Thread: Engineers Square - reasonable quality

Originally Posted by barri

Fair point Ian but this is for alignment purposes. If my Incra gauge is not bang on 90 then 45 won't be 45 and an inaccurate mitre really shows up when you make a picture frame. I sometimes use a sled for this and if the fences aren't right then an error will be obvious. I've also bought some squares from Bunnings and they are not square. I aligned my gauge with all of these and all of them gave a different reading. Also, all of them didn't give me an accurate 45. So which one do I trust. Table saw alignment is also important to me that's why many own dial indicators. Another similar precision instrument.

Use the square to get it close then scraps of timber to test adjusting as you go. Then cut your pieces.

If you use a wide board for the test the easier it is to see the error.


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Dazz, that's not accurate enough for me. The 5 cut method and my new found method using a dial indicator get me bang on square, in fact the new method gets me there without a cut although I do a final test cut on a wide board but it isn't necessary. I might be anal about this but when you spend hard earned money on expensive machinery then you want it to be right. Also 44.9 degrees on a mitre joint will shop up when you make your frame. Additive errors are a problem.

HI Barri

We sound like brothers. I cant stand any inaccuracy in my joints.

However, if we are talking picture frames then you will struggle to get them square to the perfect angle you are chasing off a tablesaw particularly if you are cutting the two pieces seperately

I cut perfect mitred picture frames using a nobex hand mitre saw;

https://www.carbatec.com.au/joinery-...pion-mitre-saw

and a mitre trimmer;

https://www.carbatec.com.au/joinery-...3kg-62-25-20cm

If doing more rustic styles where the finish off the table saw is acceptable I cut both 45's at once using a mitre sled;

https://youtu.be/ZtwK9X8o1Gw

If you use this method it matter not if one angle is 44.2 and the other 45.8 as they add up to 90deg.

I doubt even my young eyes could pick up 44.9 as opposed to 45 degrees off the square.

Hey brother

I do have a mitre sled and I do cut on both fences to get a total of 90 but sometimes I couldn't be bothered getting it out for laziness reasons. Also Incra's mitre gauges are meant to be the bees knees. I was hoping to use it for most crosscuts angled or straight. So I'm assuming rightly or wrongly that if I can get bang on 90 with it then the 45 should be 45 given Incra's reputation, accuracy and reliability

3 pages about finding a square to adjust an Incra mitre? Which model Incra mitre gauge are you trying to adjust?

I have the 1000HD and have never had any trouble getting it spot on and it stays spot on.

What am I missing?

Try Jim Davies he has a range of squares.

Originally Posted by Big Shed

3 pages about finding a square to adjust an Incra mitre? Which model Incra mitre gauge are you trying to adjust?

I have the 1000HD and have never had any trouble getting it spot on and it stays spot on.

What am I missing?

No you haven't read all posts or watched the video. This is about (getting repetitious isn't it) finding a good quality square to use in a new (new to me) method that uses a dial indicator that's just as effective as the 5 cut method for squaring gauges and sleds. BTW I have a 1000SE. If you haven't done the 5 cut method then search it in youtube. Plenty of videos. These methods are more precise than simply holding your square against the blade which is the wrong way to do it.

Sorry led you up the garden path, like you I have the 1000SE.

Notwithstanding that, I have always found it easy to adjust to get perfectly square cuts.

The problem with relying on the square and dial indicator gauge is that you are held captive to the accuracy of the gauge. Drop it, bump it, kids use it as a gun, its a hot day, its a cold day - all these things put it ever so slightly out.

And when you are talking to a .00degrees then you will probably always have an error.

The five cut method, or any other method that involves trial cuts, will always be accurate -IN THE END.

And if its good enough for Mr Ng. Then its probably good enough for us all.

A 50's American car race engineer, I think named Chuck, once said something like;
"Parts left out cost nothing and cause no maintenance issues"

Any test that involves extra apparatus increases the potential error. Sure the 5-cut method is time consuming, as is checking 45 degrees by cutting 4 pieces with mitres on both ends, but they are self proving by definition, just like checking a square against itself by the mark-flip-mark method. End rant.

If you want serious precision, you can ebay for a second hand Starrett No. 20 - stated tolerance of 1 in 60,000. Accuracy like that does cost money though, a 6" will set you back over $100, but that's still 1/4 of the new price. I bought a 12" for machine setup at work and a 36" (yes, a 3' inspection grade square) cos it was cheap; only $400 shipped from the US. I actually did use it once to set a vertical clamping system on the CNC

Originally Posted by dazzler

The problem with relying on the square and dial indicator gauge is that you are held captive to the accuracy of the gauge. Drop it, bump it, kids use it as a gun, its a hot day, its a cold day - all these things put it ever so slightly out.

And when you are talking to a .00degrees then you will probably always have an error.

The five cut method, or any other method that involves trial cuts, will always be accurate -IN THE END.

And if its good enough for Mr Ng. Then its probably good enough for us all.

Held captive!!! I have 2 dial indicators (about $30 each) and they are both reasonably accurate or accurate enough for me. This method is not reading a number off the dial indicator its all to do with watching the gauge until the indicator isn't moving while the sled is moving through the slots regardless if its out or not. If its not moving then the fence is accurately square with the mitre slots. This is more important than aligning the fence with the blade. This video shows why its more important. https://www.youtube.com/watch?v=NrTeFQ0iQ5k If your blade isn't parallel to the slots then aligning off it will lead to inaccuracies.

I've used the 5 cut method many times and it does job well but also relies on vernier calipers (which could be dropped, bitten by an insect or left out in the sun) this new method is just as accurate (yes I've tested that), quicker, simpler, no mess and no noise. The only trial cut is one at the end and I've found its always spot on. Another respected woodworker explains this method in this video https://www.youtube.com/watch?v=tZM1OBcC6ok

To say Mr Ng's method is the only definitive method is like telling an athlete their training methods don't need changing,. So sceptics ..... I suggest you try it before criticising. I'd be happy to hear from you then. If you don't like it then that's fine. You might be surprised as I was.

Accuracy costs money.

A very interesting topic .. I have used the 5 cut method, and the dial indicator method too.

But .... and this may be heresy ... I found that for my large sled ... 1m X 600mm. . a piece of Masonite fresh from the hardware shop gave me a perfect square for setting the sled .. just lay the Masonite board on the sled (against the sled's fence... and slide over to the TS fence. then adjust the sled fence up to the so thet the face on the TS fence is spot on.. clamp and screw down the sled fence.

BTW this works OK as long as you have set the TS fence parallel to the mitre slots previously.

Do a cut on the Masonite and check with a vernier ... you may be surprised how square Masonite is from the factory.

Regards

Rob

Good one Rob. If the masonite is square and big enough and your fence is parallel as you said then this is fine. Nice to hear an alternative simple method from someone who has actually tried the other methods. I might check my sleds using your method. Not heresy at all. I just prefer the other 2, particularly the dial indicator, more accurate methods but that's just me.