Thread: Milling Machine Quality

Originally Posted by RayG

Hi Alby,

For a good introduction to basic stuff, try the MIT series of videos, the one on milling is this one..

MIT TechTV – Machine Shop 4

Regards
Ray

PS I'd hang out for a machine with NT30 taper.

Ditto, and I have an R8 taper machine. I'm thinking of selling it and buying an ISO 40 taper replacement. The R8 machine has served me very well for over 20 years but I've a ton of 40 taper tooling and am looking to reduce the range of stuff.

PDW

Not necessarily a dissenting view, but at least a counter-point to consider in that MT3 can have advantages. While MT3 isn't a great choice for mill in terms of releasing, as I mentioned, it's possible to modify a drawbar arrangement such that it will push out the collet or tool holder. It's quite a simple mod too, simply a "cap" type arrangement on the head through which the drawbar passes. MT3 is (or at least was) a very popular choice of spindle bore in small workshop machines. In my workshop my drill press, one lathe, one dividing head, and one mill all used the same taper. What that means is that tooling can be interchanged very easily between machines, and I do so regularly. As I'm gaining more experience and tooling, then replacing machines and upgrading, they're coming with different (and better) tapers (my second lathe has an MT4 for example, and the mill a Swiss (W20) taper), but for somebody starting out in the area this can be a major advantage. Tooling up a machine can be ruinous!

Finally, remember these words; "You can never have too much headroom!", something machines of this size tragically lack. Unless you're in to clockmaking or similar, you'll regularly be cursing the lack of headroom. Even on machines where you think you have plenty, you'll simply take on bigger jobs and run out again! MT3 collets are (relatively) cheap and will protrude only a few mm beyond the spindle. Those few mm can sometimes mean the difference between simply doing a job, and cursing like a trooper.

I definitely wouldn't exclude a machine simply because of the taper it comes with. Hopefully the above illustrates there can be significant advantages even with what many would consider a "poor" choice. Furthermore, the alternatives often aren't exactly brilliant either. R8 for example is a rubbish taper, essentially with the many of the same attributes as the MT3 taper above, but without the ability to swap tooling between machines. It's a faster taper to MT, so releases easier, but is really only popular because of the popularity of Bridgeport machines in the US. Ideally you'd find an ISO taper machine, but it's both unlikely from what I've seen (unless your pockets are deep), and also see the comments above on headroom.

If only the world were perfect

Pete

Originally Posted by Pete F

Not necessarily a dissenting view, but at least a counter-point to consider in that MT3 can have advantages. While MT3 isn't a great choice for mill in terms of releasing, as I mentioned, it's possible to modify a drawbar arrangement such that it will push out the collet or tool holder. It's quite a simple mod too, simply a "cap" type arrangement on the head through which the drawbar passes. MT3 is (or at least was) a very popular choice of spindle bore in small workshop machines. In my workshop my drill press, one lathe, one dividing head, and one mill all used the same taper. What that means is that tooling can be interchanged very easily between machines, and I do so regularly. As I'm gaining more experience and tooling, then replacing machines and upgrading, they're coming with different (and better) tapers (my second lathe has an MT4 for example, and the mill a Swiss (W20) taper), but for somebody starting out in the area this can be a major advantage. Tooling up a machine can be ruinous!

Finally, remember these words; "You can never have too much headroom!", something machines of this size tragically lack. Unless you're in to clockmaking or similar, you'll regularly be cursing the lack of headroom. Even on machines where you think you have plenty, you'll simply take on bigger jobs and run out again! MT3 collets are (relatively) cheap and will protrude only a few mm beyond the spindle. Those few mm can sometimes mean the difference between simply doing a job, and cursing like a trooper.

I definitely wouldn't exclude a machine simply because of the taper it comes with. Hopefully the above illustrates there can be significant advantages even with what many would consider a "poor" choice. Furthermore, the alternatives often aren't exactly brilliant either. R8 for example is a rubbish taper, essentially with the many of the same attributes as the MT3 taper above, but without the ability to swap tooling between machines. It's a faster taper to MT, so releases easier, but is really only popular because of the popularity of Bridgeport machines in the US. Ideally you'd find an ISO taper machine, but it's both unlikely from what I've seen (unless your pockets are deep), and also see the comments above on headroom.

If only the world were perfect

Pete

Actually, I agree with all of that. For a mill, R8 is a better taper than 3MT only because of abundant tooling but the ability to swap tooling about between lathe & mill is certainly not there easily - I do have an R8-3MT adapter sleeve but I've never seen the reverse (nor used the one I have).

I found that in practice I rarely swapped tools, though. Most/all tooling with a 3MT I used in the lathe had a tanged shank. *ALL* 3MT tooling I used in the mill had a shank threaded for a drawbar. OK you could use a drill chuck with a tanged shank in the mill, but it wouldn't lock in place. You could screw a stud into a threaded shank tool and use it in the lathe tailstock, but it wouldn't lock in place. I realise this last bit is only relevant for people with lathes that *have* the locking recess for a tanged shank, but you get my drift.

Not like drill chucks are so expensive that you can't have a couple. I think I've got about 10 these days in different sizes & with different taper shanks.

TOTALLY agree about the headroom issue. Amazing how fast it seems to vanish once you start using rotary tables, multi-axis sine vises etc etc.

PDW

Originally Posted by Pete F

. R8 for example is a rubbish taper,

Pete

THEMS FIGHTIN WORDS

Originally Posted by morrisman

THEMS FIGHTIN WORDS

Ha ha, yes I thought that would get a reaction. Put it this way, go in to a modern machine shop, especially one with CNC machines, and tell me how many R8 spindles you see

OK you could use a drill chuck with a tanged shank in the mill, but it wouldn't lock in place. You could screw a stud into a threaded shank tool and use it in the lathe tailstock, but it wouldn't lock in place. I realise this last bit is only relevant for people with lathes that *have* the locking recess for a tanged shank, but you get my drift.

Peter, sorry it's possibly not what you meant but I fear some of what you wrote may cause confusion amongst newer members. Just to clarify for others, both R8 and Morse Taper are driven by the taper itself, the drawbar is there purely to prevent the collet, tool etc from being pulled out. Likewise the tang on the taper is there purely to eject the taper and does not drive anything (nor incidentally does the key in the R8 taper drive anything). The taper is self locking, so you most definitely can use a non-threaded taper holding a chuck for example in the mill, it's then exactly the same as a drill press or the tailstock and will lock just fine. The reason drills don't need a drawbar is because the pressure from the drill forces the taper back into the spindle, with an end mill the forces can be the other way, indeed remarkably strongly if side milling aluminium (some of the occasions I've pulled a cutter). My tailstock is MT2 (as are most small lathes), but one of the lathe's headstock is MT3 and I swap tooling there. I use the mill's tooling (boring heads etc) in the lathe, and conversely use the lathe's tooling in the mill, sometimes it's just handy and makes things quicker. An example of the latter I can think of I've done recently would be before I went away for work, I wanted to quickly center a hole in the mill. Pop a MT3 centre in the mill's spindle, raise the mill's knee, adjust the Y axis by eye and keep raising the knee until the centre is fully home. Tighten the vice and the hole will be centred quite accurately ready for boring, and no indicators were harmed in the process. Takes about 30 seconds, if that. Just one example that comes to mind.

Pete

Edit: Just to add to the above, I made up a drawbar for the lathe so that when I am using tooling that's in danger of being pulled, I use that. It also closes my MT3 Collets if I'm using them in the lathe, though I must admit I prefer ER32 and typically use it instead.

Originally Posted by Pete F

Peter, sorry it's possibly not what you meant but I fear some of what you wrote may cause confusion amongst newer members. Just to clarify for others, both R8 and Morse Taper are driven by the taper itself, the drawbar is there purely to prevent the collet, tool etc from being pulled out.

Mostly true, the drawbar puts the collet etc under tension to achieve a high friction fit.

Originally Posted by Pete F

Likewise the tang on the taper is there purely to eject the taper and does not drive anything

Now there I am afraid that you are incorrect. The tang locks into a slot (on machines so equipped) and does indeed get used to transmit torque. This is why better lathes have such a slot in their tailstock rams. I have *never* had a tanged shank slip & rotate in my Chipmaster but I have had this happen in lesser machines with a perfect fitting taper (I made it and reamed it to size); the usual solution is to use a lathe dog bearing on the compound or similar on a TS drill to prevent rotation.

I agree that a Morse taper is self-locking, but this can be and often is, in practice, overcome (if you run your machines as I do anyway - the HP is there for a reason). The tanged shank allows much more torque to be transmitted without solely relying on the friction fit.

People who are new also need to be aware that *milling* using a tanged shank arbour is a recipe for disaster. The question is not *if* it will self-release, but *how soon* and how much damage will follow. Friction fit MT arbours do not take at all kindly to side loads, they are only good for axial loads.

PDW

To add further to the R8 tang debate, there are those that remove the tang and rely only on the taper and drawbar.

Of course R8 collets don't have a tang at all, so they certainly rely on drawbar and taper.

Hi all,

I hear many people say that there is far more tooling available in R8 over MT3 or 4. I recently purchased my machine (about 2 years ago) and it came with a MT4. Having very little tooling, I pretty much started from scratch and found no such limitations with having a MT4 and finding the required tooling.

My lathe spindle has a MT5 so I have a MT4 - MT5 sleeve. Works well if I want to use my ER32 or 40 collets on the lathe.

The R8 preference over MT seems to be (dare I say it) an old persons attitude.

Cheers,

Simon

Hi Simon and Alby,
There is a place in Canada that sells the NT30 spindles for these machine at around $100 their money plus post. A few guys have bought them and installed them with no problems.
With post it would be up around $180-$200 but it something to consider as you can then run either NT30 or BT30 tooling.

BT tooling is great if your looking at cncing it down the track as you can fit pull studs to the top instead of a draw bar thread, this them allows you to use a quick change tooling system. In the mean time you just use a longer draw bar as they are threaded M12 just like the NT30 but don't have the parallel part at the top.

Dave

Just to clarify what Peter has said above, in case I gave an impression otherwise by something I've said regarding swapping tooling, any milling operation should be done with a drawbar or other means to positively lock the holder to prevent the tool from pulling out.

Regarding the tang, that argument/misconception is as old as the hills and I have no intention of going further with it. I do however stick solidly with what I have said, I believe the tang is not designed to transmit torque. I would be curious to see any manufacturer's information that indicates the tang was designed to supplement the taper in driving. Indeed I've seen a tang break when the taper slipped and it was torqued (no it wasn't me!). If the taper is slipping it's either being overloaded or is damaged.

Machine taper - Wikipedia, the free encyclopedia The discussion on tangs is under "Use"

Having said that, what things are "designed" to do and what they're sometimes tasked to do in our workshops is sometimes two very different things

Pete

Getting back to the OP request for comments regarding this mill, I was out that way today and had a quick look at the Dovetail Shaft Model MMD-45 in question at Paramounts to see how it stacked up.

Looks like quite a heavy and solid unit. Certainly not a weak kneed hobby style unit.

The trouble with Paramounts, is that they have this really annoying habit of putting things on display and not properly fitting and tightening up handwheels and other bits removed for transport, so it's off putting when these bits are all flopping around while you are trying to check it out.

It's not a cheap unit ($$$ wise) but seems like value. Nice big solid table with no back lash.

I suppose it comes down to whether you want to spend that amount on new or used.

It's a personal choice and I wouldn't buy into that.

To me it looks OK. I suppose it would pay to google on user comments for that model/designation.

Regarding Morse taper, I will say that anything over MT4 gets very expensive when sourcing attachments.

Cheers

Rob

Originally Posted by simonl

The R8 preference over MT seems to be (dare I say it) an old persons attitude.

Cheers,

Simon

Given that I *started* with MT3 and currently have MT2, MT3, R8 and ISO 40 milling spindles, perhaps what you really meant to say was, the preference for ISO 30/40-R8-Morse (in that order) is based on actual use rather than experience with only one type....

PDW

Originally Posted by Dave J

Hi Simon and Alby,
There is a place in Canada that sells the NT30 spindles for these machine at around $100 their money plus post.

Dave

Hi

Do you have the link to that seller ?

Mike

Originally Posted by PDW

Given that I *started* with MT3 and currently have MT2, MT3, R8 and ISO 40 milling spindles, perhaps what you really meant to say was, the preference for ISO 30/40-R8-Morse (in that order) is based on actual use rather than experience with only one type....

PDW

No. I meant what I said. I was just being a bit cheeky!
We can't always take ourselves too too seriously..... can we?

In all honesty, the only ISO or R8 spindles I have seen were on paper in a catalog, so I am be no means qualified to take you on in such a discussion. But I can still have a little fun!

Simon