[Momentz]

Hi Guys
I am looking to build a mill but having a hard time choosing a spindle to use with ATC, it will be belt drive so my questions are

1. With a BT30 spindle it needs to have a motor with feedback so it can rotate and locate the tooling because of the slots?

2. Can you run the BT30 spindle without the slots on the nose for easy atc setup without having to use a motor with feedback or will I have slippage issues of tool holder slipping in the spindle?

Thanks
Chris

[mactec54]

Momentz

Light cutting is ok without keys,& high speed (20,000RPM Plus ) with light cutting, if you want to do serious cutting then you will need the drive keys

[Momentz]

Momentz

Light cutting is ok without keys,& high speed (20,000RPM Plus ) with light cutting, if you want to do serious cutting then you will need the drive keys

Makes sense ThankS for your help.

Can anyone recommend a motor that will provide feedback so it will locate the drive keys when using an atc?

Thanks again

[mactec54]

Makes sense ThankS for your help.

Can anyone recommend a motor that will provide feedback so it will locate the drive keys when using an atc?

Thanks again

It can be done with a regular AC motor, and a quality VFD, you use an Index pulse on the spindle, to get your spindle orientation

[SCzEngrgGroup]

Whether you need the keys or not is a matter of how much spindle power you have. Under 2-3 HP, I doubt very much the keys are required.

Regards,
Ray L.

[cncdan]

As others have said, at lower HP the keys are not necessary.

As an example, my EMCO VMC-100 toolholders do not have any keys as designed by EMCO; it uses sk30 taper holders custom made to fit the 10 position tool turret (same taper as bt30). The spindle is only 1HP (4000rpm max) and I have not had any issues with slippage, but the largest cutters I use are usually Ø.375" max. I cut 4140 tool-steel using .375" solid carbide endmills with no problems.

I would think you might start to have issues as the cutter diameter or depth of cut increases.... more holding torque would be required.

Cheers,

[SCzEngrgGroup]

Keep in mind, R8 is used up to at least 3HP. R8 has basically the same taper angle as 30-taper, and the same maximum taper diameter, with a much SHORTER taper length, and with no keys or other similar methods. There is not a reason in the world the keys should be needed in 30-taper below at least 2-3HP.

Regards,
Ray L.

[Momentz]

Thanks everyone for there help, I will be using a 3 hp motor with spindle speeds up to 10,000rpm and using a 50 mm maybe 75 mm face mill so keys maybe needed? I will have to look into the key locating a little more.

I was originally going to use the tormach tts but people sometimes have tool pull out which I have had to with my little mill so that's why I am looking at the bt30 spindles. But atc is that little bit more difficult than a tts setup

[mactec54]

Momentz

Not a chance that you could run a 50mm face mill without drive keys, if you were running high speed all the time with small cutters then you would be fine without drive keys, any other general milling at lower speeds, which is normal, you will need the drive keys, Emco FB cnc mills figured this out, with there 30 taper spindle, they only use a .6 Hp Dc or a 1 hp Ac max for there drive motor, any more and you will have the tools slipping in the spindle, so at 3Hp for your spindle motor, you need the drive keys

The TTS does not compare to a ISO 30 spindle

[Momentz]

Momentz

Not a chance that you could run a 50mm face mill without drive keys, if you were running high speed all the time with small cutters then you would be fine without drive keys, any other general milling at lower speeds, which is normal, you will need the drive keys, Emco FB cnc mills figured this out, with there 30 taper spindle, they only use a .6 Hp Dc or a 1 hp Ac max for there drive motor, any more and you will have the tools slipping in the spindle, so at 3Hp for your spindle motor, you need the drive keys

The TTS does not compare to a ISO 30 spindle

Thanks for your input it's most appreciated, I just need to source a spindle encoder for key locating, any suggestions?

[SCzEngrgGroup]

You don't need an encoder, or any complex spindle positioning to index the spindle. A simple solenoid-operated pin-brake on the spindle will do the job, using the jog function built into virtually any VFD to turn the spindle until the pin drops in. I use this for my motor-driven power drawbars, and it works perfectly.

Regards,
Ray L.

[Momentz]

Thanks for the reply Ray.

I have basicly given up on a BT30 spindle and I am kinda thinking of R8 just because ATC is easy to setup but in the back of my mind I know BT30 is better but I cant seem to get my head around key locating without spend big $ on a AC servo spindle motor with feedback for spindle positioning, I would love to see pictures and hear how other people do this and what gear they have, input would be greatly appreciated

Thanks
Chris