Another MINIMILL post

[COPO427]

Hi, guys, we are going to be purchasing a Minimill and I am undecided as to what to get. Either the Super or the standard. We also want to have this equipped with 4th axis capability.

I am at a local engineering college and for the amount of room I have this size will be best.

I understand about the difference between a CT40 taper and a BT40 taper but not sure which would be better for the super mill? Also what does the letters CT and BT actually stand for?

Thanks for helping a newbie

[Ken_Shea]

From what I have looked at the CT will win out in popularity, cost and selection here in the states.

In the back of my mind I recall the BT as being short for British Taper.
CT-40 being CAT taper.

Exactly what they stand for and why I do not know, I would be interested in that as well.

[Geof]

Regarding CAT 40 versus BT 40 do you have a choice with the MiniMill? I thought it was just CAT 40.

If you are in the market for a MiniMill and the cost can be accommodated go for the Super MiniMill with the raised Z axis option. There is another thread http://www.cnczone.com/forums/showthread.php?t=19396 where I have posted several comments about this option. Posts 13, 21 & 26. With the 4th axis I think the raised Z is essential otherwise there is simply not enough room to fit a decent sized rotary.

[Ken_Shea]

You do have the choice of CT or BT in the Haas MiniMill.

[COPO427]

Originally Posted by Geof Regarding CAT 40 versus BT 40 do you have a choice with the MiniMill? I thought it was just CAT 40. If you are in the market for a MiniMill and the cost can be accommodated go for the Super MiniMill with the raised Z axis option. There is another thread http://www.cnczone.com/forums/showthread.php?t=19396 where I have posted several comments about this option. Posts 13, 21 & 26. With the 4th axis I think the raised Z is essential otherwise there is simply not enough room to fit a decent sized rotary.

Thanks for thre info Geof. As Ken said there is a choice on the super mini. I just wasn't sure if the BT was needed for the 15,000 RPM spindle. BT is more accurately balanced?

Well the college has told me I have $50K to spend on this machine and it must include a 4th axis. time to wheel and deal.

I did read what you were saying about the added Z clearance with the mini. I did not realize this and thank you for pointing it out.

[Geof]

Originally Posted by COPO427 .....I just wasn't sure if the BT was needed for the 15,000 RPM spindle......

I know you can get CT40 holders balanced for 20,000rpm so obviously they are okay for 15,000.

But I have a question/comment. Are you intending to get a 15,000 rpm spindle? In a college environment with students? I don't want you to think I am disparaging students either in general or individually but I used to teach college classes. Students by definition lack training and experience. With a 15k spindle it is fairly important that balanced tooling be used but at 10k you can get away with not being quite so picky. I know a 10k spindle can be run for extended periods, without apparent damage, using a holder so badly out of balance you can hear the machine droning several hundred feet away through two walls. I am not willing to see if a 15k spindle will handle the same abuse.

[COPO427]

Originally Posted by Geof I know you can get CT40 holders balanced for 20,000rpm so obviously they are okay for 15,000. But I have a question/comment. Are you intending to get a 15,000 rpm spindle? In a college environment with students? I don't want you to think I am disparaging students either in general or individually but I used to teach college classes. Students by definition lack training and experience. With a 15k spindle it is fairly important that balanced tooling be used but at 10k you can get away with not being quite so picky. I know a 10k spindle can be run for extended periods, without apparent damage, using a holder so badly out of balance you can hear the machine droning several hundred feet away through two walls. I am not willing to see if a 15k spindle will handle the same abuse.

I understand your concern. I was just going by the specs on the super mini which has a 15,000 RPM spindle. No I probably will not run up to the max 15K. So it sounds like I can get away with the CAT 40 tooling package.

thanks

[Geof]

The 15000rpm spindle is a $7000+ option.

[COPO427]

Originally Posted by Geof The 15000rpm spindle is a $7000+ option.

AHH my mistake. I was reading the brochure and all it says is a max spindle of 15K. I went on their website and the 10K spec is there. Thanks for pointing that out.

So these professors here want me to get a 4th axis( rotary table). I ask why and they say it looks cool. I just don't see why we should waste the money when it is for special applications that they just don't understand. Seems like a lot of money to just be sitting around.

They think you just order a rotary table hook it up and wham the part is done. They don't realize that it costs an extra 2K just for the wiring for the 4th axis. Ohh these phd's...

[Geof]

Originally Posted by COPO427 ...So these professors here want me to get a 4th axis( rotary table). I ask why and they say it looks cool......

Well it does look cool. Sometimes you have to humor the kiddies so they don't throw a tantrum.

[COPO427]

Originally Posted by Geof Well it does look cool. Sometimes you have to humor the kiddies so they don't throw a tantrum.

Ya I guess if I was paying $32k a year to go to school I would throw a fit too. hehehehe

[Geof]

Originally Posted by COPO427 Ya I guess if I was paying $32k a year to go to school I would throw a fit too. hehehehe

Ouch!!! It was a few years ago but when I did my graduate work it was around $800 a semester and I received a stipend for being a teaching assistant.