how to check if fence is 90 degree to blade

[russ_1380]

HI,

I am cutting some sheet into rectangular panels, I need to ensure they are square (all corners 90 degree).

I recently saw a good web page that showed a simple way to check if your machines fence is accurately set at 90 degrees. (for example; a sled on a table saw where the fence is 90 degrees to the blade, when viewed from above)

Currently I am using the 'measuring the corner to corner technique' , but I can't remember how to do the other technique which I saw.

The technique went something along the lines of:

-Use your fence and make a 90 degree cut o a piece of scrap.
-Cut this piece in half
-Position the two pieces side by side
-Flip one half over
-Align the two pieces together and see if there is a gap

-The gap would then indicate that the pieces were not true 90 degree angles. (Out of square)

I can't really describe it too well, but it was a really simple technique that would show you if the panel was not cut perfectly 90 degrees. Then you could use this to alter the fence angle and try again. With trial and error you can set it so you can make perfect 90 degree cuts.

(Apologies for the poor explanation, I'm hoping someone knows what I'm rattling on about)

Can someone please explain this technique to me?

Cheers


Russ

 

[wizer]

I think you've explained it well. The gap would be the error doubled. So you need to alter the fence half the amount of the gap.

or just get one of these

 

[russ_1380]

ah that looks a good tool!

http://books.google.co.uk/books?id=z-pz ... q=&f=false

If this link works, this is what I was trying to explain. Page 68. It was annoying me that I couldn't remember the webpage

 

[Niki]

Hi Russ

I believe that you refer to the Miter gauge fence or a Sled fence. If so, the fence should not be at 90º to the blade but, at 90º to the Miter slot or the Miter gauge runner...

The alignment sequence of a table saw is: first, you have to align the blade to the miter slot and then, you set the miter gauge fence to 90º to the miter slot and after that, you align the rip fence parallel to the miter slot (some people love to set the rip fence a little bit "toe-out" at the far end.

The checking procedure that you mentioned is known as the "one cut test" and it's good but, more accurate check is the "5 cut test"
http://www.thewoodshop.20m.com/five_cut_method_swf.htm

The "Wixey" is perfect for setting the Miter gauge fence at 90º to the Miter gauge bar but also a "Lo -tech" method with a good and accurate triangle will work...

Regards
niki

 

[9fingers]

Are these Wixey angle devices any good.
For blade setting as in Tom's picture, surely to get any degree (ha!!) of accuracy the device has to be aligned parallel with a diameteral line on the blade?

Anyone got one and find it more than a gimmick?

I have one of their scales on my thicknesser and that is good so I have brand confidence.

Bob

 

[wizer]

I have one an use it to set my planer, band saw and TS. I can't really comment on it's accuracy except to say that it's 'good enough'. I haven't checked it's results in any sort of controlled way. I'm willing to tho. How would I confirm it's accuracy?

 

[9fingers]

Well Tom,

A pretty sensitive test might be cutting mitres with the blade set over at 45 degrees and see how a four sides frame turns out?

Bob

 

[wizer]

Well that's on my list anyway, so I'll run a little test when I do. Unless anyone has already tried it?

 

[woodbloke]

I think you've explained it well. The gap would be the error doubled. So you need to alter the fence half the amount of the gap.

or just get one of these

That will only work if you can guarantee that the table top is dead horizontal...or have I missed something? - Rob

 

[9fingers]

Well that's on my list anyway, so I'll run a little test when I do. Unless anyone has already tried it?

Tom, May I suggest that you take the saw blade out and draw a radial line or series of lines in a permanent marker betwixt centre and the teeth.
When you use the wixey, turn the blade till one line is vertical and align the gauge up with that. Otherwise the clinometer will just measure the compound angle of the blade and the gauge case assuming it works the way I think it does.

Bob

 

[9fingers]

Post deleted - must learn to read!

 

[russ_1380]

cheers Niki,

That link was just the kind of thing I was looking for! Yes sorry I got mixed up with which was adjacent to which. I'll get the hang of it soon.

The reason I wanted to know; been making a shelving cupboard with my festool. I knocked up a quick jig to help me crosscut the shelves reasonably accurately. (near enough 90 degree). That got me thinking about how i'd do the adjustment (if i had one) on a table saw.

My festool does the job for now and is excellent on larger cuts, but I can't wait to get my table saw for 'real' accuracy!

Out of interest, I think I'll be going for that Deft one (new).

Thanks

Russ

 

[Niki]

That will only work if you can guarantee that the table top is dead horizontal...or have I missed something? - Rob[/quote]


I don't have the Wixey or other one but as I know, you can "Zero" it at any angle so, it doesn't matter if the table is horizontal...

As I mentioned before, you can use it to adjust your Miter gauge to any desirable angle....just clamp the Miter gauge runner (or bar) in the vise, "click" the Wixey to the runner and "Zero" it...now, move it to the Miter gauge fence and adjust it to whatever angle you want and lock it.

As for accuracy, they say that it is within ±0.1º and as I read on the American forums, they are very satisfied from it.

Regards
niki

 

[wizer]

Indeed. You Zero it out on the surface. It doesn't matter what angle the first surface it at, it will reference from it.

 

[Niki]

Hi Russ

A quick way to adjust the miter gauge fence is with a triangle like the one on the pics...

The same triangle can help you setting the rail at 90º to the board...

Regards
niki

 

[russ_1380]

Nice one

I've bookmarked this page so i can re-read it when the table saw comes. Its one of those tools I've always wanted and probably need to get the required accuracy for neat looking projects.

I'll take the plunge one day and sign the cheque.... :shock:

 

[BigShot]

Nice post there Niki!

I've been wondering how to go about that job for a while now... why are these things often so much more simple than I expect?

Thanks for the 5-cut link too. I saw that a while back and had forgotten all about it. I'll be putting that to use soon.

Great thread!

 

[Nev Hallam]

3,4,5 or a big square, surely all the rest is a bit much, I have no problem making square sheets of mdf using either a large square, or corner to corner or a basic square jig.

 

[woodbloke]

Indeed. You Zero it out on the surface. It doesn't matter what angle the first surface it at, it will reference from it.

Tom and Nikki - understood...thanks - Rob

 

[9fingers]

Zeroing will need to be done with the gauge placed in line with the axis of rotation of the blade.

I'm willing to be proved wrong but I feel that this device will need to be used so precisely to get good results that it could fail to be useful.

Bob