Table saw blade shift

[Aaron Koch]

I'm trying to resolve my table saw alignment. I aligned the saw near max height parallel to the miter slot to within ~.002" front to back per my dial indicator; the problem comes when I lower the blade and it goes out by of alignment from front to back by .008"-.010". I heard tons of stories about this on the RIDGID R4512, enough to make me steer clear of it. So I bought a Craftsman zip code saw which has cabinet mounted trunnions which I thought would exempt me from such issues. Google searches yield no hits (that I've found) related to alignment shifting with cabinet mounted trunnions, so I'm stumped. Any ideas what's going on?

[John TenEyck]

Are you measuring the same tooth and rotating it front to back? If not, that might be part/all of the problem - warped blade or there's dirt/dust somewhere on the blade assembly against the arbor flange. Rotating the blade and measuring the same tooth eliminates this potential source of error. If that ain't it, I have no clue.

John

[Dennis McDonaugh]

I couldn't align my table saw with my dial indicator. The results were all over the place by a few thousands of an inch and not consistent. Instead I used a T-square and got it aligned. Is it a few thousands of an inch off? Possibly, but it cuts square enough that I don't have trouble making anything with it.

[Ty Williams]

I couldn't align my table saw with my dial indicator. The results were all over the place by a few thousands of an inch and not consistent. Instead I used a T-square and got it aligned. Is it a few thousands of an inch off? Possibly, but it cuts square enough that I don't have trouble making anything with it.

I'm not trying to be rude, but that means one of two things: Either you have no idea how to use a dial indicator properly or there's significant slop in the mechanism of your table saw somewhere. After using a dial indicator to set things up both for metal working and for wood working, my first bet would be that you're doing something to influence the reading. Until you've worked with them for a while, you don't really quite grok how easy it is to make the setup you're trying to measure move by several thousandths of an inch. Very slight changes in pressure of your hand, head transfer from your hand into the tools, even shifting your weight on your feet (depending on floor stiffness) can all produce measurable changes on the dial indicator. There's a whole book about this kind of stuff called Foundations of Mechanical Accuracy. It's an amazing read if measuring precisely and accurately is something you're interested in.

[Dennis McDonaugh]

I'm not trying to be rude, but that means one of two things: Either you have no idea how to use a dial indicator properly or there's significant slop in the mechanism of your table saw somewhere. After using a dial indicator to set things up both for metal working and for wood working, my first bet would be that you're doing something to influence the reading. Until you've worked with them for a while, you don't really quite grok how easy it is to make the setup you're trying to measure move by several thousandths of an inch. Very slight changes in pressure of your hand, head transfer from your hand into the tools, even shifting your weight on your feet (depending on floor stiffness) can all produce measurable changes on the dial indicator. There's a whole book about this kind of stuff called Foundations of Mechanical Accuracy. It's an amazing read if measuring precisely and accurately is something you're interested in.

Your explanation of the issues was kinda my point in the first place. For most people, a dial indicator isn't the best tool for aligning the table saw blade to the miter slot or the miter slot to the fence for the very reasons you stated. The owners manual for my saw shows a procedure for doing that alignment with a sliding t-square and that's what I used. For me, the real measure is in the quality of the cut and I'm satisfied that my saw is aligned well enough since I don't end up with teeth marks on my cuts.

[Myk Rian]

I wish you guys would make Paragraphs. Hard to read blocks of words.

[Aaron Koch]

I'm reading off the the same tooth rotated front to back.

My results are consistent if I test at the same places multiple times, what isn't consistent is the alignment at different blade heights. If you're familiar with the issue plaguing the RIDGID R4512 it seems like the same symptom. My dial indicator is functioning properly.

Steel City tech support says the issue is that the rods connecting the trunnions are not coplanar and need to be adjusted to resolve the shifting blade. Hopefully I can mess with it today and get it squared away.

[Phil Thien]

Steel City tech support says the issue is that the rods connecting the trunnions are not coplanar and need to be adjusted to resolve the shifting blade. Hopefully I can mess with it today and get it squared away.

Well let us know what happens. I'm surprised there is adjustment on those rods.

[scott spencer]

Well let us know what happens. I'm surprised there is adjustment on those rods.

Ditto...I always thought the rods on these models were indexed to prevent twisting within the trunnion bracket.

Question....does the blade angle shift at all when the blade is raised vs lowered?

[Aaron Koch]

Well let us know what happens. I'm surprised there is adjustment on those rods.

Since I haven't gotten in there to do anything yet I'm a little fuzzy myself on the mechanics and how this is going to resolve the issue, but based on my understanding of what SC is telling me the rods themselves don't necessarily adjust. There are jam nuts on the ends of the rods, the nuts are loosened and the trunnion brackets are actually adjusted to make the rods coplanar.

Ditto...I always thought the rods on these models were indexed to prevent twisting within the trunnion bracket.

Question....does the blade angle shift at all when the blade is raised vs lowered?

This could be the idea, but if the rods somehow get tweaked then the trunnion brackets are twisted and the blade is tweaked maybe? The angle does not appear to shift (I assume you're referring to the bevel). I've been meaning to get a Wixey cube but I don't have one, so I used a combo square to check this and didn't note any shifts as I raise and lower.

I'm going to try to make a video of the action, it feels/looks like something is binding toward to top maybe 1/3 of the height adjustment. Just applying pressure either CW or CCW on the height handle causes the blade to shift significantly.

Another variable - The saw had the elevation and arbor assemblies replaced. The previous owner said it was all replaced due to a bad bearing, but I wonder if that has something to do with it.

The SC manual says .010" is the threshold for adjustment so I guess I'm still within tolerances but I was hoping for better.

[scott spencer]

Are the gears free of impacted saw dust?

[Howard Acheson]

It sounds like your trunnions are out of alignment. This can happen on contractor or hybrid saws.

There is a significant area of alignment that is not detailed in most magazine tune-up articles. It is ensuring that the trunnion bars are exactly in the same plane. Proper adjustment affects bevel cuts and is indicated when there burning when making bevel cuts. Here are the corrective steps that were at one time posted on the Delta website and are applicable to any contractor or hybrid saw.

First go throught the alignment process following the steps in the attachment below.

To check whether the trunnions need to be adjusted, tilt your blade fully to the 45 degree position until you get to the 45 degree stop. Then crank the blade back to the 90 degree upright position. Now again check the parallelism of the blade to the miter slot. If the blade is still parallel to the miter slot, declare victory. If not, follow the process below from Delta to adjust them. The process is the same for all Contractor Saws or Hybrids that have the trunnion assembly hanging from the table.

1. Remove the saw blade being sure it was at it fullest height.

2. Place a flat plate (or similar flat object) on top of the two tie-bars. (The size of the plate should be at least 6" by 8", and the flatter the better. A pane of glass works well.) Depress one corner of the plate and if it rocks, the tie-bars are not parallel. This must be corrected as it will affect the alignment of the blade.

3. Loosen the tie-bar locknuts located at the rear of the saw.

4. Grasp the motor bracket and move it left and/or right. Check the rocking of the flat plate and when it can no longer rock, the tie-bars are parallel...re-tighten the locknuts.

5. Remove the flat plate and re-install the sawblade.

6. Again perform the parallelism alignment process.

7. Before tightening the rear trunnion bolts, push forward on the rear trunnion bracket to allow the undercarriage to snugly fit between the two trunnions.

[Aaron Koch]

It sounds like your trunnions are out of alignment. This can happen on contractor or hybrid saws.

There is a significant area of alignment that is not detailed in most magazine tune-up articles. It is ensuring that the trunnion bars are exactly in the same plane. Proper adjustment affects bevel cuts and is indicated when there burning when making bevel cuts. Here are the corrective steps that were at one time posted on the Delta website and are applicable to any contractor or hybrid saw.

First go throught the alignment process following the steps in the attachment below.

To check whether the trunnions need to be adjusted, tilt your blade fully to the 45 degree position until you get to the 45 degree stop. Then crank the blade back to the 90 degree upright position. Now again check the parallelism of the blade to the miter slot. If the blade is still parallel to the miter slot, declare victory. If not, follow the process below from Delta to adjust them. The process is the same for all Contractor Saws or Hybrids that have the trunnion assembly hanging from the table.

1. Remove the saw blade being sure it was at it fullest height.

2. Place a flat plate (or similar flat object) on top of the two tie-bars. (The size of the plate should be at least 6" by 8", and the flatter the better. A pane of glass works well.) Depress one corner of the plate and if it rocks, the tie-bars are not parallel. This must be corrected as it will affect the alignment of the blade.

3. Loosen the tie-bar locknuts located at the rear of the saw.

4. Grasp the motor bracket and move it left and/or right. Check the rocking of the flat plate and when it can no longer rock, the tie-bars are parallel...re-tighten the locknuts.

5. Remove the flat plate and re-install the sawblade.

6. Again perform the parallelism alignment process.

7. Before tightening the rear trunnion bolts, push forward on the rear trunnion bracket to allow the undercarriage to snugly fit between the two trunnions.

This sounds like what SC told me to do, except that my trunnions don't hang from the table.

[Phil Thien]

So what do you use as a reference to get the bars into the same plane? Plywood warps, MDF sags. I suppose you could use a piece of glass if you were careful.

[Aaron Koch]

A piece of glass seems to be most commonly suggested.