Thread: Advice on making this long bent object

Originally Posted by Arron

Let me understand this. I think in the solution you are describing the layers of plywood would be oriented vertically (understanding that the 120mm width of the component lies horizontally). Therefore if I used 12mm plywood then I would need 10 slices glued together. As I glued the slices together they would have to be very precise - but that is no big problem I just go one-by-one with a nail gun and 20mm brads - line up then fire - easy peasy). Is there even any need for glue - well it wouldn’t hurt to apply some anyway.

Horizontal strength is guaranteed by the 120mm width. Vertical strength comes from all the plies which lie horizontally which will be about 16mm worth counted vertically - which intuitively sounds good enough. If not I can substitute some 19mm pine.

It would need a fair bit of router template work. Ironically, I put my trusty old Triton router table out on the council clean up just a couple of weeks ago, wondering how long it would be till I regret it as I walked away. Having now access to a bandsaw then I can rough-cut on the bandsaw and just do a minor clean up with the router.

This idea is left field and I will have to think it through further. I did want left field though.

Thanks
Arron

Unfortunately, your original post and sketch is somewhat vague and does not give any indication of how and where the component fits into the final assembly.

From the first & second posts - "vertically" means nothing because I have no idea or concept of the orientation of the component in-service.

My interpretation of your sketch is that the curve is across the 120mm face, and that the lamination could be constructed from say three layers of 12mm CD ply plus a filler to make up the 38mm (no bending). (somewhat like a sleigh runner??) The highlighted portion of your reply seems to contradict that. So, I now take it that 10 x 12mm laminations would be required to avoid "bending" laminations.

If the curve is across the 38mm face then that changes the equation. The ply laminations strength is definitely determined by the orientation and number of plys in each direction, and the length of the ply's fibres in that direction.

Not knowing the application, nor the load or potential loads it may be subjected to, makes it very difficult to offer advice. Cosmetically I would go per my suggestion. However, if the component is to be subjected to reasonable loads it is vital that the in-service orientation of the component is known, in what directions the loads or potential loads are applied and only then can the optimal construction technique and materials be selected.

sign up to a men's shed.

Originally Posted by Mobyturns

... Unfortunately, your original post and sketch is somewhat vague and does not give any indication of how and where the component fits into the final assembly. ...

Well said. And Arrons subsequent postings have simply confused the issue further.

Perhaps Arron could respond with a 3D drawing of the proposed bed showing the specified component in situ. Then we might know objectively what the issues are. So far it is mainly guesswork.

Originally Posted by GraemeCook

Well said. And Arrons subsequent postings have simply confused the issue further.

Gee, that’s a bit harsh

Originally Posted by GraemeCook

Perhaps Arron could respond with a 3D drawing of the proposed bed showing the specified component in situ. Then we might know objectively what the issues are. So far it is mainly guesswork.

Having thought it through I’m pretty confident Mobyturns and Beardys solution will be the best approach and I’ll be putting it into practice as soon as I return from Overseas. I’m confident it will work and will be a match for my depleted toolset. Thanks for your help guys.

So today I finally got around to making thee two components. 11 pieces of 12mm CD ply each, cut on a bandsaw, stacked with pva glue and brads for clamping. The surfaces are rough but I will trim the ends and clean them up with a flap wheel and some filler when time next allows. I thought they would take a long time but only required a couple of hours of bandsawing and one of assembly - although I really am over having to do everything on the ground.

Sufficiently rigid too.

I used the method suggested by Beardy and Mobyturns - or at least my interpretation of what they were saying.

Cheers.

A5DAAD2D-33DC-4311-A4D4-323650310035.jpeg

Nice job

That is how I suggested. Still do not understand its role in your project, which hopefully is not load bearing. The cross-facing ply veneers will give it some rigidity but no significant strength imho, depending upon the load direction etc. But then again, LVL is the new "wood."

Nice work!

Originally Posted by Mobyturns

Unfortunately, your original post and sketch is somewhat vague and does not give any indication of how and where the component fits into the final assembly.

From the first & second posts - "vertically" means nothing because I have no idea or concept of the orientation of the component in-service.
...

Originally Posted by GraemeCook

... Well said. And Arrons subsequent postings have simply confused the issue further.

Perhaps Arron could respond with a 3D drawing of the proposed bed showing the specified component in situ. Then we might know objectively what the issues are. So far it is mainly guesswork. ...

Originally Posted by Arron

... Gee, that’s a bit harsh ...

Originally Posted by Mobyturns

... That is how I suggested. Still do not understand its role in your project, which hopefully is not load bearing. ...

With respect, Arron, you have sought advise and I, for one, simply do not understand what you are trying to make. It seems Mobyturns may be in a similar position.

There can be a variety of reasons why people do not feel free to reveal the design of the finished product. Usually it’s copyright issues. In this case it’s because it’s not my design and the design owner has so requested it.

Cheers
Arron

Originally Posted by Arron

There can be a variety of reasons why people do not feel free to reveal the design of the finished product. Usually it’s copyright issues. In this case it’s because it’s not my design and the design owner has so requested it.

Cheers
Arron

Fine Arron. But any discussion will be significantly qualified in that it is based on partial information.

The sketches were a little ambiguous. May I suggest that when trying to determin shape a bit of plasticine or modeling clay comes in handy. A picture taken and posted here of the finished model leaves no doubt as to what the end product is to resemble. Simples.

Originally Posted by Mobyturns

That is how I suggested. Still do not understand its role in your project, which hopefully is not load bearing. The cross-facing ply veneers will give it some rigidity but no significant strength imho, depending upon the load direction etc. But then again, LVL is the new "wood."

Nice work!

Well it bears my 100kg weight without any worrisome noises so I’m happy. Nonetheless it’s not structural.
Cheers