Combination squares

[Ivor]

I am looking around for a new combination square since I dropped my old square so it isn't anymore, square that is.

Can anyone offer me any advise on the best brand to go for. I have an adversion to Stanley products after having a bad experience with one of their "handyman" hand drills.

Is the best necessarily the most expensive?

Thanks

Ivor

[RFNK]

The best combination square is Starrett and, yes, it's really expensive!

[stevenjd]

Mitutoyo and yes even more expensive than Starret. Look very hard as the prices vary greatly.

[D.W.]

I am looking around for a new combination square since I dropped my old square so it isn't anymore, square that is.

Can anyone offer me any advise on the best brand to go for. I have an adversion to Stanley products after having a bad experience with one of their "handyman" hand drills.

Is the best necessarily the most expensive?

Thanks

Ivor

go to ebay and look for an older hardened head combination square. Should be about $50 and if it appears in even reasonable shape in the listing, it'll be square.

George Wilson here in the states suggested this to me long ago, as well as others ("stop buying unhardened squares -they wear to quickly).

I've gotten two hardened head squares from ebay, one lufkin ($35) and one browne and sharpe ($50) and both are very square.

The other bonus is when both surfaces are hardened, the sliding action of the square is FAR better. Theres' no great need to buy these in new and certified condition for woodworking.

I was curious the other day to see if there were still one or two available here at any given time and ended up buying a starrett hardened head and rule (older in very good shape) for $40 on ebay -it had just been listed.

One caveat - confirm in the pictures that the head itself has the word "hardened" on it. There are often listings of hardened combination squares where the seller is confused and thinks that the whole setup is hardened if the rule says it is, but you can see by the coarse grind marks on the side of the head that it's not a hardened head.

I've bought mid grade US made squares (the ones that sell for about $75 or $90 now) and heads, none have been as square or worked as smoothly as the older hardened squares.

[apple8]

After 20 years hopefully Ivor has sorted it out.

[D.W.]

oh my!...fooled by a necroposter.

Hopefully someone heeds my advice, though. If they don't, I've refreshed it in my head and won't forget it as soon as I would've otherwise.

[yvan]

Mind you, some people take longer than others !!!:D

[verawood]

DW,

Your information on combination squares was a good read regardless of any date consideration.
Always good to get user reviews etc.

I hope your all OK over there re C19

Cheers
Keith

[Fergiz01]

What's the consensus on fitting new rules with old stocks? I have a vintage Mitutoyo stock with a new metric Stanley rule. I've tried to find a new Mitutoyo rule but no luck.

[orraloon]

I would say if it has been checked as being square and is doing the job intended then no problem.
Regards
John

[bueller]

Have to admit this thread has been useful to me. Bought a 300mm iGaging combination about a year ago but realised recently it goes out of square if I bottom the ruler out. Been looking for something more accurate, never realised 4 piece Starrett sets could be had so cheaply from the US. Even a 2 piece set can be had for around half the new price. I do worry about paying that kind of money for precision tools without being able to inspect though.

Tempted to just go find another iGaging one that's accurate, should have checked it was square when I bought it. I have an adjustable Colen Clenton square which is dead accurate so really just need something half decent that I can keep in my tote for every day use.

[orraloon]

Before you buy a new one try this.
Squaring a Combinaton Square - YouTube (https://www.youtube.com/watch?v=eYTzq9B5YRA)
Regards
John

[D.W.]

DW,

Your information on combination squares was a good read regardless of any date consideration.
Always good to get user reviews etc.

I hope your all OK over there re C19

Cheers
Keith

Thanks, Keith - the news about COVID here is a bit oversensationalized. We're kind of rolling along dealing with it and lowering risk level each time numbers go up. Outside is still safe, and it's summer, so we're all just outside (lots of people walking, biking and fishing since they can't sit in a bar), and still plenty of takeout.

I work in an office with 25 people and have to admit that I don't personally know anyone who has tested positive for covid yet (but it sounds likely that some of us have had it without knowing it).

Did just receive my third hardened old square (it's got a couple of dings on the rule, etc) and checked it vs. my reference starrett engineer's square and it's still dead square.

Perhaps it's the height of laziness, but I do my rough hand work (sawing, marking, etc) away from my bench and like to have one of the squares over in my sawbench area and one at my bench so that I don't have to walk back and forth.

[D.W.]

(don't want to make it out like the covid thing is no big deal here, it just doesn't have the on-the-ground hysteria that it does elsewhere. I think the fear of it when it's not around is often worse than how we are by nature when it *is* around. That is, when you have a problem right in front of you, you deal with it and continue on. When you dread it and fear what ifs, then it can really drive you up a wall. How can you get relief from something that isn't even physically there to deal with.

The news doesn't help. If there's ever a break in it, they lose the ability to attract views and clicks, so they're always inclined to really drum it up and to keep beating that drum over and over).

[BobL]

This is something I have been meaning to do for some time and this thread triggered me to giving it a go.

I have had for some time two surface plates and a squareness reference block for my MW activities.

477192

The granite surface plate on the left is new and comes with a cert so its very useful to check against.
The brown cast iron plate on the right is an old plate from Anorak Bob (thanks Bob) that I have checked against the granite plate and while it has some issues, especially at the edges, the inner 2/3rds is still good for these sorts of measurements.
The small dark grey cast iron plate in the middle is one I made at a scraping class organised through the MW forum in Melbourne in 2014. The surfaces on this plate are flat and square to one thou' across all 6 surfaces so it is useful for assessing the inside squareness of "Squares"

The first thing that is done is to test straightness of a square's edges - both inside and outside edges
Here is the testing for the outside.
The Silex square is just being supported vertically by the small reference block and I'm examine the outside long edge in contact with the large surface plate.
477194

A 0.038 mm (1.5 thou) feeler gage is then used to gently probe for gaps under the contacting surfaces.
Sorry about the poor photo but this shows that the old Silex does have a shallow dint at this point.
477195

Below shows testing the inside squareness of a Toledo machinist square - only the small reference block is used for the inside assessment
The square is held flat up against one side and the same feeler gage approach is used to measure gaps on the other edge, and a ruler measures where the gaps are and basic geometry is used to determined the final deviation from squareness.

477193

To measure the outside squareness the small reference block is placed on the large surface plate and the outside of the square is held up against one fo the contact surfaces and again probed for gaps with the feeler gauge.
477196

I can't claim to have performed thorough testing ie complete flatness testing, or having probed every mm of every square I tested but quick and dirty tests shows the following out of square in degrees. The other stupid thing I did not do was register if the angle was greater or less than 90º :doh:

1) Old Silex square I found in a skip: Outside 0.047º , Inside 0.050º

2) Very old brass and wooden square: Outside 0.18º , Inside 0.085º

3) Newish Toledo Square: Inside <0.038º, outside <0.038º

4) Cheap and cheerful combo square from Timbecon. <0.038º , 0.050º

The largish outside value for the brass and wooden square is understandable give the handle surface is just timber.

The limit of the measurement is the thickness of the 1.5 thou' (0.038mm) feeler gauge which across 150 mm translates ~0.02º - a thinner gauges would be better

Unfortunately I could not find my 1 thou' feeler gauge so had to settle for a 1.5 thou' but I have ordered another one so I will repeat this when it arrives.
Hopefully I will remember to measure whether it's + or - from 90º.

This method is especially useful for checking the squareness of small squares.

[banana]

are any of those deviations from square significant enough to turn up in a knife line test?

i have trouble comprehending the impact of tenths and hundredths of degrees; i can't tell from the numbers whether to conclude that they're all a bit wonky and need work, or that most are almost perfect

[elanjacobs]

are any of those deviations from square significant enough to turn up in a knife line test?
I think the more relevant question here is "Are any of those deviations significant enough to matter AT ALL?"

Given that we're working with timber, I'd say the answer is somewhere between not really and no.

If it helps, the formula to convert degrees to mm/m is 1000*tan(angle), so 0.05 degrees is 0.8 mm/m. I'd say that doesn't really matter a whole lot.

[BobL]

I think the more relevant question here is "Are any of those deviations significant enough to matter AT ALL?"

Given that we're working with timber, I'd say the answer is somewhere between not really and no.

If it helps, the formula to convert degrees to mm/m is 1000*tan(angle), so 0.05 degrees is 0.8 mm/m. I'd say that doesn't really matter a whole lot.

I agree.

What I was showing was there's no need to fork out out a whole lot of money to get a square square.

[banana]

thanks, that makes sense. the rule of thumb i've learned from woodworking youtube is that if you can strike the same knife line using the same side of the square from both directions, it's "as square as you'll ever need it to be for woodworking". but i don't yet have the experience to have a feel for that in practice, nor the precision measuring tools to translate it into something quantifiable, so the extra context is helpful :)

[BobL]

thanks, that makes sense. the rule of thumb i've learned from woodworking youtube is that if you can strike the same knife line using the same side of the square from both directions, it's "as square as you'll ever need it to be for woodworking".
:2tsup:

This assumes your reference surface the stock (the bit that sits up against the reference surface) is straight but a piece of newish MDF is usually straight enough.

The limits of human vision to be able to distinguish between two very fine lines with good eyes in sunlight is about 0.1mm but in practice it's more like 0.2 mm, but because a flip angle is used this translates to 0.1 mm.

Old codgers like me with dodgy eyes are going to be at least twice as poor or worse.

The final angle resolution then depends on the square's blade length.
For 100 mm long blade the angle is then arctan(0.1/100) = 0.057º
For a 300 mm long blade it's arctan(0.1/300) = 0.019º
This assumes there is no uncertainty in the zero position of the stock which is not meteorologically correct.
One way to bring that into the calculation is to not use the blade length but the stock length as the length factor in these calculations.
The stock length is shorter so the angle then increases but not usually by much.

Whatever is used these are plenty good enough for WW but may be a problem for metal workers.

The squareness of my cast iron reference block is arctan (0.025/150) = 0.0096º and this would not be good enough for some metal work operations.

Super precise right angle comparators are, like surface plates, made from granite and they come in various grades and sizes, the top end ones eg for checking CNC machine alignment are square to 0.00002º or better.

[elanjacobs]

I have some Starrett master squares in various sizes and their stated accuracy is 1/60,000 or 10 times Bob's reference block, but you won't get much change from $600 for the 6" (I did not buy them new, I'm not that loaded :p ). They are designed for inspection/calibration and were kept for making sure machine fences and saw blades were square.

Pretty much all my cabinetry work was done with a $40 Irwin square and that was plenty good enough.

[Bill Houghton]

What's the consensus on fitting new rules with old stocks? I have a vintage Mitutoyo stock with a new metric Stanley rule. I've tried to find a new Mitutoyo rule but no luck.


At least in the United States, combination square rules tend to come in two thicknesses, which I think of as "carpenter" (thinner) and "machinist" (thicker) grade. It's enough of a difference that you can't fit a machinist rule in a head intended for a carpenter's rule, and a carpenter's rule inserted in a machinist-square head will be sloppy and may not lock because the clamping bolt slips out. Other than that, though, I've found the rules of a given type are pretty consistent. I've interchanged any number of rules and heads. There are a few of the right thickness but the wrong slot for a given head; but they're not common.

[Chris Parks]

A PEC rule did not fit my Starret head due to being thicker. Anyone want to buy a metric 100mm rule?

[dimithri]

Dont need to be that perfect for woodwork. Ive adjusted a few of my vintage ones to be square, they have held square every since. I compared it to a friends starret. Over 30cm, i couldnt tell the difference in the lines. Good enough.

[woodsurfer]

Would anyone know of a replacement metric 12inch, yeah i know, rule for my late Dads Moore and Wright square, it would be 100 YO, the rule measures 2.24to 2.27 mm thick, thanks , Ross

[Fergiz01]

At least in the United States, combination square rules tend to come in two thicknesses, which I think of as "carpenter" (thinner) and "machinist" (thicker) grade. It's enough of a difference that you can't fit a machinist rule in a head intended for a carpenter's rule, and a carpenter's rule inserted in a machinist-square head will be sloppy and may not lock because the clamping bolt slips out. Other than that, though, I've found the rules of a given type are pretty consistent. I've interchanged any number of rules and heads. There are a few of the right thickness but the wrong slot for a given head; but they're not common.Hi Bill,

I went and checked how the replacement blade fits into the stock, and you're right - it's too thin. Everything is all square when it locks down which is the important thing but now that I noticed this I cannot unsee it. I've fortunately found a replacement Mitutoyo blade so will go down that road. Thanks for the heads up.

Zac.https://uploads.tapatalk-cdn.com/20200728/eea18bd5217c0e785bb01af6e3247f6d.jpg

Sent from my Nokia 4.2 using Tapatalk