SL-20 Spindle Transmission High - Low

[SBC Cycle]

Hey guys. I've consulted the manual and the online specs of the SL-20 and can't seem to find an answer on this.

At what speed exactly does the standard spindle (4000 RPM) switch from low to high gear? It appears to be somewhere around 1200 -1300 RPM but I'd like to know if it is published somewhere. I have the C axis postitioning if that makes a difference (unlikely).

I'm running a G72 cycle and as I'm facing it switches gears about 0.100 from the end of the cut then switches back almost immediately when it retracts for the next pass. Maybe it doesn't hurt anything but it seems like a lot of unnecassary wear and tear.

If the constant gear changing is not bad for the machine, maybe I'll just pick the CSS up a notch so that it's not doing the low-high quick swap right at the end of the cut. If all this gear changing is a little rough for the machine I'll clamp the spindle speed to just below the limit for low gear. What do you think?

[Geof]

I always thought the SL20 was direct belt drive, no gearbox. I just checked the specs for it on the Haas website and it only gives one torque figure which suggests it does not have a gearbox. Do you have something different to normal?

[SBC Cycle]

Well that would make sense why it's not listed anywhere. I can say it's doing something around 1200 RPM.

I did a little more research and found a reference to something called "On the fly switching". This must be it. It refers to the "Dual Drive system which consists of a dual-winding motor - Wye and Delta - and an electronic switch to change between the two windings".

EDIT: BTW, to be more specific - this is a 2007 SL-20 20HP Vector Dual Drive machine with optional C axis positioning and spindle orientation.

It then goes further to explain that the dual winding systems is to provide the wide power range needed during CSS cuts.

Ok, so I assume it's no big deal then that all this clicking and clacking is going on. But I guess I still have a question about whether I should avoid running right to the limit of "low", switching to "high" and then back to "low" within a split second. It sounds horrible.

Here's the link for that little tidbit of info:

http://www.haascnc.com/flash/Lathe_F...leFeatures.asp

[Geof]

The clacking is the relays switching between wye and delta. I would clamp the spindle speed. If you are only 0.1" away from the end of the cut clamping the speed at what the rpm is at around 0.15" from the end is not going to lose you much time.

[SBC Cycle]

Ok, that makes sense to me and that's what my gut was telling me. Appreciate the insight Geof, thank you.

[CHAD LAWSON]

The hass machines use two through away contactors with a relay to change from delta to wye on the fly. changing speeds may prematurely wear these components but i have found coolant usually will do it first. For some reason hass puts these atleast on the sl30 down behind spindle motor and trany. they get real nasty there in a half ass box. The complete set of components is less than 400 dollars but if you ever replace them do yourself a favor and move them to the electrical cabinet. The box they have installed them in is not even sealed.

[SBC Cycle]

The hass machines use two through away contactors with a relay to change from delta to wye on the fly. changing speeds may prematurely wear these components but i have found coolant usually will do it first. For some reason hass puts these atleast on the sl30 down behind spindle motor and trany. they get real nasty there in a half ass box. The complete set of components is less than 400 dollars but if you ever replace them do yourself a favor and move them to the electrical cabinet. The box they have installed them in is not even sealed.

I very much appreciate the good tip. I'm going to check that tomorrow to see if my SL-20 is similar. Thank you