home made air assist nozzle

[geekinesis]

Hi
I have made an improvised prototype air assist nozzle by cutting layers of acrylic in decreasing sizes to make the cone shape. At the moment the end of the cone is about 5mm above the work surface (1/5 inch)

It is based on similar cones which fit over the lens holder and direct the air downwards with the laser beam exiting through the nozzle. The layers of acrylic are glued together with the bolts allowing the cone section to move slightly for finer adjustment.

Before I hook it up to a compressor, and do some cutting, does this distance sound about right?

Also does the lens heat up? I have read comments that it might but I am not sure. If it does heat up, should I have an inline filter to reduce the moisture content in the air?

What kid of compressor should I use. How many Cubic feet of air per minute etc. What psi?

I want to avoid cracking the lens, which is why I want to get a bit of feedback and advice.

I am happy to post dxf files.

ps, the one thing I need to modify is a way for the nozzle to detach when the cutting head returns to the initial parked position. If it didn't detach it would hit the edge of the table when the machine starts up. I am planning to include a magnet to hold the nozzle section rather than bolts.

[Litografa]

geekinesis - perfect solution, I am also thought about DIY nozzle when I have got price of 60 Euro from GCC but really there was no time to make drawings.
If possible - please upload your files here. Thank's

[geekinesis]

hi
I will post drawings soon. I am still working out the best design. The main problem is detatching the nozzle when the cutting head moves to the home position

[dar303]

Nice work!
Strangely enough I built a cutting nozzel wit air assist yesterday too!

Here it is:

The nozzle is made from a 30mm diameter and 45mm length of aluminium round stock.
I have a 12,5mm ZnSe-lens with a 50mm focal point in there. It is sandwiched between two O-rings and held between the mounting plate and a recess in the round part.
The precision isn't that good but it works surprisingly well!
The airpump is some kind of medical kompressor that a friend gave me.










The result on black anodized aluminium


Here is a short film shot with my mobile phone:

YouTube- Synrad 48-1 CO2 laser with diy-lensholder/air assisted cutting nozzle

YouTube- Synrad 48-1 CO2 laser with diy-lensholder/air assisted cutting nozzle

Sorry for the threadjack but it is nice to exchange building ideas. The focus point is a bit too far out so I'm considering adding a threaded extention that you can turn to different lenghts, something like a hollowed out M10 bolt or something.

[Litografa]

I love this forum because here is peoples with hands growing from right place
Excellent work!

[geekinesis]

Hijack away, its good to get a few ideas from other people. I dont have access to any tools apart from the laser cutter, hence my laser cut design.

Good idea to focus the air with an adjustable nozzle.

I made a second nozzle section from cast silicon rubber because I need it to be flexible enough to bend out of the way when the cutting head moves over the edge of the table...

It works surprisingly well as silicon can withstand heat very well.

[dar303]

Smart idea! Post a picture or a video of it in action! What kind of laser do you have?
I'm building the rest of the machine myself and will propably have a rigid frame to mount the Z-axis (with the laser(s)) on and have a moveable X/Y-table for the workpiece.
Are there any sources for metal "honeycomb" material in the EU?
I would like to have a small "pan" with an vacuum-exhaust and some honeycomb to take care of the fumes from underneath when cutting organic stuff. It should be detachable for runs in stone or metal.

I hope to add a second laser around 808-1024nm later.

[geekinesis]

I have a rabbit 3040. Its got a 40w co2 laser.

I am just working on adding pc water cooling systems and air assist. I will post a video of it working once my new air pump arrives Its still all a bit experimental.

I am not sure about honeycomb in the Eu.

I havent got to the point of building my own laser cnc yet but am considering it for when I need a large cutting area.

[lasersafe1]

Okay, so I've seen quite a few examples now of the air assist nozzle. Everyone seems to reach a bottleneck when it comes time for the unit to travel to the home position over the rail.
Why don't you just move the home limit to the working side of the rail? It's not like your going to lose any travel because the laser was unusable over the rail anyway.

[geekinesis]

hi
i have the home position set in newlydraw to be on the cutting area,
the problem is when the machine starts from cold. Ie when you first switch it on. The head immediately returns to a position behind the cutting area and over the rail. This is hard coded in the control board.
If you know a way to change this I would be interested in replies.
The only solution would be a new control board.

[lasersafe1]

Your control board doesn't have a clue of where the home position is until it has retracted the x and y stages and hit the limit switches that set the home position. On my unit, these limit switches are an optical interrupter. The moving carriage has a small aluminum "knife" that slides through the optical interrupter to signal the home position. If you don't want your x stage to retract all the way over the Y carriage, then you simply make a new aluminum knife that is longer and will interrupt the beam sooner during the retract cycle.

You will also want to slip a little rubber hose over the stage that will limit the ultimate travel in case something goes wrong. Otherwise you may end up bending your new knife or crushing the optical interrupter.

The same theory would apply to a mechanical limit switch.

Originally Posted by geekinesis hi i have the home position set in newlydraw to be on the cutting area, the problem is when the machine starts from cold. Ie when you first switch it on. The head immediately returns to a position behind the cutting area and over the rail. This is hard coded in the control board. If you know a way to change this I would be interested in replies. The only solution would be a new control board.

[geekinesis]

Ok thanks for the info. Problem solved
I will try that later