Buildlog.net Open Source Laser

[benwyne]

The new z-table looks great! Personally I'm much happer now that it's build out of the extrusion.

Have you given any thought to an auto-focusing system? So that the z-axis could move to maintain a 55mm focus length on an uneven surface?

[bdring]

I assume that would be for etching. It might be hard to detect the distance exactly at the laser spot. How acurate are those distance sensors for spot size? The sensor would have to shoot at an angle to avoid the laser and that might throw off it's accuracy. Hitting a surface angled towards or away might throw the thing off too.

I had an idea a while back about two laser pointers aiming from the each side. They would manually adjust to where they converge to one dot at the exact focal point. Any time you see two dots, you are out of focus. Something like a Wii remote could be used to auto focus the table.

I was also thinking the other day that it could be done in software. Say for example you wanted to etch on a wine glass. Even if you had a rotation thingy, the wine glass is not at a constant diameter. You could program the table to compensate for it in software based on the geometry of the part.

You also have the issue of the beam not hitting square to the surface when the surface height is changing quickly. That might degrade the image and might need to be compensated for in power.

[aargelio]

do you need a special circuit with the INS-FM16 coolant flow meter?
it have four wire.
Flow meter-(white and yellow )
LED 6vdc ( red and black )

[bdring]

Comment From Buildlog Author

Yes,

You need some sort of missing pulse detector. This can be done several ways. It could be as simple as a 555 timer or a microcontroller. I used a PsoC microcontroller initally and then a PIC. I actually don't have it hooked up now. I was planning to put it on my XMOS controller. I still have the flow sensor in the circuit and use it as a visual indicator of flow.

Here are two incomplete web pages on the subject.

http://www.buildlog.net/cnc_laser/ps_in ... c_pic.html
http://www.buildlog.net/cnc_laser/mach_ ... intfc.html

[bdring]

After about a 1000 requests, I have started making some kits. There is a page here detailing the kits.

http://www.buildlog.net/cnc_laser/kits.html

If you want any parts, please email me at bdring@buildlog.net. Please don't use the forum for kit requests.
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[bdring]

I am working on a comprehensive Bill Of Materials. This will boil everything down to a basic shopping list.

Of course I decided to write my own web based ERP system to enter and maintain it...( never take the easy way out)

It should be ready in a few days.

[bdring]

The Bill Of Material feature is working now. You can check it out here.

http://www.buildlog.net/cnc_laser/erp/bom.html

This is a database driven Bill of Materials. It is not 100% correct or complete yet, but it is easy to change and maintain. If you see any problems let me know. I know that there are a lot of missing supplier part numbers and prices. I need to take the time to enter those.

I was actually quite surprised how cheap the Misumi framing is.
http://www.buildlog.net/cnc_laser/erp/b ... rtNo=FRAME

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[pixpop]

Do you have a spec/source for shoulder screws to mount the VXB 3/16 V groove bearings? I did look in the BOM, but may have missed it if it's there.

Neil

[bdring]

Comment From Buildlog Author

I do not use a shoulder screw. I use a #10-32 screw and sandwich a nut between the mounting plate (see the LASER_CAR_ASSEMBLY). #10-32 is almost exactly the right size. I have to sand down a half/thou on some of the screws. Typically a shoulder screw is not used because you never want the inner race to be able to spin. The more common method is the eccentric shaft (see image) that allows you to tension the bearing against the rail. Bishop Wisecarver is the inventor of these things. You can get some info there. These guys sell them cheap, but not the 3/16" size.

f you really want a shoulder screw, I usually get them at Stock Drive.
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wheels3.JPG (15.58 KiB) Viewed 36808 times

[pixpop]

Brilliant!. This works great. Why did you use a nut, rather than a washer?

I just got a piece of 1/8 Al, and tapped a 10-32 hole. I sanded down the screw as you suggested.. doesn't take much. Fits beautifully with no nuts, and just a single washer to space the bearing away from the Al plate.

Thanks for the tip,

Neil