Laser Cutter Rebuild

So here are a few warnings about the redsail knockoffs 60w 700mmx500mm machines on eBay
right now. I've worked on a lot of laser cutters out there and this one is no different. 1st I'll tell you the good things. The frame and case is pretty good and the shipping crate is well made and plenty of foam to protect it. They are using linear rails and belt drives however they are free floating so there is a good amount of slop. The control panel is the updated color version with a hidden ethernet connection that is functional. The machine and all the accessories are 110v right out of the box.

The bad news

1. The tube they ship it with isn't actually a 60w tube. Mine came marked as a 55w but has the dimensions of a 50w. However the power supply is a 60w and it cuts like a 50w tube.

2. The focus lens came already chipped and flaking off.

3. The ad showed that a cw-3000 chiller was included but instead they shipped it with an aquarium pump. They would not ship me the right chiller.

4. Beware of their wiring. Mine came with 22 gauge wiring for all the power. So I rewired mine with some 16 gauge since the wires were melting on day 1.

5. They run the main power for the laser/control and 3 plugs on the back through the E-Stop which after only 1hr of running more than over loaded it and melted it into a nice pile of plastic. Which you can see in the picture.

6. Not a big deal but the z-axis is a non-stepper motor so while it is powered it is not capable of doing auto focus. However with a proximity switch, stepper driver and nema 23 motor you could rig one up.

7. If you replace the tube you will need to replace the optics and mounts since the y-axis motor gets in the way.

8. The mirror and optics they ship with are horrible and not worth anything if you ever want to do anything more than 50w.

So be warned that you should expect to do a tube upgrade, rewiring and get a real chiller if you get one of these machines.

If you plan on replacing the optics and tube you should really take the top off the machine. The reason for this is because you want everything at right angles and equal height but with the top on you will be stuck fighting it and never getting anything really straight. It's not hard so it's worth the work. It's held on with about 10 bolts around the lip of the machine. Pull those out and pull of the wires that are in the way. it lifts straight up.

This is my comfort modification. If you raise it up 9" you can slide a good chiller and blower under the machine. It also has an added benefit that while standing you can load material in and out of the machine without bending over.

Start by cutting off the front support that runs from left to right. You can use a cut-off grinder or a metal jig saw. Leave the back one on. It won't interfere with anything and it will give good horizontal support.

Next build a wood frame from 2x4' to raise it an additional 9 inches. I rip cut the 2x4 to be the width of the legs so that it looks pretty, you don't have to if you don't want to.

I then used 1x4 in the same place and the original horizontal supports so that I could screw down the cutter to it.

I drill and bolted the new structure to the base with 1/4" bolts and washers and did the same to mount the cutter to the top.

You should skin the box with 1/4" or 1/2" MDF or plywood. This is not just for aesthetics but is also structural.

You could weld up a new base or skip this all together. I just have hand tools and a portable table saw so this was my solution.

Now mount up the laser cutter to the top and lets gets busy on the rest of the work.

The problem with the machine I got was the Y-axis motor was under the tube so installing a longer one would get in the way of the y-axis motor. The other problem is that they used a horrible mount with lots of flex and slop in it so I was skipping steps and all my circles came out as eggs.

So I got a new robust motor mount.

http://www.lightobject.com/Nema-23-57-series-stepp...

I then moved the motor to the inside and turned the cable chain around to make room for everything.

It's important to keep everything tight and square. The motor should be mounted parallel and centered to the teeth on the bar across the machine. If it rides or drifts to tight to the edges then the belt will wear down over time.

Doing my mount i had to cut a small chunk out of the lip of the cover of the machine to make a tight fit. No big deal with an angle grinder or dremel with a metal blade.

This is the fun part and the annoying part. We need to define a good beam path from the tube and all the mirrors and the lens. Remember when I mentioned how important right angles are? Well this is the part where it all matters. Your tube needs to be perfectly parallel with the Y-Axis and your 1st mirror needs to be perfectly parallel with the X-Axis and your 2nd mirror needs to be parallel with your laser head which is also parallel with your tube. Basically you are bouncing your beam around and if you are not hitting each mirror at 90 degrees then your beam will drift. The other thing you need to remember is that everything needs to be level. The tube should be level and the center of all of the mirrors should be at the same height and the center of the tube.

The design of this cutter doesn't have very much room for the 80mm diameter tube in height so we have to get the mount for the tube as low as it can go and still get around the y-axis bar that runs along the back. The best mounts I found for this are at lightobject.com and you will need two of them. If you look at the picture you will notice that even then they were not low enough so I drilled and mounted them from the underside.

http://www.lightobject.com/Pro-Laser-Tube-Mount-80...

Even with mounting this low I still had to do some cutting away of some of the top to make room for the beam. I cut the top off about 2" where the beam hits the 1st mirror and goes through to the second one. I then cut off the inside top part about 2" along the X-Axis so the beam could bounce off the second mirror to the head without obstruction.

Once you have the laser tube mounts installed you can grab and 3d print my 80mm laser tube simulator 3d files. You don't really need them but it does make alignment a lot easier. They can be used to show where the beam goes and help you set the height and center each mirror.

http://www.thingiverse.com/thing:1121476

Why replace the mirrors? Well the ones that came with my cutter were small 18-20mm mirrors and cheap gold flake deals and they easily burned with the 100w tube so I decided to get bigger 25mm mirrors and 20mm lens that were better suited for a 100w laser.

Here are the mirrors (3)

http://www.lightobject.com/25-mm-Molybdenum-MO-Ref...

Here is the lens

http://www.lightobject.com/High-quality-20mm-ZnSe-...

Now lets get the 1st mirror mounted so that the beam hits center of the mirror and the mirror should be at a 45 degree angle to the tube and to the second mirror. The mount should also be square to the second mirror as well. I suggest using a straight edge and a framers square.

The problem I ran into with the first mirror is that it was too tall and i had to cut it down with the grinder again and then tap the set screw holes all over. Lightobject.com does carry a nice first mirror mount but it only comes in a set and the rest of the set won't work for what I needed. So I ended up buying it from ebay. I included a picture in case the link no longer works.

http://www.ebay.com/itm/181878042820

Now onto the second mirror. I chose this particular one because it had a good mount that could slide left/right up/down and turn. This really made mounting and aligning really easy. Once again lightobject.com has some but none with a good mount already included and basically this whole laser cutter has trash parts so very little could be reused. I just removed the old trash and bolt on the new goodness

http://www.ebay.com/itm/171853897217

Finally the head. lightobject.com has great heads but none with a good mount again. So this one has a mount and is good for left or right mounting and it was easy to bolt to the linear block already on the cutter.

http://www.ebay.com/itm/181565278587

So keep mounting and aligning everything and squaring everything up and don't mess with the tube yet. You can do the real aiming and aligning of everything later. Right now we just want to measure it as best as we can.

Once you get the optics and tube mount you can put the top back on but lets not get to the tube yet. I didn't like the vent coming out of the side of the machine so I covered the vent and cut a hole in the back and vented out the back door of the machine.

Here is the vent cap

http://www.thingiverse.com/thing:1121639

This is the flange I used

http://www.ebay.com/itm/121057502097

I also wanted to relocate the USB and power plug to the back of the machine where the old plug outlets are. First I removed the plugs and removed the wiring for them because the wire was horrible and melted it with the blower and chiller and pump on it. I moved to an external power strip with control ports on it that turned on of off plugs if I turn on or off the laser cutter.

The power strip I used

http://www.ebay.com/itm/321897034679

Here are the 3d printed parts for filling in the blank holes left by removing the plugs and/or replacing them with a usb port and/or moving the power to the back of the machine.

http://www.thingiverse.com/thing:1121650

This is the USB extension cable I used.

http://www.ebay.com/itm/111556007548

Coming soon will be a mount for extending the ethernet out the back using this cable

http://www.ebay.com/itm/291083210243

Finally as part of the cooling system I removed the water flow sensor and wired it into the chiller alarm according to the drawing in the chiller manual which was using pins 1 and 3.

OK finally you can install the tube and wire it up and install the water lines but now you have a giant tube sticking out the side of your machine. You should consider covering it up. Here is my 1st revision for a tube cover and I'm currently working on a second revision which I have posted the files but I have not tested yet so I don't have pictures. The reason for the second version is that I wanted it to bolt on with 8mm threaded rod so it could take a real bang if it got hit. The first design requires you to be really gentle around it or it might snap off.

Design one which is pictured.

http://www.thingiverse.com/thing:765057

Revision 2.0 which is a lot stronger but requires 8mm threaded rod and nuts.

http://www.thingiverse.com/thing:1121681

Align everything like you normally would, attach all the old wires back up and you should be good to go.

I plan on doing another write up on doing all new wiring in the near future so stay tuned.