Thread: Buying a Vintage Mitre Square?

Or you could make one,

But I'm sure you know how dangerous tool making can be.
It's extremely addictive.

Cheers Matt


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To test it, you just need a board with a straight edge and use it as your reference edge.
Use your making knife and scribe a perpendicular line using your square on your board to the reference edge. Then flip the square over and scribe another line using the same reference edge. If the two lines meet as one. then its square.
Since you have 4 right angles with that t-square. I presume you have to repeat it 4 times.
Its easy on combination squre to re-align to square. As to fixing one of these I have no idea.

Someone may have a better fix but one way would be file the outside edge.
Regards
John

Originally Posted by justonething

To test it, you just need a board with a straight edge and use it as your reference edge.....

JOT, you got fooled by the perspective of the pic., so did I, when I fist looked at it. But Luke is talking 'mitre-square', not T-square, & if you stare hard, you can see that the blade is at 45degrees to the stock....

Luke, I suppose you could test a mitre square by doing the flip-test. Your two scribe marks should form a perfect right-angle, any error showing up as doubled, as for a trysquare. Trouble is, you need to be able to check the right angle in some easy & accurate way, & I can't think of one, off-hand, other than using a simple set-square. The other way would be to check it against an accurate protractor, or a 45* set-square, or a carefully-made 45* block..

I guess it must depend what you're making, but a mitre square is something that has never entered my 'need to have' list. When I need to mark out a 45 angle, I just set my sliding bevel against my Veritas protractor scale. It's quite accurate, but of course a sliding bevel is notoriously easy to bump out of set, so I have to keep checking as I use it! A good fixed mitre would certainly be more reliable, one would hope.....

Cheers,

We check 'em the same as we do an ordinary square - the flip test - but using both sides of a "known to be square" offcut corner.

ie. set the mitre-square so we can scribe a line in from the corner. Flip it to the other edge and compare.

Typically we use corners of offcuts from MDF sheets... they're normally machined quite squarely and we have plenty of scrap to spare. Sometimes they're not cut truly square, so if it appears there's a discrepancy we check again on another, different corner to:

A. see if the gauge is still out by the same amount, which means it just ain't right.
B. ensure we didn't accidentally use a corner that we might've cut. (Our main SCMS tends to wander off-square when the wind blows just right and no-one should assume a panel saw is cutting square unless they have a known good set-square in their hand which makes all the above moot anyway!))

Draw a 90* line from the edge of a board with a known good square, bisect the angle with a compass and ruler (if you're not sure how to do that, there's a good animation here: How to bisect an angle with compass and straightedge or ruler - Math Open Reference ), check the mitre square against the bisector line.

I know it's not ideal because you have to rely on other tools and your marking being accurate, but I can't think of a true self-test for 45*

Originally Posted by IanW

JOT, you got fooled by the perspective of the pic., so did I, when I fist looked at it. But Luke is talking 'mitre-square', not T-square, & if you stare hard, you can see that the blade is at 45degrees to the stock....
Cheers,

I had to squint for 30 seconds to see for what it is.
To do a test, I guess you'll have to do a double flip. once over the blade, and once over the stock. You should get exactly the same line. That's not a solution because opposite angles are always the same regardless of their magnitude. Dont know what test it should be I am afraid.

I have the same antique type Luke and it has been good to be able to reach for when needed . Its been a while though and I'm trying to remember all the uses . I know one is when I have lengths of made up moulding and I need to mark out the cuts. Same with applied cock bead around drawer fronts. Sometimes its just on a full size set out , drawing up something before making . And then sometimes a year or two goes buy and I haven't needed it. Thats probably more to do with my style of furniture type changing or when I was more in the office and one of my guys was doing the building that I wanted to do.

As for The tool to check it and one that gets heaps more use in making stuff. So get one of these if you don't have it .

Its a Trammel Available in old style that works just as good as new ones.

https://www.google.com.au/search?q=t...w=1120&bih=542

I think this is a good way to check it? Some of the above methods mentioned may well be heaps more easy though.
I used my trammel to mark out a large protractor, 24" radius roughly I marked in the degrees I needed to see and it works very well . Because its marked out on such a large scale it craps all over a small tiny protractor for accuracy . It takes it to a not needed level I think .
I use a large home made wooden bevel on it and recently used it checking the angles on that sofa frame I put on instagram .

This sketch is out of whack but describes what I mean . Obviously the mitre blade should be pointing at B2
IMG_3785.JPG

If you draw the arc with your Trammel at a radius of 24" then divide it up the large size means down at the user level of your Mitre square its very accurate . Once its marked use a straight edge resting on the mitre blade to check . If its out what do you do ? Probably like John said in post 4 , grab a file . As long as the rivets aren't loose I suppose , check them first.

The trammel is very useful in marking out plenty of things in huge sizes down to small . Have you got one ? It makes table set out for round with three legs easy to get spot on . The list just goes on for ever actually .

Rob

Edit , I just saw Elans post describing what I said . It would pay me to read all the thread before posting !

Just buy a Shinwa Miter Square

Shinwa Mitre square, standard - 45°-90° : Tools from Japan, Japanese woodworking tools direct from Japan.

Accurate & cheap

7152262081.jpg

Luke

Go an purchase a cheap plastic drafting triangle from the local newsagent. Should costs about $2. These are super accurate. Just slide it into the vintage mitre square.

To be frank, I would rather have one of Colen's (actually, I have two of them, large and small ). You still need to check these for accuracy every now-and-then, but they are easy to recalibrate. The vintage square, if out, will be very difficult to do. Still, check it first, then decide whether it is worth buying.

Regards from Perth

Derek

I share your sentiment - I'm not from Oz so maybe some of the sentiment for oz tools is lost on me. I've now for a while favored getting an older tool instead, and would choose the one from tooltique, too.

I would buy it and just use it. I'm sure that it is relatively good in terms of accuracy, certainly good enough to mark and cut a joint. I have a plastic drafting square as derek describes, and I would use that on the gauge if I thought about it ahead of time, but I'd be a lot more likely to look the gauge over and see if it looks like it's been dropped or if it looks like someone has filed the blades or modified it in any other way. If the answer to that is no, I would just use it.

By the way, I just went over to tooltique (I've bought planes from them) and see what it's listed for. If you decide not to buy it, let me know, as I'd like to have it if you don't want it. The price is pennies compared to what it would cost to make something as nice.

I am not going to buy it out from under you, though, but definitely will buy it if you don't.

I have a couple of nice old brass & Rosewood trysquares similar to the mitre square pictured. They're in my "stuff that's too good to chuck out but not good enough to use" box of stuph. The reason they're there is because they are both more than slightly out of square. I've tried fixing the more beat-up one using the centre-punch in the tight corner method - didn't do much other than make a few nasty dents. It's still too far off to be usable. Filing & sanding the blade straight & square is the better way, but it's a very tedious job and so they sit waiting til I get the time & patience to fix them.

I share your liking for tools that look like they've lived a decent life already, Luke, but when all's said & done, by getting a Clenton mitre you can be sure you get a tool that's accurate or at least easily recalibrated should that become necessary. But the only Clenton mitres I could find have a "half" blade! I don't know why Colen opted to make them that way - when using a sliding bevel, I always set it so that the blade is halfway along, because it's so often useful to have both the acute & supplementary angle available.

I guess if I ever feel I have to own one, I'll just have to make it......

Cheers,

Clamp a short (30mm long) piece of 20mm angle iron to the blade so that the flat is lined up with the edge of the blade.
Clamp or hold the handle so that an edge of the handle is accessible.
Zero a digital angle finder on the handle edge and place the DAF so that its sides on the blade edge to measure the angle of the blade.
I use this method to set odd angles on squares and sliding bevels.
it is possible to do without the angle iron if some sideways support is provided for the DAF to sit on the blade as the embedded magnets in the DAF will usually stop it sliding down the blade.

A comparison of the precision of the measurement between this method and using an external reference like a straight edge or a board for 90º measurement is interesting.

Using a straight edge or a board as a reference requires the comparison of two lines.
In really good lighting (and I do mean much brighter than any workshop I have ever been in) the limit of resolution of a young human eye is ~0.1mm.
As there are two lines and lighting is usually not that good and most of us have far from young eyes then the uncertainty in the measurement is at least 0.2mm
For a 100 mm square thats 0.2% , but in all likelihood it's more like 0.5%

A digital angle finder has a limit of 0.05ª but as there are two angles the uncertainty (no eyes or lighting limit) is 0.1º in 90º, or ~0.1%

Assuming you can find a straight reference surface long enough, for large squares the line comparison can be more precise.

What I like about the DAF method is that I don't need to worry about straightness of the reference surface, lighting, my eyesight, and having a really sharp marking knife.