Sliding tablesaw outrigger alignment

[Travis Porter]

I am trying to get my outrigger fence aligned on my sliding tablesaw, and quite frankly, I can say it has been a PITA. For those unfamiliar with what an outrigger is (I was until I started looking at these things), it is the big cross cut assembly that you can cross cut an entire sheet of plywood or other long boards.

First, I tried using a framing square with my dial indicator only to find that my square has a bow in it and is not straight. So, I read the "unofficial Felder survivors guide" and it talks of doing a five sided cut on a board to determine how much you are off. This works, but it doesn't do a lot to help you adjust it. I did get it within 3/64 on a 24" square board, but when you multiply that by 4 for when you are cutting a full 8 foot long board or sheet of plywood on the slider that 3/64 becomes 3/16" and not as accurate as I want it.

My next alternative is to get what they call a "polish square". It is a very thick square (1/4 inch) that is high precision and is 18" by 8". Using it with the dial indicator is also a PITA. I have adjusted the fence back and forth and have gotten it close, but still haven't got it quite right.

So, I have been thinking. Why can't I lay a full sheet of plywood long wise on the slider and get the outrigger square to the slider using the sheet of plywood. I have some cabinet grade ply, and I don't think I have ever had a sheet of ply that wasn't square so shouldn't that work?

 

[Gotcha6]

Have you thought about Pythagoras? Measure out a 3-4-5 triangle or any multiple thereof (12-16-20, 30-40-50, etc. You should only need a good straightedge and a corner reference point.

 

[Travis Porter]

Have you thought about Pythagoras? Measure out a 3-4-5 triangle or any multiple thereof (12-16-20, 30-40-50, etc. You should only need a good straightedge and a corner reference point.

I did that a little on a small scale (30, 40, 50), but to your point, maybe not on a large enough scale. Not a bad idea.

 

[Gofor]

So, I have been thinking. Why can't I lay a full sheet of plywood long wise on the slider and get the outrigger square to the slider using the sheet of plywood. I have some cabinet grade ply, and I don't think I have ever had a sheet of ply that wasn't square so shouldn't that work?

I have gotten ply that was not square, (one end out 3/16") and also ply that did not have straight edges. However, that is not the norm. I would do a corner to corner measurement first just to be sure. Sounds like a plan to me. Why make it more difficult than necessary? If one end is out, just trim as necessary with straightedge and skil-saw.
The trouble with the 3/4/5 method is getting the exact apex point on the 2 acute angles, and making sure your rule is accurate at all three measurements. If you use the plywood and do the diagonal measurements, it does not matter if the scale on the ruler is accurate as long as you get the same measurement.

Go

 

[Jay Brewer]

Hi Travis. The best way to setup the the crosscut fence is with the 5 cut method. It can be a pain , and time consuming, but these saws are capable of perfectly square cuts. According to the 5 cut method, my saw is out .002 every 3 feet of stroke.

First make sure your using MDF or melamine for your test panel around 3 foot square. The "Guide explains how to do the cut so I wont get into that, but instead of breaking the piece in half and measuring the difference in the 2 pieces, I use a pair of digital calipers to measure the top of the cut and the bottom of the cut/

Example: lets say the top of the 5th cut is .480 and the end of the cut is .500. That means you are out of square .020 , then divide that by 4, so you are out of square .005 over the length of your panel.

The best way I have found to adjust it is to use a dial indicator attached to the outrigger ( I use a magnetic base), were the indicator is touching the crosscut fence a the same distance from the blade as your panel is wide ( 3ft panel = indicator 3 ft from the blade). After zeroing the indicator, this will be your reference of how much you are moving the fence. In the example above it would be .005.

Hope this has helped, and not made it more confusing, I can post pics of the setup I use if you need them.

 

[McRabbet]

Jay -- great advice and welcome to the site -- Please go to the "Who We Are" forum and introduce yourself to our fellow members. We're glad to have you, but that way more members will know you're here!

 

[Travis Porter]

OK, that makes sense. I didn't use MDF so that may have had an effect as well. FredP came over today after we went to Fernhollowman's and we tinkered with it using an 8ft sheet of plywood and seem to have gotten it pretty darn close. I have some MDF so I will whip out a sheet and do the 5 sided cut again and see what I get and go from there.

Thanks for posting! At least I don't feel like I am nuts anymore.

 

[Bernhard]

Travis,

May want to check to make sure the sliding table runs all the way parallel. Cut a piece of of lumber or ply, mdf or whatever as long as the slider. flip one half over and align both pieces. Hopefully, there is no gap. If there is a gap, slider needs to be adjusted first to run parallel to the blade. If the slider is not parallel, the alignment of the outrigger will be off different degrres over the length of the slider.

Had another braiin fart: What about using 2 straight edges and the 12/24 precision square? Use the straight edges to lengthen the legs of the square. Use a dial indicator near the saw blade and align the outrigger.

Cheers,
Bernhard

 

[Travis Porter]

I got the thing pretty close using a full sheet of ply with Fred today. It is now within between a 1/32 and 1/64 over an 8 ft board. I think part of my problem is my POS dial indicator. It is super el cheapo and doesn't help. I am going to get a better one and then see what I can do. Regardless, it is close, very close.

As for being parallel, I am pretty sure that it is. I have done quite a few cuts with the short crosscut fence and ripped on the slider. If it wasn't parallel, I would have the blade binding as well as my blind cuts for tenons would be off and they are not. They have been perfect.

BTW, don't forget the catalog Tuesday!