Ideas for an aluminium beam to copy a "turbosaw"

[difflock]

You forgot the gaffa tape mate

 

cough cough

Seriously considering using double sided "Gaffer" tape:thumbup: as wot is used within industry.

All I need is sommat with a high shear strength rating.

Or a metawotsits acid based self priming epoxy.

but the tape ud be cleaner.

Rather in the first instance find a suitable depth section "of a piece"

as opposed to gluing/riveting/bolting.

Currently looking for a suitable petrol engine.

And a 3 or 5 toothed 600mm dia ripping blade.

Need to get all of the constituant pieces lined up first.

[Woodworks]

Heavy section aluminium preferably, if needs be several sections welded together.

Or do I get the cousin to fold heavy gauge sheet aluminium and weld into a beam.

Nervous of distortion with that approach mind.

Thought of three alum ladders set in a triangular format.

but not long enough (that I can find)

Erm

An old triangular lattice style galv mild steel radio/windmill "mast" to carry a runner (or two)

m

 

Why not bond the sections you want together? No risk of distortion through excess heat then.

 

Edit. Had missed you last post. West system epoxy I think is fine on ally. You sand back the faces before application and again when wet with the epoxy. I know a chap who built a boom for a 45 foot yacht like this and has been faultless.

Edited April 18, 2014 by Woodworks

[difflock]

Why not bond the sections you want together? No risk of distortion through excess heat then.

 

Edit. Had missed you last post. West system epoxy I think is fine on ally. You sand back the faces before application and again when wet with the epoxy. I know a chap who built a boom for a 45 foot yacht like this and has been faultless.

 

Ca? (wrt Manuel of Fawlty Towers)

I no unnerstann?

PS

An American DIY airplane building site was heavy on the sanding roughning prior to adhesive application, it is the "again when wet" bit I dont follow.

PPS

 

Ah just realized I will need a bevel gearbox to rotate the sawblade shaft around.

getting blinking kinda complicated.

 

m

Edited April 18, 2014 by difflock

[Woodworks]

Sounds like have got the wrong end of the stick. Thought you were looking connect to sections together to create a beam.

[difflock]

I am, two identical round topped sections (each 183mm by103mm) glued together bottom to bottom, to produce a 366mm deep by 103mm wide beam with a curved profile to the top and bottom.

Might even run a plastic coated steel wire rope up the middle,(there will be a 40mm by 40mm box betwixt and between, to prestress the beam.

being aware of the dangers of galvanic corrisson.

cheers

m

ps

see

http://www.commercialbodybuilding.co.uk/pdfs/JA-Aluminium.pdf

page 40 ending 5564

but dammn

they have discontinued my preferred round topped section on page 43(i just remembered)

so ignore the round topped bit and the wire rope prestressing.

ps

Ah "tweeked" my back so lying in bed while the "Sun splits the stones" outside

gerrr!

Edited April 18, 2014 by difflock

[Woodworks]

Not totally clear but if it is flat to flat epoxy should be fine. Only weakness with West epoxy is if it is likely to get hot as this would weaken the glue.

 

I have some ally and epoxy here so could do a strength test if you are serious.

[difflock]

Thanks Woods, but no need.

As I said I figger the top compression, bottom tension effect would only produce shearing force along the midline. and if only carrying 100kg (& guessing there) very very unlikely to be sufficient shear force to be an issue.

Essentially to achieve virtually "zero" sag or or mid beam deflection the beam requires to be very stiff=very deep in section, and way way way "over engineered" in terms of load carrying in normal circumstances.

I seem to recall leastwise.

regards

marcus