I haven't tried it on my Mark V for comparison. Next I may have to try my 1998 & 1956 Bandsaws to see how they compare.

Based on what I see here, I am not a bit surprised. I don't see how it can be any different with any standard Shopsmith configuration.

Because of what I now see, I plan to wedge the second bandsaw table the same way so that they are interchangeable with coplaner tables.

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