This new website will cover my CNC conversion and many projects to come!
Just got my new Grizzly G0602 10x22 lathe this week.( Actually July, 30, 2008)
Came via UPS Feight in just 2 days. Met the driver downtown, backed up to the trailer
then we slide it off onto the bed of my pickup. 453 Lbs., no problem.
Used my chain hoist to pull it off the pickup into the basement onto a rolling skid I made
to move it around the basement. Then one more hoist up onto the bench and I'm ready to go.
After breaking it in, the first job was to turn down and thread the post for the Aloris AXA Tool Post
so that it would work with the lathes original tool post t-nut.
Wholesale Tool Has a cheaper import version.
Changing the gears to thread was NOT quick but it cut the threads great on the steel post.
The old 7x10 doesn't even compare to this lathe. This one will make a good candidate for CNC.
Click image to enlarge
Lifting onto Bench
Aloris AXA Toolpost
Here's a few videos of the lathe in action.
Ballscrew Turning Z Axis Part 1
Ballscrew Turning Z Axis Part 2
Ballscrew Turning Y Axis Part 1
Ballscrew Turning Y Axis Part 2
Cutting Hardened Steel with Ceramic Insert
Turning ballscrews isn't that difficult as the videos show but decent tooling is a must.
I used a 3/4 CNMG toolholder (milled down to 1/2 inch) and CNMG-432 inserts. You can get a tool holder that has a 1/2 shank that should fit most lathes. MscDirect has a good quality toolholder and the CNMG-322 80 degree inserts for it.
Wholesale tool has a cheaper CCMT tool holder that uses single sided 80 degree inserts.
If you are interested in hard turning, MscDirect has CCMT ceramic inserts, don't use them on the ballscrews, the interupted cutting will shatter them.
It's important to run the proper speed and feed to get decent tool life. I could turn about
15-20 ballscrews from one 4 edged insert. Ballscrews are case hardened, some to a Rockwell 58C or harder. They get much softer once down below .450 diameter.
The basic rules of turning are the bigger the part and/or harder the part, the slower you go. You don't have to take a shot in the dark about what to run at, speed and feed charts are made to help you out.
For threading the ballscrews, I used an Aloris 60 degree threading tool. I made my own tool holder but you can get the AXA tool holder and threading blade from MSCDirect. This blade should last a lifetime, just freshen the cutting edge on the grinder now and then.
Speed (RPM=SFM x 3.82/Diameter)
SFM or Surface Feet per Minute is the main piece of data to worry about. For hardened steel, most charts give 75-150 SFM for a carbide insert. Aluminum is about 1000 plus SFM. SFM is based on the hardness of the material usually given in Birnell Hardness BHN or Rockwell C. The harder the materal the lower the SFM and if you plug that into the calculator above, you'll see the RPM is lower too. I used 100 SFM for the ballscrews (hobby machines should stick to the lower end of the scale).
In the Calc it gives 611 RPM for .625 dia. I set the lathe at 560. As you can see, as the diameter goes down the rpm should increase. Most hobby lathes have a limited rpm selection and can be a pain to change so I prefer to use the starting rpm all the way till the end and change to 1200 rpm just for the last 2 finish passes.
Feed (IPM= RPM x IPR)
Feedrate IPM (Inches Per Minute) is found by multiplying the RPM x IPR (Inches Per Revolution) sometimes called FPR (Feed Per Revolution).
The charts will give a range on those too but we should stick to the lower end there as well. Charts were developed for professional equipment.
I used .007 IPR for roughing the ballscrews (.025 DOC), .0025 for the finish pass.
Calculators and Charts
Insert Designation Chart - Carbide Depot
Note: Roton gives instructions here for annealing the ends of the ballscrews to make turning easier if you can heat them to 1200 degrees.
G0602 Ballscrew Thread Cutting