lasering at a 45 degree bevel

[David Fairfield]

I have an idea (always a bad sign :o)

How feasable would it be to design and machine a clip-on mirror to laser cut straight lines at a 45 degree angle for a nice bevel cut?

I'm using a 45 degree jig to angle the material... but there's got to be a better way!

Input?

Dave

[Joe Pelonio]

When I saw your topic I thought about a jig, have done it before, but you are right, it's not a great option.

I would think that the precision accuracy required would make an additional mirror a nightmare to set up. Besides the focus issue there's placing the material in the machine correctly, and if something went wrong near the edges of the table at an angle it could hit and damage the inside of the machine or cut through wires/belts.

[Dan Hintz]

For straight lines parallel to the X-axis, it would be easy. For anything else, it's not so easy as you need to keep the 45 degree bevel perpendicular to the direction of travel. So, as long as you don't mind limited cuts or picking up your piece and turning it 90 degrees for each edge, you'll be fine.

[Mike Null]

This equipment is for marking rather than cutting but just get a load of this technology.

http://www.keyence.com/products/barcode/lasermarker/mlz9500/mlz9500.php

[Gary Hair]

I'm with Joe on this one. I would be afraid of the beam bouncing off of the table, or material, and doing damage. I would be afraid of the damage to the machine, but more afraid of damage outside of the machine - eyes and other body parts...

I would build a fixture and keep the beam pointed straight down.

Gary

[Gary Hair]

This equipment is for marking rather than cutting but just get a load of this technology.

http://www.keyence.com/products/barcode/lasermarker/mlz9500/mlz9500.php


I just talked to them, they have an office about an hour from me. The price is between 30k and 40k, depending on the options. This is a 30 watt laser with a marking area of 300mm x 300mm, 11.8" x 11.8", so pretty small. It is very cool that it has a 42mm focal range, it does some amazing work on round and variable height objects. for the price though, I'm not rushing out to buy one.

Gary

[David Fairfield]

I only need to put the bevel on two parallel edges, so it would just be a matter of cutting the bevel on one edge, flipping the part, then cutting the opposite edge.

I don't think the "stray" beam would be a problem, because it would be angled downward away from working parts or the operator.

The problem with the jig fixture is alignment. At the scale I work, the tolerances are minimal and its tricky to get the pieces to stay where I need 'em. Working on a flat surface would simplify matters.

Dave

[Joe Pelonio]

The problem with the jig fixture is alignment. At the scale I work, the tolerances are minimal and its tricky to get the pieces to stay where I need 'em. Working on a flat surface would simplify matters.

Dave
Have you tried using double sided foam tape to keep the fixture on the table and the material on the fixture? I used VHB and it's easy to remove as long as you do it soon after.

[Gary Hair]

I don't think the "stray" beam would be a problem, because it would be angled downward away from working parts or the operator.

It may be angled downward but it will reflect back up again. Think of a mirror, the angle the beam goes in is the same angle it goes out. If you are using 45* then the beam would come off the table at 90* from where it entered. Use a square and see where it would bounce - I would think twice about this if I were you.

I understand how it might be difficult to make a fixture, but if you make it well enough the alignment problems would go away. If you think it's hard to make the fixture now, think how hard it would be to make it with your remaining eye after the beam bounces off the table...

Gary

[David Fairfield]

I suppose a backstop could be made of wood to absorb the energy, as the beam would only be cutting in a single, straight path.

But hmm I guess I'll be back to building a better jig. Maybe even using a stone age table saw :rolleyes:

Dave

[Rodne Gold]

Bear in mind that either way you do it , the beam is no longer a round spot but becomes elliptical and loses a lot of power density. Dunno what thicknesses you cutting but I wouldnt imagine a lower powered laser cutting very thick stuff , especially since the beam travel thru the media will be longer due to the 45 degree angle.
Surely a beveler is much easier and far quicker to use for straight lines than fixing a jig etc?
If you did want to do this , I would build a fixture to angle the whole cutting head or the part that includes the final mirror and optics , that shouldnt be too difficult.

[David Fairfield]

Hadn't considered the eliptical spot issue. I'm cutting thin material (1.5mm) but thats probably enough to throw things off.

Beveler?! Now there's a concept! What's a beveler, will it work on wood veneer without shredding the edges? Where can I buy one??

Dave

[Dan Hintz]

As long as the beam hits the final optic square, the final spot will still be circular... change the angle of the final mirror (in relation to the moved/angled lens) and you're done.

[Mike Null]

The photos, bad as they are, are of .55 mm birdseye maple endgrain veneer beveled with an engravers beveler.

The beveler is dull but still produced a good edge without tearout. I marked the edge on one of the shots with pencil for better visibility. I used a piece of plastic on the top while I passsed it through the beveler.

Before you buy a beveler you might consider a chamfer bit on your router table with a laminate top and bottom to protect against tearout. Even with that you may get a little tearout at the trailing end.

[Dave Johnson29]

with a laminate top and bottom to protect against tearout. Even with that you may get a little tearout at the trailing end.


Mike,

Wouldn't you bevel from both ends and cross over and lift just past the middle?

I do not have a beveler, but that's what I do when beveling by hand with a plane.

[David Fairfield]

Very promising, thanks Mike! I tried a new, small chamfer bit on the router but it just tore my plywood to heck.

[Mike Null]

Dave 29

My normal method of beveling a small piece is to do the ends first then bevel with the grain. Hopefully if there is any tearout on the end it'll be cleaned up on the sides.

Is that what you meant?

[Rodne Gold]

Dan if the beam is at 45 degrees and it hits a straight object it will be elliptiical in shape - IE at the place it cuts , so it makes no diff what you do - its either a straight beam and a 45 degree object or a 45 degree beam and a straight object ...either way the spot wont be round at the point of cutting

[Dan Hintz]

Well, it's only elliptical on the top surface... once that initial spec of material is vaporized the dot is back to being circular (at least so far as the substrate is concerned), no different than cutting into a piece that's 40% thicker. So you'll have only 70% of your dialed in power at the initial blast, but that's irrelevant for most materials.

[Rodne Gold]

The laser doesnt actuall "roatry drill" its way thru the material unoess the material acts as a wave guide , it actually uses a burst of power at the spot (which is eliiptical) to vaporise . Even if it had to use multiple bursts , the spot would always be eliptical to a 45 degree surface

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[Dave Johnson29]

My normal method of beveling a small piece is to do the ends first then bevel with the grain. Hopefully if there is any tearout on the end it'll be cleaned up on the sides.


Nope, Just for one edge. See pic.

[Mike Null]

Dave

I see what you mean and no I do not do that as I usually place a board behind the trailing edge to help support it from tearout. This veneer was so thin and not cut square all the way around that I didn't take any other precautions.