New Build Plan.

[bush flyer]

I'm looking to build a laser after having built a CNC router with a water cooled spindle. I have been reading about the lasers from china but a lot of people are not very happy with them.
I tried to engrave photos by using Artcam Express and the router but it was very hit or miss affair, shallow engraving to one mm worked the best but some photos just would not work most ended up as fire wood. I have started to design my own laser but I may be over engineering it by using 16mm supported rails and SBR pillow blocks for the Y axis and 12mm for the X axis , I want you use belts to drive the X and Y axis but I think the weight that I have in the X and Y axis are going to be a bit heavy for the belts in any rapid movements so I may have to start again. Anyway before I get in further in the design, I would like some advice. The main reason I want to have a CNC laser is to laser engrave a photograph on to wood aluminium slate etc. just like I have watched them do with a Epilog Laser but that is way out my price range. can someone also tell me can I use mach 3 to control the laser I want to use the same type stepper motors and drivers as I have on my router, And far as I can see I will need CorelDraw or some other photo shop but what controller in the cnc laser will I need so that It will engrave as well as cut?
This is my first post here and I hope I can start a build on this forum if all goes to plan.

[_ID_]

You will have problems with Mach3. It has build in delay of few milliseconds to let the cutting tool speed up (M03 command). With laser you will get an entry mark (larger burned dot). Some people have come up with solutions like wiring laser on/off to Z step instead of turning spindle/laser on/off with M03 command. Z+ would mean laser ON and Z- laser OFF. You also need some kind of post processor to change the G-code for you. Another thing is that you want to do raster engravings(photos). This probably wont happen with Mach3 as rastering is not made with G-code. There are some tools to convert an image to G-code but the result is seldom useful.

[bush flyer]

Thanks _ID_,
Ok Mach3 is out as I would like to do quite a bit of photo engraving and it would be nice just to connect the laptop and engrave a picture. What shall I use.

[mattrsch]

If you want easy engraving I would highly recommend a dedicated laser controller loke this:
http://www.lightobject.com/AWC608-Commercial-DSP-CO2-Laser-Engraving-Cutter-Controller-P321.aspx

[bush flyer]

Thanks mattrsch,
That is just what I need to get clear, so if I got this Co2 Laser Control System Anywells AWC608 and CorelDraw I should be able to change a photo to grey scale and print it in the laser. I know that's simplified but you get what I mean. This is the only point I need sorting out before I start collecting parts for the build.

[sshwarts]

If I may jump in here....

Yes is the short answer. You use the software that comes with the controller (LaserCAD and/or it's Plug_ins) to process the image. Those instructions are then loaded into the controller which runs the laser. This is not the only way to control the laser (there's other solutions that have been discussed here), but it's one that many including myself, use.

Scott

[bush flyer]

Perfect sshwarts it's now added to my shopping list. Now I just have to lighten the gantry frame as I have designed it using sbr16 and sbr12 supported rails instead of using V rail and wheels but as I want to use timing belts on the X, Y, axis I my have to go with the V rails and wheels, or is it not to much a problem with the weight even at the speed the laser will travel?

[sshwarts]

There are others here that would have more experience with linear rail. I would imagine it's a function of the steppers you use and the drivers of them in terms of slinging the weight around. I used MakerSlide as the the later 2.0 design did.

Scott

[bush flyer]

I'm in the middle of designing a CNC laser and I was having a look at some CNC lasers online, and I noticed that on the gantry I could only see one linear guide rail HGR type, and the laser head is bolted on to the bearing through a plate. Now the reason I'm asking is I need to cut down the weight of the gantry as I have designed mine at the present with two SBR12 rails and three lumps of 10mm aluminium bolted on to the four pillow blocks, then the laser head is bolted to that. Now my main concern is the weight of all this flying about when raster engraving, this is why I am asking about is having one linear guide rail of the HGR type would be OK or do you need two, and if you only need one should it be a HGR15 or HGR20 or what size would you use, it would be 700mm length?

[TLHarrell]

Smaller one is fine, and a single HGR/THK style works just fine for a laser head. The THK style is constrained in all axes except motion in one line. It will not twist, turn or tilt, so no other linear bearing is needed to constrain the axis.