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Is the Big Plus spindle really that much better?

ben29

Aluminum
Joined
Jul 29, 2012
Location
st.louis,mo
The company I work for is going to buy another rx650 mill and I am trying to convince them to go with the big plus spindle. We do all aluminum and zinc castings, so not a lot of heavy milling, but we have some tight tolerances. I was hoping one of you could really make a case for the big plus as I have no experience with it. Thanks.
 
The big plus is often packaged with other things, like the high torque spindle, and through spindle coolant. My 450 and 700 have these, although I don't have a pump yet for the TSC. I'm very happy with mine so far, although I have not done a side by side test with non-big plus. The high torque is limited to 10K though, so if you need more speed than that, I would not bother.......... To me, the high torque and big plus go together...... ymmv.........
Still runs fine on 30 amps.
:)
 
yes

The BIG-PLUS(R) Spindle System | BIG KAISER Precision Tooling Inc.

http://www.big-daishowa.com/pdf/general_ca_pdf/features.pdf

You are increasing the cantilever stiffness of the holder by a considerable amount

Just off the cuff, you are going from roughly a 70 mm dia to a 100mm dia assuming tis a bar

Max deflection under point load for a cantilever PL^3/3EI

assuming all is equal for the two, you are left with the deflection being a function of C/I

If we assume a bar shape pi/4r^4

So we are working with R to the fourth power or around 4X stiffer 4x less deflection.

Yeah its more complicated than this, but hey there is some simple math to support a complex decission.
 
I am impressed by the rigidity of the cat50 big plus machine I just installed... but I am comparing a pretty beat up 40 taper linear way standard cat 40 cartridge spindle machine to a box way big plus cat50 thats brand new. It all comes down to money.... if you can make the numbers work they should buy it, but you won't know for sure until you buy one and run it a while.
 
YES. The benefits of dual contact have been well documented for many years now. I can't even imagine buying a new machine without either big plus or an HSK spindle. It's not just about increased rigidity, it's also about increased stability at high RPM.
 
Big Plus spindles are fantastic. Have one in our Mori-Seiki NV5000. Also the Big Kaiser and Big Daishowa tooling is also superior. We run their Mega and Mini chuck collet holders and I have NEVER and I mean NEVER had runout on the tool more than .0003". Absolutely fantastic, every single time
 
yes

The BIG-PLUS(R) Spindle System | BIG KAISER Precision Tooling Inc.

http://www.big-daishowa.com/pdf/general_ca_pdf/features.pdf

You are increasing the cantilever stiffness of the holder by a considerable amount

Just off the cuff, you are going from roughly a 70 mm dia to a 100mm dia assuming tis a bar

Max deflection under point load for a cantilever PL^3/3EI

assuming all is equal for the two, you are left with the deflection being a function of C/I

If we assume a bar shape pi/4r^4

So we are working with R to the fourth power or around 4X stiffer 4x less deflection.

Yeah its more complicated than this, but hey there is some simple math to support a complex decission.


Big Kaiser claims UP TO 40% more rigidity over a regular CAT 40. It's in their literature. It's not some magic bullet to get 50 taper rigidity in a 40 taper package. A lot sales guys talk it up like it is though....
 
The company I work for is going to buy another rx650 mill and I am trying to convince them to go with the big plus spindle. We do all aluminum and zinc castings, so not a lot of heavy milling, but we have some tight tolerances.

I'm normally a proponent of dual contact, but not in this case because you're looking at a significant RPM penalty @ 10K. I'd want at least 16K on an aluminum-cutting R650, which is not available with dual contact.
 
I would second that, you need the 16k, but my 450 came with both 16k and big plus. But no idea what they have now.
Gary
 
Hmm, not sure why dual contact would have a limiting factor on rpms. With dual contact you will have more dampening and rigidity. Also z-axis repeatability between tool changes will be greatly improved.
 
I'm normally a proponent of dual contact, but not in this case because you're looking at a significant RPM penalty @ 10K. I'd want at least 16K on an aluminum-cutting R650, which is not available with dual contact.

You can add Big Plus contact to the 16k spindle on all the Brother machines. I would not add it unless the application needed it. Spindle growth in higher RPM applications is different. I would never add it to the 27k spindle. The spindle itself not only grows down, the spindle grows out. The taper on a taper spindle just sucks up a bit when there is not dual contact as it was originally designed to do. I doubt you would see much difference unless you were running very small tools at the top of the rpm range.
 
Andy or Frank,
Aren't the bearings also larger in the dual contact spindles on the Brother machines? Or is my memory slipping away....
 
Andy or Frank,
Aren't the bearings also larger in the dual contact spindles on the Brother machines? Or is my memory slipping away....

Memory is slipping Mike ;)

Same spindle with a new bottom ring. The most expensive part of making the Brother Big Plus is the wash system for the face contact.
 
Andy or Frank,
Aren't the bearings also larger in the dual contact spindles on the Brother machines? Or is my memory slipping away....
Mike, your memory is very good. The 10k High Torque spindles do have larger bearings, not because of the Dual Contact though. Yamazen stocks the 10K HT spec machines with Dual Contact and CTS Interface. Most other models can be field retrofitted for Dual Contact and requires the special Tool Wash system and spindle cartridge change out. The bearing size is the same between standard and Dual Contact spindles but the drawbar force is uprated.
 
Memory is slipping Mike ;)

Same spindle with a new bottom ring. The most expensive part of making the Brother Big Plus is the wash system for the face contact.

interesting to hear of this.
I wsa always apprehensive to mix dual contact holders and non-dual because i was afraid of chip contamination from the gap with non-dual holders.
Guess it's a non-issue on Brothers!? :beer:
 
Ok, so I had associated with the dual contact, not the high torque. But, my machines have Dual Contact AND High Torque.
:)
(in addition to the really cool spindle wash when changing tools)
aaaand the really really fast tool change, and 10k forward to 10k reverse in maybe a second.
:)
 
interesting to hear of this.
I wsa always apprehensive to mix dual contact holders and non-dual because i was afraid of chip contamination from the gap with non-dual holders.
Guess it's a non-issue on Brothers!? :beer:

I would not use BBT tool holders in a non BBT spindle. The bottom ring is different on the BBT and non BBT. Non BBT machines do not have face wash.
 
Back to the original question, Big Plus or Dual Contact is a great option on a Brother, especIally since Maritool is now offering a nice selection of Dual Contact BT30 holders at a great value. The Big Plus machines can run either the standard BT30 tooling or Big Plus (BBT30,NBT30 or Dual Contact) which is nice. That being said the standard BT30 machines can handle plenty. To me it's about reach, or larger tools such as larger face mills or boring heads etc... When you need to hang an end mill out there is when I think you will see the most benefit. Discuss your apps with your Brother rep and I am sure you will be able to determine if the upgrade will benefit your situation.
 
I would second that, you need the 16k, but my 450 came with both 16k and big plus. But no idea what they have now.
Gary

Ah, nevermind what I said then.

When the Speedios first came out, I was under the impression that dual contact was only available on the high-torque 10K spindle.
 








 
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