Thread: How to test squareness of cut?

http://www.woodcraft-manningham.org....les-square.pdf

There a quite a few ways to test squareness of CMS and table saws.

The one above is just one I picked up after google showed me.

Cheers

Glenn

thanks for this, wolften. I don't understand why he takes a 20mm final cut and compares the height to get the magnified error for the table saw, but not for the CSMS. Why the difference in the two procedures?

Jill
As I see it, it is because, with the SCMS you cut 90 º to the fence, the fence cannot be moved but the table/blade can and with the TS you cut parallel to the fence and have to adjust the fence not the table/blade.
Hence, if you just cut 20 mm off on the SCMS, your cut will be parallel to the edge but your piece will be out of square.
The SMCS test can be used for your mitre guide to check whether it is square to the blade.
Cheers
Wolffie

Thanks Wolfie

That is a really clear explanation. Rather than break that 20mm strip you could also measure it using calipers. By quantifying the taper you could more precisely see the effect of your adjustments; and minimise the yo-yo effect.

Originally Posted by JillB

thanks for this, wolften. I don't understand why he takes a 20mm final cut and compares the height to get the magnified error for the table saw, but not for the CSMS. Why the difference in the two procedures?

Good question, Jill. From just analysing the geometry involved, it looks like the 20mm strip method (or a 5mm strip) would work for both saw types. The error (taper) would be magnified more in the 800mm table saw cut, as opposed to the 150mm SCMS cut - just the scaling effect.

Cheers

Graeme

thanks for this, Graeme. I checked the Festool user manual online today (UK version), and it uses the same 4 cut method for doing a pre-calibration test inboth the horizontal plane and the vertical plane.

They actually cut a 20mm wide piece for the final cut and measure the width at each end. They give a formula for measuring the angle error.

The manual says care should be taken in over-using this calibration procedure because it has such a fine accuracy that it could be easy to get carried away and try to over-calibrate the saw. The factory calibration threshold is ±0.16°, but this calibration procedure is capable of measuring errors as low as ±0.001°, which is nearly impossible to get!