R8 instead of MT3

The Boxford VM-30 was the one I was thinking of.

It is also worth thinking about what units you prefer to work in when deciding on tooling. Old MT arbors will be 1", Autolocs will probably come with imperial collets and boring heads will take 1/2" tooling. Not much good if you want to use metric slitting saws and MOD gear cutters which tend to be 22mm bore, metric shank milling cutters and Indexable boring bars.

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

I have an R8 x MT3 for my mill. It works well. The downsides are that it requires removing he adapter from the spindle to change MT tools and the fact it sticks out so far. It is definitely not for milling.

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

I did have a big turret mill with int30 spindle, good for holding clarkson and bristol ericson collet holders and the four tapped holes were great for bolting fly cutters direct to spindle face with minimum overhang.Abosolute pain in the backside with 3 mt adaptor, the adaptor had to be removed from the spindle taper to get at the extractor slot,to get over this I turned down a few taper shank drills to a parallei slot and held them in the collet chuck though only really suitable for light work, On the larger mills (50 inch table) 30 int is really too small,I should have looked for a machine with 40 int, there is not much 30 int tooling on the second hand market whereas there was/is lots of 40 int, so in the end I bought a Meddings 3 mt pillar drill 100 to 3500 rpm very good machine. to back up the mill for heavy drilling Regarding a choice of 3mmt and R8 one should look to the future,should you wish to upgrade to another machine I think a machine with R8 would command a better price. I have now downsized to an Elliott 00 omnimill (a gift from a neighbour) vert and horizontal spindle,this is the early version with 3 mt spindles ,on later machines the horizontal spindle was updated to 30 int, I suppose this gave a better drive for horizontal spindles and still allowed the use of 3 mt drills in the vertical spindle as there is a lot of daylight under the vertical spindle nose, A 3mt horizontal spindle nowadays (55years after the machine was made) makes thing difficult as availability of s/hand long arbours is virtually non existant,so if buying an older machine with horizontal MT spindle make sure it has a at least one arbour, with collars if so it will probably be for one inch cutters.And make sure the bearing collar which runs in the overarm support fits,.

If you had the choice when buying, without doubt R8.
If a machine was secondhand and MT3 that wouldnt rule it out for me either and never a problem removing takes 15 seconds, no lock up, nothing its used.