How do you drill a hole

[ChrisR]

a foot long, 6mm diameter, in a thin board?

I want to make a comb hinge. There's no particular constraint on the finger width, maybe 40-50mm so there would be half a dozen of them on the edge of the board (ply).
(The ply is about 250 wide and will have another on the other opposite side edge.)
The hole/board thickness may get changed. Say hole is 6-8mm.

The lighter bit is where the finger sticks out. OK you knew that...

I have a thought but will wait for yours.
Any tricks?

 

[Burnerman]

Consider making an aluminium jig which when held in place will give you the centre you require - perhaps with a 3mm guide pilot hole.
Use the jig to mark each piece separately and once youre happy with it, upsize to 6mm.
John

 

[ChrisR]

Errm, not sure what you have in mind.
This help? Faces are numbered including the ones you can't see.
The Zip attachment is just the Word .docx =the sketch file, which is 3-4 repeated shapes. You should be able to edit:

 

[big-all]

is this a flap that will be fully supported in the up position
or something a tressle table where the join will be mid span

 

[Burnerman]

For sure, extra long length HSS jobber drills are easy enough to get from Cromwell tools or similar - the issue is stopping the drill running off, and getting it plumb in the first place.
(Initially I thought you were going to laminate this piece, hence the confusion).
I think a pillar drill would be essential, do you have one?
John

 

[foxhole]

Might help to tell us what you are trying to achieve?

 

[Roger928]

Go to 1.50 min....

No drilling involved.

 

[ChrisR]

Yes I see I can get 300mm drill bits, and yes it's the wandering-off which I'm concerned about.
I thought someone might have a cunning method.

It's the wheelchair footplate extension thing posted here.
It makes a very long post to explain all the constraints and desirabilities of the the overall requirement. I can think of a dozen ways to go about it, but in most cases hit a particular snag, as with this one. Hence I'm looking here for a technique rather than a design.

That thought I had, as it's plywood, was to use two, part-thickness sheets with a semicircular groove in each half, made with a core box bit or started with just a saw. It's plywood anyway so the glue line wouldn't be much different.

Plan behind this one was to use brass tube pieces rather than a rod, with a series of bales catches in the tube section ends. Then if Dad steps on the flap, it comes apart non-destructively.
When the flap is up, it doesn't matter where it goes exaclty, >90° will do.
For testing if that works, I still need a long hole.

 

[Notch7]

Very difficult, i can foresee many scrap pieces.

 

[ChrisR]

Thanks Rog that's the sort of thing I was hoping someone would come up with. I'd had thoughts around it using 3 sheets of ply to leave a groove, but not seen it done. I wondered abouth the same core box bit. I don't have a saw bench so his method didn't occur to me

 

[ChrisR]

Very difficult, i can foresee many scrap pieces.

With what exactly? The brass tube?

 

[ChrisR]

There is another way, clear if I take the lid off that other sketch. Bit of a pain though:

 

[big-all]

Yes I see I can get 300mm drill bits, and yes it's the wandering-off which I'm concerned about.
I thought someone might have a cunning method.

It's the wheelchair footplate extension thing posted here.
It makes a very long post to explain all the constraints and desirabilities of the the overall requirement. I can think of a dozen ways to go about it, but in most cases hit a particular snag, as with this one. Hence I'm looking here for a technique rather than a design.

That thought I had, as it's plywood, was to use two, part-thickness sheets with a semicircular groove in each half, made with a core box bit or started with just a saw. It's plywood anyway so the glue line wouldn't be much different.

Plan behind this one was to use brass tube pieces rather than a rod, with a series of bales catches in the tube section ends. Then if Dad steps on the flap, it comes apart non-destructively.
When the flap is up, it doesn't matter where it goes exaclty, >90° will do.
For testing if that works, I still need a long hole.

as it gets wet and dries out the wood will expand and shrink
just a thought
are the foot treads adjustable from side to side
my thoughts adjust to the center off where you want the foot to be
make up a new tread the size you need then dependent on skills and space
perhaps 2 batons with a rebate to slip over the tread
or locating batons and velcro straps
or any other way you can think off
as long as its safe and quick release

 

[ChrisR]

No the plate as it is, is just that slab of plastc, no adjustment.
It doesn't need to be adjustable. It does need to be easy for the lass to knock the flaps up with her feet without trying to bend down to reach it, which would be dangerous.
The foot shapes you can see are there (actually a different chair) just for anti-slip I think.
First thing I looked at was buying slabs of plastic. You can get the stuff, £30-£40 for not much, but I don't know much about working with them. You glue ABS with solvent and ABS sawdust, apparently. Use slow, sharp tools, etc.
Both the mother and the Occ Therapist were anti any ridges or open joins.
Parents can be a problem, they want to lay down th has to be, so they can feel important, though what they say often doesn't make sense or doesn't matter.. This one is bright though and has done her homework.

For a trial I'll slip something over the existing, maybe 4mm ply. That'll tell us about how wide it needs to be, or how wide is too wide. The DMD she has means she can walk a bit, still, but that will get worse. She needs to be able to move her feet freely - but not off the sides which is/will be the natural inclination. But then the ankles grow crooked.

Water would be a problem so I'll have to sand and seal the thing somehow. (It takes hours to do drawings for a 3D printer, but when it's done, it's finished plastic, which saves hours.) Maybe I'll use something like Danish or Tung oil - easier to slap more on than varnish. I guess you don't normally oil plywood!

AS youcan see fromthe pics inthe other thread, the substructure of this thing is steel, so there's scope for straps and f-off magnets. Magnets would be another way to make a step which would "snap" if someone hrave stepped on it

OK next "how would you make this":

This is like a countertop flap hinge: I could maybe just use those but they tend to be too big, and/or the fixings screws would go into the steel tube which I'd rather avoid. Then, again, they aren't designed to be stomped on. Remionder - if the plate is more than 12mm, it won't lift, so I can only increase the edge thickness, where the metal tube isn't. Maybe an inch.
Ctop hinge:

My variations:
Either two pins and a "boat":


or one with just one pin and two under-fingers:
which actually leaves a smooth corner when its folded up
.

 

[big-all]

you just wont get structural strength into any wood less than 12mm
you can use a piano hinge as i said before to take a bit off weight if set up properly but only a few kilos per ft so never any real strength just a bit off side support
metal and brackets probably welded are more than likely the only option that will give you piece off mind