Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: HimyKabibble on August 10, 2009, 05:17:16 PM
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Are CAT30/BT30/NMTB30 the same, different, interchangeable?
Regards,
Ray L.
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NOT the same, same taper, different flanging, different key lugs.
Depending on what your spindle is like as to IF they are interchangeable. IF I had a nmtb30 and wanted to do a tool changer I would fit Cat30 or BT30 tool holders by changing out the lug bars. That way you would have the tool holder slots to work with on the tool holders. Sometimes people rework there cat spindle to hold BT holders sometimes the opposite depending on how much of what tool holders are available. IF you change the holders you have to also change the tool holder fingers in the atc.
HOPE that helps, (;-) TP
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Depends, tapers are all the same but flanges are different. This will probably not matter to you unless you have a toolchanger then you will likely have to get the ones to suit. The CAT will need you to either modify one of the dogs or remove one as the slots are uneven in size on the holder.
If you have the Bristol Erickson QC that is common on Bridgeport CNC's then you will need QC30 holders and that is all you will be able to use as their flange dia is 48mm as opposed to the 50mm of the others.
Hood
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Ok, so if I understand correctly... They can be interchanged, sort of. The tapers are the same, NMTB has a short cylindrical section, the others don't. The main difference will be in the height of the pull stud, and how the flange keys to the spindle? I don't know for sure which taper the spindle I'm looking at has, but I'm guessing it's NMTB, which appears to be the most common, right?
Regards,
Ray L.
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Not sure what NMTB is, think it might be what we call international, ie just a single thickness flange of 8mm thick and 50mm dia. They have the extended straight portion on the top of the taper but you can make up pullstuds for CAT, BT etc that will allow you to use them with the same drawbar as the INT (NMTB) I did that for the Beaver mill, it can take Int40, DIN40 (similar to CAT 40 but metric) BT etc
Top right is for Int40 left is the one I made up for DIN(CAT). The bottom one is for a Hurco 30 taper I made a load of for Brett.
Hood.
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Hood,
Sounds right. Here's the reference I found on all the different tapers:
http://www.tools-n-gizmos.com/specs/Tapers.html
Any clue what pullstud tension these want?
Regards,
Ray L.
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Afraid not, all I know is the hydraulic pressure of the Beavers drawbar is 900PSI and the cylinder is about 60mm ID but not certain on that.
Hood
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Afraid not, all I know is the hydraulic pressure of the Beavers drawbar is 900PSI and the cylinder is about 60mm ID but not certain on that.
Hood
Hood,
Do you know how much travel is required to release the tool?
Regards,
Ray L.
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Tha would be about 3300 lbs on the rod side of the cylinder.
The only spindles I have seen on common knee mills are R8, NMTB30/40, ISO30/40, Kwikswitch200/300, Erickson QC30 and a few Morse tapers.
The nature of the spindle drive/quill /High/low gearbox normally prevents the others from being used.
(;-) TP
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Isn't the pressure mentioned used for releasing the drawbar?
Seems to me that the release pressure would need to be adequate for breaking loose the taper and could be many times the actual drawbar tension.
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Isn't the pressure mentioned used for releasing the drawbar?
Seems to me that the release pressure would need to be adequate for breaking loose the taper and could be many times the actual drawbar tension.
The force required to release the taper, even with R8, is relatively small - no more than a couple hundred pounds. The major force is the tension required to keep the tool in place, particularly with collets. If using a "hard" holder, like an endmill holder, much less tension is required - It appears to me that 1-2K pounds is adequate with a hard holder, particularly with a 30-taper.
Regards,
Ray L.
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Ray you are correct the drwbar forces for a 30 taper run from 1-2k lbs. You do not have to worry about collet toolholder like the r8 collet in 30 taper there are none(;-) They all use solid holders. There are collet type holders but the tapers are solid.
Now do be advised that the 30 taper series are getting rarer every year. Most machines start at cat/BT40 type these days. But they also have a lot higher faster spindles as well. It just raises the cost of NEW holders a bit every year as they become more obsolete. AND for the most part they are NOT cheap like the r8 holders (;-)
(;-)TP
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NMTB holders are made for a draw bar , not usable for toolchanger. If your going to change spindle , go for the 40 taper.
A 3/8" air impact @ 80psi is enough to operate the draw bar.
Ed
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1k to 2k drawbar tension and 3.3K release tension . . . . . this seems to me like reasonable numbers.
In my many years of using R8, I've always had to whack the loosened drawbar with a hammer to free the collet. (the drawbar wrench qualifies as a 'hammer', incidentally ;)) Releasing MT tapers requires an act of congress.
I would err on the side of 'way too much' force for releasing any taper, even a steep solid one.
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Ray you are correct the drwbar forces for a 30 taper run from 1-2k lbs. You do not have to worry about collet toolholder like the r8 collet in 30 taper there are none(;-) They all use solid holders. There are collet type holders but the tapers are solid.
Now do be advised that the 30 taper series are getting rarer every year. Most machines start at cat/BT40 type these days. But they also have a lot higher faster spindles as well. It just raises the cost of NEW holders a bit every year as they become more obsolete. AND for the most part they are NOT cheap like the r8 holders (;-)
(;-)TP
Terry,
Unfortunately, a 40-taper spindle is not an option. 30-taper is all that's available. I've found several sources for 30-taper holders, and prices seem no worse than R8, though there clearly are fewer sources. My plan would be to immediately buy a lifetime supply. It's either that, give up on a toolchanger entirely, or buy a used VMC.
Regards,
Ray L.
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1k to 2k drawbar tension and 3.3K release tension . . . . . this seems to me like reasonable numbers.
In my many years of using R8, I've always had to whack the loosened drawbar with a hammer to free the collet. (the drawbar wrench qualifies as a 'hammer', incidentally ;)) Releasing MT tapers requires an act of congress.
I would err on the side of 'way too much' force for releasing any taper, even a steep solid one.
On my current drawbar. unscrewing the bolt actually pushes the taper out, as the drawbar assembly is pushed down by a pair of air cylinders. There's no downforce initially, but after the drawbolt unscrews about 1/8", the socket bottoms out, and further unscrewing creates downforce. Even with the bolt seriously OVER-tightened, it has never failed to pop out on release. It doesn't seem to require a huge amount of force, though I have several hundred pounds available if needed.
Regards,
Ray L.
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RAY if you are talking NMTB30 I agree you can buy them cheap sometimes but vary amoung manfs as to specs (;-). BUT IF I were to do an ATC I would use CAT30 or BT30. The grip grooves for the fingers are already there and work. and the studs have already been engineered to work properly. AND those are NOT so cheap and harder to find in 30 taper.
Just my take on it, (;-) TP
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I have bought some stuff from this guy, his prices seem good and shipping to the UK was also good, he has BT and CAT30 if I remember right. The ER32 collets and straight shank holder I got were exceptional quality but maybe I was just lucky. Not sure how prices compare to USA retailers or how much shipping would be.
http://www.ctctools.biz
Hood