Category Archives: CNC - Page 16

Change your CNC Router Jog Speed with Mach3

mach3 without jog screen shown

No jog control screen

So how does one change the jog speed on their Mach3 powered CNC machine?  By default, Mach3 sets the jog speed to whatever the maximum surface speed that your machine is programmed to via motor tuning.  If you want to slow things down temporarily, say to zero an axis, just do the following:

  1. Hit the TAB key
  2. On the new menu that pops up, adjust the percentage shown in the picture to the right.
  3. Use the keyboard arrows or GUI buttons on this pop out window to move your cutting/extruding head around.
mach3 with jog screen tab pressed

Hit "tab" and the jog control screen appears

That’s really it, note that this doesn’t affect the surface speed when moved using Gcode, so if you’d like to leave the jog speed set to 50% to keep you from bashing your machine around under your own control, this isn’t a problem.  You can also set the jog to “step” which will make things go in little increments every time you press the arrow key.  This could be useful, although I haven’t yet taken advantage of it.

This solution is probably obvious to most people.  After Read more »

A CNC Cut Geneva Drive

animated geneva mechanismA Geneva Drive is defined by Wikipedia as “a gear mechanism that translates a continuous rotation into an intermittent rotary motion.”  Although replaced by servo drives in many cases, these were once used in movie projectors and to power rotary tables in industrial assembly lines.  This is where I first saw this type of drive, and after redoing practically the entirety of these machines, the venerable Geneva mechanism was still at the heart of it, working like a champ after 20+ years.  Like most cam-type devices, they may not afford nearly the adjustability or the “easy” electrical programming of a servo of PLC controlled device, but they will run for literally decades on end with little maintenance.

So after that introduction, I recently machined one out of MDF on my router.  I plan on making one that works a bit better, and is possibly motor-driven, but check out the video below for my prototype:

This is a crude model a this point, but I’ve included the G-code and DXFs for the mechanism at the end of the article.  Everything was cut with a 5/16 inch bit that I’ve been using as a flycutter on my router, providing a relatively high pocketing speed.  Unfortunately, Read more »

Dramatically Improve Your Zen Toolworks Pocketing Speed with a Dremel 115 “Flycutter”

Today I tried doing a 1/8 inch depth pocket cut with my Zen Toolworks router.  I’ve never tried this particular operation before, but with the new F8 leadscrew upgrades (my latest post on this), I expected it to go pretty quickly.  Compared to the stock leadscrews, the F8 screws are incredibly fast as seen in my pocketing video below.

Although the lateral travel is incredibly fast, the 1/8 inch cutter, although good for many things, doesn’t seem to be the best choice for doing pocketing operations.  With the improved screws, once can easily attain a lateral travel of 100 IPM (inches per minute).  Unfortunately, when the router is cranked up to these speeds, the cutter just doesn’t have the proper rigidity to make good cuts and ends up skipping around and bending during travel.

After trying this operation several times, I eventually was able to cut the pocket at a speed of 30 IPM (inches per minute).  For all of these cuts, I was only taking .015″ per pass which was probably conservative, but using this 1/8 inch cutter, doing a 2 inch circle 1/8 inch pocket took 19:24.  Yes, Nearly 20 minutes.  A long time.

Dremel 115 High Speed Cutter from Amazon

Fortunately, I had a Dremel 115 bit with a 5/16 inch cutting head (I originally used this cutter to mill my router bed flat).  This, like many Dremel bits, fits Read more »