R4511 Table top alignment instructions

[DaveWoodWork]

When people started talking about aligning their table tops with the saw blade at both 90 and 45 degrees, it got me to thinking about the procedure. While I know this is old hat to many, it was not immediately intuitive to me. I had to go through the process in detail on paper until I felt I understood things. I wrote the process up and decided to share it with whoever might be interested. It seemed to have worked for me. Hopefully others may find it useful. Feel free to point out the errors I've made (I'm sure there must be some).

My instructions are attached as a PDF file. Have fun!

Dave

[Bob D.]

A very nice write up Dave complete with informative photos.

You didn't throw that together in an hour.

Washers can easily be 'tuned' to the required thickness with some wet/dry paper and a little elbow grease.

Much of what you have said in your article would apply to a contractor saw except of course that the table can not be moved, you have to shift the position of the carriage which is slung from the underside of the table. But checking for parallelism between the blade tilt axis and the miter slot is important on a contractor style saw but probably not as easy to correct as a cabinet saw.

[BadgerDave]

Very nicely done Dave. I'm sure that your hard work will help many new owners with their own setups.

[chrisexv6]

I know when someone here mentioned doing this (I think it might have been you, DaveWoodWork), it sure didnt make much sense to me. Then I went home and put the blade a 45 and stared at it for a bit, then the light bulb lit up.

My way wasnt nearly as scientific as yours, so I may re-check my measurements using your guide as a guide.

Thanks!

-Chris

[Bob D.]

Well I had nominated this thread when it first came up and then withdrew the nomination because when I went to the TOTW thread it says the poll is closed. To me this meant that no one else would be able to vote for Dave fine alignment procedure as the nominations had just closed soon after I made my nomination. I emailed Josh and explained why I had removed my nomination so that this thread could be nominated again in the following week.

But, I see that Badger Dave has now also nominated it and the nomination was placed in the same week as when I nominated it, so apparently it is not closed as it plainly states under the poll results.

So I now add my vote again to this thread not knowing how much more time there is for other people to vote for it.

Come on you lazy woodworkers, click on the button and VOTE!. :soapbox:

[The Grey Knight]

Good info, I still have to do this to my 4511 that I put together last weekend. I am guessing we all had to realign the top since we took them off to unload the saw.

[airChris]

Great write up -- it seems that from the results contained in the file (appendix B), it works.

But I was wondering.... It appears that you are using pythagoras theorum to derive 't'. In appendix A you write "Remember back from high school that the square of the hypotenuse is equal to the sum of the squares of the adjacent sides." As far as I remember (and it's been a while), phythagoras only applies to right triangles, not isosceles triangles. Or have I overlooked something ??

Chris

[DaveWoodWork]

..., phythagoras only applies to right triangles, not isosceles triangles. Or have I overlooked something ??

Chris

You are correct. Remember, I said to angle your dial gauge down 45 degrees. That together with the 45 degree tilt on the saw blade gives you a 90 degree angle for one of the angles. The triangle is a right triangle with two equal sides. You can measure at other dial gauge tilt angles, but then you'd have to use sine values to calculate the side, something I was trying to avoid.

Good pickup. I enjoyed geometry in school, but I've had to dust away quite a few cobwebs to use it here.

Dave

[Smack]

You are correct. Remember, I said to angle your dial gauge down 45 degrees. That together with the 45 degree tilt on the saw blade gives you a 90 degree angle for one of the angles. The triangle is a right triangle with two equal sides. You can measure at other dial gauge tilt angles, but then you'd have to use sine values to calculate the side, something I was trying to avoid.

Good pickup. I enjoyed geometry in school, but I've had to dust away quite a few cobwebs to use it here.

Dave


a right triangle does not have to have equal sides, just a 90-degree angle. An isoceles triangle has 3 equal sides.

[DaveWoodWork]

a right triangle does not have to have equal sides, just a 90-degree angle. An isoceles triangle has 3 equal sides.

Correct. A right triangle does not have to have equal sides, but in my setup, the resultant triangle is both a right triangle and happens to have two equal sides. An isoceles triangle has two equal sides. An equilateral triangle has three equal sides.

I specifically measured my saw blade with the blade angled to 45 degrees and the dial gauge angled down at 45 degrees. In the attached diagram taken from appendix A, angle BAF will be 90 degrees due to the blade and gauge angles. Angle ABF is the dial gauge position angle, which we set to 45 degrees. Since all the angles in a triangle must add up to 180, we know that angle AFB must also be 45 degrees. Since two of our angles are the same, we know that this is an isocelese triangle (http://mathworld.wolfram.com/IsoscelesTriangle.html) and the two corresponding sides must also be equal (both equal to d). Since this is a right triangle, we can calculate the hypotenuse (side t) using Pythagorean's theorem (http://mathworld.wolfram.com/PythagoreanTheorem.html).

Dave

[Smack]

An isoceles triangle has two equal sides. An equilateral triangle has three equal sides.



Right you are.

[FINER9998]

so if i understand dave's write up, the 45 deg. adjustment on a contractor saw would be made by shimming between the trunions and the underside of the cast iron table, to which the trunions are attached?

[DaveWoodWork]

so if i understand dave's write up, the 45 deg. adjustment on a contractor saw would be made by shimming between the trunions and the underside of the cast iron table, to which the trunions are attached?

Correct! You want to correct the relationship between the plane of the blade and the plane of the tabletop. Hopefully it should be pretty close for a contractor saw.

Dave

[FINER9998]

DaveWoodWork... after studying the write up ( and it really is an impressive piece of work), and understanding the basic alignment principle, i can't seem to follow the example in appendix b. i follow the first paragraph, but paragraph 2 states:

"Based on my calculations, I knew that I needed to raise the right front table support point by an additional .039
inches (.023 x 1.7). Since it was already shimmed up .026 inches, I needed a total shim height of .065 inches on
the front right."

where did the 1.7 come from? secondly, isn't .039-.026= .013? yet the above paragraph says a total shim height of.065" was needed on the front right.

on a contractor saw, where the trunion mounting points are equidistant from the rear of the table, shim thicknesses sy and sz would be the same, right?

and when, in the tabletop alignment worksheet, item "d"
addresses 'further/closer", i'm not quite sure of how to interpret that.

this approach is better than hit and miss, but i need a little clarification. any other volunteered information regarding the application of these principles to contractor saws similar to the 3660 would be appreciated. thanks.

[DaveWoodWork]

Hi Finer9998,

Thanks for carefully reading the Appendix B. Upon re-reading it, I realized that it was based on an earlier method I had used rather than the method described in the document. Please ignore that Appendix B. I've included a revised version of the PDF file here (and will also replace the original one in the post if I can) that has a corrected Appendix B.

For a contractors saw, if the trunnion mounting points are symmetrically spaced, then the shim thickness should be the same on each side. We are only interested in correcting the front-to-back tilt to make the miter slot parallel to the tilt axis of the blade.

The "Further/Closer" item on line D of the Worksheet is merely to establish whether the tilt of the tabletop is positive or negative relative to the tilt axis of the blade. It will tell you whether to use F(iii) or F(iv) for your shim calculations. For a contractors saw, if the back of the blade is further from the tabletop than the front of the blade, then you will need to add spacers at the front trunnion attachment points to get things parallel and visa versa.

Thanks again for picking up my error. As far as I can see, the calculations should apply to a contractors saw as well. With symmetrical trunnion attachment points, the calculations should be simpler on a contractors saw. I don't know how difficult it is to shim the trunnion attachment points on your saw though. The R4511 is my first table saw, so I'm still learning.

Dave

[FINER9998]

DaveWoodWork...thanks for such a prompt reply. the PDF you posted does clarify the adjustment calculation. again, it is an impressive piece of work about an aspect of saw alignment that i haven't seen addressed in any of the manuals i have perused or online "tips" and procedures i have viewed. so the actual adjustment to your 4511 was ~1/16" on the right front support and ~5/64" on the left front support? have i got that right?

and regarding the "Further/Closer" item on line D of the worksheet, if the blade moves away from the table top, i.e., the dial indicator's pointer moves further away from the dial face, then that is indicative of "further", necessitating the use of F(iii)?

lastly, would item E in the worksheet vary with the size of a blade (12" vs. 10") and the point of contact on the blade? smaller gullets, or finding a flat surface closer to the outer edge of the blade, would cause item E to vary from 7.5", right?

your paper is both informative and entertaining. i haven't used that kind of geometry since i don't know when. thank you for taking the time to describe the situation so clearly and providing a worksheet so the adjustment can be stepped through by others with realtive ease.

[FINER9998]

oops, duplicate post.

[DaveWoodWork]

... so the actual adjustment to your 4511 was ~1/16" on the right front support and ~5/64" on the left front support?

Correct. That is the final amount of shimming required for each side and the approximate thickness of the washers I placed.

and regarding the "Further/Closer" item on line D of the worksheet, if the blade moves away from the table top, i.e., the dial indicator's pointer moves further away from the dial face, then that is indicative of "further", necessitating the use of F(iii)? Correct. If the back side of the tabletop is sloping up with regards to the tilt axis of the blade, then the back measurement will be "Further" (larger) than the front measurement.

lastly, would item E in the worksheet vary with the size of a blade (12" vs. 10") and the point of contact on the blade? smaller gullets, or finding a flat surface closer to the outer edge of the blade, would cause item E to vary from 7.5", right?Correct. Whatever the distance is between your measuring points is what you would use here. For my 10 inch saw blade, the distance as measured along the tabletop between my front measuring point (bottom of a gullet) and back measuring point (bottom of the same gullet with that gullet rotated to the back) was about 7.5 inches. This is used to calculate the slope. You measure how "tilted" the tabletop is relative to the blade (change in Y axis) and you need to also know over what distance this change occured (change in X axis). Slope = Change in Y axis / Change in X axis.

In my research, I found very few articles/posts that even mention adjusting the alignment with the blade at 45 degrees. They would just say to put in some shims and recheck until you have it right. I thought there must be a more "scientific" way to do it. This is my newbie attempt to figure that way out. I had to dust off some of my math to accomplish it. Like you said, mathematics was one of my favorite subjects in college, but I've had little call to use it. I'm glad someone else found the paper entertaining.

Dave

[rofl]

And nothing is right about a love triangle.

Just wanted to help a little.

[FINER9998]

here is a recent online review of the 4511 by tom begnal of fine woodworking.com.

http://www.taunton.com/finewoodworking/ToolGuide/ToolGuideProduct.aspx?id=32140&tab=_editor

the last paragraph of the review talks about the 4511's 45* blade alignment issues. hey dave, maybe you should send him a copy of your write up. it might cut the time he has to spend "under the saw".

[3rdtime]

DaveWoodWork, just want to thank you for a great article. I had tuned up everything else on my new R4511, but did not realize there might be an issue with the 45* setting. Never had any difficulty on my other saws. This one however, needed approximately 1/16"+ washers on the front locations. I used the formulas, but due to cabinet fluctuations, I needed to adjust the final thickness from the fomula results. I also didn't have a dial indicator, so I had to just measure the horizontal difference from front of blade to back using a steel rule and the miter gauge. This became my "t" dim. Now I just have to finish it up so I can cut wood. That's why I bought it, not to spend 2 weeks fine tuning everything the factory threw together on a friday afternoon. :D