R8 is my personal preference. Bridgeports use R8.

If the choice is offered [and assuming that you don't already have loads of MT3 tooling available] I can see no good reason not to use R8 … It's a properly specified fitting for the job.

MichaelG.

I had this choice when I bought my milling machine. What swung it for me was that my lathe used MT3 in the headstock, therefore by making the mill MT3 all my direct collets would work in both machines.

In respect of MT3 taper removal, I have an extractor for the mill courtesy of an article in MEW, and a similar extracter for the lathe. I have no deed to batter the end of the collet to get it out.

Peter G. Shaw

Some of the first jobs I had for my mill required me using fairly large morse taper drill bits so I went with MT3. I have a self extracting drawbar so no release issues. Many mills have them and they’re not difficult to make. I still use MT drill bits in my mill from time to time, they can be had for good prices at the shows. I often have a collet Chuck in the mill as well so changing cutters is not an issue affected by the machines taper anyway. I’d go MT3 again if I had to make the choice. Having said that many don’t seem to know how to use them and over tighten on MT tapers, it’s not needed.

Another vote for R8 (well it would be from a Bridgeport user)

Having used both R8 and MT3, if the spindle is good and the register for the R8 is the correct size, then R8 can be often purchased quite cheap for after market parts like boring heads etc.

The MT3 like been said, a lot of people do over tighten them.

An advantage of an R8 over a MT3 , is if the collet or piece is undersize, the back of the R8 keeps it well aligned while the front taper clamps down on the tool and it still runs quite well. That is not the case with the MT3. If you only ever have nominal cutters etc, then the MT3 is fine.

See what else you want in the way of other holders and drill chucks and arbors etc and price them up and availability.

Often availability of accessories that you will use can be a real deciding factor, and not just price alone.

Neil

I like R8 as its much easier to release tooling from the spindle. It's also an industry standard due to the ubiquity of Bridgeport Mills, this means lots of good quality tooling available at a decent price.

Julia

I seem to have arrived at this particular party just as everyone is leaving, but I'll throw my metaphorical hat into the ring, anyway.

When I upgraded my mill from an MT3 spindle one to a much larger VMC, I decided to go with R8. However, having several accessories with MT3 shanks, my first purchase was an R8 to MT3 converter sleeve. That allowed me to at least start using the machine without a massive outlay. As the need arose, or funds allowed, I gradually replaced the ER collet chucks, etc, with R8 ones and similarly replaced the arbor on the boring head. I don't regret the decision I made and neither, I suspect will you, Bill. Enjoy your new machine when it arrives!

John

Do you have the means to turn a drill with an MT3 shank? If yes go R8 on the mill, if no go MT3.

MT3 won't fit in an R8 adaptor, there's not enough meat left so there is no such thing as a compact R8 to MT3 socket.

I bought a Rong Fu mill drill a long time ago, and agonised over this choice as I thought then that the R8 was by far the better choice up the spout of a milling machine, but it made my stock of MT3 shank drills unusable. I swallowed hard and went with MT3 and have never regretted it even if the comments about the taper being a pig to eject sometimes all ring true.

I agree with Jason's comment that ISO30 is a better choice. If only….

I would go for morse taper. There is an abundance of good quality old morse taper tooling around, often much cheaper than more modern R8 stuff. If you have a lathe its likely to be morse taper which makes tooling interchangable between the two. Ive never found morse taper difficult to extract? a short sharp tap on the top of the draw bar and its out?

MT3 adaptors are available for R8 but as drills with an MT3 shank are over 22mm in diameter they are getting pretty long and use up a lot of the Z height. If you want to use a mill as a heavy duty drill then I think it will need a generous Z height. Mill spindles do not normally have the convenient taper drift ejector slot so the drill will need ejecting with a drift down the drawbar hole. R8 is also not ideal for large drills as the adaptor will need removing to eject the drill from the adaptor sleeve. There is no denying that the mill is very useful for accurately positioned drilling but as spotting drills and jobbers drill can readily be used in ER or R8 collets then it’s likely that most people most of the time won’t need MT3 drilling. A boring head will give the chance to make a hole as big as the boring head can manage.

Mike

Becaused some of my tooling is used in both the lathe and the Mill, I use M3. Usually, a sharp rap will break the grip. If not, I made up a means of forcing the tapers apart in the Mill/Drill, Using a shop made Pusher (An inverted puller ) avoids hammering the bearings too much. If the 1/4 BSF threads do not break break the grip, a light tap when tight (The setscrews, not me! ) always separates things.

Howard