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Have I made a mistake buying a MT3 mill?

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s d23/06/2023 11:46:34
30 forum posts
11 photos

Chester have a deal on their VS30 mill atm so I took the plunge. I've been looking at so many different models and manufacturers I didn't notice the Chester is MT3 not R8. I have no experience with either as I've never had a mill.

Will I regret it?

Andrew Johnston23/06/2023 12:09:20
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7061 forum posts
719 photos

Personally I'd say yes. but I am biased as both my vertical and CNC mills are R8 taper. There is an argument that with MT in the mill you can share tooling with the lathe. But you'll need to have a fairly large large to have a MT3 tailstock. And I've never felt the need to swap tooling. For a start the lathe tailstock doesn't need a drawbar, the mill definitely will. You might get away with drill chucks in the mill without a drawbar, but I prefer to have drill chucks dedicated to the specific machine tool.

Andrew

JasonB23/06/2023 12:19:15
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25215 forum posts
3105 photos
1 articles

I have mills with both and both have small disadvantages as well as disadvantages

I do sometimes use the MT3 tooling in the hobby lathe such as the boring head and flycutter (MT4-3 Reducer if in the head stock) when I use it as a poor mans horizontal mill, straight into the MT3 tailstock when the boring head is being use dto offset the tailstock ctr

Likewise I sometimes use the 13mm keyless chuck that lives on the lathe in the mill when I want to hold bigger than my usual 10mm chuck. No problem a sit is tapped M12 for a drawbar and when in use in the lathe I just have a short length of studding with a screwdriver slot that can be screwed in so the tailstock will eject the taper.

The R8 mills do self release with a couple of turns of the drawbar but I've not found a quick tap with a copper hammer an issue on the MT3 will which is the mill that gets the most use. Not all R8 are set up to self release. Never had a problem with MT getting stuck

MT3 can be tilted a bit sideways so you don't need to wind the head up so much to change tooling as you do with R8

Edited By JasonB on 23/06/2023 12:19:32

Andrew Tinsley23/06/2023 12:19:39
1817 forum posts
2 photos

Andrew J makes good points. However I have lots of MT tooling going back years. Too expensive (and too late regarding my advanced years) to change to R8 tooling.

Perhaps Andrew is a little harsh, as there really isn't a right or wrong answer to your question, simply a matter of choice. Andrew works on "big stuff", usually with industrial machines. So R8 is a no brainer for him. For hobby sized kit then the answer is not so clear cut.

Andrew

Robert Butler23/06/2023 12:21:39
511 forum posts
6 photos
Posted by s d on 23/06/2023 11:46:34:

Will I regret it?

Yes there is an abundance of R8 tooling at reasonable cost.

Robert Butler

Peter Cook 623/06/2023 12:24:43
462 forum posts
113 photos

I suspect it will depend on what you plan to do with the mill.

R8 ( and MT) collets are designed to hold specific diameters of material, so If you only ever use a small number of sizes of cutters then R8 ( self releasing) would be better. If however you will be using lots of smaller cutters, then you might want to consider an ER collet system where the collets hold a range of sizes ( and are cheaper than R8 or MT collets).

If you go the ER route, then once the MT3 shanked ER collet holder is installed, you will only rarely need to get it out, and probably will not really notice the difference.

On my small (MT2) mill I usually hold drills in the ER collets unless I am planning a significant drilling session with multiple sizes.

Nicholas Farr23/06/2023 12:25:26
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3988 forum posts
1799 photos

Hi, my Warco Major has MT3, and I've not had any problems using it.

Regards Nick.

Edited By Nicholas Farr on 23/06/2023 12:28:27

s d23/06/2023 12:28:03
30 forum posts
11 photos
Posted by Peter Cook 6 on 23/06/2023 12:24:43:

I suspect it will depend on what you plan to do with the mill.

R8 ( and MT) collets are designed to hold specific diameters of material, so If you only ever use a small number of sizes of cutters then R8 ( self releasing) would be better. If however you will be using lots of smaller cutters, then you might want to consider an ER collet system where the collets hold a range of sizes ( and are cheaper than R8 or MT collets).

If you go the ER route, then once the MT3 shanked ER collet holder is installed, you will only rarely need to get it out, and probably will not really notice the difference.

On my small (MT2) mill I usually hold drills in the ER collets unless I am planning a significant drilling session with multiple sizes.

Yes I'm planning to use an ER32 collect chuck and collets for mills and drills 90% of the time. But until I start I won't really know for sure.

JasonB23/06/2023 12:29:28
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25215 forum posts
3105 photos
1 articles

I'm not sure R8 is due to working on and with "Big Stuff" the actual cross section of a MT3 is no bigger than R8.

The Bridgeport being R8 would really have been the deciding factor and up to a few years ago most hobby mills would have been MT so that really decided it for you. No we see R8 being a lot more common on the smaller machines, whether that is due to the large American market having a lot of R8 ex Bridgeport tooling about who knows

I'm sure if the Bridgeport came with INT taper then Andrew may have gone for that, I would not be averse to a small quick change INT20 for the CNC and if the same tooling could be used on the other mills all the better. I think the late JS was able to spec his Sieg machines with this type of taper.

SillyOldDuffer23/06/2023 12:30:53
10668 forum posts
2415 photos

I haven't yet.

I bought MT because at the time MT tooling was more common than R8, and because it allows some tools to be shared between lathe and mill.

In practice most of my milling is done with ER collets so I rarely change between MT tools.

Main problems with MT, I think, are:

  1. The need to undo a drawbar means it's not as quick change as later systems (I don't care)
  2. Failing to tighten the drawbar means the tapers might spin and be damaged (not a problem for me yet)
  3. Over-tightening the drawbar, especially if a cold tool is inserted into a hot spindle, can jamb it in place. The tapers can also stick if left in place for a long time, perhaps due to very slight corrosion or oil gumming up. Removing a badly stuck taper is difficult!
  4. Tapping the drawbar sharply with a dead hammer to unstick the taper causes many to assume bearings must be damaged. Actually, although MT has been in wide use for about 150 years, there's very little evidence of this. Nonetheless people believe it. My mill is 7 or 8 years old, bearings are OK.
  5. MT relies on a friction grip, which is very strong, but other systems provide positive locking. These allow more power to be put into the cutter, probably more than a hobby lathe can cope with, but accidental breakages of tools and holders become more likely.

Of these only the possibility a seriously stuck taper worries me. So far I've avoided it by not leaving MT tapers screwed tight for long periods - I undo them every six weeks or so and give them a wipe.

I think the main advantage of R8 in amateur hands they don't jamb. Plenty of tooling available for R8 now, so one of my original reasons for choosing MT has gone. Nor is it common for me to swap MT tools between mill and lathe.

For what I do MT is fine, R8 avoids a potential problem but in practice MT vs R8 makes no difference in my workshop. Be aware that not everyone thinks R8 is the best of all possible systems! I'm happy when tools do the job, and don't upgrade them unless there's a specific benefit.

Dave

s d23/06/2023 12:32:25
30 forum posts
11 photos
Posted by JasonB on 23/06/2023 12:29:28:

I'm not sure R8 is due to working on and with "Big Stuff" the actual cross section of a MT3 is no bigger than R8.

The Bridgeport being R8 would really have been the deciding factor and up to a few years ago most hobby mills would have been MT so that really decided it for you. No we see R8 being a lot more common on the smaller machines, whether that is due to the large American market having a lot of R8 ex Bridgeport tooling about who knows

I'm sure if the Bridgeport came with INT taper then Andrew may have gone for that, I would not be averse to a small quick change INT20 for the CNC and if the same tooling could be used on the other mills all the better. I think the late JS was able to spec his Sieg machines with this type of taper.

I notice all the smaller machines I looked at were either R8 or you could choose morse as an option. I was a bit surprised the Chester was morse only, I stupidly assumed is was R8 because there was no choice.

s d23/06/2023 12:35:52
30 forum posts
11 photos
Posted by SillyOldDuffer on 23/06/2023 12:30:53:

I haven't yet.

I bought MT because at the time MT tooling was more common than R8, and because it allows some tools to be shared between lathe and mill.

In practice most of my milling is done with ER collets so I rarely change between MT tools.

Main problems with MT, I think, are:

  1. The need to undo a drawbar means it's not as quick change as later systems (I don't care)
  2. Failing to tighten the drawbar means the tapers might spin and be damaged (not a problem for me yet)
  3. Over-tightening the drawbar, especially if a cold tool is inserted into a hot spindle, can jamb it in place. The tapers can also stick if left in place for a long time, perhaps due to very slight corrosion or oil gumming up. Removing a badly stuck taper is difficult!
  4. Tapping the drawbar sharply with a dead hammer to unstick the taper causes many to assume bearings must be damaged. Actually, although MT has been in wide use for about 150 years, there's very little evidence of this. Nonetheless people believe it. My mill is 7 or 8 years old, bearings are OK.
  5. MT relies on a friction grip, which is very strong, but other systems provide positive locking. These allow more power to be put into the cutter, probably more than a hobby lathe can cope with, but accidental breakages of tools and holders become more likely.

Of these only the possibility a seriously stuck taper worries me. So far I've avoided it by not leaving MT tapers screwed tight for long periods - I undo them every six weeks or so and give them a wipe.

I think the main advantage of R8 in amateur hands they don't jamb. Plenty of tooling available for R8 now, so one of my original reasons for choosing MT has gone. Nor is it common for me to swap MT tools between mill and lathe.

For what I do MT is fine, R8 avoids a potential problem but in practice MT vs R8 makes no difference in my workshop. Be aware that not everyone thinks R8 is the best of all possible systems! I'm happy when tools do the job, and don't upgrade them unless there's a specific benefit.

Dave

Thanks Dave, this makes me feel a little better. Jamming was the main worry, or if there would be less rigidity with lightly tightened morse tapers than R8

BC Prof23/06/2023 12:39:35
182 forum posts
1 photos

Over the years I have owned a Warco minor equivalent, a Warco VMC , and having downsized my workshop, a Warco BD 16. All MT3. I have had no trouble sourcing accessories . at a reasonable price . I have also had no trouble with releasing the MT3 taper .The self releasing drawbar on the BD16 makes life even easier .

Brian

Mike Poole23/06/2023 12:56:01
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3676 forum posts
82 photos

The morse taper is designed as a self holding taper but still requires a drawbar for milling applications. I find the self releasing property of all tapers designed for milling to be a good idea. I think the Morse taper was designed for drilling and lathe tailstocks are frequently used for drilling so a morse tailstock became common. With an adapter sleeve morse tapers can be used with an R8 spindle. One thing I really hate is hitting spindles to release tapers so if a morse taper spindle is not fitted with an ejector system I would seriously consider adding one.

Mike

s d23/06/2023 13:36:12
30 forum posts
11 photos

Thanks for all the replies. Consensus seems to be split about 50/50 which I'm OK with. I'd prefer R8, but the next Mill that's similar in capability is from Warco and considerably more expensive.

Andrew Johnston23/06/2023 13:51:43
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7061 forum posts
719 photos

A few extra notes:

The R8 taper is common because of it's use on Bridgeport mills. There seems to be a rule of thumb that it struggles with transmitting much more than 2hp. Above that the INT series, and variants, are much more common as they are positively driven via dogs. My horizontal mill is INT40, but has a 5hp motor, so R8 wouldn't be much use. Knowing what I know now I wouldn't go for INT30 as tooling is rare; INT40 and INT50 are far more common.

I use the TTS tooling system on the Bridgeport and CNC mill, so I rarely swap R8 collets. I only have three, the special 3/4" one for the TTS sustem, a 5/15" one bought for a one off commercial job and a 1/2" collet. The 1/2" collet gets used with the right angle and Quillmaster heads for the Bridgeport, not for tool holding.

Most of my manual milling is done with 6mm and 10mm side holders. I rarely use ER collets for tool holding on the manual miil.They do get used more on the CNC mill. For other cutters on the manual mill I have large sidelock holders and Clarkson Autolock chuck copies.

The R8 taper rarely sticks, if it does a sharp tap is all that is needed. I've noticed that the taper sticks more on the CNC mill than on the Bridgeport. I suspect that is partly down to inaccuracies in manufacture on the CNC mill and also that it gets far less use than the manual mill. I try and leave the R8 collet loose on the CNC mill if I am not going to be using for a while.

As has been said there is no right or wrong answer. smile

Andrew

Mark Rand23/06/2023 13:53:14
1505 forum posts
56 photos

Personally, I'd say that both MT3 and R8 fall a long way short of INT30 for small to medium sized milling machines.

Bazyle23/06/2023 13:59:14
avatar
6956 forum posts
229 photos

MT3 is perfectly adequate for 99.9% of model engineering needs. Real men use Int30 at least anyway. Putting R8 in a smaller mill than a BP is just like putting a supercharger on a Fiesta.

s d23/06/2023 14:46:54
30 forum posts
11 photos
Posted by Hugh Stewart-Smith 1 on 23/06/2023 14:44:32:

S D ,

Don't have regrets, you've got a good deal.

The only 'But' is that for around £200 more you could have got something similar but with 1.5kw brushless motor and belt drive instead of the 1.1kw motor and plastic/nylon gears in the head. Although you would have to pay £250 or more for a stand and tray. Spare parts could be a bit of an issue in the future but otherwise it's a very good price.

MT3 versus R8 - I wouldn't worry about that now. You've done well.

Hugh

Please tell, which Mill is that? I thought this one was brushless?

JasonB23/06/2023 15:51:26
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25215 forum posts
3105 photos
1 articles

If it is this one then I can't see any mention of brushless which would tend to say it comes with a brushed DC Motor.

The knob on the right side of the head will be the Hi/Low gear change which can actually have advantages over a direct drive brushless as the gears give a bit more mechanical advantage to the motor and it does not have to run as slowly where they can start l lack guts. This is why the brushless option tend to need a more powerful motor.

At low speeds say when using an HSS slitting saw I can stall the SX2.7 with it's 750w brushless motor far easier than the X3 which only has 600W but Hi low range. Gears make a bit more noise but if it's your only mill I would rather have a bit more low down grunt. Different on the CNC when it's doing 5000rpm but I only tend to use small cutters on that.

Edited By JasonB on 23/06/2023 15:56:51

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