Buildlog.net Open Source Laser

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Gas Spring Calculations

Postby bdring » Wed Mar 17, 2010 4:01 pm

I found a good gas spring at McMaster Carr. The gas springs are McMaster p/n 4138T551. I did some graphical calculations on using it. As I understand it, I want to fully extend the spring at my full open which is going to be about 80deg. I want it to almost fully compress as it closes, but I want the spring to have some over-travel so the last few inches actually push it closed rather than pushing it open.

The spring is available in a lot of strengths, but I will go for the lowest, I really only want a minor amount of assist and enough to hold it open. Any extra is just unwanted stress on the enclosure.
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gas_spring_calcs.jpg
Click to enlarge
Bart
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Exhaust Blower

Postby bdring » Sun Mar 21, 2010 12:49 am

I have had this dust blower for about 4 years. It did a lame job on my router. The shop vacuum did much better. I decided to hook it up to my laser with it located right at the wall to minimize leaks that could cause gas to re-enter the shop. It is almost ready to go. It was a lot of work to plumb in and get it out the side of the house. I got ride of the bag and all the other attachments.
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cm_blower.jpg
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Self Replication

Postby bdring » Mon Mar 22, 2010 10:52 pm

Self Replication

My ultimate goal with this open source laser is to make it possible to build one with no special tools. I want all of the complicated part to be fab'able by another laser. If enough people build one, there will be an easy supply of parts.

I finally got around to cutting one of the laser's own pieces. This is the laser carriage plate. You can see the original (installed) and the new piece. I put a piece of white foam board under all the pieces to give a little contrast in the picture. I have not cleaned-up the assist hose routing since I made the new cover. I actually have some new self coiling tubing I want to try.
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self_rep.jpg

self_rep2.jpg
Bart
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Vectric Post Processor

Postby bdring » Wed Mar 31, 2010 12:38 am

V25Aspire_Final_Logo.jpg
V25Aspire_Final_Logo.jpg (5.77 KiB) Viewed 27589 times

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I have been using my Vectric Aspire program to laser cut some parts. I made a post processor file for it. Aspire is way overkill for laser cutting, but it should work for all Vectric's other programs as well. Cut-2D is probably a good candidate for lasering and is a decent price. You can download a semi-working version for free.

The post processor is for use with Mach3 and the E1P1/E1P0 control style. I will detail my E1P1 control method in a later post.
Attachments
_bdring_Mach2_3_E1_Arcs_inch.txt
Rename with a .pp extension
(4.72 KiB) Downloaded 782 times
Bart
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Re: Buildlog.net Open Source Laser

Postby dfowell » Wed Mar 31, 2010 2:06 pm

Hey I have been reading your blog and following your laser build, I am working with lasers in my shop big lasers and wanted to build my own I was wandering if you have a parasolid of your laser build and drawings to scale so i can attempt to build one, Thanks Good Job

very impressed
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Re: Buildlog.net Open Source Laser

Postby bdring » Wed Mar 31, 2010 4:11 pm

Comment From Buildlog Author

Sounds great!

What CAD system do you use? Can you use STEP files? All DXF drawings are to scale and 1:1 where practical.

I assume you have seen the drawings page.
Bart
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Re: Buildlog.net Open Source Laser

Postby bdring » Sun Apr 04, 2010 8:12 pm

I finally got around to cutting the window for the cover. It looks pretty good. I didn't put all the screws in place yet, because I will be painting it. I think I might add a window to the front too. It is nice to be able to see the work at a low profile when it is cutting/engraving. I put the gas springs in too, but they are distorting the hinge a little. I think I just need to add a few extra mounting holes right near the ends of the hinge. I have some simple handles too that will go on after painting.
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cover1.JPG
Bart
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Finishing Enclosure

Postby bdring » Sat Apr 10, 2010 10:14 pm

I did some finishing on the enclosure skins. I just painted them gloss white. Before I painted the front skin, I split it into three sections. I want the middle section to be easy to remove to get occasional low access from the front.
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Painted.jpg
Painted Enclosure

I also got thew gas springs working. They were putting too much stress on the hinge. I previously had to alternate the screws because the heads were bumping into each other when the hinge was completely closed. I got some flat head M3 x 5mm and that allowed all holes to be used without the heads interfering. It works well now. Edit: I realized the gas springs are mounted upside down and fixed. The McMaster info page on gas springs says the fat end should be mounted above the thin end wherever possible. I think this makes the seal last longer.
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GasSprings.JPG
Gas Springs
Bart
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Re: Buildlog.net Open Source Laser

Postby Ben » Sun Apr 11, 2010 5:37 am

The painted enclosure skins look great! My laser enclosure also has the front broken into three sections. The gas springs seem to hold the door open nicely; does it stay closed even when bumped or jostled?
-Ben

My Lasers:
40w CO2 Laser (Chinese Glass Tube), Directed Energy Inc. 30w RF CO2 Laser (Needs Repair), Laakmann Electro-Optics 20w RF CO2 Laser (Needs Repair), 7-10w RF CO2 Laser
Coherent 12w 808nm FAP LASER DIODE
MELLES GRIOT He-Ne Laser
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Re: Buildlog.net Open Source Laser

Postby bdring » Sun Apr 11, 2010 1:49 pm

Comment From Buildlog Author

If I shake the table the cover wiggles a little but does not appear to want to close. It feels like it takes about a 1/2 lb of force to pull down. It is pretty close to vertical so there is not much force on the springs when fully open. It pushes itself open for about the last 2-3 inches. All other positions it wants to close. I was mostly interested in having it hold itself open and assist me in opening. The spring is available in 15, 20, 30, 40, 50, 60, 90, 120 pressures. I chose the lightest one.

There is a lot of adjustment capability because everything is mounted to the slots. I did not play with it too much. If it tended to close by itself, I could increase the support angle a bit. The nice thing about gas springs is that they keep a constant force throughout the compression, unlike a spring which increases.
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