Combination Square

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Combination Square

This topic has 13 replies, 7 voices, and was last updated 18 April 2011 at 17:00 by Peter G. Shaw.

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13 April 2011 at 14:37 #66841
Peter G. Shaw
Participant
@peterg-shaw75338
Hi folks,

A check please!

Recently, like a few months ago, I bought one of those combination square sets, ie the type with a 300mm grooved ruler, 90°/45° head, centre finding head, and a protractor head. My query concerns the protractor head.

Setting the protractor at 0° and inserting the ruler shows that the ruler most definitely is not parallel with the base of the protractor head. Investigation shows that the ruler does not appear to bedding correctly at one end of the slot in the head in which it should fit. This appears to be a tiny piece of metal which was not removed when the head was made. Removing this metal, a fairly simple filing job, should (because I have not yet dared do it) allow the ruler to sit further down into the slot and thus more nearly become parallel to the base of the head.

My question is therefore, should the edge of the ruler, when sitting correctly and parallel to the base of the head actually be flush with the base? It does look as if this is what would happen if I remove this offending bit of metal. If this is the case, it would make my rectification job easier.

For what it is worth, the other heads seem as if they are reasonably correct. Also, the zero degree mark of the protractor scale is correctly aligned with the fidudiciary mark although there is no guarantee that this is itself correct.

Regards,

Peter G. Shaw
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13 April 2011 at 14:37 #16639
Peter G. Shaw
Participant
@peterg-shaw75338
13 April 2011 at 15:02 #66843
Nicholas Farr
Participant
@nicholasfarr14254
Hi Peter, most of these that I’ve seen will be flush with the bottom of the protractor when at 0, however I have a M/W one that is 1/2 degree out and there is no piece of metal that you mention preventing it to sit in the slot correctly.

Some of the slots in different makes I seen have a raised portion in the middle of the slot lenghwise with it, as if it has been saw cut either side so to speak. I think you will have to study your one and decide if it is worth trying to improve it, or to allow for error when in use.

Regards Nick.
13 April 2011 at 15:04 #66844
Gordon W
Participant
@gordonw
My cheapo set I bought needed just the same work done, but was largely a waste of time because the degree markings are miles off. Bought a cheap protractor to reset them and finished up just using the protractor.
13 April 2011 at 20:17 #66853
Peter G. Shaw
Participant
@peterg-shaw75338
Nick,

Thanks for that confirmation. Having experimented since the original posting, I can get the ruler down the side of the bit of metal and this does indeed get the ruler much nearer to parallel with the base. It is still proud and at a slight angle when the protractor is lined up on zero so it looks as if I need to gently file both sides of the slot to enable the ruler to be both parallel and flush. Should not be too difficult as there is only a length of about 10mm x 2.5mm to file at each side: the centre being concave away from the ruler.

I suspect that originally the slot was made by two saw cuts with the waste cut out as a second operation because on at least one of the other heads the ruler slot is exactly like that.

Gordon,

Yes, mine was a cheapo(ish) set, about £30, but from what I can tell, once this problem is corrected, the protractor looks as if it may then be reasonably ok.

The device may be cheap. And it certainly will not do one of the jobs I wanted it to do. Nevertheless, I don’t think it will take that much work to improve it to a point where it may be of some use rather than a piece of scrap lumber.

Regards & thanks,

Peter G. Shaw
13 April 2011 at 21:16 #66858
Sub Mandrel
Participant
@submandrel
I am a big fan of cheap’n’cheerful tools that can be made to work, but cheap combination sets are just a good source of ‘hack’ rules as far as my experience goes.

Neil
13 April 2011 at 22:21 #66866
Nicholas Farr
Participant
@nicholasfarr14254
Hi, there is cheap, and there is cheap and nasty. The cheap ones you tend to find in DIY stores, are just DIY quality. I have bought cheap (compared to M/W and Starret ect.) from one or two traders at the various exhibitions for workmates in the past which have been very good value for money, and are accurate enough for most jobs people use them for. I’ve even compared one set against one that a work colleague had that was made by one of the reputable makers, and the difference was unoticeable, even the colour was the same, its accuracy was the same also.

As I’ve said earlyer I have a M/W which is half a degree out.

Regards Nick.
13 April 2011 at 23:14 #66868
Nobby
Participant
@nobby
Hi Guys

If it helps I have a Brown& Sharpe protractor . When its set a zero the blade is not level with the base its about a 1 mm plus Set at 90 degrees it checks out against my bottle square I use a cheapy one for DIY

Regards Nobby
14 April 2011 at 12:10 #66889
jomac
Participant
@jomac
Hi, Peter. Iv’e got 2 of the cheaper protractors, the first and better one, some one used the blade to hammer down something into a slot, so I took one of the blades out of one of my squares. And guess what, the slots are OK just that the rule is wider, still work though, The problem with the elcheapo’s is that there is too much slop in the degree ring, which makes it inconsitant, also the original degree mark are, as said before, out by up to 1 degree. So I went on e/bay and brought a vernier protractor, it’s cheap but very accurate, only problem is the type I brought, its hard to set up, and seem some what limited, in the range of degrees you can measure (sorry if this sounds confusing its because it took me ages to work out how to use it). There might be some other ones that are more suitable on e/bay, you just have to sift through the other rubbish to find the right one.

John Holloway.

PS. no smilies, they stop the post from running properly.
14 April 2011 at 19:11 #66903
Peter G. Shaw
Participant
@peterg-shaw75338
Well now, I have done a little filing this afternoon and improved it no end, and will eventually get the ruler to be flush with the base. The major problem is the need for frequent dismantling to file, then re-assembly to test it. But I am getting there.

As John (jomac) says, there is a lot of slop in the degree ring, so really it will only be of use for relatively coarse applications where high accuracy is not required, eg carpentry, or building.

Other than that, well, I suppose I should look on it as a learning exercise.

Perhaps I can find a carpenter or a builder who needs one!

Thanks for all the comments.

Regards,

Peter G. Shaw
15 April 2011 at 12:47 #66920
Eddie
Participant
@eddie
Hi

A good permanent solution for any accurate degree measurements, even in carpentry is a digital angle box, measure in decimal parts of a degree. Just stick it to your ruler and away you go.

Eddie
16 April 2011 at 15:30 #66976
Peter G. Shaw
Participant
@peterg-shaw75338
Well, I have done it. I have got the ruler edge parallel to and flush with the base of the protractor head when the head shows zero degrees.

So that’s ok, but the rest isn’t. 90°, 60°, 45° & 30° are not particularly accurate compared with other devices and using 60° triangle etc.

The fixed 90° & 45° head does seem reasonably accurate. The centre finder head does not allow for a line to be dead on centre, but can be used to produce say 12 lines and thus enclose the true centre. If I can decide what needs doing, I should be able to improve it.

All in all, it is not worth the money. And it still will not do what I orignally bought it for. Which shows I did not really understand my requirements. Still, “c’est la vie”. And £30 will not exactly break the bank.

Eddie,

What is your digital angle box? Is it something like this Wixey device? Digital Angle Gauge with Magnetic Base at about £24?

Regards,

Peter G. Shaw
18 April 2011 at 07:03 #67037
Eddie
Participant
@eddie
Hi Peter,

Yes I have a Wixley.

As it is required to cut miter and bewels accurate when making segmented bowls, multisided and angled frames nothing can replace it except a vernier protractor.

I compared the prices between the two an the digital box won on price and ease of use.

Enjou your day.

Eddie
18 April 2011 at 17:00 #67084
Peter G. Shaw
Participant
@peterg-shaw75338
Thanks Eddie.

Peter G. Shaw
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