Measuring Without a Tape
A carpenter I was working on a job with once related an experience to me. He used to work for one of the smaller commercial companies around here that also did residential work. He said he once saw the owner of the company get frustrated with an employee up on a roof fiddling with a tape to measure cripples going up a hip and valley. Supposedly the owner walked up to the house, started cutting hip jack and valley jack by eye, and threw them up to the guy on the roof one by one as they each fit perfectly into place.<!—-> <!—-><!—->
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Now I’ve heard of people cutting by eye before, but going up a hip and then a valley? Not only would you have to cut several of the pieces at different lengths in succession, you’d have to eyeball the angle just right on each end as well.<!—-> <!—->
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Right about now I’m guessing about half of you are thinking: “Journey, I don’t think you could actually be gullible enough to believe that. About 35% of you are probably thinking: “I’ve seen some pretty tricky stuff.†The other 15% of you are probably thinking: “I cut stuff by eye all the time, but nobody’s going to believe me if I tell them.<!—-><!—->
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Well, I’m well aware that it’s possible to cut by eye – to a small extent I do it myself. It seems the smaller the piece, the easier it is to eyeball. However, it’s one thing to cut a perfect 5-7/16†and quite another to cut a perfect 5’ – 3-7/16â€. It’s also another thing to cut a perfect 5’ – 3-7/16†with a perfect pitch for your hip roof.<!—-><!—->
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I’m curious, what’s the wildest thing you’ve ever seen cut by eye? Let me know also if you have any tips for performing this technique besides the obvious “practice.â€<!—-><!—->
–T
Replies
The thing about hip or valley cripples is that if you have the measurement for one, you could figure the length for all of them, since the incremental increases or decreases in length are consistent. And if you know the layout for one, you could figure it's length, because the distance from the hip will be the run used to figure that jack. No reason for anyone to be up there trying to pull a tape from the plate to the hip (it'd be pretty tough to do anyway, because you're measuring to an indeterminate point on the hip).
So while there's no need to pull a tape to figure jack rafter length, you would still need a tape, or some unit of measurement, to mark your cut line. By eye, and getting it perfect? Nah, I couldn't buy that.
View Image “Good work costs much more than poor imitation or factory product” – Charles Greene
CaliforniaRemodelingContractor.com
Edited 11/4/2007 1:27 am by Huck
ie ... common length difference.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Yeah - why would a guy be up there with a tape, when you can look up the common length difference in book of tables (I think one even comes free with a SpeedSquare)?View Image “Good work costs much more than poor imitation or factory product” – Charles GreeneCaliforniaRemodelingContractor.com
I agree that measuring the cripples is pretty stupid. Hopefully the guy was a 1st or 2nd yr apprentice. If it was a journeyman, I personally would’ve visited the local union hall and requested that his card be revoked. Not that it would really matter though – no guy that does something as stupid as that is going to stay employed for very long.<!----><!----><!---->-T
If it was a journeyman, I personally would’ve visited the local union hall and requested that his card be revoked.
Really?
Requesting someone lose union membership for "measuring twice and cutting once"?
While in theory the cripples should step down incrementally under perfect circumstances...in the real world, under actual existing conditions, this isn't always the case.
Personally, I'd be rather happy to see someone double checking themselves.
But then, speed has never been a priority of mine, when it comes to framing.
J. D. ReynoldsHome Improvements
when you can look up the common length difference in book of tables (I think one even comes free with a SpeedSquare)?
Or just look on the framing square.Joe Carola
Theres probably more to that story than your fellow carpenter told you.
I personally have cut hundreds, if not thousands of rafters by eye on layon roofs. I almost always measured the lengths though.
Theoretically speaking though, it might be very easy to have a situation that was quite easy to eyeball the lengths too. For instance, I normally lay a sheet of plywood over my horses to give me a large table surface. The OSB that we have has lines on it every two feet. If I was cutting the rafters for a simple 5/12 layon and the runs weren't that great, I could mentally calculate all the lengths, and then use the 24" lines as reference lines and make the cuts accurate enough to fit in. By cutting them in pair (I almost always do), they would meet perfectly at the rim, but would slide to wherever they needed to be to fit tight.
I personally always start the layon rafters from the peak and run them 24 oc so the first length would be 2' 2", then 4' 4", then 6' 6", etc. As you can see, I easily could "eyeball" the rafter lengths up to 8' 8" using the visible lines as a guide and if the spacing was off a half inch or so, no one would notice.
I have cut many rafters using some form of those techiques. Up there on those layouts, I am not that anal about getting the rafters exactly on the 24" layout. If I cut one short, it's going in, even if it means I'm creating a 22" oc layout. The plywood will just zoom by that stuff up there and I'll be the last that can ever see it. It's functional and thats my goal.
Incidently, I doubt that I could cut any rafter at the right angle anymore. It matters a lot that I used to cut rafters and parts all day every day and it's been a long time since I've done anthing like that for an extended period.
FKA Blue (eyeddevil)
Thanks, that’s very insightful. I didn’t think about a possible sheet of OSB. Starting at the top with a 26” piece is very insightful as well. So is the point that they might’ve been unnoticed a little off layout.<!----><!----><!---->
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That’s something ells the guy was notorious for: Calculating rafter lengths in his head. That’s something a lot of guys saw him do. Now if you had memorized the hip or valley rafter length per foot of run for a 5/12 pitch, and also memorized the difference in lengths of jacks on 24” centers (26”, or 2’ – 2”), then it would be reduced to matter of multiplication and addition. If you start at the top with a 26” piece it becomes simply a matter addition.<!----><!---->
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From you’re post I can see that you’re obviously very knowledgeable about framing. You’ve got me wondering; do you have any tips for calculating common rafter lengths in you’re head besides the memorizing of length per foot of run?<!----><!---->-T
One of the reasons that I could whip that example out was because I've probably done a variation of it many times in my career LOL.Actually there are several "easy" pitches to remember. 9/12 give you a 15" unit length. I would do them in my head all the time. 12/12's are easy too because you get a 17" unit. In recent years though we almost exclusively worked on irregular roofs.I don't really make a habit out of studying the tables to remember, but rather develop the memory from actual applications. From memory...and its fading because I"ve done so little field work: 12.65, 13, 13.42, 13.67, 14.24, 14.69, 15. I'd go look to see how I did, but I really don't care if I'm wrong or right because if I was going to do a job, I will have picked up my calculator and run calcs to determine several different important numbers that we need to start and in the process would re-familiarize myself with the pertinent unit lengths. Because I don't use a construction master, I usually familiarize myself with a different number: the square root (√) of the sum of the pitches i.e. 5/12= sqrt169 12/12 = sqrt 288 etc. When required to plug in the unit length, instead of plugging in 16.97, I plug the term in as √288. I then use this number as my multiplyer. FKA Blue (eyeddevil)
When I read the original post I wondered how long it would be before you'd post!! :) Guess you beat everyone to the punch.
Now that JourneymancarpenterT has asked for more tips, you gonna pull that truckload of tricks/ speed tips out?Live by the sword, die by the sword....choose your sword wisely.
The vast majority of my rafter cutting techniques are of the "up in the air" variety. I've most likely cut more rafters while on the roof than I ever did on a set of saw horses. So, there are a lot more guys in here (Tim, Diesel etc) that have better rafter cutting tips. The reason is that I've worked almost exclusively on trussed homes where the trusses are 75% of the roof with 25% conventional. Most of the conventional is layon type stuff and each situation is different calling for a different approach. For me, being versatile was much more important that having the mindset that I'd always use a calculator or alway uses a framing square. In any event, I was always much better at showing someowne a trick onsite rather than remembering them later and putting them in writing. There is so much that can't be conveyed but would be easily apparent if someone was standing and watching. For a simple layon that I described in my first post I most likely would cut that entire layon up on the roof. One trick I might do is set a workplank in the perfect spot to use as a cutting bench and also nail the tops. If I had to cut a set 5/12 on 5/12 rafters and the longest one was 13', I might whip out my tape, and mark on my cutting plank all the lengths from memory: 2'2", 4"4", 6'6", 8'8", 10'10" and 13'. After that, you'd never see a tape or square. Some casual observer might think I was eyeballing all the lenths as I moved them to my workplank and seemingly cut them by eye without marking.One other trick that I often used, when I was having a hard time getting the angles to be correct (by eye) was to put a level and plumb cut mark on my work plank. Then, before I started my cut, I'd look at that accurate angle on the workplank. This "burns" a visual reference in the brain and normally if I'm having a rough time, I quickly generate the proper image in my brain and can make cut after cut with a very high degree of accuracy. Understand that for me, this was very easy when I was working everyday, all day with the same pitches. Because we did all our overhangs and pinework before we started our rafterwork, I would have already made many perfect and accurate plumb and level cuts on the job before I got to the roof to do those layons. I think that probably has a lot to do with a lot of my eyeballing success. Admittedly, I have cut a lot of finish pinework by eye, but for the most part I mostly always marked them all using my framing square. FKA Blue (eyeddevil)
Blue,
One of these houses, I'm going to try the "panelize" technique you post way back. I love that detail and we have a simple house coming up where I think I may try that or a variation. We'll see.
Glad you are back posting. You are the veteran here, so keep going, I got my pencil and notepad. Ready to take notes.
Tim
Thanks for the kudos Tim.Panelize once and you'll be hooked. It really isn't rocket science. For practice, try panelizing the garage only on one job. FKA Blue (eyeddevil)
I used to work with a guy who REFUSED to measure baluster layout.
I don't work with that dumb asshat anymore.
I also caught him "gluing" a hanging stair landing together with latex caulk one time.
edit: He's now a foreman with a very large commercial contractor. *rolling eyes*
Edited 11/4/2007 9:44 am ET by jesse
I was helping a 5 man crew install a beer system. Their boss, Donny, was in the process of cutting dozens of 9"lengths of plastic strapping from a large roll of the stuff.
He went to his toolbox to get a tri-square, it wasn't there, he went to his other toolbox, not there either. I could see him getting visibly agitated, and he began to curse. "Freaking guys!, Always in my freakin freakin toolbox!!! He was about to pop a vein and take a strip off his entire crew when one of the guys pipes up, "Hey! Like Donny needs a tri-square to measure Nine inches!
Gord
JouneymancarpenterT
My tower has to be mine.. It's round, it goes up one side and down the other of a 17/12 pitch roof and then up one side of a dormer before it lands back on the second floor where it started out on.
No way to ever calculate that so it was done by eye.. when I was done the top plate was about a quarter of an inch from dead nut perfect and a squeeze together with my thumb and forefinger and everything came together perfectly! 18 feet in the air from the second floor where it started out.
BY eye!
No way to ever calculate that
have to disagree with you on that View Image “Good work costs much more than poor imitation or factory product” – Charles GreeneCaliforniaRemodelingContractor.com
Now, why, for all that is good in this world, did you have to go and do that?
This isn't going to end well.Remodeling Contractor just on the other side of the Glass City
hee hee hee
(I didn't say I knew HOW to calculate it, I just dispute that it CAN'T be calculated!)
View Image “Good work costs much more than poor imitation or factory product” – Charles GreeneCaliforniaRemodelingContractor.com
Edited 11/4/2007 1:02 pm by Huck
Huck,
Ok do the calculations.. for me and I'm willing to bet you wind up off.. There are pictures over at 85891.1
Besides that the time factor involved will be monumental,
Finally while you may be able to provide me the correct bevel, angle, and length of each timber, I'm just too dumb to so In the end I guess I should have said no way for me to do that..
cutting things by eye is /was commonly done.
Be wondering if the observer of this incident skipped pointing out the Owner had a framing sq. with him.
No "Eye" to it, just use the scales and drop each length while you are laying it out.
I have done it.
Cutting with a tape ? what tape , where's my friggn glasses oh tape ok.
Best buddy of mine was a hobby machinist. Game we played with him was to hold a vernier caliper, dial away from him, open it somewhere between 0 and 2", and have him look at it and guess the measurement - no touching.
Unbelieveably, he could ALWAYS get with a thousandth or two.
Now, a hi-jack -
He quick the corporate engineering job we had, started machining titanium bike parts. Did okay for a while, I took the ad photos for the bike magazines, but eventually made all the mistakes a small business makes. Lost it all but one mill (including the paid-for house), but wouldn't go bankrupt - worked a couple jobs; paid it all back.
Eventually, hit on this as a possibility. Still had one mill and a lot of titanium expertise. Quit corporate life again. Got successful. Moved back to a 8000 sq.ft.+ $MM house in Atlanta; snuck in a whole 3-phase CNC and laser shop in the basement as it was built. Got really successful.
He and his wife and her nephew do all the work. Insurance won't let all of them leave the house at once; couriers bring them customer gemstones and it would be a he!! of a great target.
You honestly wouldn't believe what they CLEAR in a day, 7 days a week. Paid off the house in ONE YEAR!
This guy - http://www.boonerings.com/
Forrest - proud of the guy
"Unbelieveably, he could ALWAYS get with a thousandth or two"not terribly unbvelievable to me. The family comes from the Alsace Lorraine and lots of machinists going back to the days before machines were invented. Story goes that back then, while they were sitting aound waiting for somebody to invent a machine they ould build, they sat aound on the door stoop in the evenings and whittled (Ooops, get the story straight here now Pif) - they filed machine screws out of blanks of forge metal. A man had to be able to get the hex head perfect within two thousandths of an inch before he could qualify as a master.I don't know how true the tale might be, but I grew up hearng some version of it and if you know how stubborn germans are, you won't doubt it.;)but I do klnow that I often suprise customers by guessing a length or space dimension within a quarter inch or so when it is less than three feet
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Paul, often do the same accurate "air measuring".
Might have had a career in the carnival.
drat.A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
OK, How much do I weigh?;)I wouldn't try cutting roof parts by eye like this, but I think like Jim that the original story leaves out the fact that afdter one measurement, and knowing the pitch, the guy had all he needed to proceeed on, but the un-initiated just saw 'magic'
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Yes, magic.
You are hard to figure the weight of as you're always carrying around a lot more baggage with if nothing else-10 lbs of pockets-filled or not.
After the shower w/o the glasses on-168.
nah-159A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Now I know this isn't along the same lines as the rest of you are talking about but if I don't have a tape and I want a rough idea for a length I use my hands. My left hand span is 10 1/2 inches my right hand span is 10 inches, my span across either hand (not including the thumb) is 4 inches and my tip to tip arm span is roughly 6 foot 4 inches. I 've used this for years and years to give me a rough idea of a dimension though I wouldn't cut a piece of wood by it. I taught my wife to use it years ago and she uses it to check out clothing for approximate sizes for her and myself. Actually she's pretty good at it and even knows where her size is by using hand spans and knuckles. She does normally carry a feminine tape measure but she won't let a bargain go by just because she forgot her tape.
roger
182 buck naked this morning.155 would be fine shape for meI was topping 190 a month ago 'till i decided that was not a good thing
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Well, it's been a yr and a half.
You'd better start watching what you eat.A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Yeah....and now back to measuring inches....
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
"after one measurement"<!----><!----><!---->
Actually, it was after no measurement – besides the lines on the OSB.
-T
Edited 11/4/2007 5:47 pm ET by JourneymanCarpenterT
but that is according to the story you heard - from somebody who may not even know.Ever hear your grand-Dad tell a fish story?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Yeah, but after Jim's explanation in post #2, any carpenter could probably do it now.-T
My old boss and I (when I was a framing carpenter) were replacing a wide fascia on a house (replacing punky, funky nasty "exterior-grade" drywall with signboard (MDO)) and I was up on a plank on ladder jacks and he was on the ground. I'd call down length and width measurememnts, but he cut the trapezoidal shapes by eye and pass them up to me. Several needed minor adjustments, but he was very close most of the time and several didn't need any more trimming.
He also did a lot with math--say we were putting in a curtain wall on a gable end, and the slope was 6/12, he'd say, "Well, we add 8" to each stud as we go." (I gave an easy example that I could figure out, but he could do all sorts of slopes.) Or on any wall with a sloped top plate, if he didn't know the slope he'd measure the difference between the ends and divide that by the number of studs and know how much to increse each stud length. He'd have the wood cut and handed to us while other carpenters would be marking off 16's and measuring the lengths, or marking boards held in place. Most of this he'd figure in in head as fast as he could say it. If I stopped and got out a pencil and wrote it down, I'd eventually get the same answer. He also knew how to do all the math tricks with a framing square. He was mad when he gave the other guy I worked with and me the little book on how to use a framing square and a couple days later asked if the other guy could cut some rafter seats (birds mouths) using the square. The guy said he hadn't had time to read the book yet, so I said I'd take a stab at it and I did passibly well. Couldn't do it now to save my life though!
"The guy said he hadn't had time to read the book yet,..."Wrong answer there! FKA Blue (eyeddevil)
I've built a few sheds without ever using a tape, or a level, lots of fun.
Backhoe, skilsaw, chainsaw, and nailers.....
did use a string for the diagonals, otherwise whatever fits. <G>
BTW, it looks it too, but does not need to survive this old bird.
my dad was a master and could cut a whole hip roof on the ground and just hand everything up, BUT the house must be square and the walls straight, For awhile i almost could do it but never had a calculater just by stepping off on the sq, once you have one jack its just the difference but dont forget to take off for the thickness of the ridge/hip rafter, I have 6 old framing sq books some of the real old ones go into detail, My dad could lay out the octogon and hexagon roofs thats too much for me though, I used to carry a little blue roof framing book i got from the union