So, my 3020CNC router was underperforming lately and I wondered why.
Well, there’s one problem! Here, another:
Hm! But why would this happen? I remember when I got it new, the machine had no play on it’s axes…
While dismantling the head it became aparent that the bottom bracket screws had become loose, thus forcing the bearings sideways, and well, you’ve seen the rest.
I Ordered some new bearings and luckily, after testing all 10 (6+old 4), four where good enough, but that’s what you get with cheap bearings. And since I was at it, performed some mods.
1.- Protecshun plate:
The router has this plate to cover the guides and ballscrew from debris, however, to do so, it reduces dramatically the throat of the machine especially if you want to work on parts with wildly different heights.
And I thought, well, certainly I can replace that with some form of foldable screen, right?
I picked some leftover paste stencil and cut a little longer piece than the protection plate, to account for flexion.
Also, remember that drilling very thin sheet is fucking dangerous. Here’s my setup to keep both hands away from it.
I used a 3mm normal drill to open the holes, then increased to 4mm and after that, got a step drill wich works beautifully in sheet metal, up to 7mm holes.
Also, used a dremel disc by hand* as makeshift sandpaper to round all the edges.
*Power tools and sharp sheetmetal don’t mix, gloves
or no gloves.
Shape that, baby!
Using a leftover bar I had around, I gave the sheet a thick bend, and rolled the front edge in the mill vice, so it would not catch on the bottom bracket AND prevent stupid flesh cuts.
Nice! Let’s screw it on!
Dang it, the screws are too long without the plate I removed…weird.
Well, being not in the mood to cut screws, I used some washers.
That looks so damn sexy! Also, throat comparison between plate and sheet:
Heh, nothing a bandsaw can’t fix:
Look ma, no washers!
While playing around with the Z axis, I notticed that unlike the X and Y, the ballscrew is NOT captive with a flanged ball bearing. So, the height is only kept at bay by the preload spring in the motor, wich might work for soft materials, but that won’t do for aluminium, for example.
Luckily for me, I have this habit of buying bearings from time to time, just because. It has paid out before, and this time yet again is another +1 into that habit. So, I just had the perfect needle thrust bearing for this:
I tried to preload it a bit so it would prevent any axial movement, but not too much as to become a drawback for the motor.
Aaaand…I ripped the screw threads in the adapter.
M3 screws for a loose fitting adapter tend to do that when you tighten them. I remachined into M4, and also reduced the diameter of the screw head to fit in the previous hole.
Also, did you know that unlike linear guides, cheap ballscrews don’t have captive balls? ME NEITHER!
I’ll admitt I panicked a bit when heard two distinct clinks.
I unscrewed it very carefully until some balls where visible and popped the two escapees back in there.
Nice! after measurements, the difference in sizes was in the hundredths of mm, not in the mm region, so, well worth it! (remember, this is a cheap cnc, it will flex somewhat in all axes).
I should check on motor Y axis squareness, but that will be another day.