CNC Router
After making several printed circuit boards and drilling all of those
holes, I decided it was time to build a simple CNC router/PCB drilling
machine. I figured I would also be able to use it for making bezels,
cut outs in panels, and other enclosures. I selected a set of plans
from John
Kleinbauer’s CNC Router site. John calls this machine the 7th Sojourn
and plans were quite inexpensive. John specializes in machines for
beginners who are getting started in the hobby and want to build a
machine at a low cost and with easily obtainable materials. He uses
materials such as MDF, black iron pipe, skate wheel bearings, and
threaded rod.
Here are several pictures of my machine at various stages of
construction:
This is the beginning of the base frame. The material is ¾” MDF which
is available from most home improvement stores. MDF is very stable,
flat, and hard. It also machines easily with sharp, carbide cutters and
saw blades. Most people drill and tap the MDF and assemble it with
machine screws. I found that I had a tendency to strip the holes so
used another method that I have had luck with in the past. I drilled ¾”
diameter holes in the piece that would normally be threaded at right
angles to the attaching hole. I then glued a short length of ¾” oak
dowel into the hole. Then I used 2” - #8 square drive wood screws to
attach the pieces. Although a little time consuming, I am very pleased
with the results. The frame is very strong.
Here’s the router with the completed Y axis. John’s plans call for
using ½” black iron gas pipe for the rails with 90° elbows, nipples,
and flanges. Although the pipe was fine, I could not get flanges that
were flat enough to give me consistent rail height when I tightened
them down. I switched to ¾” drill rod instead and the results appear to
be quite good. I stacked the two end pieces that support the drill rod
in order to drill the ¾” holes in them and alignment seems to be fine.
This is the completed Z axis with stepper motor mounted and ready to
go.
Here’s the completed machine without any of the wiring done.
Finally here’s the machine with the wiring to the motors completed and
the tool holder completed and mounted.
Here’s the tool holder. I’m using a Dremel MultiPro but instead of
mounting the whole unit, I mounted the flexible shaft spindle. This
gives me less weight hanging off the X axis and also mounts the weight
closer in to the axis. So far it seems to work fine.
Here’s the finished machine with the computer hooked up and ready to
go. So far I’m using TurboCNC
and it seems to work quite well. The computer is one I had put out of
service. It has a Pentium II 233 and is just running DOS 6.22. I’ll
probably look for an old laptop since it takes up a lot less room but
this works for now.
I made some simple cuts
on some cedar I had laying around and everything seemed to work fine. I
need to get some carbide bits yet in order to really put it through its
paces. So far with a 24
Volt power supply for the motors and a Xylotex controller
I have been able to get about 18 IPM. That’s in 1/8th microstepping
mode and I haven’t spent any time trying to optimize it yet. I still
have several things to do yet:
- Disassemble and paint all of the MDF pieces
- Verify alignment of all axes
- Cut off ¾” drill rod
- Replace guides on X and Z axes with Delrin pieces
- Mount and wire home switches
- Install an emergency stop switch
- Optimize speeds and accel rates
- Install a table with hold down capability
In the end I made very few changes from John’s plans:
- Used the ¾” drill rod in place of the pipe
- Made slightly different gibbs for the X and Z axes
- Used stainless steel threaded rod – much improved over
standard stuff
Well that’s it – I guess now it’s about time to start thinking about
another machine. I would like to build one with a larger surface –
maybe 24” X 36” and with the capability to take a larger router like a
Porter Cable 690. But that’s another story.
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