Getting a milling head ready for use

[choochoo_balooParticipant @choochoo_baloo]

Afternoon chaps,

I'm in the final furlong of my Senior M1 mill refurb.

I'm looking at the S head milling head and wondering if there is much to do for using it other than generously oil @ all button oilers? Photos below for thos unfamiliar with this unit.

This is my first proper milling machine, so wasn't sure if I should:

• remove and clean off of drawbar and fixings
• cleanout and re-tune the spring mechanism for the quill

etc before using it in earnest!

[choochoo_balooParticipant @choochoo_baloo]

[Martin ConnellyParticipant @martinconnelly55370]

Check the state and tension of drive belts if it has them.

Martin C

[old martParticipant @oldmart]

That is the body of a Clarkson Autolock in the spindle. It is missing the end nut. It will have to come out, just slacken off the drawbar about a couple of turns and hit the end with a copper, or aluminium headed hammer. Your spindle takes Morse taper 2 tooling.

[Simon Williams 3Participant @simonwilliams3]

+1 from me on Martin's suggestion to check the drive belt. The two cheek plates pull off the side of the assembly to expose a pair of four speed cone pulleys and a dear little vee belt. The state of that belt will shape your experience with using this machine.

So much so that I suggest you buy a new one and just fit it. If it is the same as mine it is an SPZ500. Changing this on mine made a disproportionate improvement to the amount of power actually reaching the cutting head, and also the smooth running of the machine. It is tensioned by loosening a nut to the right of the motor mounting flange and swivelling the motor.

Changing the belt is a matter of locking the quill fully extended, now the belt will pass over the top of the spindle pulley and under the bottom of the motor pulley. Or at least it does on mine.

Have you perchance the rest of the Autolock chuck stashed away somewhere? If you would like a picture to explain what's missing let us know!

HTH Simon

[ianjParticipant @ians]

" clean out and re-tune the spring mechanism for the quill "

Unless it's really necessary I would not dismantle the quill return spring assembly as it's a right pain to get it back together. If the quill is sticking and not returning,fully extend it and clean it then use a light oil in the top oiling point.

 

Ian

Edited By ian j on 27/04/2020 19:55:09

[choochoo_balooParticipant @choochoo_baloo]

Thanks for the swift and comprehensive advice chaps. A few follow on Qs please:

Drive belt

Here's a inter cone belt – seems in good nick. But I'm listening so shall I go for a modern Fenner link belt, as is reocmmended for Myford lathe

https://www.lathespares.co.uk/myford-super-7-drive-belt-headstock-link

Collets

Yeah forgot to photo the Autolock box hat came with the machine. Nut is lurkign at the bottom thankfully.

So what's special about this design vs the generic ER32 type I see on modern Chinesium machines.

Drawbar

[I'm a newcomer] So I slacken the hex head at top of column – is that one long bolt that threads into the accessory (Autolock in this case)?

So I knock the bolt head with a soft hammer, but wont the autolock body still be thread onto drawbar?

[Frances IoMParticipant @francesiom58905]

they need the threaded cutters but they hold a cutter in place with a guarantee it wont move – there are usually many such cutters available tho might need re-sharpening

[SteviegtrParticipant @steviegtr]

Once you have tapped the draw bar & the chuck is loose. Continue to undo the draw bar until the Clarkson drops out into your hand. That head looks the same as my Tom senior light. With the 1/2hp motor & MT2 fitting. Or is that a larger unit. Link belting is a way of changing a belt in a situation where you cannot get the new belt on. Some members swear by them. I swear at them. 

Steve.

Edited By Steviegtr on 27/04/2020 21:47:44

[old martParticipant @oldmart]

The belt looks fine to me. The autolock looks like the type with the left hand threaded ring at the top which you snug up against the spindle after tightening the drawbar. This stiffens the rather small and flexible MT2 fitting. Check the autolock collets, if they are marked in fractions, then use inch size cutters, and if they are marked in millimetres, then use metric cutters.

[old martParticipant @oldmart]

The belt looks fine to me. The autolock looks like the type with the left hand threaded ring at the top which you snug up against the spindle after tightening the drawbar. This stiffens the rather small and flexible MT2 fitting. Check the autolock collets, if they are marked in fractions, then use inch size cutters, and if they are marked in millimetres, then use metric cutters.

[not done it yetParticipant @notdoneityet]

Old mart,

As a pre-emptive posting:

You appear to avidly dislike MT2. Do remember this is only a 0.75kW machine, so not exactly high powered so I would have thought that Tom Senior had the design – regarding the drive – about right. Only drives to 1660rpm, so seems a reliable, well designed machine, to me – as are all(?) Tom Senior products.

I might agree that INT-30 would have been a better standard of tool fixing, but, please, lets not even think of going down the ‘convert to R8’ route again.

[old martParticipant @oldmart]

I didn't mention anything about changing the spindle in this thread. I was in the fortunate position of having a big enough lathe and a mill to do the work. Not many people will be able to do it.

With MT2, I would get an er25 collet which goes to 16mm diameter. These usually have 10mm threads for the drawbar rather than the original 3/8 BSW. Getting 10mm studding to make another drawbar is easy, although during lockdown it could be by post.

[SteviegtrParticipant @steviegtr]

Posted by not done it yet on 28/04/2020 07:41:27:

Old mart,

As a pre-emptive posting:

You appear to avidly dislike MT2. Do remember this is only a 0.75kW machine,

Is it 0.75kw as mine which is the light, but appears from those pictures to be the same head. Is 0.38kw.

Steve.

[not done it yetParticipant @notdoneityet]

I checked the specifications on the net and assumed they were correct. Sorry if I was too easily satisfied with the basic specs on lathesdotco….. there likely is a difference between the standard vertical head and the lightweight for that machine.

Even more reason for just sticking with the MT2, I expect (especially after the reported failings where other machines have apparently been modified from MT to R8). My mills both have MT2 sockets and both would have been even better if ISO3O, but hey-ho never-mind, very rarely is anything perfect in this world of ours.

[old martParticipant @oldmart]

The standard Light vertical has a 1/2 hp motor, 0.38kw as Steviegtr mentions. The Museums drill mill has a 1 1/2hp motor which is one of the reasons for the modification.

 Taking the quill spring out is a pain and if it feels smooth without disturbing then leave well alone.

Edited By old mart on 28/04/2020 15:38:46

[SteviegtrParticipant @steviegtr]

I am getting my head around mine now. Not doing anything silly in the way of cut depth etc. Seems to be quite stable. The guy I bought mine from said some users had fitted a Bridgeport head on the Tom Senior mills. Never seen one though.

Steve.

[ianjParticipant @ians]

Here is the spec for the light vertical. Looks like 2MT, R8 and 30 INT were all options.

 

 

 

Edited By ian j on 28/04/2020 17:52:28

[choochoo_balooParticipant @choochoo_baloo]

So I attempted to remove the Clarkson Autolock. Drawbar head backed off 2 turns, even a reasonable whack with my copper head hammer aint shifting that taper…thought I should stop before damaging.

Is it just a case of a really firm whack? I have a 3lb lump hammer – think I'll try that with a block of wood.

 

Secondly I do not understand how this Autolock device actually works:

• that pictured spanner is a sloppy fit across the flats on the end nut – is this intentional?
• what are those 3* 120 deg spaced holes on the big ring on the Autolock body for?
• I read on this thread that folks often wrongly assemble their Autolocks, can someone break it down in simple language for me?

all in all a bit mysterious…..please advise!

 

Edited By choochoo_baloo on 29/04/2020 02:18:26

[Nigel McBurney 1Participant @nigelmcburney1]

Your Autolock is the early type with two pegs on the collet,the method I was taught in the 1950s to assemble the cutter and collet differs from the info on various websites for the later autolocks which had collets with two flats,so have a good read before using the autolock. The advantage of the Autolock is the cutter just does not slip or move in the collet,though threaded cutters must be used. the disadvantage is that the collets only accept the specified shan dia,where as the ER system accepts cutters or drills which generally vary over a range of one mm and milling cutters with plain shanks or threaded shanks.Though if I was cutting say keyways in very tough steel I would use an Autolock in preference to a ER collet .Its best not to hit the autolock too hard to remove it as it could damage the spindle bearings, A tapered wedge between the spindle nose and Autolock is kinder to the machine,there are commercial wedges sold to remove drill chucks with morse taper shanks ,these are made from steel with a slow taper with a central slot which fits either side of the shank. An ER collet set nowadays is the best system for mills as it is so easy to change collets and tools, plus if the collet holder has a morse shank,they can also be used in the lathe tailstock to securely hold taps ,which nearly always slip when held in a Jacobs chuck.

[Simon Williams 3Participant @simonwilliams3]

Oh dear! Having the Autolock chuck taper refuse to let go isn't good news, but don't go bashing it any harder just yet, there is too much to lose by damaging the internals of the quill. There is much on the forum about the troubles of removing a stuck MT2 taper, with suggestions about the cause being fitting a cold taper into a hot socket, as the pair of them cool to a common temperature the taper socket shrinks onto the arbour, and it can be a devil to get them to let go of each other. It sounds from your description as if this might be your starting point.

The answer is hopefully hidden in your second question about the threaded backing ring with three tommy bar holes.

You will have noticed that the thread in this is left handed. The purpose of the ring is to be snugged up against the nose of the quill taper, this stiffens the tool set up and changes the resonances to compensate for the shortcomings of a No 2 morse taper fitting.

What you can do at this point is to use the threaded ring to pre=load the taper in the "coming apart" direction. There is a pair of spanner flats on the nose of the quill, but you will need a very thin spanner to get onto them, so you may have to hold the body of the chuck to allow you to push the nut firmly up against the nose of the quill.

Tighten this as much as you can up against the nose of the quill, hopefully without brutalising the tommy bar holes in the ring, which is hardened so don't be too frightened of it. The idea is to establish a significant preload pulling the male taper out of the quill by pushing the ring against the outer end of the quill.

Now lock the quill (ball handle LHS of the quill). Now smite the end of the drawbar sharply, having made sure that it is loose and there is a bit of clearance under the head of it.. I'd use a copper hammer for this, you need a good sharp crack to break the taper. Patting it with a soft hammer or through a bit of wood won't do any good, and I think your 3 lb hammer is a bit too heavy, I'd go for something maybe half that weight.

I've got a face mill which jams every time I use it, I haven't broken anything yet by hitting the drawbar with a 12 oz hard hammer. No idea how brutal is too brutal!

Give it aa couple of good whacks, don't keep beating it if it won't come loose. If it won't we're into thermal shock as the next resort, but you need some dry ice to cool the Autolock chuck and that's going to be difficult at the moment. Ice and acetone will also work as a freezing sulution, but that's getting even more complicated.

I'm charging the camera battery at present, and will post some pictures of how to assemble the chuck – hopefully correctly – later.

Do let us know how you get on.

HTH Simon

[choochoo_balooParticipant @choochoo_baloo]

Thank you Nigel and Simon – I know it takes a while to type out thorough replies.

I kind of follow both of you. I think it's a case of a picture paints a thousand words. So I shall take post so close ups, annotate them, and post inline quoting your above replies, to check which part corresponds to which step of your instructions.

As said, one lesson I have learnt is to fully understood the method first, without rushing! Will post in a little.

[not done it yetParticipant @notdoneityet]

Personally, if the sleeve will not aid the removal in conjunction with a soft mallet, I would be making a gap between collar and quill and resorting to wedges, which can exert a greater degree of force between quill and tool holder – especially if the wedges have a very shallow slope. If tight wedges and a tap is unsuccessful, only then would I resort to other measures.

[Simon Williams 3Participant @simonwilliams3]

Hi again, instructions for assembly of a cutter into the chuck seem to be comprehensively covered in a parallel thread "Clarkson Autolock Help" which is currently live. There is some debate on whether the sleeve nut should leave a gap at the base – FWIW I was taught to leave a gap and to tighten the cutter into the collet till it ran out of travel then just nip the sleeve to lock the cutter against the centre tip and clamp the collet. But I can vouch for breaking the end out of 1/4 cutters by heavy-handedness, so maybe I wos tort wrong.

Any way, here's a picture of the same Autolock chuck dis-assembled.

The two components on the right of the picture are obviously the main body and the back ring. It might not be obvious if you're looking at the complete thing stuck in its taper that the back ring has nothing to do with clamping the cutter, it's only there as a stiffening device to improve the mounting rigidity. The thread is a multi start left hand thread. It's probably not intended as an aid to extracting the morse taper, but I don't see why not.

It's also been commented on that there is no way of holding the body against the force of turning the sleeve nut, other than sticking it in a No 2 MT socket and hoping it holds. Which, given that your problem is that the MT2 currently holds too well, is a bit of a catch 22. I'm minded to grind two flats on the main body so I can grip it in a vice but I haven't been brave enough to put in into practice yet.

HTH, keep us posted!

Rgds Simon

[old martParticipant @oldmart]

I have one of these MT2 Autolocks in a wooden box, but have never tried to turn that sleeve, so I had no idea that it was multi start. I suppose it could be tightened as much as possible when the Autolock was being removed, to assist the tapping of the drawbar, every little helps. Just make sure it is backed off when refitting so that it doesn't interfere with the proper tightening of the MT.

I milled flats on the thick part of the er25 collet holder that I bought some years ago using a solid carbide end mill. If you buy one now, it will probably have flats on it already.

You can buy MT2 collets which hold metric cutters directly, I'm not sure how large they go.

Edited By old mart on 29/04/2020 21:37:33

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