MT3 or R8

Possibly more stuff available on ebay for R8, but length might be a problem with stuff intended for a Bridgie.

I'd go for the R8 personally, but others may think differently.

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

Main differences is MT3 isn't a self releasing taper, R8 is. Tool changing with MT3 will require much bashing to release tools.

MT3 was better at one time in this country due to hand downs but with the advent of a lot of import equipment it is now gaining a better foothold and will continue to do so.

-- Regards,

John Stevenson Nottingham, England.

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Thanks Peter and John for the advice. It looks like I'll be ordering the R8 if I can do a deal with Warco. regards, Iain

Obvious question but do you have any existing machines with one of these tapers ? Would have obvious advantages to standardise on a single fitting.

Another gR8 [deeply sorry for the horrible txt pun] thing is you can buy (male) R8 to (female) MT adaptors so can use MT tooling if you acquire it.

I have never seen a male MT to female R8 adaptor.

Lathe has 3MT on headstock and 2MT on tailstock, but only have centres and drill chuck with tapers so no problem realy in having R8 on mill.

Iain

You end up with a fairly long and flimsy bit of kit sticking out of the quill though. OK for light drilling but not for anything you want to put side loads onto. It eats up vertical clearance to the bed too which might cause problems on a small machine.

I'm not sure that would be possible because you'd need two drawbars trying to occupy the same space. R8 to Morse is ok because the drawbar holds the R8 and the Morse is self locking. I can't immediately see a way of doing the reverse.

As to the OP I'd go with R8. The tooling is more widely available for small mills and not too dear. As John says it's also quicker and easier to release and change R8 tooling. It's not the sturdiest system in the world but it's sufficed on Bridgeports and similar sized machines for many decades. You can hold up to 7/8" or 22mm in them and the chances of you needing anything bigger than that on a small machine is basically non-existent. I've never needed to go bigger than 3/4" on my Bridgeport clone.

-- Dave Baker - Puma Race Engines

FWIW, I have both (two mills, 1 MT3 the other R8).

The MT3 can be a pain because of the non-releasing taper but the R8 has also caused problems due to three things:

a) The locating pin in the mill head (that aligns with a groove in the R8) seems to be weak point and occasionally needs to be replaced.

b) Some of the Chinese import tooling doesn't fit! A couple of items have had to be turned down to fit, which is OK if they're reasonably soft but can be pain otherwise.

c) Most R8 tooling uses an imperial UNC thread for the drawbar attachment. Some tooling seems to use (IIRC) M12 which obviously requires a different drawbar.

None of this is a big deal once you are set up and running and the self-releasing aspect of the R8 is a boon but IME it can also be a pain in the butt until you have it sorted.

Mark

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R8 should be 7/16" x 20 UNF, there was only ever one standard.

-- Regards,

John Stevenson Nottingham, England.

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Quite right. It's a while since I had to make one!

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It serves no useful function and most old machines no longer have one and don't miss it. Friction on the taper suffices to hold the tooling while the drawbar is tightened.

That's easy then. Don't buy cheap imported tooling. There's little worse than trying to do a decent job with a crap tool.

R8 tooling has a 7/16" UNF thread and anything different is either defective or not R8 by definition and should be sent back.

-- Dave Baker - Puma Race Engines

If you do a lot of drilling, especially in larger diameters, the MT3 beats R8 in my opinion. You only need a few MT3 milling adapters which are fairly expensive but I have found MT drills to be cheap and plentiful around here (Seattle).

Horses for courses...

Kelley

I don't know how R8 works, but I do have a Warco economy mill with MT3 and lots of bashing can be required - an alternative to this must be better!! I never leave anything in the taper after use and always clean the tapers before and after use. A second problem is that you have to lock the quill while you bash and that can damage the quill and make managing the backlash on the fine feed more difficult.

I got a tilt milling vice thrown in with mine and it's not fit to use as a door stop. I should have sent it back, but I'd starting "improving" it before I realised how much effort it would take!

Under the Green paint of the Warco seems to be Blue and Cream paint which I'm sure I've seen somewhere else.

If you have space, get a knee mill - I've seen decent Bridgeports go for less than the Warco Economy.

Having said all of that, My only regret has been not having three times the workshop space! And I have had a lot of fun out of the Economy Mill.

Steve

I don't know if this would be practical on your machine but I have an old Bridgeport head with a 2MT. The draw bar has a collar on the top which screws onto the end of the quill, so the drawbar is effectively fixed in position at the top end. When you unscrew it from a piece of tooling it pushes the tooling out of the morse taper. The collar is LH thread, so when undoing the drawbar it doesn't undo -this may not be strictly necessary, perhaps a carefully positioned thrust bearing in the design could get rid of the need for this. I haven't been using this machine long, so I can't really say if it works all the time but I thought it was a good idea when I saw it.

Regards

Kevin

Chronos do an ER32 collet holder with an MT3 taper for a half a ton. Has anyone here used one of these ? It seems like an ideal solution to the sticking taper problem so long as you mainly use it on one machine.

Boo

Hi, I have the Chronos (Vertex) ER32 collet holder on an MT3 taper in my RF25 mill. It is a superb piece of kit and obviously handles anything between 3 - 20mm without having to disturb the MT3 taper. It rarely needs to be removed for the work I do and appears to hold very well indeed without excessive tightening. I do however get a bit worried at he amount of "spring" the collet needs to take to hold some of the standard imperial sizes but they do so without complaint and with excellent accuracy. I've been using them for about a year and they remain fine at the moment.

Obviously, you will still need to remove the collet chuck to mount boring heads, morse taper drills and direct taper indexable cutters etc. If you have a round column mill like mine the difference in length between a normal end mill/slot drill and a drill over 8mm or so means the head has to be repositioned, a real bind on these machines. This is the main reason I have decided to replace the RF25 with a VMC when (if) funds allow.

However, the ER32 is extremely flexable and has been a superb improvement over my old Osbourne threaded system. I have no reservations in recommending the ER system and in particular the Vertex version, the finish and operation has been superb.

Best regards Keith

ER collets are wonderful. With just 4 collets you can hold all the common sizes of imperial and metric cutters.

Another thing to take into account here in the UK is that with rationalisation and manufacturing cutter manufacturing is changing.

Whereas we used to have all small cutters below 1/4" mounted on 1/4" shanks and step ground down to size, many of the new cutters are being made from same stock as size.

This is especially true with metrics. Where again a 4mm cutter would have had a 6mm shank and ground to 4mm the newer series are parallel with 4mm shanks.

ER series take this into account and by being split from both ends the compress equally, something that single ended split collets like the R8 can't do. They go bell mouthed the tool walks out.

ER collet chucks are available in many shank forms MT, R8, NMTB and ISO so it's easy to get one to fit you machine.

Warco now sell a backplate mounted ER collet chuck to fit on a lathe. This can then advance the uses of the collets provided you choose the same size for mill and lathe. There are no gaps with ER series collets so unlike 5C's where you have to make up specials diameter sizes a standard set of ER collets will cover.

I feel it's only an over sight hat the manufacturers haven't realised that they could put an ER taper directly into the end of a mill spindle.

John S.

-- Regards,

John Stevenson Nottingham, England.

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Me too

Another great thing is that they will grip drills on the flutes/anywhere along their length, so you don't need stub drills nor do you need to change to a drill chuck (especially useful on something with limited Z-travel or an unkeyed column). If you are really stuck for space, with a collet, you can poke the drill bit in through the top of the quill.

WRT the spindle idea, an advantage if you want to make your own is the simple ER taper of 8 degrees. ER closing nuts are easily available, and have the advantage of releasing the collet as they are unscrewed (unlike the ER20 chuck I have on the Taig where you have to drift the collet out after the nut is unscrewed).

You probably know this already, but Taig are supposed to be releasing an ER16 spindle "any time now".

And now a (stupid) question. Is it possible to buy imperial ER collets? I have a 1/4" shank edge finder and it needs three hands to install: one to stop the edge finder falling out of the collet; one to tighten the closing nut and one to hold the spindle. The 6-7mm ER collet takes a lot of squeezing until it starts to grasp the shank. A

Thanks in advance for your help.

John

Can't help with the Imperial ER20 source but Arc Euro Trade list some ER11 Imperial collets (available June), so the "concept" is OK. It could be that the smaller collets have a more limited range but obviously someone other than you (and I) also want to see Imperial ER collets. They are listed with their collet sets at