Milling machine taper choice ?

[NigeParticipant @nige81730]

Making choices about a milling machine and don't know enough about differing spindle tapers to make an informed choice. I have looked at a number of catalogues so have an idea about the different collet systems that hang on the end.

Choice is between morse taper and R8 and though I have experience of MT I have none with R8. As I don't posses any collets or milling cutters as yet there is no drive to buy one or the other because of previous investment in tooling so looking for sound engineering reasons, if there are any, to make my choice.

[NigeParticipant @nige81730]

[Old SchoolParticipant @oldschool]

Not an expert bought my mill with an R8 taper on the advice of an expert it was good advice it works well and you can get the tooling out easily unlike morse tapers a lot of mills don't have the slot in for using a drift .

[Howard LewisParticipant @howardlewis46836]

If your lathe is 3MT then it may be worthwhile going for a Mill with a 3MT spindle. That would make tooling interchangeable between the two, if and when you wish.

Even when I had a 2MT Myford ML7, I opted for 3MT since an adaptor sleeve would allow tooling, such as an ER25 collet chuck to be used in the lathe, as is, or in the Mill with a step up sleeve. (Years on, is almost always used this way, in Lathe and Mill, except when needed for the HV6 Rotary table which is 2MT)

Otherwise you could find yourself with two sets of tooling, one Morse taperfor the lathe, and another R8 set for the Mill.

You may finish up with two different drawbars, (3/8 BSW and Metric) for each machine, but they can be made easily, and be cheaper than buying two sets of Collet Chucks, Flycutters or Boring Heads.

Others may differ from this view!

You makes your choice and pays your money.

Howard

[NigeParticipant @nige81730]

Thanks Howard. The ML4 is 2MT and 1MT at the tailstock. Having decided to get a milling machine I had discounted the need to mount a collet system of any sort in the lathe so was not bothered about 'compatibility', might that be a mistake?

Looking at Collet chucks they don't seem to come commonly on 1MT mounts.

I wonder how the Sieg and Warco milling machines with MT spindles get over the possible problem of 'stuck' morse tapers? I guess the answer is to not over tighten the drawbar in the first place? Do the manufacturers specify a torque setting for tightening draw bars?

[NJHParticipant @njh]

Nige

This has been asked before and the concensus was that R8 was the better option unless you have a lot of MT items that you want to use . The R8 taper has the advantage of being self ejecting hence the “stuck” MT item does not occur ( with the need to belt the daylights out of it to release it – with the consequent risk to the bearings,!,)

Me – well I have a MT version – but the R8 was not available in the distant past when I bought it. If starting out now ( without the load of tooling I have accumulated ) I would choose R8.

Norman

Ps Yes seeing your last post the secret is not to be too “Macho” with the spanner !

Edited By NJH on 21/10/2017 16:06:36

[JourneymanParticipant @journeyman]

Posted by Nige on 21/10/2017 15:53:35

I wonder how the Sieg and Warco milling machines with MT spindles get over the possible problem of 'stuck' morse tapers? I guess the answer is to not over tighten the drawbar in the first place? Do the manufacturers specify a torque setting for tightening draw bars?

Most of the machines with MT2 or MT3 tapers are now fitted with self-ejecting drawbars, so no worries regarding stuck tapers. On a lathe you would normally fit an ER chuck rather than use one on a taper shank with a drawbar through the headstock. The lathe chuck also means that longer items can be turned provided they fit through the collet and down the spindle bore.

John

Edited By Journeyman on 21/10/2017 16:27:16

[Anonymous]

I've never really understood the argument for common tooling between lathe and mill. About the only tool I use on both the lathe and mill is a drill chuck. But I've got more than one drill chuck.

I use R8 on two of my three mills, ie, on the vertical and CNC mills. You only need one drawbar (7/16" UNF). The CNC mill has a "quickchange" system based on a ¾" R8 collet and parallel shank toolholders. The idea being that you don't need to remove the R8 taper, just loosen it, and it is supposed to give better Z repeatability. I also use the same system on the vertical mill, for many, but not all, tools. The boring head, autolock chuck and tapping heads are plain R8. Note that the small setscrew in a R8 spindle is not for driving the taper, it is simply for alignment. They're a right PITA, and I've removed both of mine.

I wouldn't even contemplate Morse tapers for a milling machine spindle; of the two R8 every time.

Andrew

[Thor 🇳🇴Participant @thor]

Nige,

I agree with those who recommend buying a milling machine with a R8 taper since you don't have any collets yet. Using R8 collets will give you a bit more headroom than using an ER collet chuck. If you do want to share collets between the lathe and milling machine you could buy an ER collet chuck for the milling machine and make an ER collet chuck for your lathe.

Thor

[John MCParticipant @johnmc39344]

My mill for which I made the spindle now has a 4 mt, was the right choice at the time but with the benefit of hindsight and some further experience I would have chosen an International taper, no need to give it a p****r to release it and accurate, like a morse, wear in R8 type collets on the parallel location can cause inaccuracies.

If you are buying ex-industrial equipment (my favoured way) you will get this choice, not sure if "home workshop" kit uses the International taper.

John

[NigeParticipant @nige81730]

Journeyman: Thanks for that comment, it clears up that query.

Andrew: Thank you for your comments and thoughts. I looked up R8 and in the reading on Wikipedia it says that R8 tapers are keyed, would that be in addition to the small set screw that is not driving the taper. The image on Wikipedia appears to show a keyway on what appears to be the parallel portion of the collet but no sign of a set screw though it might be that the picture I am looking at is not typical; my inexperience showing I'm afraid

[jimmy bParticipant @jimmyb]

I wish I'd gone to R8 with my mill. I chose MT3 so I could use tools on the mill and lathe.

9 years later, the tools never get swapped around.

Next mill WILL be R8!

[John HaineParticipant @johnhaine32865]

R8 every time, even over Int type (except maybe on CNC). Collets are reasonably cheap – e.g. from Arc £4.58 inc VAT and go up to 19mm 3/4 inch; ER32 go up to 20mm at £5.81 incl. AND you have to buy the chuck as well! R8 collets go straight in the spindle with minimal overhang, grip like ****, and don't get stuck. What's not to like?

I've got an Int.30 spindle on my little CNC and it's OK, but you either have to have the right shank on a collet chuck (I have ER16 for this machine) or use individual holders. They both give a lot of overhang and you lose headroom under the mill.

[Andrew TinsleyParticipant @andrewtinsley63637]

R8 seems to becoming a standard these days. A friend has an international 30 taper and I find this to be superior to R8, but this seems to be largely confined to professional gear. So R8 would seem to be a logical choice.

Andrew.

[Thor 🇳🇴Participant @thor]

Hi Nige,

The R8 collets have a keyway in the parallel portion, the setscrew is in the spindle so you have to align the keyway in the collet with the setscrew when inserting a collet. This video might be of help.

Thor

Edited By Thor on 21/10/2017 16:55:33

[JasonBModerator @jasonb]

Posted by Nige on 21/10/2017 15:53:35:

I wonder how the Sieg and Warco milling machines with MT spindles get over the possible problem of 'stuck' morse tapers? I guess the answer is to not over tighten the drawbar in the first place? Do the manufacturers specify a torque setting for tightening draw bars?

Quick sharp tap with a copper hammer releases my MT3, never had it get really stuck.

I also use quite a bit of the tooling on the lathe on occasion – Boring head to offset the tailstock for tapers, flycutter to face of large castings true to a bore that has been machined with the part on the cross slide, ER chuck as it will hold larger drills than my drill chucks, slitting saw where having work horizontal on the lathe means less work sticking out than vertically on the mill.

A lot will depend on what tapers you have on the mill already, if small then not much point having tooling for both as it will mean you need a small mill taper, My Lathe is MT4 head and MT3 tail so easy to use tooling in both.

The SX2.7 I have to play with is R8 and it is nice enough to use and will eject easier than MT3 though with 10yrs tapping the drawbar on the X3 the bearings still seem fine.

J

[MuzzerParticipant @muzzer]

+1 for R8. 30 taper may be sightly better from a technical POV but it's a minority sport, so not so easy to come by tooling and it costs more. Personally I'd suggest going for R8 for smaller machines and 40 taper for bigger ones. My milling machines are 30 and 40 taper and the bantam is 3 and 5 MT.

As suggested, there may not be a great deal to be gained from "common" tooling. If you have a milling machine, it seems a compromise to buy tooling that is also compatible with the lathe? The exception being drill chucks but you want more than one of those anyway.Of course, there's no "right" answer, as ever.

Murray

[jimmy bParticipant @jimmyb]

Wished I gone for R8 with my mill. Like most, I thought I could share tooling with the lathe.

8 years later, the tooling has never been shared, just duplicated…..

[EmgeeParticipant @emgee]

Posted by John Haine on 21/10/2017 16:43:54:

I've got an Int.30 spindle on my little CNC and it's OK, but you either have to have the right shank on a collet chuck (I have ER16 for this machine) or use individual holders. They both give a lot of overhang and you lose headroom under the mill.

John, with an INT30 taper it is possible to enclose the ER16 taper into the tool shank, just the depth of the closing nut would be below the spindle end.
Emco used BT30 tooling which is the same dimensions arbor as INT30, a large part of the ER25 collet seat is within the shank and has minimum protrusion from the end of the spindle.

Emgee

[Neil WyattModerator @neilwyatt]

I would go R8 now, but it was easy to make a relaible self-ejector. Before that I never got an MT3 taper stuck, I used to tap them out using a bar with a bit of brass silver soldered on the end, but I decided a self ejector was good practice..

Neil

[duncan webster 1Participant @duncanwebster1]

R8 for certain, I've had both and wish current machine had R8. You can get an R8 male to MT2 adaptor which uses very little headroom. Buy some R8 collets for holding milling cutters, less overhang than a chuck and unless you're being really ambitious the cutters don't pull out

[nigel jones 5Participant @nigeljones5]

Ive got two milling machines – one R8 and one MT3. The R8 wins every time. Hate the MT so much that ive bought a cheap chinese er32 collet set and thats permanently in the MT mill.

[Chris Evans 6Participant @chrisevans6]

R8 every time, tooling is cheap and plentiful my collets go up to 3/4" and 20mm for the metric set. Take no notice about the alignment key, I've used R8 equipped Bridgeport mills for over 50 years and most had the alignment key removed as does my present machine.

[Anonymous]

Posted by Nige on 21/10/2017 16:37:47:

I looked up R8 and in the reading on Wikipedia it says that R8 tapers are keyed, would that be in addition to the small set screw that is not driving the taper. The image on Wikipedia appears to show a keyway on what appears to be the parallel portion of the collet but no sign of a set screw

The keying is not in addition, the setscrew is all you get. As you saw the collet has a keyway on the parallel portion. The setscrew is in the spindle and protrudes into the bore to mate with the keyway in the collet. The setscrew has a plain cylinder on the end that actually mates with the collet keyway. It allows the collet to be aligned in a specific orientation every time, but I've no idea why the original designers thought it necessary.

Andrew

[Anonymous]

Posted by John Haine on 21/10/2017 16:43:54:

R8 every time, even over Int type (except maybe on CNC)

I've got an INT40 taper on the horizontal mill, and would like it on the vertical mill. It's probably overkill for the CNC mill though. No way I'm going to be swinging this Dedlock cutter on an R8 spindle:

As far as I can see INT40 and INT50 tooling is quite common, but INT30 rather less so.

Andrew

[Author]

Posts