WIP Pt 1: Combi drill/sanding table for vertical drill press

[AES]

As we all know, the as-delivered tables on vertical drill presses tend to be somewhat small for wood working and I’ve been thinking about combining an add-on wood worker’s drilling table and a drum sander fixture to my drill press for some time. My new “combi-table” is an amalgam of ideas I’ve found around the net (especially on this Forum of course) and apart from the sanding drum lower bearing support feature, which may be a unique idea, there’s very little original AES thinking here.

The idea was to have one table that can be easily used for both normal drilling and for contour sanding with nil or minimal changes between each mode, and with decent DE (dust extraction) in each mode.

Here’s the new combi-table in contour sanding (Picture 1) and in “normal” drilling modes (Pictures 2 and 3):

The pillar drill is a cheap Rexon 12-speed model (210 to 2,580 rpm), 13 mm (1/2+ inch) capacity, 800 W. It has dual belt drive, so changing speeds is a bit of a fiddle, especially as it’s mounted on the bench, bringing the drive belts up above eye level. I knew that this would be inconvenient when I bought it but as I couldn’t afford an electronic or gearbox model at the time I decided I would have to live with it. It’s OK in practice – mostly it stays set at about mid-speed anyway.

As I also do some metal working I thought about making the combi-table easily removable, but in the end decided not to bother. I think that just by removing the fence if a metal work piece size dictates, it’ll be quite possible to use this table for metalworking too.

Picture 4 shows the cast iron table on the pillar drill as it was delivered, plus the 4 off 8 mm (3/8th inch) dia holes I drilled & tapped behind and in front of the existing 45 degree slots. It’s easy enough to remove the 4 bolts to revert to the original cast iron table if ever necessary.

It was also necessary to slightly shorten the arm of the existing table raising/lowering crank handle to provide hand clearance under the new combi-table. This is simply a piece of scrap 3 mm (1/8th inch) MS plate (Picture 5):

Nothing in the construction is particularly clever or difficult, and no wood or metal parts are anything other than scrap, except for some 100 mm x 8 mm (4 inches x 5/8th inch) coach bolts used as spindles for the sanding drums, plus a 1 Metre (3 feet 3 inches) length of 25 mm (1 inch) ID smooth bore flexible plastic hose for the through/under-table part of the DE. The only other specially-bought items were the T track and the Jigs Kit (knobs & T bolts) from Axminster Tools, but these do of course provide materials for many other projects. And Yes, I do have a small metal working lathe, but nothing seen here makes a lathe essential – it just makes things a bit easier and quicker perhaps.

The basis of the whole thing is a screwed and glued “tray” of off-cuts from 12 mm (1/2 inch) plastic-coated ply (smooth black outside, grey “bobble finish” inside). Basic dimensions are 400 mm (15¾ inches) wide x 295 mm (11¾ inches front to back) x 75 mm (2¾ inches) high overall. This includes 2 laminations of 8 mm (5/8th inch) thick MDF for the top surface. The “wings” extend outwards on each side by about 150 mm each, so bringing the usable table width from 400 mm to 710 mm (approx 28 inches). Picture 6:

{to be continued}

AES

 

[AES]

The orange ring and blue pipe stub poking up in the centre of the tray as shown in Pic 6 (Pt 1) are part of the under/through table DE. The 2 ply supports in the centre of the tray and the 2 black ply supports will form part of the extending “wings” feature. Pictures 7 & 8:

Although drilling with the drill press table up at almost eye level is very convenient, and helps accuracy, I found the problem with this set up is that metal swarf and wood chips get liberally sprayed all over the bench and surrounding floor. Not so clever! As I wanted to use the new table for drum sanding as well as for drilling, obviously the dust and general mess problem would only get worse, so I incorporated dust/swarf extraction into the design from the start.

The original cast iron table is mounted on a lockable hollow central tube which allows the table to swivel independently of the rack & pinion height/swivel adjustment. So I thought that particularly when sanding, using this tube for under-the-table/through-the-table DE would be a neat idea. Hence the blue pipe stub and orange retaining ring, as seen at Picture 6 (Pt 1). The underneath of this pipe and its connecting elbow to the flexible hose is shown in Picture 9 above:

As a side note, like many other members of this Forum I think, I’ve had constant problems with virtually every tool I buy coming with widely varying DE outlet diameters (and shapes sometimes too)! So over time I’ve built up a weird collection of bits of plastic plumbing, waste water goods, rain water fittings and electrical conduit. This includes various rubber & plastic rings, odd lengths of pipe, elbows, joiners and other weird bits & bobs - plus some ply and MDF adaptor rings I’ve had to make on the scroll saw, and most important, various “Jubilee”-type hose clamps. It’s from this varied junk collection that I sourced all the bits & pieces shown, apart from the clear flexible hose which I bought specially (pretty cheap at our local DIY Emporium).

I used smooth bore hose because as the through/under table DE is only a nominal 25 mm (1 inch) OD, I didn’t want any extra air flow resistance that a convoluted hose might add, especially as it’s all only coupled up to my Kärcher wet and dry shop vac. With a 3 mm (1/8th inch) wall thickness, this hose is pretty stiff but can be coaxed into tighter curves with judicial use of the heat gun. As seen in Picture 10, the whole lot couples up to the shop vac without having to move the wheeled bench holding the metal working lathe and so far seems a convenient set up.

The idea of using a pillar drill for contour sanding drums seems pretty common, and I’ve seen lots of commercial and shop-made items on the net. But I’ve also heard that the bearings on pillar drills are not really designed to withstand much sideways (radial) loading. Hence my decision to make the centre spindles of my sanding drums with a small extra spigot on the lower end. The diameter of this spigot matches the ID of a spare ball race I found in another of my scrap boxes! Picture 11:

That ball race is mounted in the centre table support, below table top level. When in sanding mode, the upper end of the drum sander shaft is gripped in the drill chuck as usual. But with the height adjusted so that the lower rim of the sanding drum is below the sanding insert table top height, as is usual when drum sanding, the bottom spigot will be supported against side loads by locating into the ball race. This may very well be “excessive engineering” (one of my failings I think!) but I also hope this will protect the pillar drill bearings to at least some extent. Only time will tell.

This all makes the centre support a bit complicated – because it must act both as a centre support when drum sanding and also allow “breathing” for below/through-table DE both when drilling and sanding. Picture 12:

The bearing is set into an aluminium bush turned out of scrap which in turn is set into the softwood centre support using a ring of ordinary bathroom silicon sealer (Picture 13). This to provide a resilient “doughnut”. If in use the silicon proves to be too soft then it shouldn’t be very difficult to come up with some sort of harder resilient ring, perhaps in hard rubber. Picture 14 shows the initial set up, using a suitably sized transfer punch (guaranteed straight!) to hold the bearing/bush/support assembly central while the silicon hardened overnight.

{to be continued}
AES

 

[n0legs]

That looks great =D>
I like the lower bearing idea, that's got to save some wear and tear on the quill when sanding =D>

 

[AES]

Thanks n0legs.

AES

 

[AES]

The silver-coloured rods along the bottom of the basic tray (Pictures 12, 14, and 15) are the supports for the LH & RH extension wings seen in Pictures 7 & 8. Nothing special here either, simply 10 mm (3/8th inch) MS rods, threaded at one end to screw into the 10 mm prong nuts let into the extension wing cheeks; and drilled and tapped 3 mm (1/8th inch) radially at the other ends. 3 mm bolts make end stops to prevent the wings being accidentally pulled right out of their location holes in the main tray.

Pictures 7 and 8 (Pt 2) show those extension wings as thick softwood, but I revised that idea and the later pictures show the final build which uses good quality 22 mm (7/8th inch) birch ply for the wings.

To provide adequate support for drilling larger work pieces (Picture 3 Pt 1)), obviously the wings shouldn’t droop below table top level. So to start off with, the exit holes in the ends of the basic tray carcass are a pretty good fit on the rods and positioned carefully at base level. But in Pictures 12, 14, and 15 (Pt 2) we see that the centre support housing is actually a “bridge”. As already said, this provides clearance for the through-table DE. But as the centre support cannot run all the way from the front to the back of the tray carcass (because it must clear the wing support rods), the centre support is actually secured to the basic tray carcass front and rear with 2 short pieces of 10 mm ply let into the ends of the centre support. These provide extra support for the wings, right where it's needed, at the end of each rod. Pictures 6 (Pt 1) and 12 (Pt 2).

Behind the pillar drill column I added a further 200 mm (8 inches) extension to the basic front to back table dimension. See Pictures 7, 8, (Pt 2) and 16. At present my collection of drill bits, countersinks, plug cutters, Forstner bits, hole saws, etc, etc, clutter up my (very small) bench. So this rear extension will become a handy storage for all these. When bought, some came in rather nifty boxes, some I bought as loose singles. Quite what I’m going to do about all these I’m not yet sure – for example, just stack all the boxed items up on the extension “shelf” behind the drill press? Or perhaps remove all the boxed stuff from their boxes and make up customs stands for everything? The 2nd option obviously takes up less space, and is probably more convenient on a day to day basis, but I haven’t finally decided. Any inputs on this will be more than welcome – yup, this is a real WIP!

The fence is pretty straightforward, dimensions 42 mm (161/2 inches) wide x 100 mm (4 inches front to back) x 100 mm (4 inches) high for the fence itself (200 mm – 8 inches high to the top of the shop vac connector). Apart from the 4 off MDF vertical supports, the main structure is 22 mm (7/8th inch) birch ply. Pictures 17, 18, and 19 show the simple structure, slightly complicated by the need to provide both under/through table DE plus through-the-fence DE. Once again my weird collection of plumbing and conduit bits and pieces provided all I needed and allow for direct connection to the shop vac. The small white boss in Pictures 18 and 19 (empty in the pictures) is for connecting the flexible through/under table DE hose. It can be blanked off with a screw-on cap when not in use.

{to be continued}

AES

 

[custard]

apart from the sanding drum lower bearing support feature, which may be a unique idea, there’s very little original AES thinking here

Wow! You're underplaying what is an extremely smart idea. If you've found a way to counter lateral stress and movement you could easily turn your drill press into a machine capable of drum sanding to precise dimensions, all you need is the small final step of a fence that's adjustable in 0.1mm steps, maybe something along these lines but made from plastic or ply,

http://www.bridgecitytools.com/default/ ... allel.html

Or these,

http://www.starrett.com/metrology/metro ... tBy=wp/asc

Or simply with a fixed end to the fence and the other end adjustable by a screw thread.

I'm sure there's a lot of luthiers, marquetry guys, toy/model makers, and string inlayers who'd be very interested in that.

Congratulations on an excellent idea!

=D>

 

[mseries]

I like this, I have thought about such a thing with a lower bearing but never progressed further than thinking about it. Good to see it being realised. When I have more time I may progress it myself. (How many times have I said that)

 

[AES]

@custard:
QUOTE:
Wow! You're underplaying what is an extremely smart idea.
UNQUOTE:
Well thank you Sir. It's always nice to get a compliment but as I consider myself as a rank beginner in all this woody malarkey, and as I've also seen from many of your posts that you're clearly a highly-experienced expert, then that's really nice.

No sarcasm intended but as I was thinking about all this, before starting, it seemed an obvious idea, though perhaps a bit over-engineered.

My own application is only for fairly rough shaping (up to a pencil line for example) for small-ish bits of toys, etc. Nothing really special or high precision.

Thanks for the links, I see what you mean about the adjustable fence. But IF (a big if you note!) I was going the high-precision route, or if anyone else wants to try, I'd offer the following observations:

1. I guess the centre spindle of the drum should be bigger than the present 8 mm dia;
2. The OD (and therefore the ID) of the lower support bearing should be larger than the bearing I used;
3. I suspect the bathroom silicon would be too soft to adequately support the lower part of the drum against the sort of forces that MAY be experienced when sanding to a specific size. Probably a hard rubber ring, or possibly a plastic/nylon bush from someone like Banbury Plastic Fittings would be better? I don't know but will report back after I've had time to give the present setup some decent use.

But again, thanks for the compliment - I've had a LOT of help from many members here and hope that at least my efforts here will help someone else.

Krgds
AED

 

[monkeybiter]

Thanks for the great and detailed WIP, we could do with more of those.

Did I miss the method for aligning the table on the pillar if it spins a little after height adjustment, not so important for drilling but necessary for the drum sander bottom bearing. I suppose keeping the collar loose on the pillar until aligned would work.

Are your sanding drums of your own manufacture?

Do you think a soft bearing housing is necessary for the lower end of the sanding drum, won't this almost negate it's benefits?

These are by no means criticisms, but genuine queries from someone equally interested in the same goal.

 

[AES]

Thanks for your comments mseries. My response is in very similar vein to my reply to custard, above - very nice to get compliments, especially from someone who so obviously "knows 'is onions"!

Krgds
AES

 

[AES]

@monkeybiter:
Thanks for your comments too, especially re the detailed notes - I was a bit worried that I was writing too many words and often stating the obvious a bit. I wish I could say that it took longer to write the job up than it took to do the job, but that would be a lie - until retirement I spent a lot of time writing technical reports so it comes quite easily to me, whilst EVERY job in the shop ALWAYS takes me a lot longer than I feel it should.

Re your comments/questions, I certainly do NOT take these as criticisms but am glad to get all inputs. A couple of responses from me:

1. The job is only just finished so I've hardly had time to use it much at all, so as said in the write up, the bathroom silicon ring maybe, A) totally unnecessary, or; B) too soft. I just don't know - as they say so often "it seemed like a good idea at the time"! Anyway, as already said in my reply to custard I would anyway choose a bigger bearing if doing this again;

2. Aligning the bottom spigot of the sanding drum with the bearing is no problem - the drum is first fastened (tightly) into the drill chuck while the table top level is still below the bottom of the drum. As the table top insert has a hole just a bit larger than the OD of the sanding drum it's no big effort to swing the whole table assembly from side to side slightly while raising it at the same time - you just feel the spigot glide into the inner bearing hole then continue raising the table until the bottom edge of the drum has disappeared below the upper edge of the table and you can't raise the table any higher, then back off (i.e. lower) the table just "a gnats smidgen". Then lock off the table raise/lower mechanism and "Bob's yer Uncle";

3. The drum (singular so far) is shop-made. That, and the hold down clamp for drilling will be covered in Pt 4 (to come later tonight hopefully). BUT I do have a couple of smaller OD commercial sanding drums which I'll modify (sometime!) to take a bottom spigot like the one posted. In addition I plan on making a couple more drums myself, exactly like the write up to come, but again with smaller IDs, one perhaps about 25 or 35 mm and the other perhaps about 15 or 20 mm OD. All of these will naturally need table inserts with smaller holes too (the idea of course is always to have the hole in the table insert just a few mm larger than the drum OD), so it MAY be that aligning the bottom spigot with the bearing when you have a smaller hole to peer through and "feel through" may not be quite so easy. I just don't know yet.

As I say, Part 4 is to come later, meantime thanks for the interest everyone, I'll do my best to answer any further Qs.

Until later ............

AES

 

[AES]

For anyone still interested I've posted the last part of this topic as a separate new post under the heading "WIP Part 4 .........................."

AES

 

[BenCviolin]

A proper oscillating bobbin sander may deliver a better finish and deliver more bobbin to the job.

Nice photos and jig.

 

[AES]

Fair enough Ben. I'm sure if I wasn't retired, and if I wasn't doing this stuff purely as an (unpaid) hobby, I'm sure I would be investing in a proper bobbin sander. And from what I've seen, they're not all that expensive either. But my lash up cost me very little (cash) and not too much time.

A lot of others here use pillar drill drum sanders and have posted about them so having had a good old think about them I though my own efforts may be of some help to others, just as many other posts here have been to me.

Nothing in my posts on this subject suggested that the result would be better than a bobbin sander, nor was such a suggestion ever intended.

"Yer pays yer money n takes yer choice" matey.

AES

 

[memzey]

Excellent project all round AES. Well done mate. I am actually working on a table for my own drill press and have gone for a slightly different design (I will post it up when it's finished) but I may "borrow" your lower bearing idea for my drum sanding adapter if I may (that would be another one I owe you)!

 

[AES]

Good to hear from you again Memzey, & thanks for your comments.

Happy New Year if it's not too late. BTW, is your Lamello machine still OK?

Re the lower bearing idea, please go ahead and "steal" the idea - that's why I posted it.

FYI, I'm still pretty pleased with that aspect of the design, but the DE is not working as well as I'd hoped. I have some modifications in mind for that, which will include increasing the width and height of the hole for DE in the fence, plus, probably, increasing the size of the hole in the bottom of the table. But I'm still thinking about it and it's not finalised yet.

I'll post the mods when done, but "don't hold your breath" in the meantime.

Cheers

AES

P.S. You don't "owe" me anything mate!

 

[memzey]

Cheers AES and happy new year to you too. The Lamello is running a like a dream - at least it would be in a competent user's hands I suspect! I was using it on my DP table project the other day actually. I'm edging the MRMDF table in some oak I have and am using biscuits and glue for that. Re DE; I was thinking of closing in the space underneath the drum sanding table as much as possible to help focus the airflow with an internal box but I am a rank amateur in these matters so that might be entirely the wrong thing to do, let alone my slim chances of actually executing it well!

 

[AES]

You may well be right about making the DE chamber under/inside the table smaller Memzey. I dunno mate, I certainly do not class myself as "expert" in any way (except that "X is an unknown quantity and spurt is a drip under pressure")!

Try it and let us know.

AES

 

[rafezetter]

You may well be right about making the DE chamber under/inside the table smaller Memzey. I dunno mate, I certainly do not class myself as "expert" in any way (except that "X is an unknown quantity and spurt is a drip under pressure")!

Try it and let us know.

AES

An excellent build AES, extremely proffessional. However the bottom bearing isn't a new idea I have seen it in several other pillar drill drum sander builds and used it myself both on its own and to use the pillar drill as a vertical belt sander with a rather convoluted jig I made.

The silicone fixing system though I think is a good addition to reduce the transference of the vibration into the table, my bearing is just friction fit into the base of my thick table and when I use my g-clamps the bar handles vibrate very loudly, so I might just use your idea.

I think the silicone system on its own will be ample resistance though, instead of upgrading to rubber, in all honesty if you are appyling that much force it's time to change the abrasive medium!

The suggestion of reducing the volume of the DE chamber underneath I would say is also good unless you have made absolutely certain that the chamber is hermetically sealed apart from the hole around the drum, which I doubt because of the extention bar sytem with the 4 holes - also a cracking idea.

 

[AES]

Thanks for the comments rafezetter.

I hadn't seen the lower bearing idea which is why I said "may be unique" in my OP.

Re the silicon ring, yes, I think that part of it is OK, though I still wish I'd found a bigger bearing in my scrap box (hence the turned ali housing).

Re DE, I'm certain that I have to do something about the fence, both the size of the hole when drilling (it's too small) and the overall bulk of the fence - it gets in the way sometimes.

Re DE for sanding, I've been thinking about the idea memzey suggested (above) and I think he's right - it's "wasting pressure" to have the whole of the table acting as the "exhaust unit" - the central area needs to be partitioned off I think.

When I get around to it I'll make some mods to correct the above faults and post them, but as I posted in my reply to memzey "don't hold yer breath"!

Thanks again Sir.

AES