Buildlog Title: TOTALLY DIY LASER CUTTER

Builder: buildsomething

Member Since: 2010-01-05

Comment from: 2bytes on Tuesday, June 8th 2010 - 3:23 PM

Yes, I am interested in any hurdles you encounter regarding stability and deflection due to sheer size.

I have seen a CNC laser cutting set up that was made for textile use, it was over 3000mm on is longest axis. It's frame consisted of gigantic aluminum I-beams and a lot of cross support all welded. We strapped a laser pointer on one end and a block of wood on the other end and marked where the dot was. Lifting one end (which was easy with the all aluminum construction) resulted in no discernible distortion at all. It was an expensive and impressive set up, something I won't be able to match with a reasonable budget. So any info on your size:deflection issue would be helpful.

Tuesday, June 8th 2010 - 12:05 PM

I've started working on the laser again after a bit of frustration on mirror alignment. One thing that I have found is that once you start getting into large lasers or for that matter any large machine, distortion of the frame starts to become an issue. Although I have taken all precautions in maintaining rigidity of the structure using simple and cost effective materials such as MDF and box structure design, warpage does occur. Over a 63 inch span of the structure, I had about a .090" deflection in the center just due to the mass. I was able to get both rails lined up parallel using brass shims along the full length of the rail. You may have noticed that the linear rails are bolted do a piece of steel 2" x 1/2" thick. This was then bolted to the structure. Even with all that, there was deflection.

With small engraving machines, where the target area is quite small, ie 12" x 12", deflection of the structure does not come into play as much or if it does its insignificant. Since my design point was not engrave but to cut, dimensional stability was paramount over the full length of the machine and along both axis.

I'll start taking more pictures of the machine shortly and start posting them on this site. Let me know if you are interested in a particular area of the machine and I will focus (sorry for the pun) on taking pics of that region in question.

Richard

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Comment from: 2bytes on Sunday, June 6th 2010 - 4:58 AM

Richard,
Great work so far. I've begun work on a similar sized setup for the same purpose (and a few others).
I would love to see a few more pictures of your completed system as a whole.

Monday, February 22nd 2010 - 2:27 PM

Here is a side view of one of the honeycomb sections removed just to show how the material is supported.

The honeycomb is supported by many pieces of 1/2" x 1/16" angle aluminum from top to bottom along the full length of the laser. The angle stock provides an exhaust path to the honeycomb. The honeycomb material really does sag if not supported in many places. You can see some 1/4" alumimum rods support the angle stock. This was done primarily to improve the airflow underneath the angle stock....but the truth is more like I made a mistake and needed another 1/4" in height...but my first answer sounded more technical.... :lol:

The 2" holes are peppered around the bottom of the cavity and enter the plenum below to be exhausted out via a 4" hose.

Note the air assist hose located at the center. The loop is large enough for the beam to traverse through without touching the beam. I am using 1/8" silicon fuel line tubing obtained from any hobby store. Its very flexible and cheap too!!!

Note the size of the Y axis stepper......its huge :lol:

but thats all had at the time. This will be replaced with something a lot smaller....but not right now.

Richard
Attachements...

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Comment from: lasersafe1 on Sunday, February 21st 2010 - 2:55 PM

That really sucks!!! (in a good way)

Sunday, February 21st 2010 - 2:08 PM

I thought I would just throw in a few pics of what the exhaust system is doing. Since you can't take a picture of air...... :lol:

..... I thought I would put a small lit candle and watch the flame. I tried using smoke from an incense stick...could not see it because of how fast the draw was, but my basement sure smelled nice after ..... :lol:

Please keep in mind that my laser cutter at this time is totally uncovered and what you are seeing is the draw of my vacuum system working alone. My design point around exhausting fumes is to create a higher velocity draw next to the product being cut...in my case I will be cutting balsa and plywood. I will be covering any exposed areas over the honey comb material and leaving a 1/2" gap next to the product. At present, the exposed areas are covered in balsa for the pictures that I took, but I will be making some predefined shapes out of thin aluminum and use them depending upon the size and shape of material that I would be cutting. Most of my cutting will be from 3"-4" x 36 to 48" balsa and 12" x 24" light ply.

At about 6" from a gap is where I don't see any more draw, but once the system is covered, that will totally change the flow characteristics of the draw. I am running 600 cfm with a max vacuum of 8" of water at stall....way more than enough

Only time will tell how this system works out once I start cutting.

Anyway for what its worth, I thought I would share some pics.

I think I am going to go and fly some RC planes now....its sunny, no wind and only -4 deg C outside....perfect weather for a Canadian eh? :lol:

Richard
Attachements...

: No vacuum

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Comment from: lasersafe1 on Tuesday, February 9th 2010 - 5:44 PM

pixpop wrote:I have a dichroic mirror made for this purpose, but it works the opposite of the way you described. I.e., it doesn't go at a place where the IR beam bends, rather the IR beam passes straight through, and the visible beam bends. Also, the beam combining units that Synrad sells work the same way; they just screw onto the front of the laser, and the IR beam passes straight through. They have a red laser coming in at 90 degrees to the IR beam.

Yes, I have seen this as well. This got me thinking. My ULS-25 has a window that separtes the laser area from the cutting area. The window is presently mounted at normal incidence to the incoming 10.6um light. I did a quick test to see how well red light will reflect off this window and found that I get about 50% reflection and 50% transmission. Now I simply need to make an adapter that adds a 5 degree tilt on this window. The 10.6um light passing through it will be unaffected by this tilt (with the exception of a slight offset in the beam that is a function of tilt angle and window thickness). I can then add a red laser pointer within the cutting region mounted 10 degrees out of plane from the CO2 path. The red light will strike the window and reflect the light into the CO2 path. The initial alignment will be a bear, but I've done it before with other lasers to combine beams. This laser stuff is too much fun!

Comment from: pixpop on Saturday, February 6th 2010 - 2:10 AM

I have a dichroic mirror made for this purpose, but it works the opposite of the way you described. I.e., it doesn't go at a place where the IR beam bends, rather the IR beam passes straight through, and the visible beam bends. Also, the beam combining units that Synrad sells work the same way; they just screw onto the front of the laser, and the IR beam passes straight through. They have a red laser coming in at 90 degrees to the IR beam.

Of course, given that you can obviously see through them, these mirrors would work as you described.

Note that cheap laser pointers, especially green ones, generally cannot be powered continuously. They tend to get too hot and stop working until you cool them off a bit. You're better off with a laser module that's meant to be powered continuously. I've tried both green and red lasers passing through a bunch of ZnSe elements, and the red has much higher transmission.

Comment from: lasersafe1 on Friday, February 5th 2010 - 11:54 PM

Ooohhh! Those are not simply CO2 mirrors, they are Dichroic mirrors that will reflect the CO2 (10.6um) but have the capability of passing visible light. Me wants! Having one of these mirrors as the very first corner mirror after the laser allows you to combine a red or green laser onto the same beam path as the primary CO2 by shining it through the first mirror. The remaining mirrors in the system are generally complete reflectors of both wavelengths. This is great if you want the visible beam spot for setup. You won't get much of the visible light into the system. You will lose about 50% on the entry and you may 10% on each subsequent mirror bounce, but you only need to end up with about 20 microWatts of green to see it quite well on a surface. Considering the common green laser pointer starts at 3-5mW and prices are as low as $15 (Geeks.com) it's a pretty simple thing to add.

If you can spare one.... I'm interested. By all means, tell your friend at the Hospital to save anything he can!

I have seen some of those articulated arm systems going on Ebay now and then. I always wondered about the mirrors. Cool!

Friday, February 5th 2010 - 10:01 PM

Mirror Assemblies

Before I start I must admit that these mirror assemblies are not the standard run of the mill stuff that you find on most lasers. These assemblies were given to me by a friend of mine who works at a local hospital where they were....here it goes....trashing a CO2 laser because it was too expensive to fix....sheesh. Anyway, most of the stuff was already disposed of except for these mirror assemblies which where used in an articulating arm....I guess used during surgery. I was able to get 6 mirror assemlbies. If you look closely you will see 3 holes in at the bottom of each block. These are used to adjust the position of the mirrors internally. The exploded view shows the mirrror mounted in a metal ring and then the 3 jack screws, going through some small ball bearings and a wave washer adjust the position of the mirrors....pretty slick eh?

Since they were free I thought I might as well use them.....right.....right!!!

The rest of the pics show the first and second mirror assembly which returns the beam back on to the Y axis gantry.
The other pic shows the mirror mounted on the Y axis gantry, pointing towards the last mirror and lens ass'y. Those pics will be posted later.

There was a lot of machining to do, but what the heck, it was fun.

Richard
Attachements...

: Mirror Ass'y.jpg (55.89 KiB) Viewed 22398 times

: Mirror Ass'y Exploded.jpg (160.23 KiB) Viewed 22417 times

: Return Mirror Ass'y 1.jpg (52.49 KiB) Viewed 22391 times

: Return mirror assemblies; Return Mirror Ass'y.jpg (61.8 KiB) Viewed 22390 times

: Y axis mirror located on the gantry; Y Axis first mirror ass'y.jpg (47.98 KiB) Viewed 22400 times

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Thursday, February 4th 2010 - 9:46 PM

You're absolutely right there with respect to the WAGO Din rails and terminal blocks and I wish I had them, but I have so many terminal lugs and terminal strips in my junk box, that I figured I would use them up. If I was to design this at a commercial level, then that style of block is the way to go. After 40 years of being in ham radio, its unreal the amount of junk one collects. The scary part about that is that even though I may not have used a particular part in 20 years, I know exaclty where it is in the mayhem......sheesh....scarey eh? :!:

Thats the nice thing about this DIY project...you can use whats at hand as long as its safe. I like have the cables dressed up as much as possible. I used to do the "rats nest" approach, but after a while, it became a total nightmare in trouble shooting and maintenance...and beside its looks like a "rats nest"....

Cable dressing does take a lot longer, but I think its worth in the long run.

Basement time for me again. :lol:

Richard

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Comment from: lasersafe1 on Thursday, February 4th 2010 - 4:53 PM

I know that you have settled on the terminal strips and it looks great. Having worked with them in the past I know what a hassle it can be to crimp all the lugs. I have found that the WAGO DIN rail mount terminals are quite handy. They use a crimp cage that releases by poking a screwdriver into the release port. No need to strip and crimp lugs, you simply strip it and push it in. I have never had a connection fail with the WAGO. http://www.wago.us/products/303.htm

Thursday, February 4th 2010 - 3:45 AM

Wiring

Here are a couple of pics of the interface between the machine and the outside world. All external connections are interfaced using Amphenol quick disconnect plug and socket. The same is true at the power and laser supply.
One thing for sure, you really have to document everything from colour of the wire and pin location and this has to be done at each end and cable ends.....talk about going nuts keeping track of everything. I put it all my wiring documention on a spread sheet and work from there.

I have also isolated the quick disconnect panel from the internal wiring so that if I do run into a problem, I only have to replace or repair wiring up to the terminal strip. Saves a lot of headaches when replacing worn wires or trouble shooting.

As you build the cable harness, one must always light it out one wire and pin at a time. Don't wire it all up first and then check for errors.....I did that once....and only once.....never again.... :lol:

The panel holding the amp sockets was made from a piece of 1/8" x 4" x 4" angle aluminum and then machined to size. Its quite robust.

All multiwire cables are shielded and grounded. I use a lot of cable ties and those sticky pads all over the laser base. I think it makes for a nice clean finish.

Time to get some sleep.

Richard
Attachements...

: Interface between quick disconnect and internal wiring; Wiring 1.jpg (100.22 KiB) Viewed 31474 times

: Quick disconnects; Wiring 2.jpg (91.32 KiB) Viewed 31474 times

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Comment from: lasersafe1 on Thursday, February 4th 2010 - 2:25 AM

Join the club Richard. We all seem to have problems with Mach3. Some have had good results with EMC2 under Linux. I went ahead and purchased a commercial DSP to do it. Bart is, of course, making great progress with his Xmos controller. I finally achieved total success tonight with the DSP and I couldn't be happier. I will soon put a video on Youtube and link to it from the commercial controller section of this forum.

Wednesday, February 3rd 2010 - 8:31 PM

It should engrave but I do have a slight problem with text.
I've run simulations on MACH 3 and for whatever reason and when I translate into G code using LazyCam, it does not execute the text at the speeds that I want. ie.....I would like to cut at say...1/2 power at 1 in/sec and then to mark the text at say 10 ips and at reduced power. I've tried associating in the dxf format....layer 0 as the cutting layer and layer 1 for example as the text layer...with no luck. I'm not going to worrry about that yet since I have bigger fish to fry....no pun intended...getting the machine up and running as an integral unit.

Anyway, I'll ponder that one for a while. Maybe I am doing something totally stupid...which does happen from time to time.... :oops:

Richard

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Comment from: bdring on Wednesday, February 3rd 2010 - 7:08 PM

Your machine is looking great. I like the details like the layout of the wires. I love big heavy machines. My wood router could probably lift 400 lbs on each axis.

I think your router will probably be able to engrave just fine. The X axis will should be fast enough. If you are not worried about production speeds, just turn down the power. Maybe you could engrave little part numbers on the airplane ribs before you cut them out. :lol:

Wednesday, February 3rd 2010 - 3:12 PM

Here is a closer view of the X axis carriage and parts of the Y axis gantry.

The X axis rails are bolted to a 1.5" x 54" x .375" piece of hot rolled steel. Both of these assemblies are then bolted to the base. Each rail can be adjusted with shims in case there is any warping.

The X axis also drives the other side of the Y axis gantry. You can see the small drive pulley in the picture, but the drive belt was removed. The shaft is a 5/16" in diam coupled to the pulley by machining a small coupler. I didn't have a misalignment coupler so I figured I'd just machine a simple coupler.....so far so good.

The trick to all of this mechanical stuff is to use Loctite on all screw threads as well as machining small flats on all shafts so that the locking screws don't rotate around the shaft.

The Y axis gantry shown below has the mirror and focusing assembly removed for clarity. You can see the home and limit switch levers in the background. The Y axis gantry uses the same rail and carriage parts except that the gantry is now machined out of 1/4" angle stock aluminum. More pictures will be coming, once I get it all back together.

Although I may have gone overboard in my design philosophy, I had to work with what I had thus this machine is becoming very robust and solid. The bigger the machine the heavier the hardware gets....oh well.....its fun!!!

One day I might attempt designing a flyweight engraver......just for the heck of it.... :geek:

Back to the basement for me....they do let me out once in a while.... :lol:

Richard
Attachements...

: X axis / carriage and Y axis gantry; X axis carriage.jpg (83.88 KiB) Viewed 31506 times

: X axis drive ass'y view 2.jpg (71.49 KiB) Viewed 31503 times

: X axis drive; X Axis Drive Ass'y.jpg (110.68 KiB) Viewed 31483 times

: X axis pulley; X axis idler drive.jpg (72.91 KiB) Viewed 31451 times

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Monday, February 1st 2010 - 9:28 PM

I am using an old version of Autocad 2000. I am quite familiar with it so I keep on using it. I have access to SolidWorks 2007 as well, but its a totally different way of thinking and a bit too structured for my thought processes.

I'll be posting the Y axis gantry later on today or tomorrow.

Richard

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Comment from: bdring on Monday, February 1st 2010 - 9:03 PM

That looks good so far Richard. I saw your 3D model. What CAD system are you using?

Monday, February 1st 2010 - 6:33 PM

X Axis Drive Ass'y

The X axis drive uses a 3:1 reduction drive in order to increase the torque on the system. Since this will be driving the fully loaded Y axis, I figured a little reduction in speed would hurt. The X stepper motor drives both sides of the Y axis to minimize any potential binding. After I built it I tried driving the Y axis gantry with just one belt and then two and I didn't see any difference in speed or binding. I guess the rails and and carriages that I am using are robust enough to keep the system square.

The aluminum support brackets were machined from 1/4" stock angle aluminum...purhchase as off cuts from any metal market supply house. Bolts are all hex head. I am also a firm believer in using Loctite on all bolts. The blue or purple Loctite is perfect....don't use the Red or Green...those are permenant. No matter how tight you think you can tighten by hand, micro vibrations of any system will loosen them up if you don't use Loctite. I learned the hard way :!:

Everything was machined at home. The small bearings were purchased from http://www.vxb.com/ which is great site for all kinds of bearings, rails etc......prices are good and delivery is very fast as well.

Maximum speed that I have been able to get out of it driving a fully loaded Y gantry has been just around 830 inches per minute. I suppose that by change the reduction from 3:1 to 2:1 or less I will definately increase speed, but in a cutting application, speed is not the issue especially when using on a 60 watt laser. The lasers that I have seen are cutting in the range of about 60 to 120 ipm. Only time will tell when I get the whole thing working as a system. I have run the positioning system at full speed and it hasn't shaken loose yet or walked across the floor. I guess I have it tuned well.

The drive belts (not shown) and pulleys and idlers were purchased from http://www.sdp-si.com/ which is a great source for this type of stuff.

I am using GT2 3 mm series of timing belts, pulley and idlers. They aren't cheap, but the specs are impressive.

Richard
Attachements...

: X Axis Assembly; X Axis Drive.jpg (71.54 KiB) Viewed 31526 times

: X axis pulley; X Axis Pulley.jpg (60.01 KiB) Viewed 31532 times

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Monday, February 1st 2010 - 5:32 PM

Main Base Ass'y

Built from 5/8" melamine. Everything was cut at Home Depot so that edge were square and sharp. For this to work, the edges must be square and straight.
All bolted together using a LOT of # 10 1 1/4" Philips head screws.
Exhaust a 4" hole cut in the base of the structure.
Total area of the plenum holes must be much greater than the area of the 4" exhaust port....this just reduces air resistance.

Not shown is the cutting area that is a laminated with aluminum duct tape. If it burns through, then its just a simple matter of replacing it with some thin aluminum sheet...but until then...who cares.

I have use this type of box structure in other applications and it seems to hold its dimension. Since there is very little load other than pure dead weight, I really don't see any problems developing. However that being said, you might want to seal any exposed wood with some sealant to reduce the amount of moisture being absorbed over time.

Length: 63"
Width: 30"
Thickness: 7 1/2"

Richard
Attachements...

: Top View; DSC00568.JPG (523.94 KiB) Viewed 31608 times

: Close up view; DSC00563.JPG (228.66 KiB) Viewed 31580 times

: Bottom view; DSC00565.JPG (225.49 KiB) Viewed 31555 times

: Exploded view of base ass'y; Vacuum Box.jpg (74.06 KiB) Viewed 31520 times

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Monday, February 1st 2010 - 5:18 PM

Well I guess I had better post something pertaining to my completly homebrew DIY laser cutter.

My intension was NOT to design and build an engraver, but rather to create and build a laser cutter for cutting balsa and plywood for radio control aircraft, where I do like to spend my time outdoor in the summer months.

Since this is only a hobby, I am trying to design and build this machine with as many junk parts that I have in my junk collection or donated by my friends junk boxes.

Since I am also a ham radio operator, this lends to collecting a lot of electronic junk as well....and over the years....a lot of junk that has been collected.... :lol:

The laser itself is from an off shore source...of course. Its a 60W CO2 laser complete with power supply.

The system is driven by MACH3 software. The stepper are way too big for the job, but good enough for me. Power supply is rated at 56VDC at 10A.....I guess I can do some welding here as well when I get bored.

The system was designed around a using a melanine box structure. The box structure will give the system tremendous rigidity, providing its designed correctly. I base assembly where everything is bolted to is 63" x 30" x 7 1/2" high.
The system is bolted to a mobile table. Everything is designed to fit through a 30" house door.

The working area of the laser is 15 1/8" wide x 48 1/4" long. Reason for these dimensions is that most balsa comes in 36 or 48 inch lengths with the majority of width being 3-4 inches. Most aircraft plywood comes in 12" widths with the same lengths.

The internals of the box is the plenum where exhaust gases will be drawn through. Everything on the system is modular for ease of removal and maintenance. The main rails are hardened and mounted on a steel bar. This assembly is then bolted to the base.

My workshop is well equiped with a Myford lathe, a small bench top milling machine, a good size drill press as well as a good selection of measuring and hand tools. One the electronics side, I have scopes, signal generators, spectrum analyzer and stuff like that.

The concept drawing is shown below and as I add more and more to this buld log you will see the actual progress and how it mimicks the design concept.

Richard
Attachements...

StarontechLaser Model (1).pdf: Concept drawing; (138.35 KiB) Downloaded 2078 times

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Buildlog Title: TOTALLY DIY LASER CUTTER

Tuesday, June 8th 2010 - 12:05 PM

Monday, February 22nd 2010 - 2:27 PM

Sunday, February 21st 2010 - 2:08 PM

Friday, February 5th 2010 - 10:01 PM

Thursday, February 4th 2010 - 9:46 PM

Thursday, February 4th 2010 - 3:45 AM

Wednesday, February 3rd 2010 - 8:31 PM

Wednesday, February 3rd 2010 - 3:12 PM

Monday, February 1st 2010 - 9:28 PM

Monday, February 1st 2010 - 6:33 PM

Monday, February 1st 2010 - 5:32 PM

Monday, February 1st 2010 - 5:18 PM

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