Laser Specs

After some thinking and design work here is what my laser will look like after the modifications:

Cutting area: 46×26″
Outside Dimensions: 54 x 37.75 x 13″ (without panels)

I think it comes out to about 77 feet of 6063-T5 extruded aluminum angle.

6 x 53.50 width
5 x 37.75 depth
2 x 51 gantry
2 x 48 table width
2 x 27.25 table depth
4 x 13.125 height
2 x 08 z-lift
2 x 37.75 top sides

Now I can cut this foam.

I can roll the foam right through the machine and the product can roll right onto another roll.

With this bigger format (and conversion to Nema 17 motors) I’ll need new belts and pulleys:

X:
Motor Pulley: A 6T16M020DF6005 MXL 20 TOOTH 5mm BORE $5.90
Pulley: A 6T16-020DF2508 PULLEY MXL 20 TOOTH 1/4 BORE $5.90
Belt: A 6B16-15C025 Belt MXL 120 x 1/4" 1500 grove urethane kevlar $21.33

Y:
Motor Pulley: A 6T16M020DF6005 MXL 20 TOOTH 5mm BORE $5.90
3 Pulley: A 6T16-020DF2508 PULLEY MXL 20 TOOTH 1/4 BORE $5.90
2 Belt: A 6Z16-B89025 Belt MXL 95.12 x 1/4" 1189 grove Neoprene fiberglass $7.34

Z:
Motor Pulley: A 6T16M020DF6005 MXL 20 TOOTH 5mm BORE $5.90
4 Pulley: A 6T16-020DF2508 PULLEY MXL 20 TOOTH 1/4 BORE $5.90
1 Belt: A 6B16-15C025 Belt MXL 120 x 1/4" 1500 grove urethane kevlar $21.33

Z table screw spacing:
45 x 29 => 148
33 x 29 => 124

11 Pulleys at $5.90
2 long belts $21.33
1 belt 7.34
$114.90

Epilog Zing 24 Review

laser!

There is a review with quite a bit of technical information over at Model Airplane News. I’ll write my own review of this thing once I’ve learned more about it.

 

 

 

CAD and Laser Cutting using Epilog

I have been using Sketchup plus MeshCAM or Phlatboyz Plugin for CNC milling. It works great, I’m using MeshCAM for 3D and Phlatboyz for 2.5D.

Some lasers, Pokono and the ArtEngine laser use use a printer driver and they’re using stuff like Inkscape to send stuff to the laser. I think it technically doesn’t matter what application you use since it’s a printer driver. But the application has to exist on the computer sending the job. So InkScape is cool since it’s free and you can do last minute tweaks just before printing. Whereas if you were to save as a PDF you couldn’t edit it so conveniently.

I have been looking at getting things back and forth from Sketchup and Inkscape so I can reuse some of my work. There is a plugin

SVG converter

Looks like this works. After installing it (by unzipping it and then copying it to the plugin directory) you get this little tool bar.

So you cook up your image then click the button on the toolbar. Make sure you’ve selected your content. The button doesn’t do anything if you don’t select something.

You get a screen to assign colors to different types of features. You can have it invoke Inkscape (or any SVG editor if you want). I suppose you could put a /p command in there and it would go directly to the printer.

When you click the button you get the file. In my case, there was an issue that it didn’t get the little dot that the pacman was eating. Also it was mirrored but that’s an easy fix. Or you could just flip the piece over if you are doing vector cutting.

done

Fire the Laser!

I’m just down at ArtEngine where there’s some laser hacking going on. We’ve got the new Epilog 30 running.

It’s very nice. It runs from a printer driver that can interpret content into raster, vector and mixed.

We had a bit of trouble on the first vector cut from Inkscape and it seemed the problem went away when we exported to PDF and processed that.

Laser as a display device

I’ve been thinking about ways of having a surface to interact with.

I’ve been thinking of POV systems a little. Also laser projection (I was thinking if combined a laser with an acceleration it could project information on to surfaces).

I just came across this interesting project by Albert Armea. I added another video from his youtube channel since it’s pretty cool.

CO2 Laser Power Control

The only real problem that’s not really solved yet on my CNC Laser is the laser power control.

It seems there are people that run the laser from the spindal speed and some that run it from the Z-axis.

With the Z-axis setup, the idea is that the lower the cutter goes the deeper the cut. The deeper the cut, the more laser power that’s required. I’m supposing for this we need to somehow translate between the Z position and something that the laser power supply understands. It has inputs that accept PWM as well as a rheostat. I’ve heard of people talking about just taking the stepper from the Z-axis and turning a POT which is connected to the laser power supply. To me that doesn’t sound like it will work because the response time for changing the laser would be slow. So engraving and such would be nearly impossible. If you could do it electronically, then I suppose the power supply can respond to the resistance change nearly instantaneously. I suppose there must be a way of converting the Z position into PWM.

Another technique I’ve seen people talk about is to use spindle speed to control the laser power.

I think the engravers aren’t really CNC (as in Mach 3 or EMC2 style controlling). I think they use more of a printer driver. They do like a raster scan of the work piece and vary the power of the laser proportionally to darken or mark the surface. I think they are just reading a bitmap type image. Perhaps some are like the older mill type engravers that virtual-ize a printer and just require a printer driver.

Either way, I’m sure there is a device out there that I can buy that isn’t very expensive that can work for this application.

At the moment my plans are to go with one of these speed controls (DigiSpeed_GX_User030 manual).

Finally making parts with CNC Mill

Laser mounting bracket component.

Okay, I’ve been toying around with cardboard experiments and now I’m ready to make parts.

I am making mounting brackets for the laser. Here is the first part. Each bracket will have 4 parts.

This is cast acrylic. The guy at the plastics place said that cast acrylic is good for machining and extruded acrylic sucks.

It seemed to go okay as you can see by the video below. It makes a high pitched sound which I could do without.

I wasn’t sure what to use for the feedrate so I just guessed.

I tried going faster and slower and the noise didn’t go away so I just let it finish. I set zero about .001″ too high as I had a bit of flash. I also learned that you don’t need very big tabs to hold work in place.

An open source laser?

I’ve been keeping an eye on the Lasersaur project. It’s clearly a great idea to have an open source laser.

The project isn’t really open source. It is really a member-only community. The concern I have is that the project will not benefit from the knowledge and experience from the wider community. Not to mention what could be learned about different people’s needs if they project were actually open.

The pictures so far look quite nice.

Is this really an open source laser?

I was just looking at the truck that carries the lens and final mirror. It’s quite similar to my design but uses a wider variety of materials and fasteners so it’s much prettier.

Looks like it should be quiet and work well too.

But I’m wondering what the final cost will be and when the project will actually be available. The projects been going an awful long time and there is no regular reporting of progress.

I wanted to buy into the project but they don’t answer questions. I made a post on their project wall but they did not approve it. I suppose their members could be really happy but clearly perspective members may not be.

It will be very interesting to see what becomes of this. It looks like in the pictures that it’s might be a great laser but might be as expensive as buying one assembled. Possibly difficult to fabricate.

I suppose this might not seem so fishy if it were not labeled as open source when in fact it’s closed source (member-only).

CNC Laser Cutter construction

I decided to make a CNC laser cutter with some material handling capabilities for my model plane project.

Water Cooling

I have some surgical tubing for the water jacket (the CO2 laser tube is water cooled). It seems to brown the water and I don’t like that since it might accumulate some material in the water jacket. I realize I can clean the jacket with hydrochloric acid but I figure it’s a better idea to not have any material going through the system.

The laser itself has some nice white colored tubing on it to connect the various water jackets. I’m curious if anybody knows what it is so I can replace my surgical tubing with it.

Some of my friends are saying it’s silicon surgical tubing or fuel line from a motorcycle shop. I will check that out the next time I’m at the bike shop.

CNC Software

I went with EMC2 which runs under Linux. It is very easy to use. You need to download an ISO file from LinuxCNC.org then burn a CD from the ISO. Boot from the CD and presto! You have a CNC controller running off the CD without affecting the host computer. I elected to install the Ubuntu Linux software with the EMC2 right onto the computer so that I could boot from the hard disk. This allowed me to run updates and such. It upgraded everything to the latest. This is a Ubuntu 8.04 LTS. I think they are working on getting the next one going which is Ubuntu 10.04 LTS. I will upgrade when I become aware that it is ready and it is stable enough.

My lab does not have any network cables running from my server room. So I installed a Wireless Bridge. I made if from an WRT54G v8 (Linksys router) by installing DD-WRT open source software onto it. I then configured it as a wireless bridge and had it join my network which has a higher end router (also running DD-WRT). Now I have 4 eithernet jacks to plug stuff into to have internet access in my lap. I can remotely access the lab computer across the network (this includes remote desktop and ssh).

EMC2 is pretty easy to configure and run. It didn’t take too much fiddling to get it programmed with all the parameters of my gantry system.

CNC Steppers, Controllers and Power

I initially started to build circuits to control stepper motors. I discovered that you can buy components that are not too expensive. I got a xylotec 4-Axis kit. It comes with 4 large steppers with double shafts, the 4 channel controller and a 24V power supply. The EMC2 software had this outfit listed so it was easy to get up and running. All I really had to do was tin all the wire ends and screw all the wires together. Apparently with this outfit, if you wire something wrong it fries. So I was extra careful. I’m very pleased with this system. It is very powerful and is quiet.

Gantry

I made a gantry out of 1″ aluminum angle. I used the contraptor methodology of drilling holes and using nuts and bolts. I designed my own sliding elements to use ball bearings. I used yoyo bearings. I used XL timing belts and pulleys which don’t seem to have any back lash.

Also, I went through all the belts sizes and prices to find that 88″ belts were relatively inexpensive. I made a spreadsheet to compare every belt size to it’s price so I knew if I should buy belt by the foot or to a specific size. I eventually went with 88″ belts and decided to just pull the slack out. You can see how I did this in the pictures. You can also see the gantry detail and the Y-Axis truck detail. It runs pretty fast and smooth.