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

Martin C

+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

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

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.

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.

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.

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.

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

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.

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