Instructions

Figure 2

Safety first

I believe you shouldn’t approach the work at this time in a rapid g00 mode for safety

reasons; therefore, all my examples will include a short section of controlled feed rates

before the point of contact is reached. My program examples will always be complete

and will run on the backplot program that comes with your system. I have yet to find a

program that checks out with this program that wouldn’t run on the Sherline mill if the

slides were located in the proper position before the program was run. The more I work

with the EMC2, the more I like it.

Flying Sherline Airlines requires you to learn how to land before flying

The whole trick in using g41 or g42 is getting to the starting point in a very specific

manner. Also, remember that our computer is very smart and looks ahead at what you

plan to do when you enter cutter comp. If you ask it to do the impossible, it will send you

a message. What we want to accomplish is approach the starting point in two separate

moves so that we are coming into the part like a plane on final approach to an airport.

The plane flies to the first point, where it lowers it landing gear (g41—a move where the

cutter comp is entered during the move) and feeds (g01) to the final landing point with its

wheels (cutter) in position to land. Come in too steep and you’ll create a deep V cut that

is impossible to machine. (See Figure 2.)

You can overcome this error by programming a 90° radius cut to the part. Of course, the

programmed radius must be larger than the radius of your cutter. To think of a

programmed move in aircraft terms you are “flaring out” for touchdown. This has a

second advantage from a machining standpoint of not leaving a slight undercut that’s

created when a cutter is brought up to edge and immediately makes a sharp turn. This

undercut is caused by cutter deflection.