Wood and Tin foil

[mliptack]

Alright, so I've got some interesting findings.

First I have a lot less to do at work than I thought.
Second blackwrap could easily make some interesting gift wrap...
and seriously...
Using a 750watt light (Altman 6x9) at its focal point (so at any given 1cmx1cm square we might be talking around... say ~4 watts of light - Thats just an educated guess...) it causes the blackwrap paint to start to smoke within about 2-3 seconds, the smoke wisps off for about a minute or so and dissipates. The black wrap bubbles out slightly. I let the light sit for about 5 minutes and then removed the blackwrap.

Upon a visual inspection the wood was unharmed, but very warm.

During the 5 minute period of waiting, I remembered being in boy scouts when I was younger and seeing a "cardboard oven" it was real cardboard wrapped in aluminum foil, and then a bunch of charcoal was placed inside of it. I figure this is a lot like that.

I am gluing a piece of blackwrap to the wood now... and I am going to test that next...

[mliptack]

I dont think this is going to be a problem - even with glue. The light that is likley to hit it will be loss from the dichros and if that is enough to burn wood even if it is staright on to it then he needs to throw away the dichros and get some ones that work!

With a bit of luck even with several hundred milliwatts the losses will be only a few 10's of mW max - like I say if its more than this there is a different problem.

Rob

haha thats right we are talking about reflections and not stray beams... thats where my thoughts started to go... either way I think I am going to try the glue and see what the outcome is.

[Laser Ben]

Even with a horrible dichro and a 2W green, you will still only lose 100mW onto the wood. That's not enough to cause a problem. I would use a oak ply. Mine took me about 20 minutes on the table saw to get perfect. Careful not to route the corner if you use ply wood. I's get the high quality stuff or put a veneer of a nice wood over it! Make it look nice!

[laserLips]

The light that is likley to hit it will be loss from the dichros and if that is enough to burn wood even if it is staright on to it then he needs to throw away the dichros and get some ones that work!

lol

Putting the blackwrap in the seams would be a good option

I like the sounds of that

veneer of a nice wood over it

and that.

The mix of deep dark polished wood and the moderinity of the laser istelf would go well I think. Yey, I am liking the wood route

Edit:: Got any pics Ben, and Ben are you really 16?

[mliptack]

Hey actually the glue really did make quite a difference, however, you are correct I am sure even with 100mW it wouldn't do anything.

But with the glue, the wood actually started to burn withing about 1 minute of the light being on it.

Like I said, if you are diverting a stray beam and it hits the blackwrap, then it would cause a problem!

-Max

[stanwax]

Like I said, if you are diverting a stray beam and it hits the blackwrap, then it would cause a problem!

and thsi is where a more solid lump of black anodised aluminium would do - in the past I have dumped the waste from my PCAOM into a piece of anodised ally which started life as the handle from an instrument case. Even when running at 2W - where the waste beam would bite your finger - the ally did not get hot to any appreciable degree. A long as you have enough mass to dissipate the heat you will be ok. Im sure there is a scientific way to work this out but in the absence of this good old trial and error over engineering should do

Rob

[mliptack]

Well said Rob. Just out of curiosity you say that the mass is what matters... dont you mean the surface area? A larger mass would simply retain its temperature better.

and thsi is where a more solid lump of black anodised aluminium would do - in the past I have dumped the waste from my PCAOM into a piece of anodised ally which started life as the handle from an instrument case. Even when running at 2W - where the waste beam would bite your finger - the ally did not get hot to any appreciable degree. A long as you have enough mass to dissipate the heat you will be ok. Im sure there is a scientific way to work this out but in the absence of this good old trial and error over engineering should do

Rob

[stanwax]

I guess this may just be my terminology here - Yes I do mean mass cos if it aint big enough it will get hot quickly - as in the case of the foil & this has low mass but lots of surface area. However the surface area is important too so that the energy is transfered to the ambient air & so dissipated but if you have enough size the energy input will not impact on the temp of the whole item. Try heating a 1mX1m block of ally with a zippo you will be there a long time!

Like i said i reckon its trial and error and making something bigger than needed - within reason.

rob

[mliptack]

Hey Rob, we're on the same page, I was just a bit thrown of by that last post.