I finally found out what the formula for precutting the plywood is on a cone shaped roof. I’d post it in the original thread where the discussion came up, but I cant remember which thread and I cant find it.
Heres a picture of the roof and one of the precut plywood.
If some of you math wizards want to take a crack at it, go for it, I’ll post the formula (explanation) tomorrow. I’m too tired tonite.
It’s actually a very simple process, much easier to figure out than I thought it would be.
blue
Replies
I'm kinda surprised that no math wizard posted the formula. It's actually devilishly easy.
The radius of the bottom cut on the plywood is the length of the rafter.
On the cone roof shown in the picture, Steve used 10' sheets of exterior plywood. He struck the arc starting from the center of the sheet, at the bottom and worked outward. When he got to the edge of the sheet, he restruck the arc, starting at the top corner of that sheet, using the original starting point.
Hope this helps and I also hope that the person requesting the info sees this. Sorry for not remembering who it was that wanted the info.
blue
You sir, are a true master.That looks terrific. I like to see other framers doing well on difficult builds. I would love to see more of that house. Post away!
You sir, are a true master.That looks terrific. I like to see other framers doing well on difficult builds.
Carl,
A build like that shouldn't be so difficult for you since you do this $hit everyday.Joe Carola
Jealous?,...I think his work is fantastic. Have any pics you would care to share? I recognize good craftsmanship when I see it, and I encourage it. There are enough hacks around to give framers a bad name. His workmanship only goes to show that there are a strong majority of us who do take pride in our work. Again, Excellent work on your turret guys!!
Hehehe, I got you fooled Carl!
blue
this thread?.......
From:
cardiaceagle <!---->
11/6/2004 2:57 pm
To:
blue_eyed_devil <!---->
(56 of 73)
49707.56 in reply to 49707.48
Blue, you probaly already know this but for those that
have not had to deal with one of these.......
your roof sheathing cut at the facia would be....
total rafter length + total facia thickness (measured on your 18/12)....
cut the roof sheathing on a radius with that number,it will match.....
nice looking project.......regards
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regards
Carl,
My post to you had nothing to do with being jealous of anything or Blue's work. It had something to do with this comment you made in another thread about roof framing, "Ouch,...I don't know who is more confusing..... The guy with the vague problem, or the guys with the overcomplicated solutions. I'm confused, and I do this type of $hit every day. What was the question again?....Why yes,..I would love another beer. " Which I thought was pretty interesting on how you had nothing usefull to say or help the guy.
Sorry Blue, I should've posted this in the other thread.
Joe Carola
Carl, you're making me blush!
Actually, I think I posted quite a few pictures of that particular house last fall. I cant remember what the topics were; it's tough getting old!
I'll go see if I can find a few interesting ones from that house.
blue
Mr. Devil could you post the rafter pitch and the run from edge of ply to center. I'm no math wiz but I'd like to take a crack at it. I'll post numbers, and you can tell me how close I am. Like I say I'm not sure I can do it but I'm interested in trying.Are you saying this approach wlll work as a rule of thumb for all conical roofs.
I'll post a few things about that roof Quicksilver.
Heres' a few pics of that cone during the wall framing phase. We built it on the deck. I'm shooting through it while it's on the deck in the second photo. Later, we built circular stairs in it.
I posted the same pic in a smaller version for the dialup crowd.
Now, to discuss the rafter numbers: I think the diameter of that room was something like 12'. I don't remember what the pitch of that roof was, but I think the front gables were 16/12. I think the cone was too.
I calculate all my rafters from the outside of the overhang. This cone had a 12'' overhang. That would make the span of that roof system a total of 14'.
The total run is 7'. Unit Rise is 16". Unit run is 12". Unit length is 20". 7x20 = 140".
The length of that bottom arc to strike on the plywood is 140".
blue
Are you saying this approach wlll work as a rule of thumb for all conical roofs.
Yes, this would be the formula for every conical roof, assuming that all the slopes are equal and the peak is centered.
When you think about it, it makes sense. If you put a nail at the peak and hook your tape on it, it will be the same distance to the fascia at any point that you measure.
blue
You know when I first asked for those numbers I was letting different scenarios go through my head and now after a couple of hours I can see it and man that is very cool. I spent a year and a half, almost ten years ago working for a stair builder who specialized in curves and flares and I got to learn a lot from him, but your the first person that ever made me consider sheathing a cone as a cut and dry process. I appreciate the tip, and hope I will get the chance to put it into use. I've been building larger projects for the last couple years, multi unit condos aroun 10000 to 13000 sq feet. Although they present their own challenges of scheduling and organizing I haven't confronted anything that really has me scratching my head in the frame. Where are you framing it looks like you have an in to some pretty nice work. Thanks again
after a couple of hours I can see it
I laughed when I read that. It's funny becaue I often have to run things through my head for a couple of hours before it sinks in too.
I can't accept any credit at all for figuring that cone tip. My guy Steve gets all the credit. He doesn't have much carpentry experience, but he was able to pull that out of his a** from his high school geometry days.
We don't do many round walls and cones our selves. Mostly, we do octogon rooms. In fact, we tried to talk the builder into doing an octogon on this one. At first he relented, then changed his mind back to the round.
That particular house was one of the largest that we've done in a while and it wasn't really that big. We have also done some multi units last year, but now were strictly focused on profit. We're kinda feeling our way into different things.
blue
Blue, that frame looks great. Any more pictures you can share? What's the pitch on that gable? I like it. I wish you posted more pictures of your work, because whenever you do I think we all learn something new.
I'm still struggled with pulling the trigger on a 15' truss boom, btw. Convince me sometime, huh?
Diesel, we use a 12' jib on the Skytrak. Skytrak only makes the 15' jib for their 10054 series. I have the 8042.
I think you should just rent the jib for a month or two before you buy it. You might not need it enough to warrant buying it. When we bought our rig, we added a bucket, jib, foam tires and articulating boom. We were financing it all over 5 years so it hardly made a difference in the monthly bill.
I'll bring my camera to work tomorrow. Frank will be putting together some rough circular stairs and I think you might like our style. I'll do a little expose'.
blue
I too thought renting would be a good way to get my feet wet, but nobody around here seems to want to rent them. They say there's liability issues because it's hard to tell when they're damaged to the point of needing to be taken out of service?!?! I was also told to not buy used for the same reasons. Any thoughts?
I'm still looking though. They're a bit more expensive than I originally expected. I'm also still trying to figure out what the logistics of moving it from site to site will entail. A guess on how much yours weighs?
You're right... we won't use it too much. I want it for setting LVL girders and raising gables mainly. That's a total of maybe a few hours per house. Gonna take a long time to pay for itself at that rate, but for safety and chiropractor bills alone it may be worth it. Also never know when we'll run into another truss job..... even though I avoid 'em like the plague. ;)
Another problem with renting.... I've got a Cat TH-360B. Cat has a "Cat Universal Quick Coupler" which is different from a "Universal Quick Coupler" or so I've been told. I've found Budget Forklift on the web and they can adapt theirs for a fair enough price to work with my machine. I really don't want one of the ones that goes on over the forks. The ones from Caterpillar are 12' ers and are rated at 1500lbs vs the one from Budget @ 2000lbs for both their 12'er and their 15'er.
FWIW, that Budget Forklift place has some nice looking work platforms too. A nice big 10'er is on the wish list too.
Thanks for your help and I'll be looking forward to those pictures.
Brian,
I would go for the platform before the jib. Those platforms have shaved days off framing and siding. I'll post pics today of the house we are just about done with, but the front gables are about 4 storys high! and we did all our cutting and sheathing off the platforms. It is way safer to get a platform tucked up against the wall and have a railing around than getting up there and walking the plates.
We have a 10' and a 16'. They are both nice, but the 16'er is so nice :-)
Tim,
I was curious about your 16' platform.... did someone make one for you? Reason I'm asking is cuz I read that OSHA only allows fork mounted work platforms to extend a total of 20" past the wheel span. Most forklifts are about 8' tire to tire.... add 20" and you get 116".... that's the biggest work platform I've been able to locate so far.
I'm by no means an OSHA geek... but it kinda seems like I'd be bummed if I drop close to 3G on a nice safe work platform only to find out that I'm STILL not in compliance.
Another question... maybe a dumb one, but I'll admit I'm stumped. How do you move it from job to job? Does it somehow collapse down? I'm guessing you can't just leave mounted to the lift while trailering.... unless you guys have some pretty spectacular roads out your way! ;)
Which brings me to another question that I'm curious about. Do you guys move your own machine or do you pay to have it moved? If you have someone move it for you, I'm curious what it costs you per move. I usually pay between $150 and $200 per move.... an hour or an hour and a half of truck and trailer time.
Sorry for all the questions.... but you're the guy with all the answers! ;)
I was curious about your 16' platform.... did someone make one for you? Reason I'm asking is cuz I read that OSHA only allows fork mounted work platforms to extend a total of 20" past the wheel span. Most forklifts are about 8' tire to tire.... add 20" and you get 116".... that's the biggest work platform I've been able to locate so far.
I wasn't aware of that rule. I checked WISHAs website (state version of OSHA) and didn't see anything about that rule. Otherwise our platform meets the rules. A friend of ours is a welder and used to be a framer, so we gave him pics and plans that Mark Parlee (contributes as JLC forum and wrote an article) gave us. He said he has a platform that is 24' long! We had our 16' and 10' welded for $5000 total and it has been such a good move
Another question... maybe a dumb one, but I'll admit I'm stumped. How do you move it from job to job? Does it somehow collapse down? I'm guessing you can't just leave mounted to the lift while trailering.... unless you guys have some pretty spectacular roads out your way! ;)
Which brings me to another question that I'm curious about. Do you guys move your own machine or do you pay to have it moved? If you have someone move it for you, I'm curious what it costs you per move. I usually pay between $150 and $200 per move.... an hour or an hour and a half of truck and trailer time.
We have a little flatbed that we use for garbage, hauling dirt,etc with a 12' bed. We just put the platforms in that and move them. Our excavator has a flatbed trailer that he puts his excavator on and we can put the platforms inside his dump truck. He charges $100 the last time I checked.
Have you called OSHA to see about the platform restrictions? I'm thinking that you could get a 12' certified if it's built right. Talk to Mark Parlee at JLC. Do a search and you'll see the threads with his pictures. I talked to him on the phone and he is a cool guy.
I'm pretty sure there is a way to get a platform certified and then have it built by a welder. I can take a bunch of pics of ours and give them to you too if you want.
Here's a couple of it before it was painted and delivered.
http://pic9.picturetrail.com/VOL293/2163851/4541023/70659401.jpg
http://pic9.picturetrail.com/VOL293/2163851/4541023/70659398.jpg
Diesel, I wouldn't be afraid to buy a used one, as long as I could inspect it. Even though they are only rated for 1500 pounds, I can tell you that they'll lift far, far more than that.
I don't know how much it weighs because the trucker just moves all the accessories when they move the Skytrak. And, I don't know how much we pay for the move because I don't look at the bills anymore.
We haven't invested in a platform but that is something that we probably should get asap. We do almost everything while the walls are on the ground, so a platform isn't really that high of a priority for us.
If I had to rank the order of options that we need, I think I'd put them in this order:
1) foam filled tires (I don't want to be sitting on my duff waiting for a tire repair guy).
2) The boom. (that's surprising because we also have that boom truck on site)
3) the articulating forks (when we need it, we REALLY need it.)
4) the bucket (it's nice to be able to regrade, shovel snow, etc.)
5) the platform. ( I really ought to move this up for safty reasons, but I think it's pretty well established that I'm part wildcat).
blue
Your archy must hate roofers.
Spheramid Enterprises Architectural Woodworks
I've been welding all day, what is YOUR excuse?
Beats my method of using a wire and pencil attached to the peak, nailing a sheet up temporarily, scribing the lines, pulling sheet down and cutting. Using sheet as template for following pieces and rows. Nice to see hard labor replaced with MATH.
Owen Roberts Group
10634 East Riverside Drive # 100
Bothell, WA 98011
http://www.owenrobertsgroup.com
Hey Blue, that is easy ! Thanks for letting know about that layout trick.
Adam, I learned a long time ago that math can make a lot of jobs much easier. Occasionally however, I still resort to trial and error, or string and tape methods, simply because sometimes it's just easier.
For instance, I eyeballed the back of that cone roof framing after determining that it would be quite a chore to do all the calculations. It would have been very difficult to put a line down to do the cone layon, so I "boogered" it in. Frank and Steve sheathed that roof and told me that they had to slightly "adjust" one rafter. I expected more "bads" than that.
blue
Blue,
You haven't been reading Will Holladay's book have you? :-) That formula is in his book. I think he recommends sheathing vertically with 1/4" and doulble layering the ply (staggering seams) on smaller diameter cones.
Pics look good.
I wannabe Will Holladay next time around.
Tim, I know this might be hard to believe, but I don't own any roof framing books. I don't own any carpentry books. I borrowed my carpentry books to get through my apprenticeship and I've never bought any to replace them after I gave them back to the owner. I used to just figure out the stuff from memory from my classes and a lot of things I'd just sit on the lumber pile till I figured it out.
But, let's be realistic. There really isn't anything too complicated in most residential rough framing, even if the houses are big customs. It's all pretty simple common sense stuff.
Do you think it might be a good idea to pick up a copy of Will Holiday's book?
Wait, I do remember buying a book about the steel square. It was unreadable and I never read it!
blue
Blue,
My philosophy regarding books is, if I learn one trick, the book is paid for. I would buy Will's book. I think it is a necessary reference for framers. I know it made us better and faster regarding roofs and time is money.
Nice pics of the tower. Sweet framing :-)
I agree Tim. If you can pick up one tidbit from each book, it will pay for itself many times over. I owe it to myself to at least browse through some of those carpentry books that you guys are always talking about.
blue
Blue,
Did you get my email? Sometimes they don't go through
Tim, I hadn't checked my email today. I just did and sent you a reply.
blue