I’m really frustrated.
Some of you saw my bow case in the gallery. I built the frame, rabbeted it out then inset birch plywood panels on all sides. http://forums.taunton.com/tp-knots/messages?msg=22830.1
The Frustrating thing is that in some cases the sheet stock was not snug. A “touch” too small.
To some extent, I blame this on measurement. SO I was curious. What do you all do for measurement.
I have one really precice measuring tool. It’s an Incra t-square with holes for 0.05mm mechanical pencil “lead”
Other than that I use a tape measure, a folding ruler (yup learned to love them from working with my dad), occasionally a steel ruler (under 18″ measurements).
Also, assuming your tablesaw has a “cursor” over a ruler scale (I have a Vega fence) how do you read/set the cursor? Do you center it over the line. What does centered look like to you?
Basically I’m looking for techniques for taking and reproducing accurate measurements.
In lieu of accurate measurements, I often cut scrap wood to practice. As you can imagine however, it’s tough to do with a 15″ by 30″ piece of plywood – that’s a lot of waste…
Thanks,
Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Replies
I don't measure things anymore.. Oh in a general way to determine about how much of something I'll need, but plus or minus a half inch is more than accurite enough..
Instead I use the story pole method. make marks where things need to go and if I need to divide things into even numbers of sections I use a piece of string and fold it into the required number of folds.. avoids math errors and puts marks exactly where they will need to wind up..
For example, what's 49 7/8thswhen you need to divide it into 5 sections, each board that you will use to divide it winds up 11/16ths thick?
While you're still finding your calculator I've already got the string folded and am laying out the marks..
A few comments/observations about shop measurements.
I use a measuring tape that I check against a framing square, so I check inside and outside dims. If its off I toss it. I use the tape for rough dims and use frenchys story stick for everything else."Youth is wasted on the young."
I alway use the scale on my TS -- followed by the blade tooth to fence measurement with a steel rule for critical or steel tape for non critical measurements.
I have never made a too short or too long cut. LOL!!!! Yeah, right! It was always the saws fault.
A bad day woodworking is better than a good day working -- yes, I'm retired!
On the table saw, I periodically check/adjust the little plastic piece that has the line that tells you where you are on the scale. Upon loosening two screws, that plastic piece moves back and forth enough for that purpose. My cuts are usually fine, even though I do measure tooth-to-fence occasionally.
For smaller measurements, I use rigid steel rules - 6", 12" and 24" (18" would have been better, but that's what I have). I also have a 6" hook rule, that has a little piece of steel sticking out at one end, which is real useful.
I have two identical tape measure that I use for general stuff. I have a folding rule that I am trying to get used to, but the truth is that I keep reaching for the tape rules. A common mistake I make is when I start at the 1" point to avoid the inaccuracies caused by the hook, and forget to subtract the 1" from the reading.
While I continue to struggle to find good ways to measure accurately, they just seem to make things more complicated and my errors continue to be basic - cutting on the wrong side of the line for example. So I am coming to the conclusion that the more useful approach is to use simple and robust methods such as folding rule and story poles, and develop the skill to finesse the rest as the project comes together. As we often read in these forums, beyond a certain reasonable point it makes little sense to shoot for accuracy with wood.
Edited 4/10/2005 10:43 am ET by Alfred
Try starting at 10" instead of 1" - that sure helped me. - lol
If you can find one, get a carpenters rule that has a 6" sliding extension at one end. I have one that I use for many of my "story stick" inside measurements. I really don't care about the actual measurement - just the actual length. It's really handy when I'm hanging crown and moldings.
Yeah, the 10" start should help - the diff is so much that it would be hard to miss, though I'll find a way to screw that up too. Thanks for the tip. My folding rule(s) does have the sliding end - just have to use it more often.
We used to call it burning an inch when we started at an inch. Then you repeat burn an inch till you transfer the measurement so you don't forget.
That's why carpenders are always mumbling. Burn an inch, burn an inch..........
david,
One of my buddies had a giant homemade poster on the wall of his shop that read, "REMEMBER THE INCH!"
Regards,
Ray
unhh, doesn't anyone else use the "looks about right, cut it and try method? Requires no equipment and not many brains. You can always cut it again!
Keith
Unless you are doing production work, there is no need to be accurate.
I made 24 chair. The 48 front legs vary by 1/8". Who cares?
I made 2 matched sets of 3 tables each. I expect the tables are all different widths, lengths, and heights. Again, who cares?
Nothing new here, but I'll post it anyway. I never use more than one measuring device on a project (except for checking thickness with calipers when planing). Guaranteed to get you in trouble. You really don't need a Starrett ruler to measure things, you just need the same ruler for everything.
And, once I get one piece of stocked sized, I use the stock to set the saw fence. I have a pretty funky fence on my old Jet saw, so virtually never use the fence scale itself. Only if I need a relative number: "Ah, need to move the fence over about 1/16 of an inch."
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Yes I have adopted a dial caliper as well. Comes in handy for thickness and other applications (drill bits/threads etc).Here is a chart of fractions and decimal equivalents I made back in 1998, laminated it, and have had it in the shop ever since. Quite handy.I've posted both Excel and PDF format.Looks like I'll be retiring a few measuring devices.Thanks,
Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
I use a cheap digital caliper from Harbor Freight ($20 then, now $16). Not a dial indicator, but the sliding inside/outside caliper. It displays in both inches and mm's and I find myself frequently using mm's, strangely enough. Easier for alot of things.
"Looks like I'll be retiring a few measuring devices." Yup.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Thanks, Mark. Very handy, beats rummaging around in my drill bits for the chart that came with it.FWIW, I use Starrett rules for stuff 18 inches and under, all go with a combination head -- I've several of them also, and a couple of protractor heads. Being engraved and engine-divided they're all the same. All purchased second hand with the exception of a 12 inch satin rule.Over 18 inches I use a Johnson aluminium 60 inch straight edge I purchased from one of the borgs. Doubles as a router edge guide.Beyond that, I use one of several tape measures, but use the same one for all measurements on a project.As someone pointed out, consistency is more important than dead accuracy.For diameters, I have a B&S 6 inch dial caliper, not for dead accuracy but because the Mk. I eyeballs got to where the old Starrett caliper (a 4 or 5 inch one) was hard to read.Fast check for diameters on turnings, an open end wrench works fine.Regards,Leon Jester
I like your wrench example. Great. I recently learned this trick... when I set the fence on my bandsaw, I use a drill bit - 1/2" bit puts the fence right at 1/2" - just watch for blade flex and back off a touch.Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
You're welcome, Mark, although I can't take credit for the original idea, I'd gotten it from one of the folks at our local turners club.Like the drill bit idea.Regards,Leon Jester
I've got more measuring gadgets than I can shake a stick at, but quite a few years ago I got frustrated with too many problems similar to yours. Now I really try to transfer as many marks as possible rather than actually measuring them. You probably could have cared less about how long the ply actually was - just that it fit snugly. If your rabbeted frame was square and you had a good straight edge on your ply and one squared off end, you could rest the squared corner of the ply into the rabbet frame then just transfer a mark on the other end where it meets the rabbet wall. This also avoids any problems where you think the parts should be duplicate, but because you might have gotten a slight difference between two "identical" frames, you then end up with ply that fits great on one side, but no so good on the other. Sometimes you really do need a measurement, but a lot of times all you need is a mark transfered off some mating part. I look at it as sort of a cross between story-sticking and scribing to fit - it's just that your story stick is a mating part.
Waddaya mean it wont fit through the door?
I highly recommend this book:
Measure Twice Cut Once by Jim Tolpin
http://www.amazon.com/exec/obidos/tg/detail/-/1558704280/qid=1113243950/sr=8-1/ref=pd_csp_1/103-0029534-5455827?v=glance&s=books&n=507846
Before I read this book, I could never figure out why things just never seemed to fit right.
Todd
I use the one tape method (Starret 16') as my reference. At the start of a project, I'll mark a scrap at 12" and cut it on my SCMS. I check it against the tape and then I zero the scale on my SCMS stop system. From there I zero my TS fence with the same 12" scrap. For inside measurements I use two 3/8" x 1" hardwood strips cut to 45* on one end and a couple of small spring clamps. For precise work I never use the tape for inside dims.
Like many others here I avoid measuring and use the actual parts. For example, for a plywood panel door I'll cut the rails and stiles. Then to cut the panel to width I'll use the rail against my mitre gauge (Fastrack) to set the fence and rip the panel. For the length I'll set the fence with the stile and then use the 2 rails as spacers to cut the panel to length. I also try to cut all pieces of a given dimension without changing the setup. If I have to go back I use a part to set the fence or stop. For depth measurements a 6" Starret combination square does the trick. For thickness measurements a General dial caliper (zeroed with a piece of 1/2" drill rod) works for me. For angles I'll cut a piece of 2x6 on my CSMS and use that as a reference block for all setups on all machines.
Regarding the cursor on my TS fence (Jet Extacta) the magnified cursor had washers under it which it raised it away from the scale and increased parallax. Removing the washers helped a lot and BTW I split the line with the cursor.John O'Connell - JKO Handcrafted Woodworking
The more things change ...
We trained hard, but it seemed that every time we were beginning to form up into teams, we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.
Petronious Arbiter, 210 BC
As many have said before. Mark your piece rather than measure. I use a scribing knife rather than a pencil.
I always try to cut that are the same length at the same time. Another words I try not to reset my fence back and forth.
If I need several large pieces the same size, I'll cut them a fraction long, stack them and cut them to size together. This way if there off, then they will be both be off by the same amount.
I use a Starret machinist square and rule for anything less than 24 inches.
Mark
I posted earlier about using a story stick. What I should have done was explain why a story stick and not a measuring device..
Wood is crazy, a board that is three inches wide today isn't gonna stay that width.. it swells and shrinks
Since the steel in tapes etc doesn't have that trait something that is measured today won't be correct tommorrow..
Wood should never be measured with a micrometer.. or any really accurite instrument. It varies too much. shrink, swell, and shrink again but never by the same amount and never the same any two days in a row..
Wood should always be relative! this piece fits that piece today. If we are talking about similar woods and similar grains then that's goona do.. However one wood will shrink or swell this much while another wood shrinks or swells differantly.. In addition the grain ( with or along the grain) matters! As well as, is this piece old growth while that piece is 2nd or 3rd growth?
Just like no machinist would ever measure a piece of metal at one tempature and assume it will remain that demension at another no wood worker should ever make the mistake that todays measurement has anything to do with tommorrows measurement..
A story stick is simply a device that will shrink or swell according to the moisture levels in your shop.. if it''s made of the same sort of wood and has roughly the same grain then it will be far more accurite than that steel measuring device that doesn't shrink and swell..
Worsest' measurin' device I have is ME!
I switched to the metric system...had too, I live in a country that uses it, (although I still have all my standard rules). I find it much easier than dealing with fractions. (Adding, subtracting, half or quarter or what have you of a fraction.)
Aside from that I use different measuring tools throughout a project only when one set of measurements won't influence another. For example, if I'm building a tall cabinet I'll use a tape measure for the length and width of the sides, top, and bottom. Now that everything is equal and square, for the internal measurements where shelves, drawers and doors will go I'll use an accurate rule. I know they're bulky but I use the stainless rules, a 100mm, 300mm, 600mm, and a 1000mm. I check them to make sure they calibrate with each other and I buy all from the same company. I only buy quality measuring tools, no half baked goods here. And finally, I don't expect exact exact measurements, I'd be picking my marbles up off the floor everytime I'm beyond .5mm off.
And finally I measure twice if there's the slightest doubt...or have a mental relapse!
Edited 4/13/2005 3:22 am ET by pqken
Total agreement. Switching to metric resulted in fewer errors due to fractional computations. Metric is just easier.
Interesting, I could go metric, I'm fluent - but hem, haw, err... I've always done it the other way :-) I like the "mental gymnastics of subtracing 7/16" from 3/4"...Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
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