BuildLog.Net

Home Built 40W CNC Laser

Project Overview

Note: This design has been superceded by the 2.x Laser. There is a blog post on it, information on the wiki and a lot of discussion on the forum.

This was designed as a "self replicating" laser cutter engraver'. What this means, is all of the high tolerance complicated parts can be made on a laser cutter. So, once one laser cutter is done, it can help make others. All of the other parts can either be purchased or made with common home tools.

This is not a mamby pamby little diode laser than can slowly cut through a piece of thin black tape. This will cut real materials, quickly. If you want to know what it can cut, go to a Ponoko type site and check out their materials list.

This was designed to be a dirt cheap, but fully capable laser cutter. Many of the material choices were made to satisfy that goal. I am sure many people will know of better materials, but usually at a higher cost. Feel free to substitute them .Almost everything that is not an off the shelf item, can be made with a laser cutter or router. To kick start the first generation of 'self replicating lasers, I have some kits located here.

The buildlog is presented blog style (most recent entry first) if you want to go view it the other way click here... Take me to the beginning of the build

How can you contribute to the project?


Buildlog Title: Buildlog.net Open Source Laser

newest first oldest first
Builder: bdring
Member Since: 2009-11-22

Tuesday, January 26th 2010 - 3:09 AM

Painted.jpg


Project Overview

This was designed as a "self replicating" laser cutter engraver'. What this means, is all of the high tolerance complicated parts can be made on a laser cutter. So, once one laser cutter is done, it can help make others. All of the other parts can either be purchased or made with common home tools.

This is not a mamby pamby little diode laser than can slowly cut through a piece of thin black tape. This will cut real materials, quickly. If you want to know what it can cut, go to a Ponoko type site and check out their materials list.

This was designed to be a dirt cheap, but fully capable laser cutter. Many of the material choices were made to satisfy that goal. I am sure many people will know of better materials, but usually at a higher cost. Feel free to substitute them .Almost everything that is not an off the shelf item, can be made with a laser cutter or router. To kick start the first generation of 'self replicating lasers, I have some kits located here.

The buildlog is presented blog style (most recent entry first) if you want to go view it the other way click here... Take me to the beginning of the build

Drawings are here
Kits are here
Bill of Material is here

How can you contribute to the project?

Participate in the forum.
Suggest changes. A lot of the design comes from your input.
Link to buildlog.net. More people + more ideas = better laser
Donate. Help fund the cost of the web site and costs associated with this project.

Note:
This buildlog started before the forum, so the earliest entries are not shown. To see the very beginning of the buildlog click here.

Grayscale/3D Engraving Tests.

The XMOS contrller appears to be setting the power as it should, but I am getting mixed results with grayscale engraving. Here is a gradient. The white box in the middle was is on purpose to see how well it turned off and resumed power. This about 0.300" inch tall and about 3.00" long. It was on a piece of maple.
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There is a lot of color variation due to the material itself. I have tried a few gray scale images, but the image usually is overpowered by the coloring in the wood. On materials like granite, the color does not change much at all. On the wood, there is a definite depth change due to the power, which sort of looks cool. I will try to get a picture of that. I need some material suggestions to try more stuff on.

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reader comment Comment from: willyinaus on Tuesday, January 26th 2010 - 8:47 PM
Glass is something I would like to see.

Wednesday, January 27th 2010 - 11:37 PM

XMOS Video

Here is a video of the engraver in action.

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Monday, February 1st 2010 - 2:26 AM

Hey Willy,

Here is your glass engraving. I had the speed about 12 inches per sec. The power was 140 out of 255.

I think I hit it too hard or too slow. The transitions from clear to engrave is a little rough and can chip off if you play with it and leaves a little bit different look. Look at the bottom of the swoosh. It looked perfect, but after rubbing it with my fingernail, I could get bits to chip off to a smoother look underneath. The interior areas are robust and don't chip.
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triumph_glass.png
triumph_glass.png (606.87 KiB) Viewed 35304 times

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reader comment Comment from: willyinaus on Monday, February 1st 2010 - 9:20 PM
Thanks for that, its really encouraging especially seeming your only using a 40w laser.

I have decided to tone down mine a bit so will update the thread in the next couple of days.
reader comment Comment from: willyinaus on Thursday, February 4th 2010 - 8:18 PM
Hi bdring, do you think this would be simple enough for a person with no real electronics experience to put together.
I have seen your schematic and i seems quite easy to understand.

I guess I could only try :D
comment Buildlog Author Comment: bdring on Thursday, February 4th 2010 - 9:20 PM
Comment From Buildlog Author

Put what together? A basic laser cutter? The whole XMOS Engraver mess?

If you can put together a CNC with steppers, the cutter put is pretty easy. The laser tube & P/S is pretty easy if you are careful. I am never afraid of the beam. The HV part is what scares me.

The XMOS part is not that difficult, but not real user friendly yet. I am working on a schematic to make a complete board. I want it to be real friendly to setup and switch between engrave and cut modes. It will probably take at least 4-6 weeks to get there. I have a million things going on at once now.
reader comment Comment from: willyinaus on Friday, February 5th 2010 - 1:54 AM
Yes I was meaning the xmos setup don't worry I am way off at the moment too many hours at work not enough play time but its all looking positive love the Glass you did thanks for that. :|

Willy
comment Buildlog Author Comment: bdring on Friday, February 5th 2010 - 3:45 AM
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. :)
reader comment Comment from: lasersafe1 on Friday, February 5th 2010 - 5:46 PM
bdring wrote:
Comment From Buildlog Author

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. :)


You are lucky to have such a passion for building things, and apparently the funds and approval from your wife. Once you have this new tool in your shop you will find all kinds of new uses for it. I already have people asking me about doing some engravings for profit.

With the ever dropping price of sealed CO2 tubes from China, you will indeed spend more making one yourself but the satisfaction will be great. What I would like to see is some really good home built high voltage supply or better yet, an RF tube and power supply. The RF would be the Holy Grail of homebuilts.

I just bought a new car that has HID headlights. I noticed the warning sticker under the hood that reads "Caution: 25,000 Volts". I had no idea that HID's had such a high starting voltage. This is possibly a cheaper source of high voltage since they are now in mass production. So indeed our DC tubes need the high voltage to start the internal plasma, but do they need to maintain the HV for running? I would think that perhaps once the plasma is struck, the running voltage can be much lower. In this respect it would behave much like the HID headlamp driver. All in all we know that whatever if built it needs to be able to switch on and off within the microseconds time frame for rapid engraving. I had a fear that the Chinese DC supplies coudn't cut it, but I am pleasantly surprised at their control speed during a fast raster.
comment Buildlog Author Comment: bdring on Friday, February 5th 2010 - 6:14 PM
Comment From Buildlog Author


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.
reader comment Comment from: willyinaus on Saturday, February 6th 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.

Tuesday, February 9th 2010 - 5:15 PM

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

I am working an upgrade to the drive system.


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.
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belt_tensioner.png

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reader comment Comment from: lasersafe1 on Tuesday, February 9th 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.
comment Buildlog Author Comment: bdring on Tuesday, February 9th 2010 - 5:40 PM
Comment From Buildlog Author

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.
reader comment Comment from: lasersafe1 on Tuesday, February 9th 2010 - 5:48 PM
I've never heard of Misumi. Where do you buy from?
comment Buildlog Author Comment: bdring on Tuesday, February 9th 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.
reader comment Comment from: pixpop on Tuesday, February 9th 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
comment Buildlog Author Comment: bdring on Tuesday, February 9th 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
reader comment Comment from: buildsomething on Tuesday, February 9th 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.

Richard
comment Buildlog Author Comment: bdring on Tuesday, February 9th 2010 - 7:48 PM
Comment From Buildlog Author

buildsomething wrote: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.

Richard


In my simple system the motor is driving the pulley which drives the belt attached to the moving part. So all I care about is diameter of the pulley on the motor. It is actually calculated in teeth, so the fewer teeth per rev (smaller dia.), the higher the resolution.
reader comment Comment from: Robert Williams on Thursday, February 11th 2010 - 12:15 PM
Will you post plans for this latest revision?
comment Buildlog Author Comment: bdring on Thursday, February 11th 2010 - 12:29 PM
Comment From Buildlog Author

Yes, as soon as I test the changes. I will probably fabricate the parts on Saturday and install them before the end of the weekend.

Friday, February 12th 2010 - 4:15 AM

I have all the changes ready and I programmed the router in Aspire. I have some Acrylic coming tomorrow (hopefully) and I will cut the parts. They nested pretty well. and won't take up too much material. It should take about 40 minutes to cut. I could easily optimize it to take a lot less time, but it is not worth it for one job.
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cutout.png

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reader comment Comment from: lasersafe1 on Friday, February 12th 2010 - 4:22 AM
Are you CNC cutting or Laser cutting? The drawing looks nice! It's amazing how things that were once hard are now becoming a button press.

After I finish the ULS upgrade I will move on to build my gantry CNC mill that I have left in a half built stage. I am presently using a small mill from Harbor Freight that I upgraded to CNC.
comment Buildlog Author Comment: bdring on Friday, February 12th 2010 - 1:16 PM
Comment From Buildlog Author
I will use my CNC router. It is just easier at this point and can fit the full raw stock without cutting down. Ideally this would be lasered so a laser can make a complete set of parts for a new machine. I have a couple stepped areas where bearings drop in. That would need a slight change. Other than that, it looks good for a laser.

I will use a 1/16 solid carbide end mill from Precise Bits. I bought a couple of these a few years ago and they seem to last forever. I must have cut 100's of parts on them and I have yet to retire one. I have even cut some 6061 aluminum with them. I also have a 0.010 end mill that I use to mill PCBs.
reader comment Comment from: 8bithack on Tuesday, February 16th 2010 - 11:37 PM
I love the work you've done on this project. I would really like to build a laser cutter for just doing cutting, no etching right now. Are you planning on releasing a "final" drawing of all the laser cut parts for laser cutting? I don't have access to a CNC router or laser cutter right now so I will probably just have them cut at Pololu or Ponoko. I'll also probably have a bunch of questions for you once I get farther into the build. Thanks for any help you can give.
comment Buildlog Author Comment: bdring on Tuesday, February 16th 2010 - 11:50 PM
Comment From Buildlog Author

I have a drawing done, but I want to do a test cut on my router. Unfortunately the material did not arrive until today. I might be able to cut tonight. If the parts workout and the cut time is not too long, I may run an extra set or two later in the week.
reader comment Comment from: 8bithack on Wednesday, February 17th 2010 - 4:20 AM
Have you thought about attempting to add a vacuum assist to your machine or have you found it unnecessary so far? It seems like it would be fairly easy to build a vacuum box to go on your Z platform. Have you had any problems when cutting with parts moving or are the cutting speeds slow enough to not get any movement on the parts?
comment Buildlog Author Comment: bdring on Wednesday, February 17th 2010 - 1:45 PM
Comment From Buildlog Author
A vacuum or downdraft system would be a great additon to any laser cutter for a lot of reasons, but not really a necessity. The laser cutting/engraving action does not affect the workpiece much. It does a good job of handling the smoke and keeps small pieces from flying around.

On my system the thing that affectes the work is the mostly the flushing fan and to a lesser extent the assist air. I could easily cut a playing card just by setting it down. If I were to try to cut a small piece of regular paper, it would probably move. Thin paper often tends to curl while cutting and small cutout pieces can blow around.

The buildsomething laser has a nice downdraft system.

FYI: I had some minor trouble with my router that will delay the cutting of the new laser cutter pieces a few days as I wait for a new part. I will try to post the files in the mean time.

Friday, February 19th 2010 - 1:39 PM

I have been trying to make it simpler to fabricate all the parts. I want a decent laser cutter to be able to make complete set of parts for another laser. Obviously there will be a few places to drill and tap, but the bulk of the work should be done by the laser.

The bearings are 3/16" thick and the acrylic is 6mm 0r 0.25" thick. There were a few places where bearings mounted in counter bored holes. This is a tough hole to make without a CNC router.

I think I have a workable solution. A through hole is sized for a tight fit on the bearing. The bearing is pressed into the hole then a oring is is used to hold it in place with some #4-40 hardware and washers. The oring is hard at 70 durometer and cheap at $3 per 100 at McMaster Carr.

I should be cutting some parts pretty soon. I am still waiting for a part for my router. A lot more of the parts are now made out of Acrylic and they all easily fit on a medium sized (P2) sheet from Ponoko
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oring_clamp.jpg

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reader comment Comment from: 8bithack on Saturday, February 20th 2010 - 2:44 AM
I would like to try and get some parts cut from Pololu before my rails get here on the 5th of March. Could you email me the laser cutting file for all the laser cut parts? I've been trying to put something together in Inkscape but it is taking a lot of time. Thanks.

Saturday, February 20th 2010 - 1:14 PM

I posted the "All Acrylic Parts" drawing on my drawings page. These are the parts laid out as I am going to cut them next week. The parts have been redesigned since the first version to power the Y axis from both ends and to consolidate most of the parts to something a laser can cut. I have a lot more work to do on the individual drawings. I have a very busy week coming up and will try to get what I can posted. I want to add the Z lift parts to this drawing eventually too.

I won't be able to make a drawing specifically for Ponoko or Pulolu right now. I had a lot of trouble making one for Ponoko before, because I don't have the exact versions of the software that they require and Inkscape does not have a way to go from CAD (at least not when I checked). I plan on getting my Corel upgraded, but that will not happen this week. I had won some free cutting from Ponoko, so they actually fixed the problems for me "this time only".
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Drawing here
cut_parts.JPG

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Tuesday, February 23rd 2010 - 4:24 AM

I was able to cut the parts. This is most of them. I will start to install them tomorrow night. The little belt clamps work great. I might change to three screws instead of four for mounting the bearings. I reduced the hole size for the bearing by about .003 to get a press fit.
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cut_parts.jpg
Cut Acrylic Parts

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reader comment Comment from: lasersafe1 on Tuesday, February 23rd 2010 - 3:51 PM
Wow! You are remarkebly close the the "24 hour laser engraver project". I would bet if all parts could be ordered cut to size then it could actually be done in a day.

Wednesday, February 24th 2010 - 1:55 PM

How thick is 1/4" Acrylic? How wide is a 2x4?

I use a lot of Polycarbonate (Lexan) and some Acrylic (Plexiglas) at work. I have long known that 1/4" is really 0.236 (6mm) thick. The material I ordered from rlplastics.com was advertised as 0.250" thick. Usually when someone specifies a dimension to that precision, you should expect to get it. I really did not care if I got 0.236", but would prefer the 0.250".

Everyone knows U.S. 2x4 lumber is really like 1.5" x 3.5", but if someone were advertising 2.000" x 4.000" lumber, you should wonder what you are getting.

Anyway, what I actually received is 0.205"? Their web site actually has an F.A.Q. saying 1/4" is 0.236 and beware of companies that might supply material as thin as 0.220. So whats with this 0.205" stuff.....awaiting answers.

Now, all my stuff is cut thinner than expected. Most of the parts will be fine, but some have tapped holes in the edge that I am worried about. The two X Axis really should have the added stiffness too.
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205.jpg

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reader comment Comment from: lasersafe1 on Wednesday, February 24th 2010 - 6:30 PM
Perhaps they were quoting British inches? I would demand a redo or refund.

Friday, February 26th 2010 - 4:04 AM

I posted most of the drawings for the Y axis modification on the drawings page.

There a a few more to go and the assemblies drawing are not a 100%, but I know some people are actively building, so I want to get what I could online.

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reader comment Comment from: Robert Williams on Monday, March 1st 2010 - 2:18 AM
Thanks... I'm one of active builders. Need info on NEMA 17 stepper motor so I can order.
comment Buildlog Author Comment: bdring on Monday, March 1st 2010 - 2:29 PM
Comment From Buildlog Author

I bought mine here.

http://www.kelinginc.net/

Wednesday, March 3rd 2010 - 4:12 AM

I drilled and tapped my belt clamps. Tapping acrylic is a little tricky, but the threads are quite strong. You just need to back out the drill and the tap many times to clear the material otherwise it gets hot and gummy and the crack the material. The tap can get stuck too if you are not careful.

Oh...and don't center punch :oops:

belt_clamps.jpg
Belt Clamps


I also updated a few drawings with some assembly and fabrication notes.

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Thursday, March 4th 2010 - 5:29 PM

I built and mounted one of the bearing bracket assemblies. These are the assemblies that hold the rear idler pulleys for the Y axis belts.

I made some changes to the way the bearing is held in place. I used two truss head screws with undersized washers and nuts on the other side. This gives clearance for the hex nuts without any spacers. I used a 3" piece of #1/4-20 threaded rod. This is bolted to the bearing before installing into the plate. This assembly has no load pulling on the bearings, so it works fine. The only load is trying to twist the bearing out. Using two bearings spaced apart by 40mm prevents this.
Updated drawings coming soon.
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bearing_brkts.jpg
CAD Model

rod_nuts.jpg

installed_bearing_brkt.jpg
Installed

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Friday, March 5th 2010 - 3:55 AM

I completed the basic assembly of the new gantry. No problems so far. I will assemble it to the Y axis next. Tensioning the belt went pretty well. I made it pretty tight to start with and only had to use about 25% of the tensioning range.

Here is the process I followed.

The laser "car assembly" is built with the middle wheel loose. It is then put on the gantry. The middle wheel is then pushed against the v rail with the adjuster screw. The wheel will cock a little when loose, so you don't need to push it too tight. It will get tighter against the rail when the screw is tightened. Try tightening the wheel bolt to see where the compression ends up. You want it to have zero play. The car should barely hold itself in place and not slide down the gantry when held vertically. Make sure there is not so much conpression that the plate is visibly bent.

Attach one of the belt clamps to the end of the belt. Mount both belt clamps to the car assembly. They should be mounted as far apart as possible to leave the maximum amount of adjustment. Wrap the belt around the pulleys and cut to length. Attach the second belt clamp. Lightly attach the belt clamp so they still slide when the tensioner screw is adjusted. Tension the belt. If you run out of adjustment range, trim about 1/4" off the belt and try again.


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gantry2.jpg

gantry_motor_end.jpg
Motor End

gantry_bottom.jpg
bottom View

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Friday, March 5th 2010 - 5:08 PM

Post Assembly T Nuts

I got these in the mail today from Misumi. These can be dropped into the frame slot after the ends are not accessible. They are worth their weight in gold if you have ever worked with T-Slot extrusions. Some have little spring loaded balls that hold them still on vertical sections. They are about $0.40 - $0.50 each.
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post_assy_nuts.jpg
Post Assembly Nuts (2 flavors)

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reader comment Comment from: Robert Williams on Friday, March 5th 2010 - 6:15 PM
New gantry assembly... just the kind of information I need! Are your NEMA 17's double shaft? Shaft diameter 3/16?
comment Buildlog Author Comment: bdring on Friday, March 5th 2010 - 6:36 PM
Comment From Buildlog Author

I bought 2 of these from Keling Technology.

http://www.kelinginc.net/KL17H147-1684B.pdf

It is double shaft, but it does not need to be. EDIT: Y must be double shaft. The drawing says 5mm shaft, but 1/4" shaft was sent to me. That worked for me because I had pulleys for them. I think pulleys are available for both sizes. You should make sure to match them.
comment Buildlog Author Comment: bdring on Saturday, March 6th 2010 - 6:08 PM
Comment From Buildlog Author

Oops...My last comment was wrong. Double shaft IS important for the Y axis motor.

Sunday, March 7th 2010 - 12:30 AM

I got the gantry installed.

The first thing I did was make sure the Y axis rails were as parallel as possible. I made a measuring jig out of an extra piece of Misumi extrusion. I then loosened both end plates on the gantry so the gantry could be twisted to make sure it is exactly 90 degrees to the Y axis rails. I used a large carpenters square to do this. I then tightened the motor end plate to the v-rail. After that was tight and square I did the same to the other end.
gantry_in.jpg
Gantry Installed

I need to install the belt and pulleys next. I think I am going to connect the two sides with threaded 1/4-20 rod. I made a coupler to the motor with a coupling nut I had. I think I got it at the hardware store a while back. I drilled out the threads on one end and left the threads in the other end. I put two set screw spots on the motor end. I hope this will allow me to do fine rotation adjustments to do the final squaring of the gantry. I will use the laser to draw an angle. If the angle is not perfect, I will twist one side forward and re-tighten the lock nut.
y_shaft.jpg
Shaft Coupler

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Tuesday, March 9th 2010 - 2:32 AM

I hooked up the power to the X Axis motor and gave it a try.
[*]10 in move shown

I could get it up to over 3500 ips, but it lost steps with an accel around 1000, so I backed it down.

I am waiting for some new pulleys for the Y axis.

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reader comment Comment from: lasersafe1 on Wednesday, March 10th 2010 - 3:05 AM
bdring wrote:
I could get it up to over 3500 ips, but it lost steps with an accel around 1000, so I backed it down.



You didn't really mean ips did you? That's 17,500 feet per minute! It looks great!
comment Buildlog Author Comment: bdring on Wednesday, March 10th 2010 - 3:30 AM
Comment From Buildlog Author


Yes, I actually caught that and edited it last night. I guess it didn't take?

Wednesday, March 10th 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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Friday, March 12th 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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Friday, March 12th 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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Friday, March 12th 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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Sunday, March 14th 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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reader comment Comment from: lasersafe1 on Monday, March 15th 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?
comment Buildlog Author Comment: bdring on Monday, March 15th 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.

Tuesday, March 16th 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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Wednesday, March 17th 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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Wednesday, March 17th 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

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Sunday, March 21st 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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Monday, March 22nd 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

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