Using A Lathe For The First Time – Part 2
Did you learn a lot in Part 1 of our blogs that begins to walk you through using a new lathe? Part 2 continues on describing even more components. There are more suggestions for optimal lathe use, as well. CNCCookbook, provides so many useful articles, tips, and videos involving CNC machines. Continue reading more from Wade Wendorf of CNCCookbook below.
Without your tool offsets, you have no idea what your parts will wind up looking like (or what your tools will look like after they are wrecked). Your manual should walk you through the process, but a quick explanation is that you setup the Z offsets based on the center axis of your spindle. As mentioned in my last article, I use a Z setter that is 2″ at zero.
On the Siemens control, these are the basic steps to setting the Z tool offsets:
- Press the “offset” button on the control
- On the offset screen you select Z axis
- Enter in an offset based on your indicator height (for me, that’s 2″)
- Use your jog pendant to jog in very slowly.
Note: Most Jog pendants have movement increments in 0.0001″, 0.001″, and 0.010″. Feel free to use the fastest to get close, but make sure you drop it down to the 0.0001″ when you get close, because you really don’t want to break your Z indicator by moving too fast.
- Touch the tool to the Z setter until the dial reads 0, then press the “measure tool” button.
Your Z offset is now set.
When I am setting up my tools, I typically cycle thru and set all my Z offsets for each of my tools before I worry about setting the X offset.
On the Siemens control, these are the basic steps to setting the X tool offsets:
- Index or change your tool to Tool #1.
- Insert some scrap material into the spindle.
- Use the jog pendant, get within 1/4″ of your part, and position the tool to perform a cut.
- Now switch to the 0.0001″ or 0.001″ increment on your pendant.
- Turn on the spindle, it doesn’t have to be super fast, 750-1000 rpm should suffice.
- MAKE SURE YOUR SPINDLE IS TURNING THE CORRECT DIRECTION for the tool to make a cut. If it’s going the opposite direction, and you try to make a cut, you have just killed your tool. 😉
- Use the jog pendant to move X to where you will get a nice clean cut.
- Now switch to Z movement, and make a cut about 1/4″ axially, then back off to where you are cutting air.
- Move the Z out of the way so you have several inches of space in front of the end of the part.
DO NOT CHANGE THE POSITION OF THE X AXIS
- Turn off the spindle.
- Get your calipers, or micrometers out, and measure the diameter of the cut you just made.
- Press the “offset” button on the control
- On the offset screen you select your X axis
- Enter in the dimension you just measured.
- Press measure X.
Now your X offset for that tool is saved. For boring tools you do pretty much the same thing, except on an internal hole instead of an external one.
Drill offsets are a little bit different.
Drills are a little trickier, but I like using a Coaxial Centering Indicator. I mount the centering indicator in the chuck of the lathe, then I sweep the center of the holes where a collet would mount to hold a drill bit. I switch the X to 0.0001″ on the jog pendant, turn on the spindle very slow, like 100 rpms, and just jog X back and forth until the needle on the centering indicator doesn’t move anymore. When I measure the offset of the tool, I just select 0 for the measurement of X. Now the drill bits are right on center.
Don’t Rapid Near your Chuck!
Let’s just say this is a warning. This was the first time I had to reset my turret and it was because I forgot I had my jog pendant on 0.01″ and smacked it right into the chuck.
Also, make sure when you index your turret, you are WELL out of the way of the chuck. I have not done that one, and really don’t want to. Those turrets index really fast, and if a tool is in the way of the chuck, something (probably the tool) is going to break.
Hint: I always recommend that people not use G00 Rapids with MDI commands. Always run G01 and set a feedrate that gives you time to react. You’ll save on crashes and stress! — Bob Warfield
Setup offsets for empty tool positions in a turret.
I learned this the hard way. When I was programming a part, I entered in a turret position which didn’t have a tool in it, and never had one in it before, so there was no offset for it what so ever. I found out that offset for an empty turret position, is basically at the spindle nose (NOT the nose of the chuck, about 4″ behind the chuck. Yep, it sucks. That was my second turret reset.
I highly recommend you at least put in an offset a few inches away from your chuck because of this.
Compilation of cuts.
Well, I hope you enjoyed this article in my series. Please take a few minutes to check out this compilation video of some of the projects completed on my new lathe, from my very first part on it, to some of my more recent parts.
Mandala Rose Works, LLC