Full Spectrum MLE-40 (4th Gen) Restoration with Cohesion3D upgrade!


(Jamie Richards) #1

Here we go! This will be a before, during and after restoration with upgrades/mods. I picked this machine up for $120 because the previous owner removed parts to put in his K40 and didn’t have anymore use for it. I like calling this model the mother of K40s because it appears to be the model they cloned from, except the cut area is larger, sheet metal is thicker, the gantry is aluminum, the entire unit, including the tube bay comes apart and it has dual linear rails!

Many of the components will need reattached, which won’t be a problem. The gantry was no longer bolted down, but surprisingly didn’t get bent and twisted during shipment. Unfortunately, the acrylic window and tube were busted thanks to the excellent handling of FedEx.

The controllers they put in these are getting obsolete and the Cohesion3D board will be an amazing improvement!

This is how the unit looked before receiving it. The following photos are courtesy of: @Starla .

Nothing a little elbow grease can’t handle.

Where’s the stepper motor?

There it is, on the floor!

That little rectangular piece is a ceramic terminal block that originally had the tube ground connected. It’s unnecessary, but I’ll leave it in.

More elbow grease needed.

Tube bay. I Need to find something to put around the tube since the original rubber grommets are missing.

This actually looks worse than it is.
Some of the wires were cut. No problem, I’ll get to those.

I originally thought someone changed the potentiometer to a multiturn design, but then found out they came standard and were disabled altogether after 2012 to become software controlled. An even more awesome software called LightBurn will be controlling it now!

Electronics compartment. I’ve seen worse. :flushed:

Rear shot of electronics compartment. :flushed:

Surprisingly, the power supplies used in these have the same type 2 plugs and would directly connect with a K40 replacement supply.

More to come!

(Cliff Bryans) #2

Looking forward to seeing more of this. Love a good restoration.

(Jamie Richards) #3

Starting to clean up fairly well!

I have a good bit of it disassembled here because I want to go through each part to make sure anything needing replaced isn’t missed. The only thing actually bolted down when I got it was the power supply.

Took a look inside the power supply to make sure some things didn’t get inside during shipping since there were some loose screws and washers. Good thing I did, there was a washer stuck inside.

Interesting internals. Slightly better quality than the stock K40 supplies.

This is where the Cohesion3D is going.

Electronics compartment is definitely starting to look better!

(Jamie Richards) #4

Gantry is bolted in. Everything is square, the higher quality (than a K40) aluminum gantry held its own during shipping.

One problem the machine had was the carriage wheels. The two on the rear of the carriage were in bad shape and had been replaced with 3D printed pieces that didn’t quite work out.

Here’s one I tried cleaning up by putting it on a drill as a sort of makeshift lathe, but even with it spinning and using sandpaper+steel wool, this is the best it would do.

So I had no choice but to order new ones. Cohesion3D now sells these in 4 piece kits, BTW.

Looks good!

Shot with both sides.

The next problem was the idler wheel for the X axis. It had an intermittent grabbing feeling while moving the head carriage back and forth and my first thought was that it perhaps had a bad bearing, but after swapping bearings, there was no change. This lead me to believe the plastic part itself became misshaped and I had a larger aluminum pulley that I planned on using sometime in the future with a DIY build using GT2 belt, so I put it to use. it is working fine and the head carriage now moves smoothly without any grabbing whatsoever.

It appears that someone changed the belt to a slightly smaller K40 belt. You can clearly see where the smaller belt left its mark. I’m going to completely eradicate the MXL setup and switch to GT2 pulleys and belts. 6mm for the X and dual 10mm belts for the Y.

Slightly larger diameter than stock, both are 6mm.

(Cliff Bryans) #5

Thanks for the update. My x axis is a little grabby as well if I tighten the belts, I will try your fix and see if that helps.

(Jamie Richards) #6

GT2 belts provide smoother operation and less backlash. GT3 belts provide even less backlash. I may switch to them sometime in the future and there is no need to change the GT2 pulleys since it’s just a better grade GT belt.

(Jamie Richards) #7

That MXL Y axis belt looks terrible.

This is its replacement! GT2

(Cliff Bryans) #8

Wow that old belt has seen better days.

(Jamie Richards) #9

Definitely a little weathered.

(Jamie Richards) #10

Some people claim I’m never happy with anything I do because I appear to be a perfectionist. Perhaps they’re correct, so I tore the heck back out of it and started over to correct a couple things I wasn’t happy with, like the limit switches. Also sat a couple things inside temporarily, hence the flaring tool.

(Jamie Richards) #11

Now that the shock is over, Harbor Freight has rubber grommets fairly cheap, so I picked up some to use on various projects, but I also noticed the frame where the lid comes down has rubber grommets as a sort of shock absorption aid and found it ironic that the grommet kit contained the same size, so I yanked out the old, squished grommets and replaced them with the nice, new and fluffy ones. :smiley:

Out with the old

In with the new, fluffy variety.

When I changed the Y belts, I had to remove the linear rails. I checked the bearings and they were great, no sideways play to be noticed an they glided along the rail smoothly.

That’s gotta go!

Getting the pulleys off was a challenge since I didn’t have a puller. I figured the easiest way would be to remove the rotor and put it in my arbor press. That would have worked had the magnet not stuck to the side of the press. I didn’t know it happened and it damaged the rotor. I am using more powerful motor for the X rail now.

For the second motor, I figured out another way to remove the pulley without removing the rotor by putting it in my hydraulic press and using two pieces of angle iron to hold it in place and a 5mm bolt to push the shaft out. I need to work on getting a puller! This worked great with no damage!

I not only wanted to redo the soldering on the limit switches, I wanted to reposition the X switch because it’s under the rail and doesn’t allow the carriage to move as far as it can while still having cut space, so I decided I was going to relocate it.

The X-Rail goes over this and I realize they were probably just trying to hide it, but that wasn’t the way to go about it. I had a different idea that would give me over 15" of cut space and still limit the carriage without going out of the cut area.

This switch has seen better days. Not to worry, I can solder. Also want to clip out that pesky center pin.

I made a spot welder a couple years ago using a microwave oven transformer. (don’t try this at home, kids) I never really got to use it, but relocating the endstop switch finally gave me a reason to!

It’s a terrible looking thing, but gets the job done!

More to come! I still have to get everything back together and resolder the switches in place.

(Cliff Bryans) #12

Care to share how you made a spot welder from an MOT, that could come in handy.
Loving the updates.

(Jamie Richards) #13

After finding a microwave oven you want to destroy, you remove the transformer. Has to be one of the older styles because the newer ones with a switching supply won’t be large enough. Be careful of the capacitor used in these because should the internal resistor fail, it could still hold a charge and you don’t want a 2KV+ jolt since it could be bad. Do not plug the microwave oven transformer in after it’s out because again, 2KV at the half amp or so it outputs can kill you instantly. Remove the secondary winding (the smaller wires and not the one that connects to AC) and discard, recycle whatever. It can be a challenge to remove. I’ve used chisels and hacksaws, both will work. You have to be careful when cleaning the secondary out of these transformers since damaging the primary windings could possibly cause a short. Get some 2/0 (awg) cable and wrap it around at least 2 times where the secondary winding was. The extra thick wire is now your secondary and can hold 600-800 amps at 2-3 volts, roughly. Make sure the thick wire is long enough to run to whatever you use as contact points. I just jerry rigged mine using leftover parts, mostly. Be careful of the magnetron in these, it’s the thing with two magnets, cooling fins and usually a square shaped cover on the bottom. The other end will have a small ceramic looking shaft with a metal cap on the end. Be extremely careful with this because should that ceramic break, you will end up with lung cancer since many of them contain beryllium. Beryllium is extremely dangerous to your lungs and it only takes the smallest amount, even on your skin to cause problems, so just a few particles floating in the air from the break can give you cancer. Wrap it in a bag, or several bags for recycling and keep out of reach of everyone! Okay, I have to give that warning even though I regularly remove the magnets, I want people to know the dangers. I had an appliance guy give me 30 microwaves at once when he bought out another place that had several non working pieces laying around. I fixed the ones that were worth it and scrapped/parted out the rest while keeping some transformers to play with.

I experimented with a variety of methods. What seemed to work well was integrating some copper tubing I had left over from a plumbing project.


Coming up with a box to put it in. I also had some leftover wood to make a rough looking enclosure.

Wanted to put a cooling fan in it because the transformer can get pretty darn hot!

I used aircraft grade cabling. I accidentally bought #2AWG instead of 2/0, but it still works, just not with very thick material.

My first test playing with it, I used a utility blade and a couple washers to make this.
I put a power switch on the back.


(Cliff Bryans) #14

Awesome, thanks for the info. And the advice about the magnetrons is always good to give because most people just don’t know. (safety First). We have a MOT set-up at out makerspace to do lichtenberg figures in wood.

(Jamie Richards) #15

Wish I could afford to start one of those, but I’d need a sizable loan. There are no places like that around here.

(Jamie Richards) #16

Oh, I thought about doing that with a couple transformers I still have. Using two together to double the voltage.

(Cliff Bryans) #17

Honestly it works quite well with just one. As well you can try different electrolyte solutions for different effect.

(Jamie Richards) #18

Getting back to the limit switches, the ones I removed to resolder are not the originals. The previous owner thought they were bad and replaced them, so I tested these ones with the continuity function on my multimeter just to be sure they’re ok and they tested good. If you suspect your switches are bad, the mechanical switches are normally closed and can be tested with a meter. If you are reading this and have a K40 with optical limits, here’s a guide to test them:

My solder job looks slightly better than original, although I could have gone a little closer on the bottom wire.

Let’s slide the heat shrink on, use the heat gun and attach it! I have this thing about using longer than needed heat shrink tubing. Won’t hurt anything.
Looks good! Those wires will be straight out to the left when I’m finished.

It triggers just before this, but gives a good idea of how well it’s mounted. I now have just over 15" cut area on the X.

Now on to the Y switch! Not quite as bad as the X.

Yay, I actually used shorter heat shrink tubing!

Next up, how I’m remounting the drag chain for the X rail without the original bracket. The answer may surprise you!

(Jamie Richards) #19

Sneak peak at how I’m mounting my drag chain. More on that later, I need to snap some new pics since many have mysteriously disappeared.

This is the old bed / table from my K40.

(Cliff Bryans) #20

Looks well used. I’m going to guess this will be replaced.