DomValente
Established Member
Engineer one wrote:
Surely Paul, the fact that he asked for an engineers square was a clue.
Dom
Surely Paul, the fact that he asked for an engineers square was a clue.
Dom
Top quality Engineer's Square
- Thread starter whiteant
- Start date
Help Support UKworkshop.co.uk:
AndyBoyd
Established Member
I use the GROZ ones from Dick, I check it every now and again and it it's been knocked out I bin it and get another they are as cheap as chips.
To check it I drawer a line flip it draw the line again and see if they deviate
To check it I drawer a line flip it draw the line again and see if they deviate
David C
In Memorium
This 'woodworkers don't need accuracy because wood is always moving' thing, is one of the most misleading old or new wives tales available, and demonstrates a complete lack of understanding of fine cabinetmaking skills..
A one thou gap looks and feels like a one thou gap.
A four thou gap in an edge joint probably means it will fall apart.
My second dvd demonstrates that it is perfectly simple to plane up a piece of wood to a tolerance of plus or minus about 2 thou without undue difficulty. The sample is usually about 15" long, 4" wide and 3/4" thick. This marvel is done with a hand tool and needs nothing more than a setsquare, winding sticks and a marking gauge.
What's more we can be achieve this a great deal more quickly than an engineer could with a lump of metal and hand tools. Stanley laterly failed to do this with machinery.
The straight edge is not necessary if using a well tuned jack plane.
I get beginners to achieve plus or minus 4 thou" in a matter of days.
The errors of squareness relative to a bench grade engineers square are significantly less than 1 thou".
best wishes,
David Charlesworth
A one thou gap looks and feels like a one thou gap.
A four thou gap in an edge joint probably means it will fall apart.
My second dvd demonstrates that it is perfectly simple to plane up a piece of wood to a tolerance of plus or minus about 2 thou without undue difficulty. The sample is usually about 15" long, 4" wide and 3/4" thick. This marvel is done with a hand tool and needs nothing more than a setsquare, winding sticks and a marking gauge.
What's more we can be achieve this a great deal more quickly than an engineer could with a lump of metal and hand tools. Stanley laterly failed to do this with machinery.
The straight edge is not necessary if using a well tuned jack plane.
I get beginners to achieve plus or minus 4 thou" in a matter of days.
The errors of squareness relative to a bench grade engineers square are significantly less than 1 thou".
best wishes,
David Charlesworth
Dan Clark
Established Member
Paul Chapman":2oi8pjb5 said:
When I posted about buying an Incra square, what I didn't say was WHY I bought it...
I have a Starrett combo square. Since Starrett is a (or was) a top name here in the states, I always assumed that it was SQUARE. Hah! Wrongo!
For several weeks, I kept having problems with cuts that were square according to the Starrett square, but were not. So I finally checked it against my cheapo engineer squares. Arrgh! Then I checked it against my Swanson Speed Square (which is supposed to be construction-grade). The Speed Square was more square!!!
It turns out that my Starrett combo square would change squareness depending on where it was set. I still use it occasionally where accuracy isn't critical.
OTOH, my Incra is used constantly. It's only weeks old and it's starting to show wear marks from all the use. It seems expensive, but on a per-use basis, it's dirt cheap!
Dan.
Woody Alan
Established Member
Is it possibly how the starrett became inaccurate through lots of use and needed replacing?
Alan
MikeW
Established Member
I would be one person chanting the mantra that woodworking does not need to be to the accuracy as metal work--but what I mean by that may not be what another means.
Accuracy is needed in top work. Accuracy to the best of one's ability is reality. Trying to achieve accuracy beyond one's ability is simply improvement. Trying to achieve metal working tolerances is insanely unrealistic.
Using accurate layout tools that are beyond one's ability to achieve in performance eliminates them as a source of error. Error will creep in during marking out and processing. Dealing with that error is simply experience.
The two materials (wood/metal) are so different. If you think you can see a 1 thou gap in wood, try metal. It looks/feels even more acutely wrong. I would reckon no one here on this forum can make a set of DTs to 1 thou accuracy across the width of a single corner, much less 4 corners. And one doesn't need to, either. Wood has a different level of compressibility. I think that for some of these really nice DTs that have been pictured here, that there actually is a degree of "too" tight a fit. Which works out wonderful in wood--not so in metal.
So too with tenons. If I am a few thou off cutting a shoulder line I can assure you it will close under average clamping pressure. A metal version simply would not.
So, nope. I don't think woodworking is anything like the level of precision needed to the average metal work done at a machine shop. The machine shop I worked at in the 1970s worked at fairly sloppy tolerances for most work. 3 zeros before significant digits.
I also think there is in woodworking a tendancy for especially new workers to fret that their work needs to be as accurate as what they may see pictured, or aspire it to be. So when someone like myself suggest they relax, finish and move on because "woodworking doesn't need accuracy to multiple decimal point" it can be interpreted as "it doesn't matter." (Nor do they actually understand what it really was like prior to the nice picture that was taken--the during building and following glue up.)
I have built fairly OK furniture for rather good commission fees. I have never, ever cared if a rail was within 2 thou of the adjoining stile before glue up. Nor did I care if it was that all 'round a door after glue up. Could I do it? I don't know. I've never tried. In all likelihood I never will try.
So there it is. My "standards" or lack thereof.
Take care, Mike "The Heretic" Wenzloff
Accuracy is needed in top work. Accuracy to the best of one's ability is reality. Trying to achieve accuracy beyond one's ability is simply improvement. Trying to achieve metal working tolerances is insanely unrealistic.
Using accurate layout tools that are beyond one's ability to achieve in performance eliminates them as a source of error. Error will creep in during marking out and processing. Dealing with that error is simply experience.
The two materials (wood/metal) are so different. If you think you can see a 1 thou gap in wood, try metal. It looks/feels even more acutely wrong. I would reckon no one here on this forum can make a set of DTs to 1 thou accuracy across the width of a single corner, much less 4 corners. And one doesn't need to, either. Wood has a different level of compressibility. I think that for some of these really nice DTs that have been pictured here, that there actually is a degree of "too" tight a fit. Which works out wonderful in wood--not so in metal.
So too with tenons. If I am a few thou off cutting a shoulder line I can assure you it will close under average clamping pressure. A metal version simply would not.
So, nope. I don't think woodworking is anything like the level of precision needed to the average metal work done at a machine shop. The machine shop I worked at in the 1970s worked at fairly sloppy tolerances for most work. 3 zeros before significant digits.
I also think there is in woodworking a tendancy for especially new workers to fret that their work needs to be as accurate as what they may see pictured, or aspire it to be. So when someone like myself suggest they relax, finish and move on because "woodworking doesn't need accuracy to multiple decimal point" it can be interpreted as "it doesn't matter." (Nor do they actually understand what it really was like prior to the nice picture that was taken--the during building and following glue up.)
I have built fairly OK furniture for rather good commission fees. I have never, ever cared if a rail was within 2 thou of the adjoining stile before glue up. Nor did I care if it was that all 'round a door after glue up. Could I do it? I don't know. I've never tried. In all likelihood I never will try.
So there it is. My "standards" or lack thereof.
Take care, Mike "The Heretic" Wenzloff
engineer one
Established Member
having thrown down the gauntlet, a couple of points.
i think mike w is absolutely right. experience gives you the ability to
make things more accurately in wood particularly, whether you or even i can plane a piece of wood accurately to within 1-2thou, and i have been lucky enough to do it when i had my last practice, it does not make the assembly any more accurate. what makes the assembly accurate is
that the diagonals are the same. :twisted:
whilst gaps can be seen, in many designs i have seen, the gaps are actually made something of, and people tend to use "shadow lines" to divert the eye.
i think if you use modern glues, it is easier to adjust for the gaps, and still get decent glue up.
you can only make to the best of your ability, and as you finish one thing,
you find where you want to improve, and become more accurate on the next job. at which point you may want additionally accurate tools, but as we have seen rather like cutting tools, you cannot assume your so called square tools are all properly square.
dom, i actually do use an engineers square in my woodworking too,
so it was a valid question, even for me :roll: :? mainly to set up machine tools.
surely when you make mortices and tenons, for instance, the value of shoulders is in the hiding any errors in the mortice, but not of course any errors in the cutting of the shoulders and their bottoms.
paul :wink:
i think mike w is absolutely right. experience gives you the ability to
make things more accurately in wood particularly, whether you or even i can plane a piece of wood accurately to within 1-2thou, and i have been lucky enough to do it when i had my last practice, it does not make the assembly any more accurate. what makes the assembly accurate is
that the diagonals are the same. :twisted:
whilst gaps can be seen, in many designs i have seen, the gaps are actually made something of, and people tend to use "shadow lines" to divert the eye.
i think if you use modern glues, it is easier to adjust for the gaps, and still get decent glue up.
you can only make to the best of your ability, and as you finish one thing,
you find where you want to improve, and become more accurate on the next job. at which point you may want additionally accurate tools, but as we have seen rather like cutting tools, you cannot assume your so called square tools are all properly square.
dom, i actually do use an engineers square in my woodworking too,
so it was a valid question, even for me :roll: :? mainly to set up machine tools.
surely when you make mortices and tenons, for instance, the value of shoulders is in the hiding any errors in the mortice, but not of course any errors in the cutting of the shoulders and their bottoms.
paul :wink:
Dan Clark
Established Member
Alan,Woody Alan":uk3y4ydm said:Is it possibly how the starrett became inaccurate through lots of use and needed replacing?
Alan
Perhaps, but the Incra is still perfectly accurate and the Starrett is not. 8) Starrett still makes nice stuff, but I'm not buying much of it these days.
Dan.
David C
In Memorium
Mike,
For a heretic the fit of the spine of your dovetail saw to the handle is awesome ~;-)# The top of the range Pax I was loaned recently is flapping about in the breeze.
Though I agree that there is no point trying to exceed one's ability and that accuracy is only needed in a few specific instances it does matter.
The fact that most bench grade engineers squares are off by a thou" or more has little impact if one has a consistent technique for using them.
The compressibility of many timbers can be helpful, but the hand sliding fit of a tennon requires good tolerances.
Dovetails in dense brittle timbers need accurate work as well.
best wishes,
David
For a heretic the fit of the spine of your dovetail saw to the handle is awesome ~;-)# The top of the range Pax I was loaned recently is flapping about in the breeze.
Though I agree that there is no point trying to exceed one's ability and that accuracy is only needed in a few specific instances it does matter.
The fact that most bench grade engineers squares are off by a thou" or more has little impact if one has a consistent technique for using them.
The compressibility of many timbers can be helpful, but the hand sliding fit of a tennon requires good tolerances.
Dovetails in dense brittle timbers need accurate work as well.
best wishes,
David
engineer one
Established Member
once again david you coat the sour pill lower down in your responce.
"even if an engineers square is off by a few thou, if used consistently it will suffice" (sorry if i have slightly overstated the fact) :?
any time you move a measuring or layout item, you are bound to accumulate errors, since every time you move, you move your stance, and thus the way in which you hold the scribing instrument,pencil, knife etc,
and the pressure you put on it. :?
also it is often awkward to stand properly over the whole piece of a board, or sheet. you have to use a position or stance which is comfortable and yet enables you to see the whole item. :roll:
for instance the standard square check of flopping the item and drawing along both sides depends to some extent on where you stand, and how you angle the scriber and whether it has one bevel or many.
one of the reasons that many experts suggest using a single sided marking knife, and then marking the struck line with a pencil to highlight.
but unless you hold the knife upright, (which may be very uncomfortable)
you still can build in some errors in marking.
unless you are making furniture to specifically fill a space, without framing to fit it, you have some room for manouvre, and the important thing is the "LOOK".
i appreciate that more of you are expert than me and have more finished items to your scrap book than me, but i spend a fair amount of time converting items into models, and i know that often when something is perfectly scaled and made into a model, it just does not look "right"
the eye is a strange instrument, and the accuracy it offers is more important than mere measurement.
as i have agreed in another thread about levelling tables/chairs it is important to start out as accurately as possible, but unless we then make everything on a cnc machine, errors WILL creep in, it is inevitable with any hand work. every time you saw by hand you cut to a different part of the line, every chisel stroke or plane stroke does the same. it is inevitable that every time you move, you do not return to EXACTLY the same place, thus you input is slightly different. :-k
more worrying is that often something is perfectly correct, and still LOOKS wrong, and no amount of accurate layout, making etc will change that.
so i guess the answer to the original question is someone like Shesto,
Tilgear, or Chronos, and buy the best you can afford, then use it only for checking your other measuring equipment or squares.
also check out the trend 3 way square, it is a neat piece of kit, but of course it won't lay flat on the workbench :?
paul :wink:
"even if an engineers square is off by a few thou, if used consistently it will suffice" (sorry if i have slightly overstated the fact) :?
any time you move a measuring or layout item, you are bound to accumulate errors, since every time you move, you move your stance, and thus the way in which you hold the scribing instrument,pencil, knife etc,
and the pressure you put on it. :?
also it is often awkward to stand properly over the whole piece of a board, or sheet. you have to use a position or stance which is comfortable and yet enables you to see the whole item. :roll:
for instance the standard square check of flopping the item and drawing along both sides depends to some extent on where you stand, and how you angle the scriber and whether it has one bevel or many.
one of the reasons that many experts suggest using a single sided marking knife, and then marking the struck line with a pencil to highlight.
but unless you hold the knife upright, (which may be very uncomfortable)
you still can build in some errors in marking.
unless you are making furniture to specifically fill a space, without framing to fit it, you have some room for manouvre, and the important thing is the "LOOK".
i appreciate that more of you are expert than me and have more finished items to your scrap book than me, but i spend a fair amount of time converting items into models, and i know that often when something is perfectly scaled and made into a model, it just does not look "right"
the eye is a strange instrument, and the accuracy it offers is more important than mere measurement.
as i have agreed in another thread about levelling tables/chairs it is important to start out as accurately as possible, but unless we then make everything on a cnc machine, errors WILL creep in, it is inevitable with any hand work. every time you saw by hand you cut to a different part of the line, every chisel stroke or plane stroke does the same. it is inevitable that every time you move, you do not return to EXACTLY the same place, thus you input is slightly different. :-k
more worrying is that often something is perfectly correct, and still LOOKS wrong, and no amount of accurate layout, making etc will change that.
so i guess the answer to the original question is someone like Shesto,
Tilgear, or Chronos, and buy the best you can afford, then use it only for checking your other measuring equipment or squares.
also check out the trend 3 way square, it is a neat piece of kit, but of course it won't lay flat on the workbench :?
paul :wink:
woodbloke
Established Member
I read somewhere (can't remember where :?) that the levels of accuracy needed in good quality work, for example, on a carcass lets say with a diagonal of 1000mm, ought to be 1/2 or 1mm out in the diagonal is acceptable. It's also a requirement to know which measurements are critical to get right and those that are not so important. As has been said before on other threads, perfection can't be achieved 'cos we're all human beans with all that implies, but it's relatively easy to be very precise when working with timber which goes someway to achieving perfection. Any work we do will always have accumulated faults no matter how skilful and careful the maker, the important thing is to realize what and where those faults are, why they were made and to try :roll: to ensure that they aren't repeated in the next project - Rob
Paul Chapman
Established Member
woodbloke":2sicbyg8 said:
I think a good example is something like a picture frame, where there are eight 45 degree cuts to make. Each one may only be out by one degree but the whole lot together come to eight degrees, which is a lot and would be very noticeable in the finished job.
Cheers :wink:
Paul
engineer one
Established Member
yes, but paul, there are actually two arguments there. :roll:
one is actually you will only get 4 angles with the same error, since you then turn the wood around, or the jig, or the mitre block, so often they can cancel themselves out. technically you are right, but :?
the other thing we are always told that sawing to an angled line may not bee too accurate anyway, so back to the shooting boards :lol: :lol: :twisted: with birds' nests to ensure you get the angle right.
the other thing is you can always fiddle the joint once you have cut all 8 angles. pin the pieces in the jig, and then cut through the joint to ensure accuracy.
paul :wink:
one is actually you will only get 4 angles with the same error, since you then turn the wood around, or the jig, or the mitre block, so often they can cancel themselves out. technically you are right, but :?
the other thing we are always told that sawing to an angled line may not bee too accurate anyway, so back to the shooting boards :lol: :lol: :twisted: with birds' nests to ensure you get the angle right.
the other thing is you can always fiddle the joint once you have cut all 8 angles. pin the pieces in the jig, and then cut through the joint to ensure accuracy.
paul :wink:
MikeW
Established Member
Hi David--thank you...
I think there's a difference in reality and goals. The reality is I cannot exceed my own abilities, often changing abilities within a single piece of furniture. My goal is (nearly) always to try and exceed my abilities.
What I can do is use accurate tools and rely on my eye. I must confess I do not have engineers squares. My most used try square for larger layouts is a 16" long Disston from about the 1875 period, for moderate sized layout, an 8" General bought for $5 (new), and for general joint layout a pair of Stanley 4" try squares from the end of the 1800s. For depth marking or even smaller layout, an old 4" B&S double square. For a combination square I rely on my 1950s era 12" Tumico.
Steel rules generally come from Woodcraft or LV, none of which have I bothered to true. I may mark a "straight" line with them, but rely on the plane or chisel to actually make the stuff "true." How do I know it is true? If it fits <g>.
Take care, Mike
I think there's a difference in reality and goals. The reality is I cannot exceed my own abilities, often changing abilities within a single piece of furniture. My goal is (nearly) always to try and exceed my abilities.
What I can do is use accurate tools and rely on my eye. I must confess I do not have engineers squares. My most used try square for larger layouts is a 16" long Disston from about the 1875 period, for moderate sized layout, an 8" General bought for $5 (new), and for general joint layout a pair of Stanley 4" try squares from the end of the 1800s. For depth marking or even smaller layout, an old 4" B&S double square. For a combination square I rely on my 1950s era 12" Tumico.
Steel rules generally come from Woodcraft or LV, none of which have I bothered to true. I may mark a "straight" line with them, but rely on the plane or chisel to actually make the stuff "true." How do I know it is true? If it fits <g>.
Take care, Mike
MikeW
Established Member
Or rather, complimentary inaccuracy :lol:engineer one":3dg0xrl0 said:
Done that more than once, Paul. It can work if the stuff is such that it can be joined straight away from the saw. In the case of something always exposed, like a picture frame, a box to be seen and handled, I will still opt to shoot it or lightly plane it freehand.
Take care, time for work at my end...Mike
David C
In Memorium
I used to read Model Engineer magazine, to while away Prep time at school. Also because I was attempting to machine Stuart Turner kits of castings in the excellent machine shop.
Live steam scale models are fascinating, and I seem to remember that they could not be made to work well because in a half scale model;
dimensions are halved,
areas are quartered,
and volumes are divided by 8.
therefore steam passageway crossectional areas and cylinder volumes had to be increased to get the things to work??
I am fond of stating this as a reason why scale models of furniture do not quite give the feel of a full sized piece. Hope there is some truth in this?
David C
Live steam scale models are fascinating, and I seem to remember that they could not be made to work well because in a half scale model;
dimensions are halved,
areas are quartered,
and volumes are divided by 8.
therefore steam passageway crossectional areas and cylinder volumes had to be increased to get the things to work??
I am fond of stating this as a reason why scale models of furniture do not quite give the feel of a full sized piece. Hope there is some truth in this?
David C
engineer one
Established Member
i do agree with both those comments david, but the other thing is that it is actually difficult to visualise how a model will look in real size.
all models of full size things can do is to allow for placement and getting a feel, to really see it needs to be the size you intend to create.
one of the reasons so many smaller steam engines use high pressure steam is because of the problems you highlight. one of the important things to remember is that as air/steam gets nearer to the surface, it is more affected by the laminar flow layers, and thus needs more speed and
pressure to achieve a similar effect.
mike, i bow to your comments about frames i was just putting forward an alternative to that of the other paul. :?
paul :wink:
all models of full size things can do is to allow for placement and getting a feel, to really see it needs to be the size you intend to create.
one of the reasons so many smaller steam engines use high pressure steam is because of the problems you highlight. one of the important things to remember is that as air/steam gets nearer to the surface, it is more affected by the laminar flow layers, and thus needs more speed and
pressure to achieve a similar effect.
mike, i bow to your comments about frames i was just putting forward an alternative to that of the other paul. :?
paul :wink:
bugbear
Established Member
whiteant":2n2ikjeg said:
Can you be more specific as to your requirments?
Some square are so "good" that they are easily damaged, and have to be used in temperature controlled rooms!!!
BugBear
David C
In Memorium
Yes,
Tolerances are more useful than descriptive words. Good is a bit vague......
I have some remarkable straight edges from Dick fine tools where tolerance is quoted;
such as 500mm long tolerance 0.004 mm.
Now 0.1 mm is almost exactly 0.004 inches (4 thou")
So I think this means + or - 0.00016 inches or plus or minus less than a couple of ten thousandths of an inch!
At 21.60 euros this has to be the bargain of the century.
I'm sure someone wise will correct my maths if I have got this wrong?
The item mentioned, cat no 707292 on page 88 of the 06/08 catalogue, has a plastic or rubber hand grip so that body heat does not warm and distort the precision edge.
There are various firms who ought to know better who sell "straight" edges with no tolerance. The one thing you can be certain of is that these are not straight enough to be much use...... specially for testing plane soles (a subject which is of great interest to me), as you can't plane a straight edge with a fine shaving if the plane sole is significantly hollow in length.
Sorry if you have heard this rant before but some manufacturers seem to ignore this inconvenient fact.
David Charlesworth
Tolerances are more useful than descriptive words. Good is a bit vague......
I have some remarkable straight edges from Dick fine tools where tolerance is quoted;
such as 500mm long tolerance 0.004 mm.
Now 0.1 mm is almost exactly 0.004 inches (4 thou")
So I think this means + or - 0.00016 inches or plus or minus less than a couple of ten thousandths of an inch!
At 21.60 euros this has to be the bargain of the century.
I'm sure someone wise will correct my maths if I have got this wrong?
The item mentioned, cat no 707292 on page 88 of the 06/08 catalogue, has a plastic or rubber hand grip so that body heat does not warm and distort the precision edge.
There are various firms who ought to know better who sell "straight" edges with no tolerance. The one thing you can be certain of is that these are not straight enough to be much use...... specially for testing plane soles (a subject which is of great interest to me), as you can't plane a straight edge with a fine shaving if the plane sole is significantly hollow in length.
Sorry if you have heard this rant before but some manufacturers seem to ignore this inconvenient fact.
David Charlesworth
Similar threads
