Comments on: PCB Milling with the MakerBot CupCake: Aluminum Leveling Platform

By: Keith Neufeld

Keith Neufeld — Tue, 05 Jul 2011 01:53:51 +0000

mas, my aluminum plate isn’t milled; it’s straight from the scrapyard. Three screws would be fine if I had a flat plate; four screws work perfectly to level this plate.

By: Dave Durant

Dave Durant — Tue, 24 May 2011 18:16:55 +0000

Yup. I’ve got Aaron’s X/Y low-rider and Rob’s PSMD on my Cupcake. And a MakerGear stepper extruder. All with gen3 motherboard and extruder controller.

I’m not sure that going to 1/16th stepping actually increases the load on the CPU. It’s just taking the gcode (which skeinforge created) and moving the steppers the right number of steps. I don’t think it cares if it takes 100 steps or 1000 steps to move an inch. (I could be totally wrong, though)

You might want to also take a look at http://www.thingiverse.com/thing:4239 , which adds bearings to the X axis. It’s not quite as nice as Aaron’s lowrider but it’s a far easier print and will give you an idea how much improvement you’ll get by using bearings instead of bushings..

By: Keith Neufeld

Keith Neufeld — Mon, 23 May 2011 21:10:25 +0000

Dave, have you used microstepping with the CupCake? I have the Pololu stepper boards on hand and was considering using them but was concerned about the CupCake’s CPU. As it’s already taxed doing the calculations for g-codes, I wondered whether it would become overtaxed doing calculations at higher precision and controlling many times more steps.

By: Dave Durant

Dave Durant — Mon, 23 May 2011 16:56:58 +0000

The X/Y lowrider from twotimes is a great addition to a Cupcake and will indeed make your X/Y movements a bit less wobbly.

Another VERY good mod is the PSMD board from Rob Giseburt: http://www.thingiverse.com/thing:4526 . If nothing else, that’ll get you 1/16th X/Y stepping instead of the 1/2 (1/4?) stepping that Cupcakes come with.

By: Jetguy

Jetguy — Mon, 23 May 2011 16:20:13 +0000

All I can say is that yes, the stock Cupcake bushings define “loose” and that is at least some of the problem. I have a printed twotimes lowrider assembled and it will remove all the slop out of the machine for sure. You definitely want to do this. If you want, you can PM me (on the MBI forum) and I will sell my working assembled version for $25 to cover the cost of the bearings in it. I also found the stock rods were soft, and the hard bearing surfaces actually pitted them over time, so I have super hard piano wire rods and use a small dab of lube on them. This will get you back to accurate movements!

Next up is the Z axis and I’m not yet sure what is the best method on that for you. You defintiely need more strength there too.

By: mas

mas — Sun, 22 May 2011 04:13:55 +0000

A suggestion for your leveling system: instead of using four screws, use three.

Four screws give you what’s called a ‘redundant constraint design’ — one that inherently puts warping or binding stresses on the parts. In this case, one of your four screws is more trouble than it’s worth.

Any three points define a plane, but there’s no guarantee you’ll get the fourth point in exactly the same plane as the first three. You’ll probably end up putting stresses on the top plate that cause it to warp.

The good news is that switching to a three-screw design is easy: just drill another hole in the center of one side. Remove the two screws from the corners on that side and move one of them to the middle.

Three screws can’t warp your plate, and they’re easy to adjust: set your working height with the screw in the upper-left corner, level the edge of the plate by bringing the upper-right screw to the same height, then level the whole plate by bringing the bottom-center screw to the correct height.

You can Google ‘three screw level’ for pictures of similar systems, and instructions on how to use them.

By: JJshortcut

JJshortcut — Wed, 30 Mar 2011 09:10:43 +0000

As i’m looking at the bit you are milling with I got the feeling I have to share these bits with you:

5 x 45° Carbide PCB Engraving Bits CNC Router Tool #T14
http://cgi.ebay.com/5-x-45-Carbide-PCB-Engraving-Bits-CNC-Router-Tool-T14-/250522253434?pt=UK_Home_Garden_PowerTools_SM&hash=item3a544a387a

5 x 30° Carbide PCB Engraving Bits CNC Router Tool #T13:
http://cgi.ebay.com/5-x-30-Carbide-PCB-Engraving-Bits-CNC-Router-Tool-T13-/250522255776?pt=UK_Home_Garden_PowerTools_SM&hash=item3a544a41a0

I, as a hobbyist using them all the time for milling PCB’s and the result is very neat (http://jjshortcut.files.wordpress.com/2011/02/18022011074-1024×768.jpg), the tool you use is more a grinding tool and not really a engrave tool. You could also use a endmill as said by Josh M, I used them to because I did not my table leveled right but since you already cleared that problem you can use engrave bits.

Good luck!

By: Keith Neufeld

Keith Neufeld — Tue, 22 Mar 2011 21:23:47 +0000

tlab, backlash is also known as lash or play, which is exactly what I describe and attribute to the looseness of the X-Y bushings and guide rods. Am I missing something, or were you trying to convey a different angle on the problem?

By: tlab

tlab — Tue, 22 Mar 2011 21:17:19 +0000

you have a backlash problem with your mill. That’s why some of your traces are wider than others in different directions.

By: Andy from Workshopshed

Andy from Workshopshed — Tue, 22 Mar 2011 06:38:47 +0000

Yes, the movement in the mechanism could be causing the NW/SE issue. Look also how the spindle rotation relates to the direction of travel, you might be climb milling in one direction.

http://wsshd.com/ehRWw2

You might find that the next limitation will be the dremel itself, I’m not how much flex there is in the bearings of that.