Buildlog.net Open Source Laser

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Re: Buildlog.net Open Source Laser

Postby bdring » Fri Sep 10, 2010 2:58 pm

eBay is a good place to start. LightObject.com also sells them. It is good to do some searching because there are always some hidden deals out there.
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I think I broke something

Postby bdring » Sun Sep 12, 2010 10:58 pm

I was messing around with the RepRap motherboard controlling the laser. Now the laser is not firing. I think I lost the common ground between the RepRap and the laser power supply. If I measure ground to ground on the scope, it jitters around between +/- 2-3V. This means the power supply enable pin was seeing in excess of 7-8volts. Something made a bit of a buzzing sound before it stopped working. I cannot fire it using the high or low enable.

Does anyone know the front end of the laser power supply before I tear it out?
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Re: Buildlog.net Open Source Laser

Postby lasersafe1 » Sun Sep 12, 2010 11:09 pm

Yes, the front end of the laser power supply is the side with all the terminals. :D

In all seriousness, the front end of my supply appears to start with an optocoupler. It would seem difficult to burn anything up beyond the optocoupler. I highly doubt anybody is handing out schematics for them.
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Re: Buildlog.net Open Source Laser

Postby bdring » Mon Sep 13, 2010 9:54 pm

The I.C. near the input is a SN74LS06N, hex inverter buffers/driver. This is socketed, so I will try to install a new one.
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Re: Buildlog.net Open Source Laser

Postby diyengineer » Fri Sep 17, 2010 2:33 am

So you built your own laser tube and PSU to stay within the budget of $1000 dollars? I'm looking at the BOM list and you never mentions a laser/powersupply.
I downloaded and printed off your PDF on how to build a PSU and LASER. Is that what you used? how much did that cost you, compared to buying one from ebay?
Thanks! :)
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Re: Buildlog.net Open Source Laser

Postby bdring » Fri Sep 17, 2010 2:35 am

No I purchased power supply from LightObject and tube from love-happy-shopping.
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Re: Buildlog.net Open Source Laser

Postby diyengineer » Fri Sep 17, 2010 2:39 am

Awesome! Thank you for the fast reply!
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Z Lift parts

Postby bdring » Fri Sep 24, 2010 2:54 am

I finally got a chance to post the drawings for the enhanced Z Lift parts. They are on the drawings page. I will probably post a kit in the next few days. I have been gluing the parts together with an official acrylic glue, Weld-On 16. So, I will probably ship them assembled.

Note: This is only recommended for people who want to eventually add a 3D printer or other add on where the Z axis needs to very stable.

.
z_carriage1.JPG

16_5OZ.jpg
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Fun with tangential knife control.

Postby bdring » Tue Sep 28, 2010 1:15 am

I was setting up a fourth stepper for the 3D printer extruder. I was using Mach3 as a test controller. I decided to play with tangential knife control while I was at it.

Tangential knife cutters rotate the knife while cutting, so the blade is always pointing in the direction of travel. They work much better than drag knives, especially on thicker materials like gasket material.

It took me a little while to figure out how to setup the resolution for the A axis (I am not a lathe guy) . You set it up as steps per degree. My setup is 200 steps/rev * 10 microsteps/step / 360 = 5.556 step/degree. You then tell Mach3 to use tangential control and set a few items: Lift Angle and Lift Z. When the knife needs to turn at a corner the z lowers the Lift Z amount. It does this any time the corner angle is less than the Lift Angle, so it does not retract at small angles. I left lift angle at 45 and change. the Lift Z to 0.05

I only simulated this by setting the knife stepper next to the machine with a little paper knife taped on, but it all worked as advertised. The only issue is that Mach3 reverts to exact stop mode in tangential mode. This means that things like ellipses are going to be really slow. If you don't need anything but lines and circles it should work at a decent speed.

I might make a carriage for this and create a video of it in action.
.
tangencial1.jpg
tangencial1.jpg (14.22 KiB) Viewed 26183 times
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Design Updates

Postby bdring » Fri Oct 22, 2010 2:03 am

I made some tweaks to the X axis based on some things I learned on other projects.

1. I changed the belt clamp to simple screws (no tapping)

x_clamp_remove.JPG


2. I changed the idler bracket to use a pocket instead of using an o'ring to hold in the bearing.

idler_pocket.JPG


3. I changed the wheel tensioner to a square nut. (no tapping)

new_tensioner.JPG


4. I also removed "non-commercial" from the license. This is to make it more in line with the new open source hardware (OSHW) direction. The drawings page has this license as well as the revised drawings. The drawings will update as they are revised.

5. BOM updated per above which affects the kits.

There will be some similar changes to the XY assembly and Z lift.
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