Check the model number. Don't pay too much.
I have a floor standing model (CDP351F) And it's borderline boat-anchor territory.
I bought it in one of those Machine Mart "VAT-free" day sales (admission ticket arrived in the post). After I set it up the run-out was terrible. I complained to Clarke, who very grudgingly replaced it under warranty (they would only take the entire thing back, not just the drill head, and I seriously doubt they checked the unit they sent out). The replacement was equally bad.
I would fettle it with better bearings etc., but I don't have any means to find out where the problems arise and thus what exactly to fix. For example, how concentric is the M2 taper in the quill, and is the quill itself straight, etc. I hve struggled to get a decent precision chuck for it -- the big lumpen thing supplied is OK for big drills, but useless for precision work -- one reason I bought it.
I know the bearings are rubbish, because it really hates being left with the belts tensioned for any length of time. To minimse the runout, I try to run it on the absolute minimum belt tension necessary.
The table is another big problem. The 'pillar' is actually a hollow rather thin tube, and the table mounting doesn't grip it very well. If you want squareness you absolutely must tighten everything up fully or the table will sag to an obtuse angle with the axis. It's easy to forget this.
The table tilt arrangement is a mixed blessing, too. There are various problems, including the fact it's not a trunnion but a pivot, and any tilt means you're drilling on a tangent to the tilt axis. That means a significant twisting force applied to the table as you drill. On several occasions I've ruined a workpiece and/or a twist drill because the table has tilted in use beyond what it was initially set to. Use the tilt with extreme caution and consider wedges on top of the table instead.
Miine has a circular, rotatable table. The rotation is handy (but beware sag if not clamped tight, see above), but the table has little 'meat' to it, and as supplied was really roughly machined. Occasionally I have another go at it with a stone, and I've managed to flatten it a fair bit, but I really ought to smooth it properly. To give it rigidity but save on metal it has webs cast into the underside. These are a complete pain: it is very hard to make clamps work as there's nothing flat underneath. The slots are too wide for small bolts -- even M10 thread needs big washers, but too big and they foul the webs. It looks pretty, but is functionally Very frustrating. Also beware the tilt lock: instead of clamping the tilt to the boss on the pillar, it actually jams it from moving by screwing down a bolt. This is like driving a wedge between the two parts, and has the effect of tipping the table down and forward, away from the pillar (ruining the squareness). For woodworking, possibly not significant; for metalworking, a right PITA.
I have designed, but not yet made a woodworking table To go on top of it. That would improve its usefulness (for woodworking) enormously, but... you'd still have to remove it for metalworking (or risk ruining the surface of the woodworking table with swarf), and I presently don't have it set up in a place with enough room for a big table to be added.
On finish quality, I also had to strip the machine and hammer the motor mounting plate straight before I could use it - it's weak, thin steel and bent significantly, either in the factory (rubbish/non-existent QC) or in shipping. Without doing this, the motor pulleys weren't coplanar with those in the gearbox!
There are only two good features: I do like the worklight, but then again it's large Edison screw, but only has room for narrow reflector bulbs - an unusual size. Because of the stupidity about tungsten filament bulbs being withdrawn, soon I will be unable to buy bulbs to fit it (and another mod will be necessary - sigh). Also, mine is an older design with three individual handle shafts to lower the quill into the work. DO NOT BUY one with three handles moulded into one single piece of plastic. They are rubbish for woodwork -- handles often get in the way, and it's very convenient to be able to unscrew one or two of them so that they don't foul a workpiece.
I haven't, so far, ever run out of quill-to-pillar depth. I have used the full height to drill into the edges of boards (but it's a heck of a setup fiddle!
There is a small amount of stuff in the Clarke range that seems to be good quality. I have a set of Clarke-branded Vee blocks that are fine. Most of it however is really cheap and nasty. For example I bought a machine vice to go with the drill. It is nasty! Also it's almost impossible to fit to the drill table (and still have the actual clamp in a useful place).
In short, if you look through the forum, you'll see a lot of people saying, "save up, and look out for a Meddings or similar to come up on Gumtree or eBay or the local paper". They're right. IF (big, big if) you can get the one you're looking at for the right price - i.e. really cheap - having a bad one is still better than just a hand drill, and it's true that woodwork is a lot less demanding than metalwork, but I regard my Clarke pillar drill as tolerable rubbish, rather than a good purchase.
E.
PS: to set it up and check it, you WILL need to invest in some British Standard marked engineers' squares, and a known straight rod of steel or brass that you can fit in the chuck you're using (I have tried using a twist drill - it is a lot harder!). I would check that the one you're interested in: make sure the drilling axis is properly parallel to the column and the table is square front to back with both of them when it's tightened up. If anything is at all out, WALK AWAY: you cannot easily fix it or shim it on those drills.
PPS: I've just re-read your original post. It is likely to be a #2 morse taper, which is usual. #4 would be massive! The bench models were very similar to my floor standing one. Only the height and base style differ in the main, although some had fewer pulleys to differentiate them. SLOW speeds are generally more useful than high speeds for woodworking, incidentally, so check the range as some of them didn't have the necessary large pulleys on the quill and jockey pulley (floating one in the middle of the two belts).
