Buildlog.net Open Source Laser

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Re: Buildlog.net Open Source Laser

Postby bdring » Fri Feb 05, 2010 6:14 pm

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I actually work for a company that makes HV power supplies for RF tubes. We do it for the satellite communications industry. One day down the road I will look into combining my work experience and the laser stuff.

I actually have not invested too much into my laser and I have done some work for others on it. If someone ever asked me if I think I spent too much on my electronics and CNC "doo-dads", I would ask them if they think they spent too much on their college education. ;)

I have made a lot of money on electronics consulting and CNC work that all came from my hobby interests. If you look carefully in one of my pictures you will see a patent hanging on the wall. That came out of a consulting job. I don't own the rights to it anymore though.
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Re: Buildlog.net Open Source Laser

Postby willyinaus » Sat Feb 06, 2010 5:02 am

bdring wrote:
Comment From Buildlog Author

I can't make any guarantees about where the XMOS is going. Right now it is doing more than I expected, so I am happy. It is actually very simple to get working (no soldering at all, but about 20 solderless jumpers). I plan to at least get a board made to make it all one integrated piece that allows engraving and pass through Mach3/EMC cutting. The schematic is basically done. I want to have some friends at XMOS look it over.

By pass through, I mean it will sit on the parallel port between the PC and CNC machine. In one mode the XMOS takes control and the other mode it just lets the signals go through from the PC to the CNC. The XMOS will still see all the signals so there will be some cool tricks it could play.

I plan to keep it open source and make it so that it could be general purpose CNC board like a simpler version of a smoothstepper, if someone wanted to take it there. The part cost is probably only about $20-30, so it will be cheap.

If you are interested in building a laser, I suggest going for it. Initially set it up as a cutter via Mach or EMC. That will take you a few months. Then, either buy a commercial board like lasersafe1 or maybe the XMOS will be what you want.

I actually don't have a real use for a laser engraver. I am in this just for the fun of it. I would much rather build every piece I possibly can than buy "off the shelf". Even if means it ends up costing me more and the results are less than perfect. I might even make my own tube soon. It will cost me a lot, but it will be cool. :)


Thats fine mate worst comes to worst I will buy a controller but I doubt that will need to happen I like things that if they break I can fix if you get my drift I think the work you do is fantastic time isnt a worry to me at all.

Do I have a use for my Laser when its done well yes it will it pay for itself I am sure but my spindle on my CNC died last week so the $300 I was going to use on the laser is now gone bit of a bugger but you get that I will start saving again at least my rails turned up after being caught in customs for a week.
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Dual Y Belts

Postby bdring » Tue Feb 09, 2010 5:15 pm

Snow Day! (sort of...power out at work :? )

I am working an upgrade to the drive system.
  • Switch to the finer pitch (.08") belt (edit: which allows smaller pulleys) to get me to 1000 steps/inch.
  • Switch to the smaller, lighter, cheaper NEMA 17 motors.
  • Drive the Y axis from both ends.
  • I want to use open ended belt stock, with easier to use belt tensioners.


While the Y-Axis has held up really well, I always thought it was a weak design. The Y axis bearing plate was machined from aluminum. I am going to try it out of acrylic. My goal is to have all machined parts out of wood or plastic. That would allow a decent laser cutter to self replicate the tricky parts.

I put the Y-motor up front. I was hoping to put it in the back, but it was not working well there. After I moved it up front I like it a lot better. The shaft is not really in the way, because it is really close to the frame member. My motor controller is in the front too. This will allow easier access to it.
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dual_belt1.png


The belt tensioners are cut from acrylic too. I am going to use my 0.06 end mill to drill a pattern that matches the pitch of the belt. There is a screw to tighten clamp the belt and the rest is pretty obvious.
.
belt_tensioner.png
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Re: Buildlog.net Open Source Laser

Postby lasersafe1 » Tue Feb 09, 2010 5:31 pm

Nice belt tensioner! Love the 80/20. It's great stuff. I want to caution you though that it might have some flexure during a fast raster, not because of the mass of the swinging head, but because of the repetitive motions setting up an oscillation wave in the whole structure. The ULS-25 that I'm working on has a light rail structure, but when it goes into the machine it is bolted down to a large steel plate that has a cutout for the cutting area. There might be a reason why the ULS-25 weighs 275 pounds.
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Re: Buildlog.net Open Source Laser

Postby bdring » Tue Feb 09, 2010 5:40 pm

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It's actually Misumi extrusion. They are 20mm increment based and quite light. I like the price and "no cut fee better" than 80/20. I use 80/20 a lot at work. That is for more heavy duty applications.

If I tried to the Y Axis really going, I might have some oscillation. I have had the X really flying and no evidence of anything.
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Re: Buildlog.net Open Source Laser

Postby lasersafe1 » Tue Feb 09, 2010 5:48 pm

I've never heard of Misumi. Where do you buy from?
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Re: Buildlog.net Open Source Laser

Postby bdring » Tue Feb 09, 2010 5:57 pm

Comment From Buildlog Author


lasersafe1 wrote:I've never heard of Misumi. Where do you buy from?


http://www.misumiusa.com/

They have way, way more stuff than 80/20. The extrusion and related parts are stocked all over the country. I get parts next day for ground delivery shipment cost. Cut pieces and specialty items take a few more days. You should be able to get a 20% discount for your first order. Snoop around for the discount, I did not hear about it until after my first order.

The only catch is most everything is metric, but when you work in CAD who cares. I initially chose them because the extrusion has a sharper corner than 80/20 which was required for better V-rail alignment.
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Re: Dual Y Belts

Postby pixpop » Tue Feb 09, 2010 7:27 pm

--> Switch to the finer pitch (.08") belt to get me to 1000 steps/inch.

I'm confused by this. Why does the belt pitch matter? Isn't it just the pulley diameter that determines the resolution?

Neil
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Re: Buildlog.net Open Source Laser

Postby bdring » Tue Feb 09, 2010 7:30 pm

Comment From Buildlog Author


pixpop wrote:--> Switch to the finer pitch (.08") belt to get me to 1000 steps/inch.

I'm confused by this. Why does the belt pitch matter? Isn't it just the pulley diameter that determines the resolution?

Neil


Sorry...good point...the finer pitch has smaller pulleys so that allows me to get better resolution. I was already using the smallest 0.200" pulley so I had to change to finer pitch
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Re: Buildlog.net Open Source Laser

Postby buildsomething » Tue Feb 09, 2010 7:41 pm

Something still doesn't make sense here. A smaller pulley does not increase resolution unless it works in conjuction with another pulley that is much larger. If the driver and driven are the same diam, no matter how small or how fine the pitch that is used, the resolution is still the same.

In my cutting laser I have a 3:1 reduction from stepper to the driven ass'y. This reduces my speed by 3X, increase my torque available by 3X and increases the resolution by 3X. In my case, I didn't need speed. I can move my 5lb gantry at speeds over 800 ipm which is way way to fast anyway for cutting.

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