I want to make a western red cedar glider but am concerned about the strength of the cedar. The weight of 2 people plus glider weight hanging on 4— 1/4″ bolts. Seems like the softness of cedar would tear out after a while. I did buy 4 steel hangers w/ ball bearings for smoothness.
trimjim
Replies
trim,
My first thought was to incorporate some large washers behind the wood to reinforce the connections. Perhaps some sort of metal plate mortised into the underside and out of site? The holes could be lined with some metal tubing?
Just some thoughts,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
tj,
Cedar would not be my first choice for the glider , Cedar gets used in decks and fences and trim and sidings often but rarely in more structural applications .
Perhaps you could insert steel sleeves for the bolts to go through .
regards dusty
The problem with cedar is that it lends itself to surface dings (being so soft).
Structurally, I don't think it would be a problem for a glider, but as Bob suggested, I would pay attention to the hardware -- using oversized washers at stress points, etc.
I use a lot of cedar for outdoor applications, mainly because cypress is unavailable in my area, and furniture grade, straight grained Doug Fir is hard to come by.
Would white oak or mahogany be out of the question?
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"It is what we learn after we think we know it all, that counts."
John Wooden 1910-
The reason for the cedar is to match my bistro table set.
Please, please, please do NOT use cedar for this.
edit:
Oh dear, I may have over-acted here. The first thought that came to mind was an airplane type glider. Sorry about that. I guess it is because of my day job - B767 pilot.
Edited 6/16/2007 9:56 pm by PeterDurand
Too funny. Peter, I had EXACTLY the same thought as you, DON'T FLY IN THAT CONTRAPTION!!!
I build em, I don't fly em. I started building them when the 767 was first introduced to you guys. Still at it working on the new one..the Dreamliner (sheesh I hate that name, brand management...don't get me going)...the 787....
Hope you guys like that one, should be a good one once we git er dun....
Jeff
I will not see those as I am retiring in 4 months and 12 days and 4 hours. Time to move on after 35 years. My ONLY regret is not being able to get my mitts on a 787.Cheers,Peter
Dear J,
Western Red is a nice wood, but there are a few reasons why I think that it is inappropriate for your project:
1) Too soft
2) Too splintery
3) Too weak
If I were attempting a glider, my first choice would be Ipe. It is pretty, very strong and will compliment your table set very nicely (IMHO). Ipe is very tough stuff and you will get many years of satisfaction for your efforts.
Best,
John
John makes a good point about Ipe.
In fact most yards that supply deck builders will have a variety of so-called exotics that might be very appropriate for your project.
Right now, I am making some benches from something called Cambarra, which is a terrific wood, but no longer available in my area.
********************************************************
"It is what we learn after we think we know it all, that counts."
John Wooden 1910-
I am sure that a 2"x12" red cedar plank would provide enough strength.
1" white cedar (about the same strength) is often used for chairs.
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Engineering or experience is the best guide.
I would go with cedar, BUT, for the load carrying areas, I would make some laminations using an adhesive suitable for outdoors. Laminate some thin stock together, then sleeve the holes with bronze or brass bushings, unless you have some bearings you can press in....Jeff
Inserting bushings for the bolts may work for a while but if used often the bushing itself may crush the cedar. How about boring and inserting an oversize hole, round or square, and inserting a wooden bushing of a stronger wood? Teak, white oak, cypress, ipe, whatever matches your cedar. This way you can match the existing furniture and not worry much about wear on the soft cedar. The wooden bushing could be a design detail if contrasting instead of blending. Beware also cedar's aptitude to staining from metal, a wooden bushing may prevent this unless desired.
I did think about using a steel bushing, however I'm not sure if that makes any difference. The hanger brackets use 1/4" bolts & have ball bearings at the attachment points. The bolts themselves won't be rotating. So does drilling a larger hole say 3/4" w/ a bushing, then drilling a 1/4" hole thru that have any effect on the fact that it's still hanging on the cedar runner? I know they do make/sell cedar gliders, so that would seem as though it must be strong enough. I'd use 1 1/2" thick by 3 1/2" tall runner & install the bolts at 1 1/2" up from the bottom. The weight would be bearing off of that.
jvk,
Your thought seems to be much the same as I had. Now, if the bolts extended throught the runner bearing the weight then I would think reinforcement of some kind under the runner would eliminate ay potential strength problems with the cedar.
I'm probably not explaining myself clearly. I'm thinking if a plate of some kind were drilled for the bolts and mortised into the unerside of the runner, the plate would provide added strength to the stress points. Also, if it could be mortised in far enough, nothing would show.
Unless of course someone were to crawl under the runners and look!
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 6/18/2007 9:55 am ET by KiddervilleAcres
The design of the glider is at least as important as the material. It sounds like you're working from some kind of plan. I'd take a look at how the weight is carried to the frame and make sure that you're not applying concentrated loads to areas that would be likely to split. Washers would help if they wind up carrying some of the weight, otherwise they're little more than decoration.
Can you post a picture of how the glider is supported?
Pete
Edited 6/19/2007 7:54 am ET by PeteBradley
No plans, just a photo of a similar unit.trimjim
Just happened to google this up:http://www.popularmechanics.com/home_journal/woodworking/1793442.htmlIf I were building this, I'd be looking to:
- make the base very stiff so it can't rack from side to side. The design in the article above uses heavy cross braces to help with this.
- make the parts that take the bolts thick to spread the load
- bush the bolt holes with a metal sleeve rather than having the bolt directly in contact with the wood. The ID of the bushing should match the bolt and the hole bored to match the OD. The length should be a hair shorter than the thickness of the wood so the bolt can be properly tightened.Good luck!Pete
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