Perpendicular Blade changes when height above table changed

[pfallert]

Mark V 520:

Facing the SS main table, blade fully up, aligned to be 90 degree to the table (aka the table is level and the blade is perpendicular to the table). The OEM Style SS blade makes a beautiful rip cut on maple, oak and pine for example.

But, later, when the blade is lowered, a rip cut on say 3/4" thick stock finds the cut is not square to the face of the stock (the stock is flat having been jointed and the stock laws level on HD workbench which has been flattened. Checked both ways and both sides and edges both ways.

Anyone know where the problem might be?

Thanks,
Paul

[oldiron]

Have you checked that the table is still 90 degrees to the blade
after raising it?

Mike

[algale]

The simplest explanation is that the table somehow got tilted in between when you checked the blade/table relationship with the blade fully up and made your successful rip and when you made the cut with the blade lowered and found the cut not perpendicular.

This could happen if you forgot to fully tighten the table tilt lock or if the lock has sawdust in the mechanism or if the locks aren't properly set up to begin with.

Mark V 520:

Facing the SS main table, blade fully up, aligned to be 90 degree to the table (aka the table is level and the blade is perpendicular to the table). The OEM Style SS blade makes a beautiful rip cut on maple, oak and pine for example.

But, later, when the blade is lowered, a rip cut on say 3/4" thick stock finds the cut is not square to the face of the stock (the stock is flat having been jointed and the stock laws level on HD workbench which has been flattened. Checked both ways and both sides and edges both ways.

Anyone know where the problem might be?

Thanks,
Paul

[dusty]

Do you have a digital level. The first thing that I would do is make certain that the blade is vertical to the plane of the WAY tubes. When you check and find that it is, you then need to make that same check on the Main Table.

Stop and think about this. The blade is mounted on the headstock and the headstock does not change as a result altering depth of cut. You stated "But, later, when the blade is lowered". The blade does not change(with respect to the WAY tubes), but the table does.

[pfallert]

Yes I have checked the table/blade angle and it has changed.
This has been happening for quite some time, but I would just adjust the table by trial and error and keep going. The problem with that is that there is so little blade height that it is difficult to measure. To do so, I have clamped a straight edge to the blade and used a square to check that.

To try to narrow down the problem, I have then raised the blade again (before making any adjustments) and it is square when the blade is in the full up position.

I have even resorted to using a digital angle gauge to check and adjust the table and the blade with the blade in the full up position. OK.

Then I lower the blade and it's out of perpendicular.

Yes, the headstock and spindle don't change, only the table changes, so that points in the direction of what happens when the table height changes.

Thank you for your replies.
Paul

[pfallert]

I don't change the table lock after adjusting the blade to perpendicular at full height. I only change the height of the table.

Another clue:
I use a close (zero) clearance insert and when I change the table height, the blade is no longer centered in the cut (not by much, but enough to make me adjust the projection of the blade from the headstock or move the table over about the thickness of two business cards. When I do this, I re-check the level of the table and it's still level. I have a Starret machinist level (checked on a level surface and it reads the same both directions, so that should be good).

Paul
ps I tried not using the right tables / tubes thinking maybe they were "pulling" the table either up or down as they were being attached. Problem is the same without the extensions.

[algale]

When you lower the table, do you ever have the tie bar guard hit the lower saw guard and get hung up on it? This happens to me all the time when I forget to close the lower saw guard sufficiently.

If this happens to you and the table tilt lock isn't gripping as well as it should, it is entirely possible the table will be jarred and you may end up changing the table angle. (Normally I find that when I drop the tie bar onto the lower saw guard, the lower saw guard gets knocked out of alignment, but this doesn't change the blade-to-table angle.

[pfallert]

Re: Saw guard.

Yes, the saw guard does get in the way frequently. And you have a valid point that it may be a factor in causing the problem.

At the SS classes that I attended (held by at least 3 different instructors), the advice was to open the saw guard to the max to increase the removal of sawdust. But, when the guard is open, there is more of a tendency to cause interference. [BTW, they all said to just keep the blade height at about 1-1/2" or no more than you want it to be available to cut your hands, fingers or arms]. Well, that does not work when you need to cut thin pieces of plywood and you want to minimize tearout. )

But this "guard" event normally happens when increasing the blade height-aka dropping the table. Not when decreasing the blade height-aka raising the table.

But, I am going to look into this suggestion because I like to stop it from happening as much as it does.

Thank you,
Paul

[ERLover]

Now I dont use mine in TS mode at all, but it would seem to me, if when the table is in a lower position and more blade is exposed, and square to the blade, then you raise the table to have less blade exposed, it is raising at an angle, not straight up.
BTW blade height should that the deepest blade gullet is just exposed above your stock you are cutting for maximum chip removal and least amount of possible chance of a kick back.

[jsburger]

Re: Saw guard.

Yes, the saw guard does get in the way frequently. And you have a valid point that it may be a factor in causing the problem.

At the SS classes that I attended (held by at least 3 different instructors), the advice was to open the saw guard to the max to increase the removal of sawdust. But, when the guard is open, there is more of a tendency to cause interference. [BTW, they all said to just keep the blade height at about 1-1/2" or no more than you want it to be available to cut your hands, fingers or arms]. Well, that does not work when you need to cut thin pieces of plywood and you want to minimize tearout. )

But this "guard" event normally happens when increasing the blade height-aka dropping the table. Not when decreasing the blade height-aka raising the table.

But, I am going to look into this suggestion because I like to stop it from happening as much as it does.

Thank you,
Paul

From that I take it that the perpendicularly problem does not always happen. That would seem to eliminate a mechanical defect with the machine. I am not sure what defect could possibly cause what you are seeing.

So the only thing left is operator procedure. You mention using a level on the table. Level is not an issue since the floor the machine is siting on may not be level. The only issue is that the table is 90* to the blade and that only requires a square.

Since this only happens when raising the table, do you sometimes use your hand on the side of the table to assist in raising the with the crank? Is the 90* table stop correctly set? Is the table always off in the same direction?