Adventures in Laser Cutting

[Panrock]

Well, I've had a phone call today... it seems there have been difficulties producing the tiny 0.28mm square holes. Apparently they are square but there is a 'slot' being produced too.

I'm to visit them at 11am tomorrow (Tuesday) to examine this shape and see if can be lived with, or whether it can be subsequently filled or otherwise corrected by me.

Steve

[Panrock]

Well when I went to the factory the results they were getting were better than I had expected, and with some further tweaking we were able to get the little squares pretty good. However this was only cutting single holes on test pieces.

However when the nipkow discs themselves were cut, the holes became near-round, despite flexure of the larger surface being kept to a minimum by ensuring the work was kept near to the clamps.

They weren't able to explain this. It remains a mystery. So now I have two discs with near-round holes.

The cost, including VAT, was a shade under £30 per disc.

Steve

[Steve Anderson]

They weren't able to explain this. It remains a mystery. Steve

Assuming they were cut with laser I would have thought that flexing would not be a problem.

The only thing I can think of (assuming the test pieces were the same material and thickness) is that with the larger disc being able to absorb and dissipate more heat energy, maybe the cutting temperature was lower, such that the corners became rounded.

"Turn up the power Mr. Spock."

Just a suggestion.

Steve A.

[Viewmaster]

They weren't able to explain this. It remains a mystery. Steve

The only thing I can think of (assuming the test pieces were the same material and thickness) is that with the larger disc being able to absorb and dissipate more heat energy, maybe the cutting temperature was lower, such that the corners became rounded.

.

How big were the test pieces which cut OK? Could they dissipate heat too or were they just very small pieces? Could the stainless steel grain direction be anything to do with it? Doubtful that though as some holes would have been OK.
Albert.

[Panrock]

This is useful!

The test pieces were only about a couple of inches square. However they were part of a larger sheet (but to one edge) while the hole was being cut.

We were turning down the power as much as possible to minimise splatter and improve definition without the hole becoming plugged. Also the start position of the cut was found to be optimal near one side of the square (not centered).

Maybe an expensive trial-and-error process would be required - making full discs each time - to resolve this.

Steve

[Steve Anderson]

Maybe an expensive trial-and-error process would be required - making full discs each time - to resolve this.

Steve

Well, if you were to try a single sacrificial disc you could punch as many holes in it as you like. Even a larger sample square of approximately the same surface area as the final disc should do. How many test apatures could you get? Thousands!

But this will take time, and you'll be using up their machine time, so bear that in mind.

Steve A.

[Andrew Davie]

Well, I've had a phone call today... it seems there have been difficulties producing the tiny 0.28mm square holes. Apparently they are square but there is a 'slot' being produced too.

I'm to visit them at 11am tomorrow (Tuesday) to examine this shape and see if can be lived with, or whether it can be subsequently filled or otherwise corrected by me.

Steve

My father-in-law owns/operates a small manufacturing company dealing in such items as micro gears. He has a lot of sophisticated machines, and was quite interested in my mechanical TV when demonstrated. He was of the opinion that he could easily manufacture such discs, even (I think) with square holes. He suggested to me that I could just get him some artwork and he'd produce a sample disc to see how it goes.

So, if you have sample art for your square-holed disc handy, I'd be happy to forward it to him and see how he goes at disc manufacture. I would predict a much lower price than PDS30.

Cheers
A

[Panrock]

This is tremendously kind of you and your father-in-law Andrew.

I'll email you the .dxf (CAD) file which was produced by Denis Asseman.

Cheers,

Steve