new Starrett combination square blade not straight

[goldspanner]

I recently bought a new Starrett blade for an older Starrett stock, and have found it to be far from perfectly straight.
Checking it against another accurate square with the stock at various points, it's all over the place.

Anyone else found this to be the case with new Starrett stuff? If so, the things I've been reading must be true.....

Will have to find another replacement.....

 

[marcros]

I bought a combination square a couple of months ago and it was fine. So it isn't a problem that affects every piece of new starrett. But my sample size is 1 so doesn't go to prove anything.

 

[bugbear]

I recently bought a new Starrett blade for an older Starrett stock, and have found it to be far from perfectly straight.
Checking it against another accurate square with the stock at various points, it's all over the place.

Anyone else found this to be the case with new Starrett stuff? If so, the things I've been reading must be true.....

Will have to find another replacement.....

Do you (happen to) know anyone with a surface plate that is known/certified to be flat within stated tolerances?

You could check with certainty wether the new blade is straight. It also needs to be parallel, AKA constant width,
which can be easily checked with a micrometer.

If a blade bought new is outside of its stated spec, you're entitled to a refund or new blade.

BugBear

 

[goldspanner]

Yeah I'm definitely going to return it. It's just getting to be rather problematic actually finding one that IS straight.

Just to be sure: If the combination square is showing drastically different measurement with the stock in different position, surely this can only mean that the blade isn't straight (concave, convex, both)? Even if the stock weren't properly calibrated surely this can only means that it's the blade that is inaccurate? (Checked it against the sole of a plane which I recently flattened, and it looks to be slightly convex).

 

[bugbear]

Yeah I'm definitely going to return it. It's just getting to be rather problematic actually finding one that IS straight.

Just to be sure: If the combination square is showing drastically different measurement with the stock in different position, surely this can only mean that the blade isn't straight (concave, convex, both)? Even if the stock weren't properly calibrated surely this can only means that it's the blade that is inaccurate? (Checked it against the sole of a plane which I recently flattened, and it looks to be slightly convex).

The sole of a plane that you flattened yourself is not really a "reference". You need something that provides more certainty.

Further, to measure a square using the "mark and flip" technique, the edge you're putting the stock to MUST be straight within the sort of tolerances you're trying to measure for the process to have meaning.

BugBear

 

[Trafalgar]

I recently bought a new Starrett blade for an older Starrett stock, and have found it to be far from perfectly straight.
Checking it against another accurate square with the stock at various points, it's all over the place.

Anyone else found this to be the case with new Starrett stuff? If so, the things I've been reading must be true.....

Will have to find another replacement.....

If the blade's lack of straightness is very apparent to the naked eye there is no need to test the square. Send the tool back for replacement.

 

[Bod]

I recently bought a new Starrett blade for an older Starrett stock, and have found it to be far from perfectly straight.
Checking it against another accurate square with the stock at various points, it's all over the place.

Anyone else found this to be the case with new Starrett stuff? If so, the things I've been reading must be true.....

Will have to find another replacement.....

Why did you want a new blade?
If the old one was not square, could the fault be in the stock?

Bod

 

[custard]

Are you sure the problem isn't elsewhere, like a dinged anvil or corrosion in the old stock? I use six Starrett combination squares, the largest with a 600mm blade, each one was checked against engineering standards all passed with flying colours. It might not be cheap but Starrett kit is usually pretty good.

 

[goldspanner]

If it was just the stock that was out, the angle would be consistent wherever the stock was on the blade. I'm getting angles that are both larger and smaller than 90 degrees at different points along the blade.

 

[matthewwh]

A new Starrett blade should be straight to better than a thousandth of an inch per foot, I have yet to see one that isn't. As a Starrett dealer we get through a fair number of them.

You can flip test a rule to double and therefore expose any error present.

Lay the rule down on a blank piece of paper, well supported on a smooth flat surface.

Press down hard on the rule, and make a mark at either end and in the middle lightly with a hard freshly sharpened pencil.

Draw a light line through the marks, (if your line misses any of them it is because the rule has been inadvertently moved - start again).

Flip the rule over so that it is now resting on the other side of the line and align it with your original end marks, resharpen the pencil and draw a second light line.

Deviations from parallelism will show any error in the edge (doubled).

If the blade is straight but you still have a problem, it might be worth carefully stripping and cleaning the attachment mechanism on the head and reassembling. At these levels of accuracy it doesn't take much of a bit of fluff or swarf in the wrong place to cause an alignment issue.

 

[n0legs]

Where did you buy the new blade, are you sure it's genuine?

 

[goldspanner]

Hi Matt,

I appreciate the advice, but at this point I'm certain it's the blade. The slot in the stock is very clean, and I'm sure to wipe off the combination square, and also the other square I'm using to check it with each time.

One side of the blade appears to be relatively straight, but the other side is definitely all over the place. With the stock set near one end, I'm getting an angle less than 90, whereas near the middle it's over 90. I've checked and re checked and these inaccuracies are always in the same place, so it's definitely the blade.

As for Starrett QC, a couple of corners had pretty heft burrs which needed filing off, which I also didn't expect for something that cost almost £40......

Was bought from from building-supplies-online.co.uk. The packaging seems legit, so I doubt it's a knock off. Perhaps I just got a dud, or their QC really has declined.

 

[n0legs]

Was bought from from building-supplies-online.co.uk. The packaging seems legit, so I doubt it's a knock off. Perhaps I just got a dud, or their QC really has declined.

Return it.
Ask for a refund and buy direct from Starrett, hopefully you'll get a good one.

 

[matthewwh]

Your first port of call should be the retailer you bought it from, I'm sure they will be happy to replace it for you.

I've not seen hefty burrs on any Starrett kit either - their stuff is almost invariably finished to jewellery like standards. Very odd.

If you do have any problems give me a shout, I'll be happy to replace it from our stock and send it up to Starrett's UK head office for you.

 

[Trafalgar]

Reviewing their tool catalog here: http://content.yudu.com/A290vg/Starrett ... m/catalogs makes me believe that quality, in theory at least, has not declined.... more precision measuring equipment than you can shake a stick at.....