Buildlog.net Open Source Laser

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Re: Buildlog.net Open Source Laser

Postby bdring » Wed Mar 10, 2010 3:30 am

Comment From Buildlog Author


Yes, I actually caught that and edited it last night. I guess it didn't take?
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Re: Buildlog.net Open Source Laser

Postby bdring » Wed Mar 10, 2010 7:06 pm

I posted the latest drawing of the XY assembly on the drawings page. I tweaked the idler pulley assemblies a little. I was using two brackets per pulley, but that turned out not to be required. I decided it would be better to have another Misumi bracket on the other side to more add side to side stiffness. If you fab'ed some parts already. They will work. You will just have two extra pulley plates.

I also got rid of the o'ring concept I was playing with to hold the bearings in place. My material came in so thin that it did not fit right and the regular hardware was holding it fine. If you have thicker material and are having trouble, let me know. I have a small amount of thicker material I can try out. I can also cut a few out of the thinner material for you. My router can be dialed in so that it is a nice tight, almost press fit.

My pulleys arrived today so I might be able to get them installed and start re-aiming the mirrors.

I also have a long term goal of simplifying the enclosure skins. I want some way to fab them without the large router that I use. If anyone has any ideas or some alternate materials, I would love to hear about it.
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Y Axis Working

Postby bdring » Fri Mar 12, 2010 3:46 am

I got the Y axis working. It was very easy to square up. The connecting shaft can easily be twisted to lock down the final fraction of a degree.

Here is a video. I had the Y axis set to a max speed of 1000 ipm and and accel of 750 inches/min/min. I easily goes five times that rate, but the the whole table states to shake. I don't need much speed in the Y so I dialed it down.
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Re: Buildlog.net Open Source Laser

Postby bdring » Fri Mar 12, 2010 4:09 am

Many of the plastic parts need to be drilled or tapped into the side. This needs to be measured, marked and carefully drilled. I thought the fabrication process could add these lines make it easier.

I tried it with the tube mounting brackets. If you look carefully you will see a little half moon by each drill location. It worked great. The drill actually centers on the mark.
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drill_marks.jpg
Drill Location Marks

3d_tube_clamp.jpg
CAD View


I made 6 of these by the way. If anyone wants to try them, I can send them at my cost plus shipping. I will include the black nylon screws too.
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Lots of clamps

Postby bdring » Fri Mar 12, 2010 4:16 am

I broke one of the belt clamps. I was tightening at a bad angle and over did it. It is way easier to measure the belt, then install the clamps onto the belt before they go on the machine. They don't have to be tight at all. The teeth do all the work and the plastic threads are sort of self locking, so they won't loosen.

Anyway, I need to make one more, so I decided to turn the router loose on making a bunch of them. If anyone else breaks one I can send a spare.
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extra_clamps.jpg
Extra Clamps
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Aligned - Working on cover

Postby bdring » Sun Mar 14, 2010 4:26 pm

I finished aligning the laser. It is accurate to a few thousands of an inch. See this post.

I started working on a cover. I originally thought a door the size of the work area would be good, But I think the reason I have held off on the cover is that I like to have full access from the top. So I have a full cover concept going. If anyone has any input, let me know. I will probably start cutting the pieces soon.

cover_concept1.jpg
Cover Concept


It is basically a L shaped extrusion assembly that will be skinned in plywood with a transparent window above the work area (not shown yet). I found some really cheap piano hinge that works pretty well with the extrusion. Below are some pictures of a mock-up. I have two scraps of plywood shown. One piece will actually be more like a optional decorative trim strip on the stationary side of the hinge. I plan to put at least one gas spring to hold it open.
hinge3.JPG
Hinge View

hinge1.JPG
Another view of the hinge
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Re: Buildlog.net Open Source Laser

Postby lasersafe1 » Mon Mar 15, 2010 2:11 pm

One consideration is the inlet size vs. the the total evacuation rate. On my Chinese M40 I would tend to start things on fire, especially during paper cutting. I added the air assist and it would blow out the flames. On my ULS-25 I don't have air assist yet, but it doesn't start fires. I presume that my air exhaust is actually drawing a partial vacuum on the entire enclosure so it cannot support ignition. My exhaust flow rate is also MUCH higher than I had on the M40. I don't have an anemometer, but I would suspect I am near 600 cuft/min.

On a side note, I ran into a web site that says that the blower in your average clothes dryer is very good for this. Indeed, have you ever felt the blast of air coming out of the dryer vent?
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Re: Buildlog.net Open Source Laser

Postby bdring » Mon Mar 15, 2010 3:14 pm

Comment From Buildlog Author

I can't imagine the partial vacuum theory being responsible. At best your blower can probably pull 10-12 inches at stalled flow. One atmosphere is 407 inches of water, so your are only changing the air by a couple percent.

You can make your own manometer with a piece of clear tubing. Some people set one up permanently near the flow, because it can show when filters need to be changed or there is blockage somewhere.

I cut a bunch of Acrylic yesterday and while the smoke and fumes behaved themselves, there was still a little stink in the air afterwards. I think I need to re-evaluate my system. I think I will get ride of my current blower and go with something larger and put it outside the building like you mentioned in this post.

I was at a junk yard on Saturday and saw dozens of huge blowers. One was the size of a refrigerator. I was tempted, on some of them, but did not buy.
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More on the cover

Postby bdring » Tue Mar 16, 2010 4:27 pm

Here is more on the proposed cover. The cover has a frame that is 2020 extrusion. The cover frame fits inside the enclosure frame, but the skins for the cover are the full width of the enclosure. This will hide any gaps and seal a little better. I have the skins made out of plywood with an Acrylic window, but the whole top skin could be Acrylic.
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cover_overlap.jpg
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Cover Tested

Postby bdring » Wed Mar 17, 2010 12:38 pm

I built the cover out of the framing material and temporarily put it in place without the skins. I think it will work. I think I will put two small gas springs to hold it open and closed. I think one gas spring would eventually warp the cover. I need to get some more plywood and the windows is due later this week.

I might also hinge the lower front or at least make it a quick release.
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cover_on.JPG
Cover testing
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