Need clarity on this machine

[markba633csi]

Trying to understand this machine- what does "no rigid tap" mean?
I see the knee is not motorized so apparently only the quill is cnc controlled
What is the big box in front of the head? I see what looks like a power drawbar up top
Not planning to buy this but would like to understand what I'm looking at
-Mark

3 axis CNC Milling Machine - tools - by owner - sale

This is a Anilam Crusader full 3 axis (no rigid tap) knee milling machine, it comes with on board shop floor programming and is very easy to program. It comes with a bunch of tooling, and would be a...

modesto.craigslist.org

 

[mmcmdl]

No rigid tap means you must use a floating tap holder to take up errors in the quill feed . Not a big issue .

 

[Eddyde]

"No rigid tap" means it can't tap with CNC, probably because the spindle isn't a servo axis.

 

[JimDawson]

Trying to understand this machine- what does "no rigid tap" mean?

There is no encoder on the spindle. There is no way to electronically gear the spindle rotation to the Z axis

I see the knee is not motorized so apparently only the quill is cnc controlled

That is correct. That is the most common configuration.

What is the big box in front of the head? I see what looks like a power drawbar up top

The box on the front houses the works for the Z (quill) feed.

Overall a nice machine, manual and CNC capability. The antique control should be upgraded. The price is not horrible if the machine is in good mechanical condition. Per the seller, it sounds like a spindle is due for a rebuild.

 

[mmcmdl]

Looks like it does have a servo motor , maybe just not accurate enough for tapping . We had the identicle machine at AAI and power tapped on it everyday . Floating holders are great even on the more modern cnc's . You can't have ANY error in pitch with a rigid holder . You'll get alot of un-wanted snapping noises which is bad .

 

[mmcmdl]

I definately agree with Jim on the control . This was probably an early 90s machine . It did some nice work back in the days but an upgrade would be essential at some point . I still have parts down the basement that were machined on this type of mill . Windscreen reamers for 30mm penetrators . To me , this would be one step up from a Proto Trac which is would I would be going after if I could find one .

 

[markba633csi]

OK, tapping question:- doesn't cnc tapping require a spindle that can instantly reverse?
Otherwise I would expect you would need to use something like a Tapmatic attachment for a drill press?
Does cnc tapping use conventional taps or can it mean single point tool also? Seems to be a broad topic
-M

 

[mmcmdl]

OK, tapping question:- doesn't cnc tapping require a spindle that can instantly reverse?

Yes , instant reversing at a programmed Z depth .

 

[mmcmdl]

I have floating holders down the basement . I'll post pics of what they look like later on tonight . Right now I have to get out in the rain and do what I need to do for this evening .

 

[JimDawson]

OK, tapping question:- doesn't cnc tapping require a spindle that can instantly reverse?

No, not instantly. The spindle needs to decelerate to a smooth stop and then accelerate to speed in the reverse direction. The Z axis only needs to accurately follow the motion of the spindle. But visually, the cycle can look almost instantaneous, but instant like flipping a switch, would not work well.

Otherwise I would expect you would need to use something like a Tapmatic attachment for a drill press?

Yes, that would work.

Does cnc tapping use conventional taps or can it mean single point tool also? Seems to be a broad topic

Standard taps, single point, and milling taps can all be used. I use both standard taps and single point thread mills.

You do not need rigid tapping capability to do thread milling.



I have never used a milling tap.