Re: Talk Me Out of a Tormach 770
Originally Posted by
RussMachine
You CAN tap on the 770 without an encoder.
Depth-control is the only drawback.
I use the R32 Collet- Tension/Compression tap holder from TORMACH.
And without an encoder, depth control isn't exact. (+/- 2-3 threads)
When tapping, the holder will "stretch" at the end of the cut when the spindle reverses.
It will cut an extra 2-3 threads while the tension head "stretches",
This isn't really a big deal when tapping thru holes, but nerve-racking in blind holes.
Also, the largest tap I can push with the tapping head is 5/16" (8MM).
Anything larger, and the spindle wants to stall.
For 3/8" (9MM) and up, I have to threadmill.
Threadmilling is actually the better choice, for depth control (in blind holes), and finer quality threads.
Excellent review of TC tapping. I have kind of embraced it with premade styles in my CAM software for tapping with the TC tappers. I have one Tormach TC tapper, and have made a few of my own on the PM1440 lathe so that I can have my most common tap sizes preloaded and premeasured. 10-32, 1/4-20, 5/16-18, and 6-32 (in that order). I tap the smaller sizes in aluminum in high gear at 500 RPM. I do switch to low gear in steel or for 5/16 or above. I also have tapped 5/16-18 aluminum in high in aluminum because I forgot to change gears before. The 1100 is slightly higher power, and slightly better low end torque. It is pretty scary in blind holes. So far for thread milling I just have single form tools (multi flute), and they take longer than TC tapping if I have more than a couple holes to tap. Are you using muti form tools? Of course you can turn higher RPM so it might be faster on a 770.
Anyway, I like the TC tapping so much I have been spending some of my time thinking about how I would make them for my Hurco KMB1 retrofit machine. Other than just sticking one in a tool holder. Its already quite long, and putting one in a tool holder would leave me cranking the knee up and down for a while. LOL It also does NOT have C-axis spindle control. I currently do single form thread milling with it.
Bob La Londe
http://www.YumaBassMan.com