making a corner

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making a corner

Postby jantje » Wed Sep 23, 2009 2:18 pm

All
I have been investing a lot of time now in the david scanner and I enjoyed it a lot :) . And I learned a lot :) .
The biggest lesson I learned recently is the importance of the corner. So I build a rock solid corner using wood and metal sheets to be able to use magnetic paper.
Man this was a big step forward in my results and ease of use.
But now about 3 weeks later the wood seems to have bent :shock: (only a couple of milimeters) and this has a serious impact on scan results. I tried to straigthen it but I failed to straigthen it "good enough" :? .
So I will make my n'th corner. But this time I want it to be the last (of lets say table size) so I've been reading through the forum searching for corner creation advise and I find very little information. I know the user manual has good instructions, but not complete enough for me. For instance the plastic sheets mentioned have no thickness. I'd guess 2 mm will not be thick enough but is 4mm thick enough? How long will this type of corner last? Can I glue a metal sheet on the plastic? Will it bend over time?
Has anyone uses metal sheets instead of the metal paint? (I don't seem to find the metal paint)
Moreover I would not know where to find these plastic sheets mentioned. I know quite some shops around but the closest I can think of is a plastic cutting plate.

My requirements to the corner are as follows
Ability to make the corner straight (be it by easy disassembly or turning)
Easy to make (the corner I mean; but easy is relative :wink: )
Easy to put in 90° (prefably some locking system so it doesn't change when removing the magnetic paper)
Supports magnetic paper
Lasts forever
The planes are perfectly straight. (We all have some experiances on this :wink: )
Not to heavy

I do not have requirements as to
Cheap (I've spent to much allready ....)
Having a open corner and stuff like that (I'm all set up to do planeless scanning)
Anything bigger then 2 times A4 (For me this is a subject for later)

Any construction plans/tips/advise is welcome
Best regards
Jan
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Re: making a corner

Postby WalterMo » Wed Sep 23, 2009 8:15 pm

Hi Jan,
This is the corner I have used to scan the backside of my car. It's completely made of wood and the walls are still perfectly flat. Important are the ledges on the backside and also important is not to store it in a humid room, e.g. the basement.
The walls are of 8mm thick plywood and each is 52cm wide and 60cm high. As you can see they are connectable by two hinges and therefore easy to transport.
To achieve easy and fast the 90° I have built-in a banana bush at the underside of each wall. The appropriate aluminium rod with the two banana jacks is lying on the corner.

But you are looking for magnetic walls. Simply glue thin zinc coated steel sheets onto them.

Walter
Attachments
Outdoor corner.jpg
Wooden corner from the backside
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Re: making a corner

Postby jantje » Fri Sep 25, 2009 3:32 pm

Walter
Thanks for the feedback.
For your information. I kept my pannel in my living room not in the cellar. ut wood tends to bend in my house :(
Best regards
Jan
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Re: making a corner

Postby MagWeb » Mon Sep 28, 2009 8:27 am

Hi,

jantje wrote:using wood and metal


well, as a woodworker one hint:

If you use some wooden material as plywood, FPY MDF or OSB and you want to avoid some bending of the material, you always should plank the boards on both sides.
If you plank it with metal sheets on one side only, the compound acts similar to a bimetal, but reacting on moisture instead of temperature. The wooden board shrinks or grows with different moisture , while the metal does not. ( that isn´t meant for metal planking only. Also weak materials, as veneer, have always to be on both sides of a board). Sometimes the drying of the moisture caused by the glue is enough to bend boards.

Walter, if you would plank your construction on the backside with plywood too (same thickness and orientation) you could avoid the risk of bending on moisture or temperature changes.

Another good thing is to prevent infiltration of moisture by sealing the raw boards with some paint (again, at both/all sides) or to use melamin coated boards.

Gunter
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Re: making a corner

Postby jantje » Mon Sep 28, 2009 12:30 pm

Gunter
Thanks for the feedback.
To be honest: I already distrusted the wood with sheet on one side solution I had opted for. What I wonder now. If I would go for a setup like walter and I use plywood on both sides. Is it still "advised" to use the metal sheet on both sides?
Best regards
Jan

PS I'm currently seriously considering to use the 15 mm thick PVC sheet I bought to make the rig. I assume there will be no bending there if I gue a metal sheet on it. The only thing that stops me is that this sheet is heavy.
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Re: making a corner

Postby WalterMo » Mon Sep 28, 2009 3:40 pm

Jan,
Normal room doors are nowadays made of two sheets of plywood with a framework of laths inbetween.
By this construction they are stable and lightweight.
Sometimes it's possible to buy a door with a less damage of the surface at a home-improvement market for peanuts.
In so doing you have enough material for future calibration corners. :D


Walter
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Re: making a corner

Postby MagWeb » Mon Sep 28, 2009 7:06 pm

Hi again,

WalterMo wrote:framework of laths inbetween


oh, that was once upon a time.... today only the upper class of roomdoors uses lathes inside.

Most doors are made with comb structured paperboard inlay. If you cut one of them, the planks fall apart... :(

Think 15mm PVC is some kind of overkill - I use simple 16mm white melamin coated furniture boards. If you want to make it magnetic you could also use magnetic paint .

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Re: making a corner

Postby RAYA » Mon Sep 28, 2009 7:15 pm

Hi Jan

I don`t think you can get non-wave plane with sheet metal on pvc sheet because it is difficult to find

full flat sheet metal and it is difficult to attach them to pvc sheet.

So why you don`t use metal frame armed 16mm MDF as planes.

Ray
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Re: making a corner

Postby jantje » Tue Sep 29, 2009 12:17 am

Raya
I'm not sure I understand what you are saying.
I have made a corner gluying a metal sheet on wood.
The sheet was actually easily found in a shop where they sell school stuff 8) . I bought a cheap magnetic white board (I paid 9 euro for a bord like the one on amazon http://www.amazon.co.uk/Large-60x80-magnetic-whiteboard-frame/dp/B00164AJPA/ref=sr_1_17/275-8350826-8894457?ie=UTF8&s=kitchen&qid=1254178616&sr=1-17). You remove the frame and the carbord behind it and you have a white coated metal sheet.
However as Gunter confirms this approach is bound to bend the wood as you can see on the picture below.
bend corner small.JPG
wood sheet and bend


I assume PVC (or any other plastic) is less likely to bend after having a metal sheet glued to it.

Are you saying that glueing on PVC is hard ?(the white cutting board I earlier suggested in my first post is polyethylene and will cause gluying problems but as far as I know PVC should be fine)

MDF in a metal frame is fine but I would have to glue a sheet on both sides or find the magnetic paint I have difficulties to find. And paint both sides as well.

Best regards
Jan
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Re: making a corner

Postby Kirch » Fri Oct 23, 2009 5:22 am

WalterMo wrote:Jan,
Normal room doors are nowadays made of two sheets of plywood with a framework of laths inbetween.
By this construction they are stable and lightweight.
Sometimes it's possible to buy a door with a less damage of the surface at a home-improvement market for peanuts.
In so doing you have enough material for future calibration corners. :D


Walter


Another woodworker here... I do alot of work with veneered panels and it is impossible to keep a veneered/laminated panels "perfectly" flat. Like plywood-similar to what you are working on with the steel on the board.
If I need something really flat I always build an additional frame. LikeWalterMo says, hollow core doors are great for this. They are light and they are cheap. IF you cut them inthe middle, you can dig out the lathe a little bit from the cut side and slide in and glue a fit piece of solid wood to cap the hole nicely. :)

In the states they are selling a laminate, formica and nevamar are common brand names, that is glueable one face and stainless steel the other face. very thin, trims with a router. I am not sure if it is magnetic or not.
Cheers!
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Re: making a corner

Postby anschoo » Wed Mar 10, 2010 3:15 pm

Thanks for the information

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