Laser cutter / engraver

You could mount one to the lens assembly carriage of a harvested DVD drive and control the stepper motor with a circuit. Maybe those electrically controlled CCTV lenses on Deal Extreme could work too. Not sure what other lenses you'd need to get the whole thing working though.

You also have more than 20 posts, so I think you can now post links.

It still won't let me post links.

I fear that using a CD/DVD drive's sled to adjust the lense position would be too coarse. I.e. Not enough control over the final position of the lense.

The problem with the little actuators which move the lense for focus / tracking control is that they are effectivly servo systems, which require feedback of some sorts. In a CD drive, this feedback is provided by the tracking. While cutting or engraving, I'll have no feedback and therefore these coils cannot be used.

The CCTV zoom lens suggestion is an interesting one. I fear that these would also be too coarse aswell - They are designed to adjust the zoom over a large range. Having said that, I will lookup how they work as I'm sure the system could be adapted. I could then make a smaller, fine adjustment version for this application.

I'm thinking of going to an optition to get the lenses made and coated. What coatings are needed for this application ? (808nm, 2Watts.)

Also I've read that the laser bouncing back into the laser diode can cause damage - Is this true ? What can I do to prevent this ?

I'm unsure if I would need to use a peltier to cool this, or if plain water cooling is enough. I guess I'll try water cooling and monitor the temperature.

The lens carriage of the CDROM drive is pretty geared down, so you'd have some decent control over it, though it might depend on the incoming beam to determine exactly how much you can move the lens(es).

For feedback, you could mount a camera to monitor the size of the beam when it hits its target. Since you're using a pretty powerful IR beam, the IR cut filters on a webcam or other device would be able to block a lot of it so it doesn't saturate (as much). You could even combine it with an IR pass filter to block out the visible light. Then pass that information to a computer program which does focusing (much like automatic focusing), and you should be able to have pretty accurate readings. You'll probably have to go this route anyway, since there's no way you should be visually inspecting this with your eyes, and you'll need rapid focusing so you can maintain continuous beam power. The camera could also be used to optically track for the design.

To prevent returning the beam back into the diode, try firing the beam at a slight angle.

I'll have a look into it then.

The idea was to have a parallel beam, so that I'd only have to focus it "once". Seems as the neoprene is quite thick (About 1cm), it would be a pain to have to make many passes taking off a thin layer at a time.

Due to the depth, I also worry about the camera not being able to see the dot when the beam is nearly through the neoprene. Very interesting idea though, I'll keep it in mind.

I ideally wanted the beam to be perfectly perpendicular to the workpiece, though it is a nice method if all else fails.
Is there not a way of getting a filter which is mirrored on once side yet transparent on the other ? I.e. Like one-way glass. (Don't know if this can work for lasers, that's the thing.) The fact that the laser is bouncing back down onto the workpiece would mean that cuts are easier. (Unabsorbed energy would be re-used, meaning that shiny surfaces should act like black surfaces.)

I wonder if the attached image idea would work well. (Keep it simple comes to mind and I think this is simple enough ?)

Neoprene? Are you planning on doing some really intricate work or something? It might be easier to just get something like a router, especially since the laser is liable to cause some unwanted bad melting...

yngndrw said:

Also, do you think this setup would be able to cut the copper off a PCB ? (Leaving the fiberglass underneath.)
Should I go for a focused beam, or a parallel beam ?

Click to expand...

Ablating the copper off a pcb without immediately charring the expoxy below sounds far fetched really. You cant do much with focussing either, since the copper is only 35 uM thick and directly glued to the board. I'd say anything capable of ablating the copper would easily set the circuit board on fire once chewed through. PCB's are supposed to be etched for good reason.

Also, even at 35uM thick copper is a fine thermal conductor, you'd need huge amounts of (pulsed) power to make a scratch on it. Continous wave will not work at all, you could even heat the copper red hot then, and it still would not budge (apart from melthing its glue and igniting the board).

Basically I want to cut these:
www <dot> vapoli <dot> com <slash> Images <slash> forum <slash> IMG_9846 <dot> JPG

These were cut out using a proper laser engraver. These ones are not so clean because the person doing them didn't have a vacuume table. Now he uses a vacuume table and they come out much neater.

Due to the thin section, I don't think I'd be able to cut them out with a "contact" cutter, I.e. A router or the like.


Shame that PCB copper cannot be removed with a laser, would make really nice quick boards is it was possible. (I guess you could also blast holes through instead of drilling, again it it was posible.)

I don't know if this should become a small CNC router instead. Unsure if a router would be able to cut the neoprene correctly, mind.

http://www.vapoli.com/images/Forum/IMG_9846.JPG
your link

Another good thing about using a vacuum table is fume extraction. This can be some nasty stuff, do not breath.
Re: circuit board making, a UV laser could expose a photo resist, your xy plotter could draw the pattern.

Thanks for fixing the link.

Yea I'll have to sort out some extraction system. On the other hand, I'm unsure if a laser is the best option for my application. I'm not sure what route to take - There's a few options:
* 2Watt laser
* More powerful laser (Can't afford that, mind)
* Router / high speed spindle (Though I doubt it can cut that out of neoprene)
* Some other non-contact cutter ?

The problem with using a UV laser and photo resist is that I still have to use acid. I currently have all the equipment for the toner transfer method (Laser printer prints toner onto paper, this is then ironed onto the PCB. The toner resists the acid.), which is a pretty quick method. The only think I dislike is having to much around with the acid for etching.

At some point, I will be getting a milling machine and a lathe, both of which will be converted to CNC. The mill could be used to cut PCBs, however the spindle won't be fast enough for the small milling bits used in PCB creation. This of course could be changed.

Edit: I'm quite tempted to just make this into a router and just cut the neoprene by hand with a knife - I make more PCBs than I will do insulation sets. Will also do away with the need for:
* Safety glasses (Well the special laser ones anyway, still need to protect my eyes from chips)
* Expensive, custom made lenses
* Water cooling and peltiers (They use a lot of power, which means more money spent on bills and more heat dumped into the room, hence more airconditioning cost)
* Fume extraction

On the other hand, it requires:
* A third axis
* A real method of holding parts down, there's a lot more force on them as it's a contact cutter
* Cutting bits which will ware over time

Decisions decisions ..

You could make a hot wire cutter.

Would a hot wire cutter work well with neoprene ? I never thought about that, I'll look into it and thanks for the suggestion.

Just wondering, how would the bottom part of the bow be setup - Surly if the neoprene was stuck to the bed using a vacuume table, the bottom half of the bow would be in the bed ?

Hot wire cutters are usually used for cutting solid foam, which can stand up on it's end. Due to the neoprene's softness and thickness it would need to be held against a table / bed - This is my only concern.

Attached is a plate I designed to attach the laser diode to. There's a slot for the pins, 1M safety resistor and cables. On the other side there's space for a waterblock or a peltier and waterblock.

yngndrw said:

Would a hot wire cutter work well with neoprene ? I never thought about that, I'll look into it and thanks for the suggestion.

Just wondering, how would the bottom part of the bow be setup - Surly if the neoprene was stuck to the bed using a vacuume table, the bottom half of the bow would be in the bed ?

Hot wire cutters are usually used for cutting solid foam, which can stand up on it's end. Due to the neoprene's softness and thickness it would need to be held against a table / bed - This is my only concern.

Attached is a plate I designed to attach the laser diode to. There's a slot for the pins, 1M safety resistor and cables. On the other side there's space for a waterblock or a peltier and waterblock.

Click to expand...

I don't see why it wouldn't just get a piece or nichrome wire from a old toaster, I used that to cut a bottle once.

Nichrome is so boring compared to a laser, after all this is a laser forum...

(I got myself a 16W RF exicted CO2 a while ago, sweeeet!

thejunkmonger: Again, the problem with a hot wire cutter is more how to support the neoprene while it's being cut. Interesting source of wire though, I'll bare that in mind.

Dar303: I would love to get one, but the cost and size of the unit is too much.

yngndrw said:

thejunkmonger: Again, the problem with a hot wire cutter is more how to support the neoprene while it's being cut. Interesting source of wire though, I'll bare that in mind.

Click to expand...

The cutter would not need to be a wire supported on either side of the material, it could be a narrow U shape that could be plunged. Corners might require a lift and rotate.

Hmm, I thought the wire would have been too thin, I'll look into that. Could make a U wire which can rotate through 90 degrees.

Maybe I could make a 3 axis base which can take attachments, instead of just having a fixed head.
I could then attach a spindle for PCBs and engraving, a hot wire cutter for the neoprene and do without the laser. (Wouldn't need it.)

This is going to get off topic for a laser forum so I'm sorry about that. Thanks for all the help that you've given me - I've learnt a lot especially about lasers. Even if it won't be used now I may make a laser head for the CNC just for the sake of it. (When I can afford to do so.)