best way to cut holes in metal lensboards?

[Jon Goodman]

Jon, professionals don't use chewing gum to fill in spaces caused by grievous negligence!

That's what spray foam sealant is for.

That's a very good approach, Terry. And more fun. Just don't get that stuff on your clothes.
Jon

 

[E. von Hoegh]

You could use a .410 shotgun. Just attach the lensboard to a piece of wood and stand a few inches away from it when you fire the gun. Hole too small? Back up and try again. Hole too large? Get some duct tape and chewing gum to plug up the holes. Good luck.
Jon

Or the OP could send his lensboard to me.
The next time the aliens come visit, I'll have them cut a hole with their equivalent of a Swiss-Army knife, which includes a small plasma torch.

 

[lxdude]

rotate the board with geared table (forget what it is called)

A rotary table.

 

[pasiasty]

For the sake of your fingers and unless you enjoy the sight of your own blood, if you're drilling or hole cutting in sheet metal, put the workpiece in a vise or clamp it securely . As the drill bit breaks though its likely to snag the work piece and twirl it around, nicely butchering your hand. The chassis punches mentioned earlier are great things, but the ones I've used require a hole drilled in the center of the work piece, so still be careful.

Instead of using a vice you may secure the lens-board to a wooden board (e.g. with small screws or nails, at the lens-board edges) - the advantage is that the drill doesn't break through to void, rather to wood; and that you may secure all 4 edges; and, last-but-not-least, you may drill a piloting hole in the wooden board.

 

[Laurent]

There is a kind of drill with several diameters, which works wonders if you can find one of the right size.

Don't know the english term for this, it looks like Dead Link Removed

 

[shutterfinger]

Step drill bit
http://www.amazon.com/b?ie=UTF8&node=256287011

 

[c.d.ewen]

I would use my Sherline Mill, drilling a small center whole so i could then rotate the board with geared table (forget what it is called) and cutting the hole as it rotates.

Securing the center of the lensboard isn't sufficient. You need to secure the outside edges too, so that the board doesn't move as the cutter goes through it. Put a piece of waste underneath and tighten everything down.

Charley

 

[AgX]

There is a kind of drill with several diameters, which works wonders if you can find one of the right size.

The largest size I got in my assortment goes up to 32mm. I assume one would hardly find anything substantially bigger.

 

[Tom1956]

Seriously, the best lensboard method I've settled on myself is to forget about metal lensboards and fabricate them out of hobby plywood from the hobby shop. With ingenuity, you can make an exact replica or BETTER doing it this way. That way an ordinary brace and bit with adjustable bit is used to bore the hole slightly smaller, then sanded to fit the lens perfectly. I am very happy with all the lensboards I fabricated this way. And the cost was perhaps 2 dollars for materials. I would never consider going back to factory-made lens boards. Mine are beautiful and trustworthy.

 

[fotch]

Securing the center of the lensboard isn't sufficient. You need to secure the outside edges too, so that the board doesn't move as the cutter goes through it. Put a piece of waste underneath and tighten everything down.

Charley

That is what the geared rotary table is for, the board is clamped to it, then the table rotates slowly, as the mill cuts the whole. Probably easier to understand for those who have a milling machine.

 

[c.d.ewen]

That is what the geared rotary table is for, the board is clamped to it, then the table rotates slowly, as the mill cuts the whole. Probably easier to understand for those who have a milling machine.

I was assuming that you were securing the board with a single bolt through the middle. Without a piece of waste under the board, as the cutter finishes cutting the hole it will (a) score the rotary table and (b) cause the outside of the board to come loose and get torn by the cutter. Been there, done that.

That's the manual rotary table; get the CNC rotary table and your dreams will be in TechniColor

Charley

 

[fotch]

I was assuming that you were securing the board with a single bolt through the middle. Without a piece of waste under the board, as the cutter finishes cutting the hole it will (a) score the rotary table and (b) cause the outside of the board to come loose and get torn by the cutter. Been there, done that.

That's the manual rotary table; get the CNC rotary table and your dreams will be in TechniColor

Charley

Everything you say it true. I was not attempting to give machinist lessons here, I will leave that to others. Rather, increasing awareness in case a person knew someone who did machining, as either hobbyist or pro.