laser Retrofit kit for CNC routers

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laser Retrofit kit for CNC routers

Postby steppenshoe » Mon Oct 17, 2011 6:59 pm

I would like to start to get some input on a laser retrofit kit for existing CNC machines using a similar set up that is here on the forum ie the laser and optics, power supply, etc. There are loads of CNC router machines that are durable and accurate enough, I am sure of that.

Here is one example of a retrofit kit:

http://cnc-machines.host22.com/lasers-co2.html

My main concern is the high accel rates my current machines run at may break the tube upon directional changes. This box set up would ride on the gantry.

I will have to think of a series of questions such as where to place the power supply an whether to just use Mach or add a DSP to the system (would be my choice) and whether I need a moving table for the Z or use it with a current traditional type Z set up. It seems the aluminum boxes holding the tube can also be situated either parallel or perpendicular to the beam and I have seen examples of both on the net.

Any comments on this project would be greatly appreciated. In the meanwhile I am going to start the 2.xx build in the size on the forum.
Attachments
150W laser retrofit.jpg
laserbox-2s.jpg
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Re: laser Retrofit kit for CNC routers

Postby bdring » Mon Oct 17, 2011 8:01 pm

Post a picture of your router.
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Re: laser Retrofit kit for CNC routers

Postby macona » Tue Oct 18, 2011 1:34 am

I dont think the acceleration is anywhere near what the tube will see during shipping. I dont think you have anything to worry about. I was thinking about doing exactly what you are a few years ago.
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Re: laser Retrofit kit for CNC routers

Postby steppenshoe » Tue Oct 18, 2011 11:53 am

I'll post a pic of one of my machines when they are back together in a few weeks, maybe less. I can probably dig out some pics of certain pics that I took like making the V rails, etc.. I used the cncrouterparts.com rack and pinion drives on the large machine. The smaller machines are screw version.

Well I am running acell at about 100 to 125 and I can say I had to go to a metal base because the hard directional changes made the machine jump and a lot. I had to bolt it it the floor and walls at on point,.. But if the tube can handle it great, I can just turn it down to 60, the larger motors don't work so great any thing less than 30 - 40.

The lasers are really packed well from what I can see and I was not really thinking of adding a bunch of padding like that. That sure is one expensive thing to test on. :)

I definitely will start the 2.xx first so I can take what I learn to the next project.

One comment about Lasersaur I sent them 64.00 and I was supposed to get access to CAD drawings, still haven't I guess I'll write it off. If anyone has them how about sending them to me, I can show you the paypal payment. :)

: okay I jumped the gun it took a while, but I did get access to lasersaur. And the plans are not bad like I have read here, not at all, just different and not even that different either. They do credit this forum.
Last edited by steppenshoe on Thu Oct 20, 2011 5:53 pm, edited 1 time in total.
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Re: laser Retrofit kit for CNC routers

Postby TLHarrell » Tue Oct 18, 2011 4:30 pm

I have an idea for the retrofit which would be of benefit, not sure if you've already though of this:

Utilize the existing CNC machine for Y axis movement only. The retrofit box would have it's own X axis built in. This would simplify things greatly as the axis would be attached to the box, and all the mirror alignment would be self contained. This would lower the requirements for machine acceleration when rastering as the retrofit would have a lighter weight head to scan. Y axis speed would be a moot point when rastering, and should be sufficient for cutting.

I could see a hybrid machine being designed as well with a moving box beam gantry with a CNC spindle on the front, and the flying optics of a laser hanging on the back or underneath. I might have to think that one over. :-)
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Re: laser Retrofit kit for CNC routers

Postby r691175002 » Wed Oct 19, 2011 2:01 am

TLHarrell wrote:I could see a hybrid machine being designed as well with a moving box beam gantry with a CNC spindle on the front, and the flying optics of a laser hanging on the back or underneath. I might have to think that one over. :-)


Sounds viable IMO. Cool enough that if I were to build a router I'd probably drop the extra $$$ to put a laser on top.

It will have to be built well and done on a decent budget to get both the speed and rigidity to make best use of both functions though.
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Re: laser Retrofit kit for CNC routers

Postby macona » Wed Oct 19, 2011 5:11 am

The router we were going to do this to that is at techshop is owned by a friend. It has a 4'x24' capacity. Yes, thats 24 feet.

It pretty much entirely built from 80/20 by a company that was up in seattle that is long gone now. It runs linear rail and gear rack down the lengths of both sides and drives both pinions through a common shaft that runs down the short axis. What was nice about this design is since there are no screws we could slap on another gantry. The one for the laser would be made lighter to handle the higher acceleration.

The way I look at it you want to keep dust making parts as far away from the optics as possible. So unless you can seal everything in a box I think you are going to have problems keeping the optics clean. A little but of wood, or worse, plastic dust get on a mirror and you can toast an optic. You could build a looser box around the mechanism and feed filtered air in from a squirrel cage fan, I suppose.
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Re: laser Retrofit kit for CNC routers

Postby TLHarrell » Wed Oct 19, 2011 4:57 pm

steppenshoe wrote:
My main concern is the high accel rates my current machines run at may break the tube upon directional changes.

....whether I need a moving table for the Z or use it with a current traditional type Z set up.



You wouldn't really need a high acceleration on the Y axis, and if the tube is mounted on the gantry in a box, it is not subjected to the X-axis loading during CNC operation. As for the loads on the tube, if you're running CNC operations at 1000IPM rapids, you may want to add more support to the tube than a collar at either end. A series of collars, or some other support will help. You may also need to set the CNC controller to make softer movements at start/stop so you don't slam the gantry to a dead stop at the end of a rapid. Still, feasible and worth considering and testing.

For the Z axis, I'd recommend doing some sort of adjustable optical setup which can be lowered to focus height when using the laser. If it's a retrofit for an existing CNC machine, I don't think you'd want to convert the table to a vertical lift. With a movable lens, it could be retracted or folded out of the way while using for CNC operation, and could protect the optics. Remember that the beam stays collimated until it hits the focusing lens. You merely have to bring the focusing lens to the right focal length for cutting.

I think the idea of a bolt on assembly would be really cool. A hybrid machine saves a huge amount of cost in linear rails, table, dust/smoke collection and electronics. The diffculty would be in designing something that is close to a "one size fits all" setup, and interfacing with the existing drivers for the one axis. There would obviously need to be some sort of checkoff list and template to fit to a machine to make sure it would work, since there are so many different machine designs out there. I'd start off looking at getting prints of all the homebrew CNC machine models available and see if you can adapt to a common feature. You could start out with "this retrofit will work with [this list] of machines".
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