bandsaw blade square through full motion of miter tool

[chapmanruss]

Buz,

If I understand you correctly you are trying to check table to blade alignment using the miter and a square as shown int the pictures below and the manual page you posted.

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Alignment 1.jpg (143.52 KiB) Viewed 1225 times

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Then moving the miter forward.

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Alignment 2.jpg (129.9 KiB) Viewed 1225 times

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This is the same as shown in the manual. The Miter needs to be square or the results will be off. The table would be adjusted by loosening the 4 bolts, re-adjusting and tightening the 4 bolts. If you are repeating the same result I would suspect the Miter is not at 90° and needs correcting or for some reason the table returns to the slightly off position as the bolts are tightened. Keep in mind the instructions in the manual page you posted is for the aluminum table and not the cast iron table I have shown above. With the aluminum table there is some adjustment room for the "T" track itself as noted in #4.

[JPG]

As I now understand it, blade twist will not affect this. The blade is being used as a POINT reference.

The adjustment that needs to take place is rotating the table about a vertical axis(looking down as a bird would).

That rotating force may be applied at either end(front/back) where there is slop in the trunion bolt holes.

After rotating return to the positioning the square 'tip' and repeat checking at the square 'heel'.

After correct alignment is achieved carefully(a small amount at a time on each bolt) tighten the trunion bolts.

Recheck. This may be a tail chasing the dog event. Key is the table not shifting while tightening the bolts.

[80spiders]

I appreciate the input from all. Since I am not mechanical in my process of thinking, I need "coaching" to get me on the correct path. I loosened those 4 bolts mounting the table to the trunnions, twisted the table and re-tightened at least 4 times yesterday without any change in the measurement when I ran the square in the miter gauge along the side of the blade via the miter track. I become frustrated with the idea that shims were needed but I could not visualize how that would help anything relative to my issue.
I will revisit the miter gauge and the square tonight to see if that is where the problem(s) is.

[JPG]

It may help to leave the bolts snug but neither loose nor tight. Then nudge the table by gentle tapping in the direction needed. Gradually sneak up on tightening sequentially around the 4 bolts.

Check the table/trunion mating surfaces for flatness.(also the bolt head to trunion)

[DLB]

It appears to me that somewhere along the lines SS changed the hole size in the trunnions from 7/16" to 13/32". If I was having this particular problem and the holes are less than 7/16", I'd strongly consider changing them. But I'd eliminate all other possibilities and confirm that I was at the adjustment limit first.

- David

[roy_okc]

Buz,

Pardon my lack of fine drawing skills, but hopefully they represent well enough what I believe to be an accurate set of statements. The table is light gray, the miter slot medium gray, the blade the darkest gray, the miter bar black, the miter "head" blue, and the square red.

Drawing1.jpg (32.31 KiB) Viewed 1190 times

The above drawing represents when all is perfectly square and parallel. With the square just touching the blade, the distance/touching force between the two will remain exactly the same throughout the travel of the miter gauge.

Drawing2a.jpg (44.55 KiB) Viewed 1179 times

(Edited to replace Drawing2 with Drawing2a, showing a rotated table rather than rotated blade orientation)

If, however, the table is rotated and the miter is no longer is parallel with the blade, the distance/touching force between the two still remains exactly the same throughout the travel of the miter gauge.

This is what the instructions seem to be telling you what and how to measure for. IMHO, the instructions are wrong.

Drawing3.jpg (40.73 KiB) Viewed 1190 times

This is what I think is happening, that your miter head is at a tiny bit of an angle and that as you push the miter gauge/square through the back end of the square, due to the back end of the square being in the direct path of the blade rather than beside it. If you got a gap at the back end the angle would be off the opposite direction.

If anybody else can find fault in my logic, please chime in.

I found one suggestion, not sure how well it would work on a Shopsmith sized blade, but might be worth a try. Put a small rare earth magnet on the widest blade you have in a spot not affected by tooth set. Then put a steel rule or something else that is long, straight, and will stick to a magnet, onto the magnet, elevated a bit above the table if possible. Then measure the distance at each end from the rule to the miter slot and adjust the twist on the table to get the measurements as close to the same as you can.

Do keep in mind that if you are squaring your miter gauge against your table saw blade, rather than the table saw table first to the saw blade and then the gauge to the miter slot, then you may have different angles for the bandsaw vs the table saw.

[DLB]

...I found one suggestion, not sure how well it would work on a Shopsmith sized blade, but might be worth a try. Put a small rare earth magnet on the widest blade you have in a spot not affected by tooth set. Then put a steel rule or something else that is long, straight, and will stick to a magnet, onto the magnet, elevated a bit above the table if possible. Then measure the distance at each end from the rule to the miter slot and adjust the twist on the table to get the measurements as close to the same as you can...

IMO this will not work on the SS BS. There is a commercial product like this for angling the fence to offset for drift, and I've used the magnet and steel rule to emulate that. It works well enough for that, but the angle is relatively large. Putting that same angle onto the table (not possible, so hypothetical) would not result in square crosscuts using the miter slot and gauge. What this method would do for you, if it were possible, is eliminate the need to angle the fence relative to the table for rip and resaw cuts.

https://carterproducts.com/band-saw-pro ... ystem-tool

Edit - Now I'm second-guessing myself. Maybe it would work, if it was possible. I don't do much cross-cutting on a BS. But I don't think there is anywhere near enough adjustment in the table to achieve the indicated angle.

- David

[JPG]

The second pix is somewhat counter intuitive though the end result is correct. It would be more understandable if the miter slot/miter gauge and square were rotated 15° and the blade remained as oriented in the first pix. Rotating the entire pix(s) 15° accomplishes the same.

The procedure is the same as main table alignment(uses slop in mounting holes to achieve parallelness). A differing detail is that travel along the square of a point on the blade is used rather than a point off the end of the miter gauge at front and back of the blade.

I think the procedure is valid, but not easy to accomplish.

[roy_okc]

The second pix is somewhat counter intuitive though the end result is correct. It would be more understandable if the miter slot/miter gauge and square were rotated 15° and the blade remained as oriented in the first pix. Rotating the entire pix(s) 15° accomplishes the same.

Good idea, I replace the second drawing with one where the table is rotated rather than the blade.

[JPG]

The second pix is somewhat counter intuitive though the end result is correct. It would be more understandable if the miter slot/miter gauge and square were rotated 15° and the blade remained as oriented in the first pix. Rotating the entire pix(s) 15° accomplishes the same.

Good idea, I replace the second drawing with one where the table is rotated rather than the blade.

Good Boy!!!