FS WA out of square
- Thread starter LiranB
- Start date
mino
Member
FS-WA is always "out of square". The notches are only orientational.
When you need precision, you need to calibrate it always when you change the set angle.
There are two basic approaches:
A) calibrate the square itself - more convenient
B) calibrate the set of a square connected to a (specific) rail - more accurate
procedures in short
A) you need a reference machinst square that fits with the square (high precision one, generic ones are not precise-enough, needs DIN Class 1 or better/equivalent), calibrate the square and there you go
B1) you do not need any devices, just some sheet of ply, MDF etc.
- set the square to the 90 degree notch and make a cut using the square+rail set though the middle of a reasonably big sheet (3'x3' at least
- flip the off-cut over the cut piece and align the reference edges so they are aligned )using 3rd sheet good piece
- check for any in accuracy (note: the difference you will see will be *twice* the adjustment to do in next step
- put the off-cut BACK where it was, but put both pieces right pushed to each other, the cut line being the "joining" surface of the pieces
- place the rail as if you were to re-cut the cut and clamp the cut-piece and the off-cut so it does not move, do NOT clamp the square or the rail
- place the square as if tyou were doing a cut, release the knob and adjust the position of the rail - reflecting the adjustment needed you have from earlier check step, once adjusted tighten the knob
- take the square/rail set away from the piece and place it there once more the same way you would if making a fresh cut
- make a cut along the "already-cut" line, effectively re-doing the cut, ruight through the middle of the old one
- repeat the check and the calibration adjustment as/if needed once more
Using above I am able to get within 0.2mm/m (0.01"/4') accuracy on my setup which is just about as good as the reference edge can provide for cross-cuts.
B2) Requires a big engineer's square - like 3'x2' big which usually go for $200 or so, this allows you to calibrate the whole rail-square asssembly against it, avoiding the multiple cuts method but also a bit out-of-reach for a hobbyist.
Lastly, you will want to validate your overall accuracy using the 5-cut method.
Apologies but no videos.
When you need precision, you need to calibrate it always when you change the set angle.
There are two basic approaches:
A) calibrate the square itself - more convenient
B) calibrate the set of a square connected to a (specific) rail - more accurate
procedures in short
A) you need a reference machinst square that fits with the square (high precision one, generic ones are not precise-enough, needs DIN Class 1 or better/equivalent), calibrate the square and there you go
B1) you do not need any devices, just some sheet of ply, MDF etc.
- set the square to the 90 degree notch and make a cut using the square+rail set though the middle of a reasonably big sheet (3'x3' at least
- flip the off-cut over the cut piece and align the reference edges so they are aligned )using 3rd sheet good piece
- check for any in accuracy (note: the difference you will see will be *twice* the adjustment to do in next step
- put the off-cut BACK where it was, but put both pieces right pushed to each other, the cut line being the "joining" surface of the pieces
- place the rail as if you were to re-cut the cut and clamp the cut-piece and the off-cut so it does not move, do NOT clamp the square or the rail
- place the square as if tyou were doing a cut, release the knob and adjust the position of the rail - reflecting the adjustment needed you have from earlier check step, once adjusted tighten the knob
- take the square/rail set away from the piece and place it there once more the same way you would if making a fresh cut
- make a cut along the "already-cut" line, effectively re-doing the cut, ruight through the middle of the old one
- repeat the check and the calibration adjustment as/if needed once more
Using above I am able to get within 0.2mm/m (0.01"/4') accuracy on my setup which is just about as good as the reference edge can provide for cross-cuts.
B2) Requires a big engineer's square - like 3'x2' big which usually go for $200 or so, this allows you to calibrate the whole rail-square asssembly against it, avoiding the multiple cuts method but also a bit out-of-reach for a hobbyist.
Lastly, you will want to validate your overall accuracy using the 5-cut method.
Apologies but no videos.
EastMountainDesignworks
Member
- Joined
- Sep 19, 2025
- Messages
- 3
This is super helpful, but maybe I'm missing something, like how physically on the FS-WA, do you adjust the angle finder when squaring it?
mino
Member
You do not. You ignore it.
An "angle finder" /no matter the tool/ is the "approximate" solution, good enough for many cuts, by definition not accurate for true precision.
EastMountainDesignworks
Member
- Joined
- Sep 19, 2025
- Messages
- 3
Forget the other angles the 90° should be able to be square, or move it to square even if it doesn’t read 90°.
mino
Member
No and no.
And it /fundamentally/ never can be. Not if the square is supporting angles on both sides of the right angle. Only a stop-based system can be precise. You may 'trust me bro' or not on this one, your choice. Just trying to help others on a fruitless journey .. searching for the 'Holy Grail' that never was nor will be.
Now, to be precise, it is possible to make a calibrate-able square that is one-side only (so 0°-90° only) with a set screw to calibrate the 90' endpoint. Yet, to my knowledge, no one ever made one. Most likely because it is mostly pointless.
Anyone with the knowledge/need to calibrate a square/rail assembly will not trust such a contraption and will use a reference square anyway as it is faster and more reliable, not to mention vastly simpler/cheaper.
Packard
Member
My miter gage for my Delta table saw has three positive stops with set screws to zero them out. I have it zeroed out for 90 degrees, 45 degrees left and 45 degrees right. All the other angles depend on visual alignment of indicators.
When I was shopping for a miter saw 25 years ago, I saw that most of the saws had as-cast detents for the various settings. Except for DeWalt which used a stamped metal detent system that was very accurate. (Unfortunately, the saw blade does not spin true, so that effort was close-but-no-cigar.)
Only the dedicated 45 degree sliding table saw (designed for picture framers) does not have adjustability. It is factory-set (and apparently perfectly accurate).
I test the 45 degree angle cuts by joining two pieces to a theoretical 90 degrees. I measure the both the inside and outside of the 90 degree joint. But note, take both pieces from the same side of the blade to get a true picture of the accuracy.
When I was shopping for a miter saw 25 years ago, I saw that most of the saws had as-cast detents for the various settings. Except for DeWalt which used a stamped metal detent system that was very accurate. (Unfortunately, the saw blade does not spin true, so that effort was close-but-no-cigar.)
Only the dedicated 45 degree sliding table saw (designed for picture framers) does not have adjustability. It is factory-set (and apparently perfectly accurate).
I test the 45 degree angle cuts by joining two pieces to a theoretical 90 degrees. I measure the both the inside and outside of the 90 degree joint. But note, take both pieces from the same side of the blade to get a true picture of the accuracy.
smorgasbord
Member
Well, Bridge City Tools Works made a few adjustable try squares. I actually own one. Here's one that was for sale if you want to see what it looked like:
BRIDGE CITY TOOL CO. AS-14 Adjustable Try Square in Original Box - 95226
Box crushed. Factory engraved. Some corrosion.
www.jimbodetools.com
Here's one that's for sale right now for a crazy (to me) $200 price:
smorgasbord
Member
I might have had the same saw. 12" blade, chop saw (no slide). I don't recall how accurate it was outside of 90º. I sold it to get a slider for larger width capacity.
My 12" Bosch "knuckle" slider has a plastic detent rack. Maybe I should spend $10 and buy a spare?
Bosch Parts 1-609-B00-222 Sliding Plate For Bosch electric saw
Buy Bosch 1-609-B00-222 Sliding Plate at a discount price. ToolpartsPro.com offers a complete range of original Bosch repair parts for your Bosch tools. Order online or call 1 (760) 280 3008.
www.toolpartspro.com
If I had a 3D printer, it would be interesting to make one with detents for the angles I use, not the rafting/crown molding stuff they build in these days. And with some trial and error, maybe could iterate on accuracy? But, I won't since I'm still working on that uber-accurate cross-cut angle sled.
mino
Member
Interesting.Well, Bridge City Tools Works made a few adjustable try squares. I actually own one. Here's one that was for sale if you want to see what it looked like:
BRIDGE CITY TOOL CO. AS-14 Adjustable Try Square in Original Box - 95226
Box crushed. Factory engraved. Some corrosion.
Here's one that's for sale right now for a crazy (to me) $200 price:
Though I was /implicitly/ referring a rail square.
With engineer's squares, there is usually no point in making them adjustable as they are a single item - so can be made dead-on.
With rail squares this is different. For accurate cuts the whole square+rail assembly must be accurate so also the rail comes to play .. and its back side is not guaranteed to be as accurate as one may need. There an adjustable square like the FS-WA is priceless. It allows to calibrate-out any such imperfections in the rail or its connection to the square. Unlike with a fixed square like the FS-WA/90 (aka GRS 16), no matter how precise it is.
Case in point:
I have two (2) FS-WA/90 and still was extremely happy when the (adjustable) FS-WA came. Some of my rails are not straight-enough for perfect accuracy and the FS-WA plus a reference square makes that a non-issue. Since I got it, I no longer use the "GRS 16" style squares for any work I need top precision with..
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