Hi guys
Making a arch way in the garden for SWMBO.
Sizing is it will be made from 90 x 45 treated pine over all hight is 2400 x width 3500. The arch has a diameter of 1340, see attached.
The finished structured will be painted. It will have plants then grown over it.

The question I have is how best to make the arch part and keep the thickness down to 45mm to match the posts?
Hey any other thoughts, please give them.
Thanks
Russell

Attached Images

arch 1.jpg (168.1 KB, 87 views)

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Russell,

how about making the arch by laminating strips of timber around an MDF form?/

You could also laminate from exterior plywood, which i think would be easier.4.5mm should flex around the radius , and 10 lamination's will give you the arch at the correct thickness and will be immensely strong.

Use epoxy glue for your adhesive and step the ends to attach to the posts,
also use epoxy resin to seal the exposed ply edges prior to painting.

jeff

That would work admirably.
Cutting kerfs into the 90x45 and filling them with builders bog after bending is another possible alternative to consider.
Cheers
Jim

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Being happy doesn't mean everything is perfect. It means you've decided to see beyond the imperfections....

Could be done as a segmental arch with pieces cut from 90x90 on bandsaw. Joints either half lap or floating tennon. Glue with epoxy.

I was thinking along the same lines of the plywood and the solid wood and just try to think out the easiest one to do but the best structurally over time This depends on me and my quality I guess. Which bring me to what's the best epoxy to use and where do you get it?

Russell

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Boat building epoxy glues would be a good start.

I'd go with epoxied laminations for sure. Check out Adhesive Engineering for the most suitable epoxy for your job.

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Visit my website
http://www.springall-fine-woodwork.com

Epoxy resins / glue are available from
1, BIAS boating supplies
2, Whitworths ,
3 Bote Cote Australia
4 FGI <

these will be able to supply you with a suitable glue / resin.

Jeff

Cutting kerfs into the 90x45 and filling them with builders bog after bending is another possible alternative to consider.
Cheers
Jim



Both these methods would be my choice, both of them being made from the same timber as the rest of the structure and best suited to the proposed project. Both also would I think have a decided cost advantage over epoxy bonded plywood.

JMHO

If you are building it to last , laminated stuff is allways a risk - I would forget about it , but it's just my opinion .The same goes for kerf bent arches - seasonal changes will make it rot in a single winter . I would definately make a segmented arch , as it's made for front doors (stuff I've done for living for quite some years , BTW) - You make TWO arches , each half of the desired thickness , and then glue &screw them together .The first is made out of 3 pieces , the other of 2 , so the joints dont match.
A church door frame , with the arch made this way fell on the floor by an accident - the door was almost three meters high by two meters wide ( sorry - 9' X 6' 8" - is that so? ) - and heavy beyond belief - much to our surprise , it didn't come apart , not even a slightest crack

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It's a slow and painful process...the secret is, dont mind the pain.(Ian Norbury)
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Regards
Ivan Chonov

Putting in a lot of effort to last just a few years... I would be making the whole thing from steel

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Don't apologise Ivan . Oz has been in the process of being metrified since 1970

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I've just become an optimist . Iv'e made a 25 year plan -oopps I've had a few birthdays - better make that a 20 year plan

Wow lots of info to get through here, thanks.
Just rang FGI they suggested the R180 epoxy cost about $35 for a 1kg kit (plus $35 to deliver) I have used this epoxy before and found it very good to use.
I like the plywood it is fairly simply to construct just got to be sure that you have no air between the lamination!
Artesano I was thinking also along the same lines of construction. Let me run one idea I had past you all.
CNC out 6 parts from treated pine 30 mm high that make the arch 1/3 of the hight of arch (45mm arch thickness by 30mm high) then put the next layer of 30mm offset by half so that they overlap the lower layer. Then the last layer is a copy of the first giving a total hight of 90mm and a thickness of 45mm.
All epoxy together with some screw to hold it till glue sets.
Seeing that I can cnc the parts out I could lap the joints where the segment meet or even key hole them. Do you think this would help or just be over kill?

Russell

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If you are going to use triple layer you wont need end joints. Only thing is, fresh glued pieces want to slide in all directions even the screws can be a bitch when being driven. Short locating spikes would be better (cut off nails will do.)

I'm with you Harry The longest lasting and most practical way to go.