First off did not see a section for laser build logs so just picked this one. If this is not the right spot feel free to move this thread.
Been drooling over the Ebay Chinese laser engravers for a while since they were in my hobby budget range. In all my watching I was always hoping someone would post a 300x500mm machine without all the extra bells, whistles, and cost so it was more around 2x the 200x300mm machines vs the 4x to 5x there were. Was about to give up on this acquisition when I found out the 200x300mm machines had NO Z adjustment. Just for grins posted on Craig's list looking for a used or broken laser cutter / engraver. Got one response from a guy ~3.5 hours away that had a old ULS 25PS. Story I got was he bought it from a high school as a parts machine for his other ULS 25PS. Right off the bat it had some issues like no laser (he kept it as a spare for his machine), unknown electronics (did not power up), mirrors and lens were shot (coating burned off in spots), and very dirty (High school shop then stored in a shed nuff said). After some negotiation came to an agreement and packed it up and hauled it home.
First thing once home tore the machine completely apart and cleaned everything. Some scraping, simple green, and a scrub brush later got most of the black and gray gunk out. Let the part dry in the sun then started hauling everything inside for reassembly. Other than some random missing screws and washers all the electro mechanical parts were there and seemed to be in very good shape. The Y gantry and Z lens assembly has almost no play in it and both slide very smooth in their runners. All 3 stepper motors Ohm out properly (will try and run them for real once I get drivers up and running). 2 of 3 home switches were in good shape the third (Z) got hit at some point in time and had a busted mounting ear.
At this point my next order of business was to get the axis moving and figure out if the electronics were salvageable.
I enjoyed your you tube videos, and I am anxious to see more of your project. I too have a ULS25PS that I have had for a couple years. Surprisingly, my Synrad laser was still working, but just died recently. Not bad for almost 20 years old. Since then I have totally upgraded the controls to DSP, and in the last few weeks have been changing out the laser to a glass tube with updated PS.
One thing is for sure, the ULS25PS is a great base of a machine to start with as it is built like a tank, and with a 24X18 XY area, it can handle larger (at least for me) projects. This is just a fun hobby for me, I have almost had more fun upgrading my machine than the actual engraving.
Looking forward to your continued progress on this machine!!
In the processes of editing ~3 hours of trying to repair the power supply down. Unfortunately this weekend was consumed by patio door replacement and rotten sheeting repair. Hope to have them done this week and will post another update on what I found then.
By the way, are you planning to use the existing ULS25PS power supply with a new glass tube Laser? Not sure if it is capable of that. If you get that to work, I will be curious of what you did.
Unfortunately both the RF tube and power supply are missing from my laser (I think they were a single unit since I just have a pair of 120Vac power cords ending where the tube and supply would be). From my reading even on the ones where the tube and power supply were separate the external power supply was only a low voltage DC one (I think 24V at a ton of current). The HVDC laser tubes need ~25kV at ~20mA so high voltage at low current.
My plan is to go with a new dedicated HVDC supply for the new tube. Almost done with the patio doors so hope to get back to editing video and getting the next progress update posted soon.
Finally got the last video edited and should be uploaded in another 188 minutes...
Long story short the power supply for the motors and electronics is shot and the control chip is long obsolete. Also the H bridges are driven from a bunch of gals and a a 8051 derivative micro with a unknown communication protocol. Instead of trying to put a bunch of work into the old control system and getting stuck back in 1994 hardware and software wise decided to just replace it all. The Z axis has a 4A stepper, Y has a 2.2A and the X is 0.6A. Searching around ebay found some TB6600 4.5A and TB6560 3A stepper driver cards. Both have known issues but they are easy enough to work around. That a 24V power supply and some bits from my scrap pile will make up the base of the driver board.
Taking the diver boards apart for rework found the TB6560 have no heat sink compound between the driver chip and heat sink. The TB6600 heat sink is glued on. But... the glue was rubbery like silicone. Since I wanted to mount these to my base plate (1/2" aluminum way better heat sink than the included ones) it needed to come off either way. To remove the module I placed a machinist parallel against the side away from the pins. Then placed the entire setup in a vice so the heat sink was on one jaw and the opposite jaw was on the parallel. Did not take much force on the vice to shear the silicone and free the chip from the heat sink. Little bit of sanding to remove the silicon residue and the module is ready for mounting on the new plate.
Got lucky and found a screw block mate to the Phoenix Contact connectors already present on the stepper motor harnesses, rotary axis (in case I want to add one in the future), and the sensor plugs (all were available from digikey). Now in the process of laying out the aluminum plate and reworking / mounting the stepper drivers.
On the topic of control I was going down 2 paths:
1.) Raspberry pi running LinuxCNC via the PICnc project: Raspberry Pi â€¢ View topic - LinuxCNC
+ full featured CNC control suite easily expanded and large user base
- Raster support iffy. Sounds like folks have done it but not a lot of detail available
2.) Ramps derivative shield for a Arduino Mega using one of the following firmware load Lazrfish - RepRapWiki Upgrade That Cheap-o Laser Cutter!
+ read to go laser cutter control.
- limited g code support (no loops) and harder to modify (Homing the ULS 25PS is not strait forward the Y must be homed and moved back ~1" before the X can be homed. Also home is in the upper right corner not the upper left as one might expect)
Right now I am leaning towards the Raspberry Pi route since I can then stick it on my network and integrate some extra bells and whistles. (Water temp, air pressure, ect)
Oak thresholds for the patio door project are on back order for a week. So hopefully I will get some of the electronics mounted and can try bringing the steppers back to life this next week.
Anyone happen to have a ULS 25PS and can send me a picture of the safety defeat switch? It is in a ~1/2" hole along the front edge of the machine under the main lid on the right side. The manual says it can be operated with a tool but that is about all I know about it. Even better would be a vendor name and part number so I can get one on order. PO removed the switch and just cut the wires off. I know I don't need it but would be handy at times.
Little progress today. Reworked the TB6600 driver. The only major issue with them is the overtemp led has a ~500 Ohm resistor on the LED tied to the temp line. Unfortunately the max rating for the fault line is only 1mA and 500 Ohms will result in way to much current out of that pin. So reworked the resistor to a 5.11k Ohm resistor to limit the current under 1mA. Tested the led with the lower resistor and at 5V it did still light up but was quite dim. Since this is buried in the machine not a big issue to me. More just for diagnostics than anything so dim is good enough.
Next up was cutting the plate down. First I reached in though the control panel and outlined the inside lip of the top cover in marker to get the exact max dimensions the plate can be. Then a short spell with the bandsaw and the plate is cut down. Also noticed there was a cover mounting screw under where I wanted the plate to be. So drilled a divet on the back of the plate so it would clear the screw head. Laid out the first driver and tapped and drilled 4-40 mounting holes. Happened to have a some short 4-40 standoffs that were the right length to mount the board above the plate but still have full contact between the module and the plate.
After that got the first connector block mounted and the two wired together with some sort lengths of hookup wire. Test fit the plate in the machine and tried hooking up the shortest cable so far everything fits and clears the lid.
At this point I ran out of time for today. Hope to get some more done this weekend so stay tuned for more updates.
Looks like you are making good progress! Regarding that safety interlock connector, I am sorry I don't have a photo of it right now, or a part number, but it is a round 2 position flat blade receptacle flush with the top of the hole it is mounted in. My machine didn't come with the plug/jumper for it (bought my machine used), but I would guess they simply used the mating plug for it with the two contacts shorted together to bypass the laser safety circuit when the cover is open.
Just thought I would share a few photos of my machine upgraded to DSP. Might spark a couple other ideas for you. Not shown is the high voltage (120V) incoming power, 24VDC PS, and Laser PS, each of which are mounted on the back of the machine.
Looking forward to seeing more of your progress. Chris..
Going for more of a roll my own system here with some plans for some interesting upgrade options. More on that once I get down the road a bit. Also going to try and fit all the electronics under the right lid including the 24V and laser power supply. Initial planning shows it will work but will be very tight. Going to add a cooling fan or two to the right side along the way.
Well Sat was a bust as I was helping someone out rebuilding a pair of carbs for a Honda Shadow. Most of today was lost to another buddy with a busted washing machine. But I was able to get some things done. First off the holes in the stepper drivers would not fit anything bigger than a 4-40 screw. My stock was pretty depleted so picked up a few boxes of the various lengths I would use. Unfortunately they did not have full boxes in some sizes so had to pay the piece price for the others I needed.
First up was drilling and mounting the remaining drivers and the motor connector blocks. Man that was a lot of 4-40 holes to put in that plate. Managed to get them all in without breaking a drill or tap so overall a good day. Once they were all in place the next item to get mounted was the fuse block and the negative terminal block. Happened to have a old fuse block and terminal block so went with them. Unfortunately it was a little large and had push on terminals on it. (rather have screws or solder) There was no good place to mount it directly to the aluminum plate without tacking up the space reserved for the raspberry pi / ardunio and interface card or be in the way of the wiring blocks. So decided to just mount it up on standoffs. Happened to have a pair of 6-32 standoffs that were just the right height to clear the wring blocks and drivers. Also added some 6-32 holes to the edge of the plate to ground the shield of the motor cables to and drilled a clearance hole for the display support post.
Got the next driver wired up to the motor blocks. (but have not reworked it yet). That wire is shield 20awg. I found a roll of 18awg unshielded that I am going to use for the power lines between the drivers and the fuse block / terminal block. Finally using some 14awg from the blocks out to the 24V power supply. (when I get that far) Tomorrow going to finish wiring up the remaining 2 drivers and start hooking up power and signal lines. Hopefully if all goes well may have something moving tomorrow.
Got all 4 stepper drivers mounted and wired to the motor connector blocks. Also got all the 24V wiring run and fuse / screw blocks mounted. Got the plate (motor outputs) and fuse labeling done. Tapped and drilled the top of the laser cutter for the new plate mounting.
On the laser cutter side I added a chunk of sticky (good stuff) velcro to hold down the traveling ribbon cable to keep it out of the Y belt (was rubbing due to a twist in the cable). Also pulled apart the X and counted the teeth on the pulley and the pitch of the belt. The stepper pulley was 20 tooth and the belt pitch is 0.075". So for every revolution of the motor the head will move 1.5". With that information if my max step clock is 40kHz and I use 8 microsteps I should end up with 2250 IPM max (not taking in account missed step due to mass / other issues. Just the theoretical max it can do.) Looking around the internet's it seams like ~1000 IPM is what folks are running so should be ok. Also while I was in there I measured the Y axis belt and the OD of the Y pulleys (did not want to remove them for counting). The belt pitch and the OD of the pulleys matched the X axis. Still need to sit down and measure the Z pitch. Sucked up all the chips from the above drilling and tapping operation and buttoned everything back up.
Test fitted and bolted the driver plate down. Everything lined up as expected with plenty of Z clearance in case I need to add more of a heat sink to the back of the plate.
Back on the bench I hooked up the Kepco RMX 24-C 24V @ 9A power supply from my junk pile. Powered up and put out 24.2V unloaded. The RC (remote control) input floats to 5V and shuts down the power supply when pulled below 0.9V and seems to turn back on around 1.2V. Measuring the current on the RC terminals I got 1.5mA which give a internal pull up resistor value of ~3.3k Ohm. The main reason this is important is the TB6560 have a nasty habit of going Michael Bay if they are not power sequenced properly. The correct sequence is 5V on first the 24V on or 24V off then 5V off. The modules I got have a internal regulator that may or may not make the required sequencing. I will be reworking them to external 5V supply and enforcing the sequencing via the RC port of the Kepco.
Before I go any farther in the wiring I need to figure out my mounting method of the Kepco. To do that I need to figure out which laser Power supply I am going to use and get it's dimensions.
Still have not picked a laser power supply but from my searching so far I am going to need every mm of space under the lid I can free up. With that in mind I decided to lift the power supply up 3/4" to clear the wiring coming in and slide the power supply as far forward as I can. Made the risers from some 3/4" thick aluminum plate and counter sinked the bolt holes where they attach to the power supply.
Next up attaching the power supply to the frame. My plan is to just drill some holes in about the right locations and transfer them to the blocks on the bottom of the power supply. Then will drill and tap the blocks and secure the entire assembly with screws from the underside. But ran out of time for tonight so a project for another day.
So now need to search for a 19cm wide or less laser power supply. Also need to find a small 12V supply to run the fans and boot strap reg for the Raspberry Pi.
It's showing signs of life... New video up on the playlist
First up I got the 24V power supply mounted as far forward as I could. Used some scrap 3/4" alum to make some spacers. This was needed to clear the wires coming in the bottom and move the power supply as far forward as possible. After rough cutting the blocks drilled some holes for 8-32 screws and countersunk them. Screwed these to the bottom of the power supply and laid everything up in the cutter. One thing I forgot about initially was the control panel hinges. Leaving space for them to swing ate up ~1cm of extra space. Once everything was in place and cleared the covers marked the location of the blocks. From there just a matter of drilling holes in the frame and transferring them to the power supply blocks. Drilled and taped the blocks 8-32 and mounted the power supply in.
Next up was a bunch of ring terminal wiring. Connected 24V out to the distribution blocks on the driver plate and 120V in from the line filter. Also wired up the 24V remote shutdown lines and left them off to the side for future connections. Did some powered testing using a frequency generator and the Z is alive. Starts up from 0 to ~4kHz and stalls under no load at about 50kHz. Plenty fast for the z axis.
My friend Flint printed me a mounting clip I found on thingverse ( Raspberry Pi Plate by EhisforAdam - Thingiverse ) for my original model B raspberry pi (no mounting holes). Did some initial placement and should have plenty of space for it and the breakout card. Held off drilling the mounting hole until the breakout card design is done.
Measured the pitch of the Z axis and it came out to be 0.050" per rev. So with that I have all the info needed to set up LinuxCNC. Next up logic design for the breakout card so I can get that on order (will take about 2 weeks from the time I order before it will arrive).