Bearings worn on a Bench Drill ?

[Jamesdrend]

I bought a secondhand taskmaster 13mm bench drill, and would like to try to reduce the wobble, as i'm compensating by using smaller drills at the moment.

When everthing is attached I can physically move the drill/arbor/spindle section from side to side. With the chuck removed, there is very little movement of the arbor/spindle section joined to the head. So obviously a loose chuck is a factor in the wobble. I'm shocked to see the chuck only stays on by friction, trying to gauge how much play there is for this explanation, and the chuck fell off, so it wasn't that secure ! However, although the arbor/spindle section has no play at rest, that may be because it is pulled upward towards the flat underside of the head, so there is little room to move. When the arbor/spindle section is lowered there is play, and the more it is lowered, the greater the play. It is odd though that when it's fully extended, it is rock solid. So firm at rest, firm when fully lowered, but play inbetween ( by as much as 1-2mm ). The pulley wheel above is firm.

Is it worn bearings, gears or something loose ? I can't believe there should be this much play as the drill drills down. How can I access the internal mechanism, as there is no side plate. There doesn't seem to be any retaining clip with the arbor/bearing section to release it from underneath the head. Do I undo the left side nuts, pull out the handle and the retaining screw on the right hand side, and the whole arbor/bearing section drops down, or do I acccess from above by removing the pulley wheel and access the casing ? If someone could point to an internal diagram of a bench drill, to show the internal mechanism at play, or draw/describe it, it would be helpful and I can see what the mechanism is and where the bearings are. I haven't found any diagram after searching on google, they either seem to show a bench drill externally or the exploded diagrams are of different drills.

Thanks for any assistance.

 

[lurker]

I have no idea of what your drill looks like
But

If you look on the opposite side to the handle you use to raise and lower there might be a protruding thread with two nuts ( one is a lock nut) try tightening these ...... If you go too tight the quill will not move up and down freely so you need a tiny bit of slack.

It's quite normal that the chuck just pushes on most drills are like this
This is known as an interference fit, ...... commonly used in engineering and perfectly good technique
but it should not fall off : :lol:
Be careful to get it square when you put it back, although it should centre itself

 

[AES]

@jamesdrend:

To add to what lurker has already said, I don't know your particular drill but most machines that I've ever seen have the chuck (plus a taper "adaptor", see below) fitting into a tapered "socket" (hole) in the quill.

As lurker says, the male adaptor screwed into the back of the chuck usually has a taper on it. There are many standards tapers for such tapers, but the most common by far is the Morse Taper series (for example, my Rexon is MT 2). The point is, to make an efficient friction fit, the tapered face of the adaptor which is screwed into the back of the chuck must be VERY clean and free from muck, grit, swarf, etc, Likewise, the hole in the quill (socket) is also tapered to fit (again, in my case it's MT 2).

The are basically 3 possibilities for causing your side to side waggle ("run out").

1st, the chuck itself is worn. If the amount of run out is unacceptable there's little you can do except buy a new chuck (having first checked that it too is not full of muck);

2nd, it's possible (especially if the machine is old and/or not well cared for), that either the tapered face of the male adaptor, or the tapered female socket in the quill, is full of muck. In extreme cases, you may even see scoring on the two male/female tapered mating faces (e.g. someone has forced the chuck and adaptor into the socket with some metal swarf hanging on it). Again having cleaned both the adaptor and socket, and peered up into the socket with a bright light, if you do see bad scoring, there's little you can do except replace the male adaptor, and/or the quill itself. Start with the adaptor first, it's MUCH cheaper than changing the quill! HOWEVER, you can get away with quite a lot (one of the advantages with taper friction fits) by GENTLY rubbing at any obvious scores and burs with emery before you replace anything.

3rd, the quill itself may be damaged/bent (unlikely), and/or the bearing may be worn out. Again, as lurker has said, some quills do have adjustable bearings. Look for the 2 nuts on the other side to the handle, just like he says. If that's your problem, and if it does have adjustable bearings then you're in luck. If not, you can replace the quill bearings on most machines but it's quite a detailed job if you've never done it before.

But your 1st job is to try and find out which of the 3 above possibilities really are the cause of your run out/side to side wobble.

First chuck up a fairly large BRAND NEW drill and turn the machine slowly by hand, comparing the business end of the drill for side to side movement with the visible bottom of the quill itself. Do either or both have side to side movement? (I'm assuming you do not have a Dial Test Indicator?). If you see movement remove the chuck and watch the bottom of the quill again as you turn the pulley of the machine by hand from above. Most likely the movement of the quill will be much less (hopefully NIL!) than you saw with the movement of the drill in the chuck. If, as we hope, it's MUCH less movement then the chance's are it's your chuck that's faulty.

I'm assuming you know how to remove the chuck because you've had it fall out. As lurker says, that shouldn't happen (actually, it's usually pretty hard to remove the chuck from the quill once the machine has been used to drill a hole once).

So the "trick" here is to make sure that both the socket and the male adaptor are absolutely clean, push the two together, just gently, then place a bit of scrap wood onto the drill table and again just GENTLY wind the chuck down onto the wood using the handle. After that drill a test hole and IF the male adaptor and female socket are clean and not badly scored, the only way you'll get the chuck out of the quill is by using the special key provided with the machine.

The above assumes your drill does have a taper quill socket and male adaptor - I'd be very surprised if it doesn't, though I guess it's possible it may not be Morse series.

Sorry if the above is too detailed and "teaching my Granny to suck eggs", but HTH.

Best of luck. There's loads of people here who know lots more about these things than I do, I just happened to be the 1st one along. There's even at least one member who does fantastic re-builds of all sorts of old and complicated machines. So if you need more help just ask.

Krgds
AES

 

[woodpig]

I've got an old English bench drill and it had a wobble before I replaced the bearings and still has it with the new ones!
I couldn't see any obvious reason for the wobble when it was in bits either.

 

[AES]

Perhaps the chuck has had it? Can't tell without looking, and I assume after stripping down you re-assembled everything after cleaning?

AES

 

[Jamesdrend]

I am a layman regarding this, so forgive the terminology, but as I am unable to post photos or even links to an external photo hosting site, that's all I can do. My account has obviously not earned enough privileges.

Let me describe the drill parts in my terms first. The drill fits into the chuck - the chuck fits onto the quill - the quill fits into a ring bearing - the ring bearing fits into a cylinder section which moves down and up inside the head ( this cylinder section has a rack of teeth at the back which meets a pinion inside the head ) - the pulley above the head is linked to the quill, not joined but linked somehow, as the quill can move up and down whilst the pulley remains stationary. The cylinder does not rotate, but the quill inside the cylinder does.

There is light scoring on the tapered end of the quill, and inside the female socket on the chuck. I will use acetone to remove dirt/grease etc ( perhaps lightly rubbing with emery paper ), and either settle for the run out, buy a new chuck or start afresh wth a new drill.

My main concern however and where there is most movement, is this cylinder section. I've tightened the nuts on the side, up to when resistance is met between the rack/pinion, but that has had no effect on the cylinder movement. Am I correct in assuming there should be almost no free side to side movement in this cylinder ? It does seem rather loose and I can move it forward and back, as well as from side to side, although only when it is lowered. I accept the rack/pinion mechanism has to be able to operate freely, so there will be a little movement, but this seems excessive. The quill and bearing are rock solid, as I can hold the cylinder and there is no movement of the quill. So that tells me that bearing is ok. The pulley is fixed firmly against the head. Therefore I feel the issue is inside the head itself, but looking all around the machine head, there is little visible access. Reading another post, it appears you gain access by removing the pulley above, but how do I remove this pulley ? There is a small round nut deep inside the pulley with four protruding ends, and slots deep into the pulley itself. You can't grip it, even if you had the correct shaped socket. There is a thread in the centre of the nut, so I am presuming you have to unscrew the pulley, but obviously it turns freely with the quill. Do I have to grip the quill and turn the pulley to unscrew ? Quill - cylindrical and tapered = more scoring. Or do you undo the nuts on the left hand side, pull out the handle on the right, and lift the whole internal mechanism ( quill/cylinder/pinion and pulley ) upwards and out of the head ? I haven't tried this yet, as i'll await advice.

 

[woodpig]

On my drill the pulley rotates on two bearing races pressed into the head. The pulley and attached bearings need to be pressed out of the head from underneath. You may be able to tap it out carefully using a suitable piece of wood and a hammer?

The quill is removed by withdrawing the pinion from the side. The quill lock and handle had to be removed first.

The spindle rotates inside the quill on two axial and one thrust bearing held in place by a couple of snap rings, one of which is so fine it was difficult to see when in place.

Your drill may be slightly different though.

Cheap chucks often seem to have excessive runout so check that and buy a decent one if you can.

 

[Jamesdrend]

Just getting my terminology right. After looking at a clarke manual, the quill is the cylinder, and what I thought was the quill is infact the taper adapter. So in actual fact, the quill is loose.

 

[Jamesdrend]

Not as bad as we all thought. I decided to pull out the handle and pinion and have a look inside, so slackened the "guiding/retaining screw" ? on the right hand side of the head, and pulled the handle out. The quill dropped down and I could see that all the teeth on the quill and the pinion on the handle are not worn at all. Put back, tightened up this guiding/retaining screw, and the quill is quite firm now. So it was just an incorrectly set guiding/retaining screw ! The screw was very tight to undo, so hadn't just become loose. The previous owner couldn't have set it correctly.

Thanks for all the advice.

 

[AES]

Sounds like it all worked out OK for you james. Good.

AES