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View Full Version : 2MT, 3MT, R8 ???..help a newbie



Sportandmiah
01-22-2009, 08:34 PM
Can someone explain how and why these are different, and why one might be better than the other? I'm a little confused. :confused:

Thanks

gellfex
01-22-2009, 08:52 PM
Morse Tapers are generally a drill press taper, meant for infrequent removal, and often without a drawbar. R8 is meant for mills with a drawbar, and is easier to knock out than a MT.

My mill drill has an MT3, so I mount an ER32 collet chuck with a drawbar to make for easy tooling change.

Teenage_Machinist
01-22-2009, 09:04 PM
Morse Tapers: zero thru Five. Small lathes and D.P.s have 2 or 3 spindles. MT3 is sometimes used instead of r8.
r8: Collets for milling machines- straight and taper. Not self holding. For shanked or collets with drawbar.

5C: work holding collets that go larger than 1 inch (forget how much larger)
3C: Mini 5c for small machines. Holds half-inch.
ER-number: Wide range, collapsing collets. A complete set of collets holds ANY size even weird ones. For work and tool holding


NMTB, Cat-number, 30, 40, 50, 60:

Milling machine taper mainly for horizontals and CNC machines.

Sportandmiah
01-22-2009, 09:12 PM
OK, so I'm considering the HF Micro Mill which has MT2. Why do some frown on MT2?

Thanks.

aboard_epsilon
01-22-2009, 09:13 PM
Wonder if Sportandmiah is thinking of buying a milling machine ...

and is wondering what's the best choice of machine ..

then you get a different set of answers ..

like cost verses availability and function of collets

or availability of tooling.

all the best.markj

Sportandmiah
01-22-2009, 09:19 PM
Let me rephrase, why do some thing MT3 is better than MT2?

Sportandmiah
01-22-2009, 09:22 PM
Let me rephrase, why do some think MT3 is better than MT2? Is the MT3 bigger, more useful? I seriously have no idea.

DENedbalek
01-22-2009, 09:27 PM
MT3 tells me that the MT3 machine is bigger and capable of turning bigger tools than the MT2 machine. My Grizzly 3n1 has an MT3 Mill Taper, MT3 Lathe Taper, and an MT2 Tail stock taper. I use an ER style collet holder that has an MT3 shank on it to do my milling.

Dwayne

SGW
01-22-2009, 09:29 PM
They all work. The Morse tapers were invented, I assume, by the Morse Twist Drill Co., and as others have said are often used in drill presses to hold Morse taper shank drills. They also frequently appear in lathe spindles and tailstocks to hold live and dead centers and drill chuck arbors. Morse tapers are shallow enough of an angle to be "self-holding" tapers; if a Morse taper is put into a socket, it locks and has to be pried or driven out.

There are also Morse taper collets. #2 Morse collets go up to 1/2" capacity. #3 Morse goes up to 3/4" capacity. Collets require a drawbar for closure. Because of the self-holding taper, one has to loosen, then tap, the drawbar to free a collet.

The R8 taper was invented, I think, by Bridgeport for its milling machine. The R8 taper is barely self-holding; an R8 collet or arbor needs to be tapped to free it, but it's a steeper angle than the Morse tapers and needs less persuasion. Capacity of R8 goes up to, I think, 7/8".

R8 is probably "better" for a milling machine, but there have been all sorts of very good milling machines made with Morse taper spindles. I wouldn't be too dogmatic about it. You can get tooling for any of them.

Fasttrack
01-22-2009, 09:29 PM
MT3, by itself, is not better or worse than MT2. The only issue is that it might be more difficult to find mill tooling for an MT2 spindle. MT3 is considerabley harder to find tooling for than R8 and MT2 is probably harder to find than MT3. On the other hand, for a mini mill, you won't be running very large endmills, facemills, boring heads, etc. You probably would only need a few end mill holders and a drill chuck.

Edit: I agree with SGW but wanted to add that you can get R8 up to 1" (maybe larger) but they are sorta goofy looking. I don't think they hold quite as well, either.

Edit: Here's one on ebay: http://cgi.ebay.com/1-R8-COLLET-NEW-TOOLING_W0QQitemZ180316068008QQcmdZViewItem

wierdscience
01-22-2009, 09:31 PM
Yes MT3 is bigger and will hold larger tools than the MT2.

However R-8 will on a mill give you a much wider selection of tooling and usually at a lower price.

I bought a mini-mill and chose the HF unit over Grizzly since it had an R-8 spindle and the Grizzly didn't.By doing this I could use all my existing R-8 tooling from my other mill.

danlb
01-22-2009, 11:04 PM
There are other considerations...

The mt2, mt3, r8, 5cm, etc are specs for the spindle and the matching shaft (arbor).

An mt collet or an R8 collet is generally integrated with the shaft, so the size of the spindle bore will determine the maximum sized tool that will fit in the collet.

Any tool sold for an R8 arbor is available for an MT arbor or a threaded arbor. There are many, many sources for threaded arbors with an MT tapered shank.

MT taper tools are sometimes more expensive. I think that might be because the MT taper has a larger surface area that touches the mating bore, and it has to be polished and concentric along the length. The R8 taper is much less exacting.

Dan

Forrest Addy
01-22-2009, 11:31 PM
in toolholding featires (spindle taper in this case0 biger is alway better. MT3 iis bigger then MT2 (0.700 and 0.937 respectively) therefore stiffer. R-8 is 1 1/4 on the big end therefore stiffer. None of these can be considered all purpose milling machine taper tooling. They have limited rigidity and torque transmission. #30 milling taper hase about the same taper dimensions as the R-8 but since it also has a keyed flange its torque drive is positive. Larger millint tapers are even more rigid.

However the spindle configiration is governed by the machine's scale and Morse and R-8 spindle are selected for smaller machines where cost, small size, and convenience are primary considerations.

That said, many smaller jig borer spindle are Morse taper. Sine precision repeat location are primary considerations andjig borers are seldomg used for any but finishing operations at very high precision. Everything has advantages and disadvantages.

Sportandmiah
01-23-2009, 01:09 AM
Thank you to all, a lot of good info for the slow learner (me). One last question: could the micro be changed to accept a MT3 or R8?

danlb
01-23-2009, 02:07 AM
I can answer this one. :)

Technically, you could rebuild the head with a different spindle.

Realistically, You would not want to. You would have to replace a lot of major parts and rework a bunch of others. You'd need a machine shop to do it.

The mt2 taper is not a problem for a micro-mill. The mill's motor and gears will not handle big tools. Look at the owners manual to see the maximum size end mill and drill size.

A lot of tools come in a straight shank that will fit in a collet. The set of fly cutters I bought for my micro-mill have a 1/2 inch diameter shank that fits well in a 1/2 inch mt2 collet.

Dan

derekm
01-23-2009, 05:45 AM
Morse Tapers: zero thru Five. a self holding taper. Small lathes, mills and D.P.s have 2 or 3 spindles and tailstocks. MT3 on larger lathes and mills. MT4 and MT5 usually on lathes
MT is available with tangs or drawbar threads. use the tangs for drilling and drawbar for milling, some mills can use both.
MT drill bits are used for larger sizes and extra precision(no added chuck or collet runout).
Cheap adapter are available to reduce MT size with very little space used (sometimes called sleeves),Available in both tanged and drawbar flavours
MT collets are available but require force to remove.
MT is more readily available in UK compared to US

r8: Collets for milling machines- straight and taper. Not self holding. For shanked or collets with drawbar. Mostly seen on U.S. market or designed machines. Often used on relatively low to medium power applications (less than 3hp). R8 more prevalent in U.S.

NMTB, Cat-number, INT, ISO, DIN, SK 30, 40, 50, 60:
Milling machine taper for larger more powerful professional kit used in both horizontal and vertical. 30 size can sometimes be found on smaller mills
while these all have the same taper they have different bits and pieces for drive dogs, autochanging, drawbar threads etc... NMTB seen on US market machines, INT ISO DIN etc..seen on international market machines. Some interchangeablity between types depending on machine and application

Collets
--------
5C: work holding collets that go larger than 1 inch (forget how much larger) very narrow holding range for each collect - a few 0.001". Collet sets need hundreds of pieces to span large ranges contigously
3C: Mini 5c for small machines. Holds half-inch.
ER-number: Wide range, collapsing collets. wide holding range typically 1mm per collet. A complete set of collets holds a contigous range. e.g.a 24 piece ER40 set holds from 2mm to 26mm with no gaps . Used for both work and tool holding.
Collet holders available to fit MT1 to MT4, R8, 30 to 50 tapers in all flavours and "lathe chuck style" register

Dunc
01-23-2009, 09:28 AM
The mill I chose offered a choice of MT2 or (for a few bucks more) MT3. R8 was not an option so no need for me to go there. The few Canadian companies (in my area mainly Busy Bee & Princess Auto) offering mini-mills seem to ignore R8 - don't know the reasoning.

I chose the MT3 simply because it offered a lot more metal. Perhaps in the back of my mind I was thinking that MT3 is the taper in my mini-lathe headstock; that said, I have not assessed what practical uses - if any - that might offer. I figured that the added stiffness/robustness could not be all bad. Granted, this mill does not have the torque that a multi-horsepower mill-drill or knee mill has.

Not much logic involved, I grant, and maybe my newbie thought processes need some re-education.

I have not had a problem with tooling as the mill vendor offered a good selection of MT3 adaptable cutting tools. While I was considering the MT3/MT2 choice I noted that there was a good selection of MT2 stuff as well. Then again, I don't have very sophisticated needs - end mills, slot mills, small facing mill, slotting saw, etc. The company offers collets and a holder as well as a boring head with an MT3 shank but I have not purchased one. Perhaps if/when I need exotic cutters I will be disappointed. One positive point: the MT3 end mill holders have both a threaded end to accept a drawbar and a small set-screw to engage the Weldon-style flat on an end mill; this prevents (diminishes?) the end mill being pulled out of the holder by cutting forces.

loose nut
01-23-2009, 11:20 AM
The few Canadian companies (in my area mainly Busy Bee & Princess Auto) offering mini-mills seem to ignore R8 - don't know the reasoning.
.


Mini mills are probably to small for R8 collets, they flair out at the bottom and would be to wide to fit in the spindle. MT2 collets are a lot smaller in dia.

Morse collets are OK as long as there is a drawbar to hold them tight, an MT collet will not take the side loading from milling very well without one and can pop out of the spindle.

All you need is a set of collets, for the tool size range of what ever type of machine you get, they all do the same job.

Don't forget an MT3 will hold MT2 collets and tooling with an adapter, gives you a bit of flexibility.

ptjw7uk
01-23-2009, 06:08 PM
Having the micro mill myself I'm stuck with the MT2 in the mill although I can also use most of the mill attachments in the tail stock on the lathe as that is also MT2 and as someone said if I get a bigger mill I can get an adaptor to take all my MT2 bits.
As the micro mill would be used for relatively small milling operations if you can get the MT2 fittings go for it. You will always find a use for the mill when you upgrade to a 'proper' mill(whatever they are)

Peter

Teenage_Machinist
01-23-2009, 09:50 PM
HIGHLY RECCOMEND AGAINST MICRO MILL!!!!


The mini mill is much better.

dp
01-23-2009, 10:16 PM
The LittleMachineShop.com has a converter for R8 from MT3 that fits a number of minimills as well as other conversions:

http://littlemachineshop.com/products/product_view.php?ProductID=1944

and http://littlemachineshop.com/products/product_view.php?ProductID=1625

One of the concerns of the minimills should be obvious in the images - plastic gears.

macona
01-23-2009, 10:27 PM
The LittleMachineShop.com has a converter for R8 from MT3 that fits a number of minimills as well as other conversions:

http://littlemachineshop.com/products/product_view.php?ProductID=1944

and http://littlemachineshop.com/products/product_view.php?ProductID=1625

One of the concerns of the minimills should be obvious in the images - plastic gears.

Thats why the belt drive option is so popular. Cant break belts, well... not with that little motor.

Sportandmiah
01-23-2009, 10:56 PM
HIGHLY RECCOMEND AGAINST MICRO MILL!!!!


The mini mill is much better.

LOL, I'll get the Mini, just for you....if you send me the remaining money to cover the cost!! :D

dp
01-23-2009, 11:13 PM
LOL, I'll get the Mini, just for you....if you send me the remaining money to cover the cost!! :D

It obviously is important to consider your intended use of the machine to determine if the a micro or mini is the better machine. If your hobby is horology then the micro may be the better choice. I'm always puzzled by such spurts of wisdom that declare one mill is definitely better than another without considering the requirement. Usually as quickly someone will say don't get cheap Chinese junk (what else is there for the home shop being made today with the same or better price/performance?). Tiffie has explained time and again the value and suitability of Chinese equipment and I have had good luck with mine - including the mini mill with plastic gears. :)

dp
01-23-2009, 11:14 PM
Thats why the belt drive option is so popular. Cant break belts, well... not with that little motor.

By the time you add in the power feeds a guy could have had a pretty decent mill!

macona
01-24-2009, 02:05 AM
Nah, you can only polish a turd so much... ;)

The main problem with the micro mill is it is way, way to slow for a mill its size. The spindle tops out at 2000 rpm IIRC. Maybe 2500. If you are doing brass or plastic this is too slow for even HSS bits at 1/8", not to mention bits any smaller. Running slow may not seem that big of a deal but when you do run that slow your feed rate drops a whole lot and it gets really annoying to use just barely cranking the handles. It is a whole lot easier to break bits when they are running this slow as well.

ptjw7uk
01-24-2009, 05:47 AM
I think someone on this forum said the bearings on the micro mill are good 16000 so just add a pulley system to up the speed.
Should be good for the small bits used at high speeds only problem would be the motors power not sure if it will be man enough.
For the money the micro is good value if you only want to machine small items.

Peter

macona
01-24-2009, 06:13 AM
With grease the bearings will take 15k rpm. But you might want to have the spindle balanced at that speed.

Thrust bearings need to be installed in the lead screw blocks. Otherwise by the time you get the lash out of the screw to block interface it gets tight.

brian Rupnow
01-24-2009, 08:40 AM
I have a small mill with MT2 taper. It works fine, and I have no problem with it. It holds the cutters securely, and releases them easily. As pointed out in an earlier post, they have a maximum capacity of 1/2" shank, however a small mill is not capable of running larger tools anyways without possibly damaging the mill itself. If you are purchasing new tooling, then MT2 is as good as any. However, if you plan on buying used or second hand tooling, then MT2 tapered tooling is rather rare.---Brian

Teenage_Machinist
01-24-2009, 01:16 PM
The only advantages of the micro that I can think of:


1( Upgrade is available for slightly better Y axis travel)
2( Sensitive Drilling Feed on quill)
3( Lead screw on Z axis)
4( True Inch Leadscrews (ugrade available, or get the Micro Mark mill which also has metal gears on the spindle)


That is all I can think of, and if you will be milling any steel, a mini will serve you much better.



Little Machine Shop sells a belt drive conversion with 4 speeds, the highest one is very high.

The Mini Mill is 500 dollars from Harbor Freight, and may be had cheaper.
The Micro Mill is 320 dollars, and if you have a real job as I do not being in high school you should be able to save, a

The mini mill may be chinese junk, but it is good chinese junk. If you mill steel the micro is not good at all. It will definitely do the job, but I really kick myself for not waiting a few more months and getting both a real vise and a real mill.

You dont need the best, but you really dont need the worst.

Sportandmiah
01-25-2009, 04:42 PM
Well, I bought the Micro Mill yesterday (no hissing please). For the price, $274.00 out the door, using a HF 20% coupon, it was a no brainer. Plus, I have no plans, at this time, of milling anything harder that 1"x1" brass or aluminum. That might change later, but for now I think this will be fine. I can always upgrade later to the Mini if need be down the road.

I'm considering the $229.00 value Micro Mill starter package from Little Machine Shop. I added items up buying them seperately, but the package makes more sense ecomonically, as it comes with everything I could ever need right now. Any thoughts on the value packages? Does LMS have the best prices?

Thanks to all input from everyone, and Happy Machining!

Teenage_Machinist
01-25-2009, 06:11 PM
Some people have better prices than LMS but not for everything. Its probably best. Enco has free shipping for larger orders, nice for heavy stuff

danlb
01-26-2009, 10:44 PM
That package covers most of the parts you'd normally need. Add a wiggler and you have it made.

You might be able to get the individual parts cheaper if you shopped around, but I did not price them out.

Dan