$8 Beam Dump Idea

The pieces [about $8 at Home Depot]:



Dry Fit:



I plan on using the same ultra flat back I used in the $50 LPM project:

Good idea that copper should take all you can give it

Finally painted the pieces ... man its dark in there

interesting... TEST IT!

Here are some quick beamdump action shots. Excuse the poor photography but I was holding the laser in one hand and operating my SLR in my other outstretched hand.

If you want to build more, try getting a tube with a bigger bend radius. Usually beam dumps use a cone like structure because the back reflection are then less. If you now point your laser lower in your beam dump you hit more perpendicular to the material, which gives more back scattering.
But it's still a very nice beam dump. What kind of black paint is it? I'm considering making a beam dump using high temperature resistant paint.

Its Rust-Oleum Ultra Flat Camo Black

^ also consider this ..... they use cones cause the reflection is always enlarging, when you hit a convex curve (i mean, the reflection from a cone side is always scattering in more large volume than the original beam)

If you use a concave surface, the eventual reflection can be concentrated in a burning point, before spread again, and if this burning point is focused on something, it can end in some damage, for high power beams.

Also, a cone will always reduce to almost zero the possibility of a direct reflection to the entering aperture.

True ... but in this case the focus point is relatively close to the impact point since its such a curved surface. In fact you can see the reflected "ring" just in front of the impact point, which is still contained within the entrance aperture.

The best would be a coating that is diffusely reflecting so that it doesn't focus, but this get's harder as the wavelength increases. Matte surfaces may be specular for a CO2 laser. A cone would then be ideal, but I haven't found anything cone shaped and suitable.

Well, i had an idea for a cheap, easy to produce and efficent beamdump (uhm, maybe i have to patent it, before post it publicly ..... )

It can be produced also without access to machines, at least until 12mm diameter input aperture, and if someone have access to machines, it can also be produced more "professionally" in bigger sizes, with the same system and, basically, with the same efficence.

For "homemade" production, is enough a drill (a column drill, or also a drill that can be placed in a vice for "emulate" a lathe p), and a file ..... get a piece of 12mm threaded bar, the ones with the bigger size threads you can find, and a corresponding 12mm "long joint" bolt (they are usually used for join two threaded bars and some shops have also 60 or 80 mm long ones) ..... place the threaded bar piece in the drill, and file one side in conic shape (always paying attention to safety !!) ..... if you have steady hands and a good rest point, you can obtain a decent regular and symmetrical shape (anyway the conical part must be long at least 20 or 25mm, longer it is, better it is), and refine it with a fine file or sandpaper ..... at this point, simply screw it in the long bolt (you can paint it and the inside of the bolt flat black before or after, as you prefer), et voila', high efficent homemade beamdump.

Let me post a draw, so it's more clear:



The cone diffuse the light on the threads inside the bolt, that also prevent the back reflections very well.

Those that have access to some machines can also made them more efficents and "professionals", using internal diameters bigger than 12mm ..... about this diameter, i choosed the 12mm dia threaded bar just cause here the 99% of the drills that you can find around don't take more than this diameter, and the "long bolts" can be found reasonably easily in hardware shops, but with a real lathe, this can be done on any diameter that the lathe can hold, and also the bolts can be substituted with tubes, threaded with the corresponding thread measure of the bar you made

The inside threaded surface have the same efficence of a "professional" waved surface (once you painted it flat black, ofcourse ), but the advantage is that it can be made much more easily with a lathe with threading function, or also just with a tap, if the lathe don't have that function ..... also, it don't need to be a precise threading long all the tube, cause once you are able to screw some millimeters of the bar in one of the sides of the bolt or tube, the rest can also be a wrong or defective thread, it only need to trap and scatter the light after all :na:

BTW, if someone start to produce them industrially, i want my part of the royalties, ok ? :eg: ..... (j/k :crackup

^^I like that design. Should be relatively simply to build at the same time.

A very nice design indeed. The CVI beamdumps I used have a very similar design. Painting it black will be the hardest part of making it, how do you get the paint in all the threads?

^ spraying a good amount inside, keeping it horizontally and one end closed, then rolling the thing for spread it on all the threads, then place it with the back side on a piece of cardboard and let the extra paint flow away (you can refine the outside after) ..... it's the more easy system (the only problem is that this paint discretely also your hands, if you don't use solventproof gloves, but after all, is for this reason that diluents and handwashing paste exists )