[chuy]

I was wondering if on HMC's is the full 4th axis an option that is turned on thru the control, IE. an option thru FANUC like rigid tap, so if the machine has 1 deg. indexing are you stuck with it as an idexer or can it be coverted to a full 4th rotary? or is something that has to do with the machine itself?

[dcoupar]

Usually 1 degree indexing is accomplished with a curvic coupling, full 4th axis is not. Big differences to the iron, control, etc. (to the tune of 20-25K option for 4th).

[Dan Fritz]

Yep. dcoupar is right. An indexer is controlled with a simple M-code, B-code or serial interface, but a full 4th axis must be able to interpolate its moves with the X, Y, and Z axes. A full 4th axis usually requires an option parameter in the control plus some additional CNC circuitry to control the servo. Then, you have to install a suitable servo amplifier, transformer, and the rotary table with a motor. Many 4th axes also have a mechanical "brake" on the rotary table that you can lock and unlock with a pair of M-codes. The brake takes the pressure off the worm gear when milling.

Indexers are a lot simpler, and there are quite a few different types. A common type is controlled with a separate 1-axis servo controller that is interfaced to the CNC with a serial (RS232) cable. You write macros in the CNC's program to "DPRNT" commands to the indexer. When the indexer receives a command, it unlocks itself, rotates to that position, then locks up again automatically. The only problem with an indexer is that you can't make an interpolated X-4th, Y-4th or Z-4th move like you can with a full 4th axis.

[chuy]

Is there anything that is visible that would tell it's a full 4th maybe something in the control or back of machine, reason I'm asking is I am thing of buying a Kitamura with an 11m control on it, but the guy isn't sure whether it's a full 4th or a indexer...is there anything that I can have them check? they don't know and it's a little far for me to go check it out myslef, don't want to buy it if it's not a full 4th.

Thanks!

[Dan Fritz]

If the control is under power, look for a 4th axis position display. If it's a full 4-axis control, it will have an X, Y, Z, and an A or B axis on the "Position" page. If you only see X, Y, and Z .... well, it's probably just an indexer.

If the control is not under power, trace the cables from the rotary table to the CNC. If the pulse coder cable from the motor on the rotary table goes directly to the CNC control, and it plugs in to a board labeled "Additional axis" or "4th/5th axes", then it's probably a full 4-axis control.

If the pulse coder cable goes to a small box on the rotary table, and that box has a skinny RS232 cable going to the CNC, then it's a simple indexer.

Send photos if you're in doubt. We'll have a look ..

[Bluesman]

Is there anything that is visible that would tell it's a full 4th maybe something in the control or back of machine, reason I'm asking is I am thing of buying a Kitamura with an 11m control on it, but the guy isn't sure whether it's a full 4th or a indexer...is there anything that I can have them check? they don't know and it's a little far for me to go check it out myslef, don't want to buy it if it's not a full 4th.

Thanks!

Ask him if there is a 4th selection for the Axis selection in the Handwheel mode. If you can go into handle and rotate the table (With the MPG) you have true 4th axis. If not it is an index table.Or just give it a simple comand and see if it rises up then indexes and lowers. A 4th axis will rotate with up first.

Bluesman

[Bluesman]

Ask him if there is a 4th selection for the Axis selection in the Handwheel mode. If you can go into handle and rotate the table (With the MPG) you have true 4th axis. If not it is an index table.Or just give it a simple comand and see if it rises up then indexes and lowers. A 4th axis will rotate with up first.

Bluesman

Sorry, A true 4th will rotate with out lifting it will just go directly to the comanded position.

Bluesman