It's new to me

[ddmckee54]

I recently purchased a small CNC router, fully intending to heavily modify it and turn it into a more respectable machine. This machine started out life as a Vevor 3018, the previous owner had upgraded it to a 4030 and upgraded the spindle to the high speed spindle motor. As built, these machines are real lightweights, the frame is made of 2020 and 2040 aluminum extrusions. But, Awesome CNC Freak has shown that with some TLC these little guys can be used to do useful work. He's machined a lot of the parts for his DIY 5 axis CNC using his modified 3018.

These are some of the cons that I see and what I plan to do about them:
1) It's a lightweight, it has no mass to it, and no base. I plan on adding a substantial base to this little guy. The first plant I worked in made laminated plastic sheets, I saw them make sheets anywhere from about 20 thou, up to 11 inches thick. In the years that I worked there, I accumulated several of their rejects. I'm going to use a 400mm x 600mm part of one of those 30mm thick sheets to make the base that every thing else will be bolted to. That 400 x 600 x 30 mm piece weighs over 20 pounds, and I can bolt that to the bench if needed.
2) They only used 10mm guide rails, those things will flex like crazy. I'm going to up-size the 10mm unsupported rails, to 12mm fully supported rails. Just going from 10mm to 12mm rails would be an improvement in rigidity, but using the fully supported rails should make that an orders of magnitude improvement. The X axis rails will be bolted to the base, further increasing their rigidity. The new 12mm Y axis rails will also be fully supported, and bolted to new 2040 extrusions - instead of being just a 10mm rail hanging in space.  I also plan on bolting those new 2040 extrusions together, which should also help to stiffen up the gantry.  If I have to, I can use this guy to mill out new gantry side-plates out of some more of that 30mm stock.
3) The Vevor control board leaves much to be desired, it's being replaced with an ESP32 control board with MUCH better stepper drivers.
4) They used about the cheapest, lowest torque Nema 17 steppers possible. There's no ID on them at all, but they're about the right size to be the 40-ish oz.in version. I already have MKS42 closed loop stepper controllers for these guys, If I need to upsize the steppers, I can go to 84 oz.in or 92 oz.in steppers in Nema 17, and still drive them with the MKS42's.
5) The stock Z axis just plain sucks, it's made out of injection molded plastic and it's only got 40mm of travel. It also has 10mm rails, but they're a LOT shorter that the X or Y axis rails so that alone makes them much stiffer. I can 3D print a temporary replacement that will give me more travel while working on a permanent solution.
6) The spindle, where to start, it's a GS-775M , 20K rpm, 75W motor. But at least it's got an ER-11 collet adapter on it. I can't complain too much I guess, my Unimat's motor is 100W, my Sherline's is about 125W, and my first CNC - back in the late 90's -  had a whopping 60W spindle motor. Awesome CNC Freak used a 200W motor with a speed reducer in his 3018, might do something like that. And then there's always that 1KW water cooled spindle and VFD that's been sitting in a box waiting for me to finish its' project.
7) This thing is drip-fed g-code through a G-code sender, I've got a used Tiny PC coming that will do just that. I've accumulated a DDCS stand alone controller and stepper drives over the years, which are also a possibility.

This and my other unfinished projects will keep me busy over the winter.

Don

[vtsteam]

Well, one nice thing about them (I don't own one btw) is that they are cheap and accessible. A heavy machine with powerful motors and spindle is out of reach for many. And they make an interesting upgrade project, which sounds like what we're in store for here! 

[ddmckee54]

"Interesting upgrade project", yes indeedy.

I got the 400 x 600 x 30mm base cut to size, and all the sharp edges taken off.  There's a lot stuff that needs to be bolted to the base, I'm thinking drilling & tapping will be best.  I'll just use longer screws for more thread engagement in the plastic.  It's HARD plastic, but it IS plastic.  I knew there was a good reason that I bought that push-pull power tapping attachment.

My 12mm rails arrived a couple days ago.  I first ordered the rails about 3 weeks ago, when they showed up I lifted the box I thought "My God, this is an awful heavy box for 12mm rails."  Turned out they were 20mm rails, I checked my order and sure enough that's exactly what I ordered.  When I contacted the seller about returning the rails, he made a counter offer.  He offered a 40% refund and I just keep the rails, saves both of us the hassle of returning them.  So now I have a pair of 20mm diameter, fully supported linear rails that are 1m long for some future project - with 2 sets of bearings.

I got the X axis 12mm rails cut to length yesterday.  I needed 450mm of rail for an exact fit, I cut them to 430mm so I could move them around a bit if needed.  The rails are hardened so I had to use the spinning wheel of death in an angle grinder to deal with them - I don't want to have to cut them more than once.  When I started mocking things up I discovered that by some happy coincidence the bottom of the bed is exactly 1/4' above the top of the bearings - talk about dumb luck!  And I just happen to have a couple of short chunks of 1/4" x 2" aluminum flat stock laying around. The bed will be in the original location, so no mucking about with the X axis leadscrew.  I think I can keep the Y axis leadscrew in the same spot, but when I print the replacement Y axis carriage I'll most likely need to move the lead nut location.  The new 2040 extrusions for the Y axis rails should be here in the next day or so, then I'll have a better idea what things could/will look like on the gantry.

[ddmckee54]

It's picture time.  This is the top of the old cnc, or what's left of it.

That's a 12" scale in the upper LH corner for size reference.

Here's the belly of the beast.

Both the horseshoe shaped top and the base are 1 piece metal castings. I took them apart to make getting this off my workbench a little less clumsy.  I'm pretty sure the base is aluminum, but as heavy as the top section is it could be Zamak.  Then again, there IS a lot of steel bolted to the top.  That orangish blob in the center is the 2 piece carriage for the Bosch 1Hp router.  It was machined using the original convoluted belt drive system that could only handle a DOC of about 0.010" at MAYBE a 10"/minute feedrate.  I remember it seemed like it took about a thousand passes.

OK, this is the new toy, it's sitting on its' base but nothing is bolted down yet.

The Sherline is visible sitting in the corner, that corner is where the old cnc sat for at least 15 years.

This next shot shows dumb luck in action.

In the background you see one of the new X axis 12mm rails with its' bearing blocks, just in front of it is the existing 10mm rail that's 450mm long and only supported by an M5 bolt at each end.  The new 12mm rails are bolted to a solid aluminum extrusion that will be bolted to the base by a pair of M5 bolts every 100mm.  The rails will be shimmed as required to make sure they stay flat.  In the foreground is the 1/4" x 2" aluminum bar that the bearings will be bolted to.  As you can see, that bar JUST fits under the work table.  Like I said, this is dumb luck in action - not prior planning.  Right in front of that is one of the 2040 extrusions that are the major support of the machine, and the just hang off 2 M5 bolts at each end.  There's about a 4.5mm gap between the extrusion and the surface.  It's no wonder that people complain about the lack of rigidity in these things, there's just so many places built into them where things can flex.  I intend to make spacers and bolt through the 2040 extrusion and the spacer into my 30mm base.

This is the spindle, in all its' glory whatever.

This assembly is 60mm at it's widest, and it uses every mm of the existing rails to get its' 300mm of spindle travel.  The problem is that the new bearing blocks are 40mm long, and there's 2 per rail for stability.  That's 80mm, and if you figure in a generous clearance Clarence - you're up to 85mm.  So any way you slice it, with the existing gantry set-up I'm going to lose 25mm of work area.  For now, I can live with a 4027 instead of a 4030.  Especially when you consider that my old cnc was a 3020.  You can also see that they didn't use any more plastic in those moldings than they absolutely had to, it's not just the rails that flex.

This shows where the new Y axis rails will sit in relation to the existing rails.  The camera really messes with things, the old 10mm rails look bigger than the new 12mm rails, but it just ain't so - I checked to be sure. 


I just got the 2040 extrusions to replace the existing 2020's.  If I did the arithmetic right, I should have about a 15-16mm between the new extrusions when they're installed.  I intend to make solid spacer blocks to fit between the 2040 extrusions and effectively turn them into a truss.  At that point, the weak link in the gantry will probably be the 15mm phenolic side plates.  If that's the case, I can try bolting on a stiffening rib, or just making some new side plates out of my 30mm stock.

The major renson I went with an ESP32 based controller is that the MKS DLC32 has the horsepower, and the programming, to function as a stand-alone controller if desired - no drip feed from GRBL required.  Just load your g-code onto a thumbdrive, plug that into the controller, and run the file.

That's enough yapping for today, I have to go make myself some supper.

Don