Constructing Janus, by Dirk

[dirktheeng]

I don't know much about galvo based systems. The two issues you need to get comfortable with are the focal length problem. The distance the beam travels after the lens is always changing. A fiber laser or diode laser might help there, and the beam angle issue, where the beam is always hitting the surface at a different angle.

Bart,

Re: the focal length issue... the idea is to use a very long focal length (on the order of 10s of meters) so that the focal zone is quite long on the order of 10s of inches. Basically, you focus the beam to an acceptable spot size and then columate it before you send it out to be used. I was also planning on using a blue ray laser and a set of optics from a supplier we use at work.

Re: the beam angle issue... this cannot be avoided, but it can be minimized by only lazing very thin layers. There is no doubt that it may leave a rough surface, but almost any 3d printer will do this anyhow. I do belive that this will be among the smoothest surfaces anyhow.

Both of these issues can also be reduced by setting the galvanometer head far away so the angle is reduced (but the control for fine angle deflection gets more complex and expensive). I would think that about 20 degrees off axis wouldnt' be too bad.

BTW, this must work ok somehow because this is how auto makers make prototype parts for cars. I've seen bumpers and fenders printed this way in really big systems. There is some post printing finish work to do to get a nice looking part, but that is the way it is with about any print system.

[trwalters001]

Hi All,

This is what's used with scanning-type systems:

http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productid=2961

As you can see, price is the problem.

If someone wants to give this a try, I have an X-Y scan head (galvo scanners only) I'll sell...

Tim

[dirktheeng]

Hi All,

This is what's used with scanning-type systems:

http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productid=2961

As you can see, price is the problem.

If someone wants to give this a try, I have an X-Y scan head (galvo scanners only) I'll sell...

Tim

Do you have some specs on it? I am interested in in a closed loop galvo with a driver board with at least a 20 degree swing on either axis. I'm interested in trying this. Even without the optics, the spot size of a blueray laser may be ok for a hobby kind of system. You can also buy a fairly inexpensive adjustable optic online that will give you a focal length from basically infinity to just about 2 inches. I'm thinking of trying that first.

[dirktheeng]

I baught a smooth stepper and an old dell desktop with XP on it. I will be able to run Mach 3 on it and have something to benchmark comparisons as we do development. I will also be able to move ahead with solid motion control and finish the laser and get cutting as well. I don't want to have to wait to get a solid controller at this point. I'm excited to see some results.

[cpdude]

Dirk,

I think you can download the beta (v17e) Mach3 plugin from the Warp9td website. However, if you need a copy just shoot me a PM with contact information and I'll send it to you. You'll need it if you're planning to fire the laser with Mach3.

Brian

[dirktheeng]

Dirk,

I think you can download the beta (v17e) Mach3 plugin from the Warp9td website. However, if you need a copy just shoot me a PM with contact information and I'll send it to you. You'll need it if you're planning to fire the laser with Mach3.

Brian

Thanks. I'll see if I can find it. Do you use the Mach 3 engrave add in? I was wondering how that works with the smooth stepper. I would assume very well as tweekie has shown some really good results with it. Have you tried it?

[cpdude]

Sorry, I haven't tried the engraving plugin. I'm pretty much a vector cut guy.

Brian

[dirktheeng]

All,

I started assembling the rear panel today as I don't have much else to work on until more orders come int and I noticed a couple problems. I'm not sure if I recieved an abnormal pannel or if others have the same problem.

The cable glands I recieved are 1/2" ID and meant for a 3/4" panel hole. As you can see from the following picture the milled part round is very close to 1/2" and not 3/4", so the glands just don't fit. I have a 3/4" hole saw, but cant really use that because I can't drill a pilot hole and keep the hole saw centered. Have others just abandoned the glands? Not worth cutting a whole new part for this, but future parts should be corrected.

cable gland problem

Also, the hole pattern for the flange doesn't line up.

Hole pattern

Without a cnc router, I can't really fix the cable glang problem (and they probably arent needed as the tubes are fairly robust), but I can drill larger holes to get an M5 bolt through on the bolt pattern as they are close. Both of these problems are super easy to fix in the production file, and I reccommend doing it.

[BenJackson]

Dirk,

See viewtopic.php?f=28&t=615

[dirktheeng]

I guess that answers that question... Thanks!