Excessive run-out on a Meddings Driltru LT3

[ndaley]

I recently picked up a rather nice Meddings Driltru, but having barely got it into the workshop, I managed to cause the head to drop onto the table, as I didn't have the locking collar tight enough. Before then it seemed to be running pretty smoothly, with little run-out, but now there's noticeable wobble at the chuck. I've measured the run-out just above the chuck at around 0.03mm but just below it's 0.25mm. I'm kicking myself for not checking all the bolts were tight before moving it, but I'm hoping it's not too significantly damaged. The machine is a Driltru, and the head has raised lettering: 9373/LT/III. I've been trying to find a service manual or equivalent for it, but I'm not having much luck so far. It's got a Jacobs chuck, so I got a pair of wedges to try to remove it to see if the spindle is still straight and just reseating it will help, but I can't budge it. The main problem is that there's nothing for the wedges to push against as there's a big gap between the bottom bearing and the top of the chuck. I've tried various ways of bracing it, with no joy.

If anyone has either a manual for this machine, or can guide me in working out what's wrong and fixing it I'd be really grateful, it's incredibly frustrating to have such a nice machine, but not have it running as smoothly as it could.

 

[Spindle]

Hi

Take up the excess in the 'wedge gap' with an open ended spanner or two?

Regards Mick

 

[ndaley]

Hi Mick,

I tried to take up the slack with with what I had around yesterday, but I'm going to have to give it another go tonight. At the top, what should the packing or wedges be pushing against? I was worried about pushing against the bottom bearing, but it that's not going to cause a problem it'll make the whole thing a bit easier. The other issue I had was knowing roughly how hard to hit the wedges, I think I was being a little too delicate, but I'm worried about hitting it too hard and bending the spindle. Am I being over cautious?

Niall

 

[Spindle]

Hi

You should apply the force as indicated below - the spanners or whatever you use should be a close fit on the chuck spindle.

When you hit the wedges, try to use two hammers and hit both wedges at once - if you can't do that hold the heaviest object you can in contact with one wedge and hit the other

Regards Mick

 

[Cheshirechappie]

You could try ringing Meddings and asking their advice - they're still in business. They may be able to supply a user's manual, too.

http://www.meddings.co.uk/contact-us/

 

[Phil Pascoe]

iirc lathes.co.uk do one.

 

[ndaley]

Thanks for the diagram Mick, that was very helpful, and gave me certainty that I was pushing against the right bit. I've tried shifting the chuck with wedges, but all I've managed to do so far is scuff the back of the chuck, snap the circlip that sits under the bearing and bend the wedges! It's being remarkably obstinate. The chap I got the machine off of said that it had been pretty much unused for about the previous 9 years, so I'm wondering if the chuck could be corroded on. The rest of the moving parts in the machine seem to have been carefully greased, but obviously the taper isn't. Is there a particular penetrating oil that is good for this sort of thing, or some other trick to getting it off?

Niall

 

[Myfordman]

After dropping the head and the above butchery, I rather feel that the drill might fare better put in the hands of someone with some sympathy towards machinery.

 

[ndaley]

Myfordman, I appreciate your concern for my drill, and I assure you, I share it. I am trying, as best I can, to understand how the drill is assembled (Meddings have been most helpful and sent me the parts list and exploded diagram), and how to rectify the run out. As I mentioned above, the run out above the chuck seems reasonably low, but below seems high, so I'm hoping that it is all from the chuck itself, or the seating onto the spindle. I have found many places suggesting that a pair of wedges, with some packing as Mick suggested will dislodge the chuck, indeed the person I spoke to at Meddings recommended the same thing. Whether I'm simply not using the wedges correctly, or the chuck really is on that much harder than usual I don't know, but I appreciate the help and suggestions I've had from the others on this thread, and I'm hoping that I can successfully sort out this issue and reinstate the machine to it's former quality and function. I'll gladly accept any hints, tips, pointers or helpful instruction anyone here can provide, I'm eager to learn.

 

[Lons]

Might be a stupid suggestion but would it be possible to buy, borrow or modify a wedge, preferably metal with a slot cut out to accommodate the spindle? Bit like the ones used to serperate ball joints.

Looks like Myfordman wants you to re home the drill with him at a cheap price :lol: :lol:

 

[Myfordman]

Apologies if my earlier reply was rather blunt - that was not my intention and neither am I trying to suggest re-homing. I already have 4 pillar drills of differing types so no need for more.

I was trying to suggest that the OP gets some hands on help before potentially doing some more damage. However well intentioned, the efforts to date look to me like they are heading towards causing more damage.

I have removed a stubborn chuck in the past by drilling up inside the jaw end and tapping a thread through into the void between the male and female taper and then using a bolt to press on the end of the drill shaft. There is not a lot of metal there, perhaps 3mm thick but enough for a few threads of M6. Use a HT bolt or socket cap screw to apply pressure and then use the wedges in combination.
It is possible that a little penetrating fluid might help but the precision surfaces of the taper fit usually means there is no room for plus gas or similar to get it.
There is no point in hitting wedges so hard that you bend them. Small taps delivering localised shock are what is needed and as Mick states use something really heavy to take the load of the shocks otherwise it is the bearing that are getting the shock and if the shaft is not bent yet it will soon be.

Further thought - most but not all drills have a female taper inside the shaft and when the quill is lowered a vertical slot is revealed into which an ejector can be tapped and the chuck and taper can be removed.
The diagrams Meddings have provided should show if this is the case. With the chuck and its male taper removed as a unit, you then separate the two on the bench.

Good Luck

 

[Phil Pascoe]

Niall - do you know if all "Drilltru"s have chucks with a morse taper mounting? I don't suppose your info told you that? Does anyone else know?

 

[ndaley]

Thanks, for the comments, There's no slot for a drift wedge, and the diagrams from Meddings confirm that the spindle is a single piece with a taper on the end. The chuck takes a JT6, so I'm really hoping that that's what the taper is too! Oddly, they had no record of the serial number from the panel on the side of the drill being a Driltru. The only machine they'd sold with that number was from 1945, some 13 years before the Driltru line even started.

Myfordman, thanks for your suggestions, I'd seen that technique described elsewhere, but that's about the clearest and most precise explanation I've read. A lot of other places seem to suggest giving the wedges a fairly hefty whack, which I tried after gentle taps (which seemed more logical to me) didn't work. I had the opposite wedge braced when I did that, so hopefullly the spindle and bearings are ok, there's no extra run out anyway.

 

[Myfordman]

JT6 (Jacobs Taper No 6) is a very common size for 1/2" chucks from both Jacobs an other chuck makers.
Beware more modern far eastern chucks which can have B series tapers. These a short sections taken from longer morse tapers and won't fit your drill.

You might be able to remove the complete quill relatively easily*, then with an assistant to support the weight of the quill in a horizontal position, one chuck wedge can be supported on some sort of anvil - vice or even a block of wood or a brick whilst tapping the other wedge from above. Have bundle of rag etc for the chuck to land on as it will(should, - might?) come off sideways.
Having human support to the quill will reduce the shock experienced by the bearings and deliver it where needed.

* release the tension on the return spring and remove. Pull out the quill operating pinion and spider and usually the quill can be removed downwards and lifted clear.

 

[dickm]

Not much consolation, but removing Jacobs chucks can be a real pain. Tried to take a big one off a Morse 3 arbor, using all the recommended techniques and failed miserably. Reading around various forums it seems like this is not an uncommon situation . Fortunately, someone on this forum was able to give it a home where M3 was the norm. Not much help, but at least you needn't feel you are alone.