One of the most commonly incorporated parts to be found in these designs are Dremel-brand handheld tools, using router bits, attached to the Z-Axis. Well, I took a look at Dremel tools, at my local hardware store, Wal-Mart store, Target store, and a few other places, but I've found that they're all very expensive, for use in my upcoming project.
Well, I tackled this problem today. I built my "router" on an arm that will be attached to the Z-Axis on my CNC machine. Hopefully, others could use a similar tool, and will find this interesting.
Step 1: Tools Required
1/8" Steel-Cutting Drill Bit
3/32" Steel-Cutting Drill Bit
#4-40 SAE Tap
#1 Philips Screwdriver
#2 Philips Screwdriver
Step 2: Parts List
1 Solid Metal Rod, 3/8" diameter (or 1/4", if 3/8" is not available).
1 #4-40 SAE Screw, to act as a Chuck
1 Dremel-Brand 1/8" or smaller Router bit
2 flanged bearings, with I/D the same as the diameter of the solid metal rod.
1 pipe, with I/D the same as the O/D of the bearing.
1 electric motor, AC or DC, high RPM, medium Torque. (I got mine from a broken cordless drill)
Brass hobby tubing, with I/D the same as the diameter of the solid metal rod.
Scrap sheet metal.
A handful of Wood Screws.
Step 3: Prepare the rod
First, I drilled a 3/32" hole through the bolt, about 1/4" up from the end. Then, tap this hole.
Next, I drilled a 3/32" hole into the tip of the bolt, right in the center. I found it very difficult to drill right down the center of the bolt, not skewed to either side, but it was possible. This could be easier, if you have a heavy-duty drill press to use. After drilling this pilot hole, drill it back out to 1/8". Drill past the set-screw's hole, by about another 1/4". Clean up the threads for the set-screw after drilling.
Drill the center of the bigger timing pulley out to the diameter of the bolt. Slide the pulley all the way to the head of the bolt.
Cut a short (about 1/4") section of hobby tubing, using a pipe cutter, and Slide this on Next.
Slide one of the Bearings on next.
Next, cut some more of your Hobby Tubing. This has to be cut to a very exact length, so that there is a very tiny amount of slack between the bearings and the outer pipe, when fully assembled. I actually cut mine twice, to make sure I could get it exactly right. There is about 3 thousandths of vertical play, which is about exactly right. This fits between the two bearings, so that tightening down the assembly doesn't put stress on the ball bearings or the bearing races.Cut the outer pipe to length, and put the assembly into it, then slide on the other bearing, and tighten the whole thing down with the hex nut. Make sure that the rod spins freely, even when everything is tightened down securely, but, also ensure that the vertical play in the mounting of the bearings in the outser pipe is very minimal.
Now, insert the 1/8" dremel router bit into the end of the bolt, and install and tighten the set-screw.
Step 4: Prepare the Motor
If your timing pulley is not a good fit, you might use epoxy to affix it to the output shaft of your motor. This has worked for me, on other projects, in the past, but centering the pulley is important.
Step 5: Screw the assembly and the motor to something
Attach the timing belt between the assembly and the motor, and pull the belt tight, then anchor the motor down, in the same way as you anchored the assembly.