Thread: Help needed with Petagonal Lamp Design

1. Book-matching will fall out of bed at the fifth joint. Think about it.

2. Chain saw and belt sander might be easier than planing for the core.

3. For stability, I'd add cast iron, lead, or steel to the base, with a robust connection to the shaft.

Cheers,
Joe

I'd be inclined to make the whole thing out of Jarrah, rather than MDF which is then veneered

Also, I'd make it as a pentagon from the get-go rather than as a square that was planed into a pentagon

Originally Posted by ian

I'd be inclined to make the whole thing out of Jarrah, rather than MDF which is then veneered

Also, I'd make it as a pentagon from the get-go rather than as a square that was planed into a pentagon

Hi Ian, I was considering a single piece but am trying to be more sustainable with materials plus it would have to start off as quite a massive chunk of timber, especially the base it being around 400mm at it's widest. I'm not keen on the laminted gluelam beam look espeicllay that this is going to be a higlight piece of in the room.

The reason i want to use veneer is so i can have continuity in grain seeing that the post and base will be illuminated when the light is on at night, and visible in the daylight also.

What I'm really asking is, is wet area MDF suitable to take veneer?
Cheers

What they said .
When you have tapered the Jarrah pole to your satisfaction , take it to a WoodTurner who has Long Hole Boring capabilities to have the cable hole drilled up through it .

Nice design , keep us posted with pics WIGdj

That was my plan in the beginning but now i have a featured piece of timber chosen that won't cover material for the base and post if left solid. I'm trying to make the project more sustainable also so would like to minimise the 'unseen' material used but still have it stable enough. Hence wanting to cut veneers and then match as closely as possible the post and base with neighbouring pieces.

I will post progress pics when it happens for sure, no doubt i'll have many other questions in the process
Cheers

Hi Joe,
I'm intending to bookmatch the base then match one piece to each corresponding face of the post. A chainsaw on MDF may be a bit aggressive and hard to control.
Good idea with the weight in the base, will keep an eye out for some old roofing lead
Cheers
Dan

Originally Posted by WIGdj

Hi Ian, I was considering a single piece but am trying to be more sustainable with materials plus it would have to start off as quite a massive chunk of timber, especially the base it being around 400mm at it's widest. I'm not keen on the laminted gluelam beam look espeicllay that this is going to be a higlight piece of in the room.

The reason i want to use veneer is so i can have continuity in grain seeing that the post and base will be illuminated when the light is on at night, and visible in the daylight also.

What I'm really asking is, is wet area MDF suitable to take veneer?
Cheers

WIGdj
my appologies, I should have been more explicit in my original post

a post made from solid MDF or Jarrah will be very heavy and a real bear to drill a hole through for the power cord. I should have mentioned this in my first post and explicitly suggested a hollow construction.

If it were me, I'd make up 5 full length timber splines to go in the corners of post, I'd then make up a series of MDF pentagons spaced at say 300 centres to hold the splines in the correct position. I'd then glue (and pin?) thick Jarrah "plates" to the splines to form the outside surface of the column. I'd plug the top end with a piece of solid Jarrah and add additional MDF to the bottom to give stability.

Grain matching on a 5 sided taper will be a real challenge, if not impossible -- 4 edges will match, but the 5th will look odd.
To overcome this you might need to consider spiraling the grain up the post.
Alternatively, go for a hexagonal column

Good idea, attached is a sketch of what i think you mean?!

Another idea is to glue 2 pine/lesser jarrah timbers together (with a trench running down the length before gluing for the power cable) shaped to the required size. After reading through the forum re MDF I'm not to confident that it'll be stable enough.

I understand what you're saying re bookmatching 5 sides so I've also attached a veneer cutting plan of what i think may work. I should have been clear from the start that i want to match the post timbers to the base timbers, rather than match the adjoining post timbers.

As it'll be an angular structure, the light will vary from face to face changing the colours no matter if the adjoining faces are matched or not, so matching the post face to the adjoining base face is the closest i'll get to continuity.

I have to physically do some trial runs with some scrap to see if my theory works taking waste etc in to account.

As always i over complicate each project and change my mind a thousand times on the run, but it's great to get different ideas

Originally Posted by WIGdj

After reading through the forum re MDF I'm not to confident that it'll be stable enough.

Yep , you've got it there . The strongest part of an MDF post will be the glue line .
If you go with the split timber , trench and glue up method , don't forget to lay a mouse wire along the groove before the final sticking together . Its a bugga of a job trying to thread the lamp cable past all the runs , dribbles and drips of glue afterwards

oo yeah good point re the glue in the trench, will have to make sure the cable travels freely when the time comes, cheers for that

I think the person (ball & chain) that I'm making this for is influencing things subliminally as i have changed my mind again.

Reading through some posts regarding veneers and direction of grain, i think i have to make the grain of the base run east west, and the grain on the post run north south?!. Which is good in that i don't have to worry too much about matching the base to the post now, though have to find some timber that's 210mm wide if i want a nice even look. That'll mean having to dig in to my 'too good to use' stack but it'll make all the difference, or i could book match east west, hmm, that's an idea. This talking to myself is paying off