Saturday, June 28, 2014

Project CNC - CNC Controller Board Pictures

Top of Controller Board

Bottom of Controller Board

Assembled Controller Board
Finally posting pictures of new controller board for CNC machine.  It is fully tested and functions great.  Arduino Nano on left of board and stepper drivers in the right.  At least this is one less thing to worry about (motor cables falling off breadboard).

I ordered 1/4" 16tpi Acme screws from McMaster Carr to replace the #10-24 threaded rods that I'm currently using.  I ordered 2 nuts for each axis so that I can make new anti-backlash nuts like the ones I am currently using.  Finally settled on lead screws instead of belt drives because I felt that they would be more likely to be able to handle all the debris produced by the machine (from cutting materials).  Once I replace the lead screws I will need to switch the stepper controller boards to micro-stepping mode to maintain (and improve) resolution.

Wednesday, June 25, 2014

Project CNC and Project 3D Printer - New supports for Y-Axis guide rods (CNC machine)

I originally planned on using the initial supports that I cut for my 3D Printer (Y-axis also) but they were just a bit to short.  My choices were either cut out a pocket for the stepper motor in the base board, add spacers under the supports or just cut new ones.  Well... I just decided to cut new ones, its quick and just as important it'll look a lot nicer.

Both supports (old and new-just cut) were cut from 1/2" thick HDPE kitchen cutting board.  I like the material since is cuts and drills fairly easily, is non reactive to most chemicals, not electrically conductive, and does not shrink or expand with temperature or humidity changes (at least not to any significant extent).

Here is a picture of both supports - the new one on the left and the old one (originally meant for the 3D Printer) on the right.
Both are unfinished.  They both still show the "tab's" added to hold pieces in place while cutting, as well as left over flakes from being cut out.  Even with that it is easy to see the difference in height for the guide rod holes.  In addition, I squared off how the top meets the base to make more room for the mounting scews.

Monday, June 23, 2014

Project CNC and Project 3D Printer - Pictures of current Works in Progress

Progress pictures on CNC mill:
Planning changes in configuration of CNC mill:
     A.) Secure Y-axis directly to base
          1.) designed supports in Inkscape
          2.) need to finish in Makercam and cut out the new pieces from HDPE cutting board
     B.)  Change "waste board" to Poplar board leveled to machine with T-Slot rails for securing
           work pieces, will need to route areas for the rails to fit flush to the leveled board.
T-Slot pieces with 1/4" screws and Thumb nuts for workholding
Progress on 3D-Printer Build:
Left side of Z-axis

Left side of Z-axis with stepper and linear bearings

Top is Lft, side of Z-axis, middle is X-axis shuttle, bottom is Rt. side of Z-axis
Overall Frame
Cuts made in bottom of frame to allow travel of Y-axis and Y-axis belt
Cuts in frame, in above picture were done by hand with a Pull Saw (sawdust from cuts still visible).

Left side is initial test cut, Right side is corrected dimensions
 In trying to design a direct drive feed to my printer hot end I ended up having to take an experimental approach.  Initially I designed and cut what I thought I needed (using Inkscape and my CNC machine) and after test fitting and a few redesigns I came up with the part on the right (3 separate layers fused together with M.E.K.)
With bearing attached

Showing path cut for feeding Filament
 My objective was to have a hole drilled through this piece for filament but due to clearances, stepper shaft length, length of fitting for stepper shaft, bearing size... etc, I ended up having to mill a path through the top layer of the piece deep enough for the filament and then fuze a layer of acrylic over top of the piece.

Showing thickness of piece

How PLA filament feeds through

Bolt ground down to fit against stepper motor

Wednesday, June 11, 2014

Project CNC - Weekend CNC Adventure

(This post is from  about 3 weeks ago - I posted it to my draft folder instead of Publishing it to the blog - so here it is finally.)

Z-axis fixed and functioning perfectly. So, that's a good thing. I figured that I can finally cut out my redesigned Y-axis guide rod supports for my 3D Printer build. 
With everything set: 
  1. wiring connections (check)
  2. 1/8” single flute end mill tightened in spindle (check)
  3. added “%” and homing to G-Code generated by MakerCAM (check)
  4. previewed G-Code in OpenScam (check)
  5. secured HDPE piece (from kitchen cutting board) to work surface (check)
  6. tool zeroed to work surface (check)
All ready to go, using fast shallow passes, I started the run (I set it to cut out the outer edges of 4 supports and then return and cut the hole for the rod and slot for tightening mount after – I've had some issues with MakerCAM when I want to add tabs to pieces and have found that if I do my profile cuts first with tabs I seem to get fewer freezes in MakerCAM).

While the second piece was being cut out I saw that the end mill bit was going to cut into one of the mounting screws for the piece – as fast as I could - I hit pause in Universal Gcode Sender followed by shutting power to the steppers and spindle/router.  I was to late – the bit hit the edge of the screw head sending some sparks out. After removing the end mill all I could see was one faint scratch part way up the side of the bit.

It turned out that small defect was enough to render the bit useless.  I tried using it - first shallow pass was Okay but the next pass the bit did not remove the cut material (acrylic chips built up around the bit) and overheated causing the the cutting area to melt.

Having no other recourse, I ordered new single flute end-mills (for milling plastics) - this time I ordered 2 each of 1/8" and 1/16" (the 1/16" I got to cut acrylic for edge lighting).

Monday night I decided to try cutting out some acrylic to make an open top box – I wanted something that would fit my wallet and phone that I could place in a drawer to keep them both separated from everything else (I generally end up losing one or both at least once a week so I was hoping this might help).
After determining what size box I would need, and the thickness of the acrylic I have on hand, I laid out the pieces in Inkscape – imported into MakerCAM – and finally edited the code. The piece for the bottom of the box came out fine but when the cut began for one of the side pieces the Y-axis stopped moving (motor was moving but not the bed).  I paused Universal G-Code Sender and cut the power to the spindle and stepper motors again.
After checking everything I determined that the nut on screw drive was partially stripped and the mount for the nut was worn down allowing it to spin a bit.

So... I cut a new mount for the anti-backlash assembly, this time using Poplar instead of Pine (in the hopes that a hardwood will stand up better).  I have been learning to cut dovetail joints and my practice with that paid off in making a clean and tight anti-backlash assembly.  So far it has worked perfectly (I did replace the lead screw and swapped the brass nuts for stainless steel ones).

New Twitter Feed for quicker updates

Learn By Making Twitter Feed

It's been quite a while since I've used Twitter at all but after seeing SpaceLab's Twitter Updates I thought it would be a good idea.   Recently, my open time for posting has been very limited - as has my opportunities to work on current builds.  Since I feel like I am falling further behind on updates I thought it might be a good idea to at least post shorter updates as to what is happening.