AES
Established Member
This follows on from the previous (Parts 1,2, & 3) and is the last part (for now) 
Like much else here, the drilling hold down clamp is based on several designs I’ve seen on the net. I made no attempt to copy any particular model, just took several ideas and combined them. The basic dimensions are 200 mm (8 inches) long overall x 30 mm (11/4 inches) wide x 50 mm (2 inches) high to the clamping area. See Pictures 2 (Pt 1, clamp in use), 20, and 21 (below). It’s made from 2 laminations of a red-ish hardwood (VERY heavy and very hard - sorry, I have no idea what species, it came from some scrap I found on a building site). I just sketched the curves free-hand direct onto the wood, and cut the semi-circular “clamping button” free-style out of the rest of the piece. Before laminating the 2 halves together (screws and 5 minute epoxy) I roughed out the roughly 80 mm (3 inches) long slot for the clamping bolt and finished it with a sandpaper-wrapped dowel after the epoxy had hardened. The clamping T bolt and knob came from the Axi jig kit and the nominal OD of the threaded part of the bolt is 4 mm (3/16 th inch). The 2 pieces of scrap aluminium sheet are simply to retain the clamping button in place while tightening and loosening the clamp. So far it seems to work fine on the few jobs I’ve drilled on the new table. I may make one more the same, or based on my usage, may vary the design a little. I guess a second one will be needed, but another advantage of an add-on drilling table is that standard G cramps, Kwik-Grips, etc, are easier to use than with only the original cast iron table.
The sanding drum was one of the simplest jobs. 3 x 66 mm (25/8 th inch) diameter x 21 mm (3/4 inch) thick MDF wheels cut from scrap with the hole saw; glued together and trued up on the (metal working!) lathe.
During a discussion on the UKW Forum, I posted that I thought a section of bike inner tube glued to the resulting drum would be a workable idea, but another member posted that perhaps this rubber would be too thin. Quite by coincidence I found a better substitute in my local Aldi – a roll of self-adhesive contoured “rubber” about 3 or 4 mm (3/16th inch) thick. I think the stuff is intended for use as a non-slip base for tool chest or kitchen drawers, but so far it seems to be fine as a resilient surface on a sanding drum. The roll is seen on the LH side of Picture 22, and the finished drum with the material applied is shown in the centre. To be sure of adhesion I gave the bare drum a coat of clear varnish after sanding, followed by a coat of contact adhesive before applying the Aldi self-adhesive rubber material.
Originally I cut normal paper-backed abrasive as sand paper for the drum, but found that it tore quite quickly. So instead I cut up a 150 grit sanding belt which is cloth-backed (it came from a defunct belt sander), and this seems to work better. The abrasive is retained on the drum by means of a vertical radial slot cut with the band saw, in the middle of which a suitably-sized vertical through-hole is drilled. I quickly found that the width of this slot and the position of the hole is quite critical – the slot should be just slightly wider than twice the thickness of the abrasive, and the hole must be positioned mid way along the slot, between the OD of the drum and the inner end of the slot. The abrasive is retained by 2 screws, one below and one above the drum, making sure when securing the abrasive that the screw goes between the 2 thicknesses of abrasive, so forcing the abrasive firmly into the slot.
You can see my original effort in the picture, which was a mistake - I drilled the screw hole right at the inner end of the slot. Therefore when inserting the screw the ends of the abrasive weren't correctly forced into the slot. Stupid mistake! I had to drill the screw holes bigger, insert a length of dowel, then re-drill the screw holes into the correct position (midway along the slot).
The drum centre spindle was already shown in Picture 11, but here it is again:
A simple machining job with a lathe, but by no means impossible without – I have only owned a lathe for 2 or 3 years! The basis is an 8 mm (3/8th inch) diameter coach bolt, 100 mm (4 inches) long. The mushroom head and the short square part of the shank is sawn off and then the remaining plain shaft is threaded 8 mm for a short length. A 50 mm (2 inch) length of 10 mm MS bar is then drilled and tapped all through 8 mm. This is fully screwed on to the new thread and secured with Loctite thread locker. Finally an Allen-headed 8 mm bolt is screwed into the free thread remaining in the bar and turned down to 10 mm if necessary, also using Loctite to be sure it is locked firmly. This dodge simply extends the length of the original coach bolt, which was the longest I could find.
The other (threaded) end of the bolt is now dealt with – simply by turning down approx 10 mm of the original approx. 20 mm threaded length. The newly machined dia should be a nice fit into the ID of the below table support bearing.
Finally a short hole of the same diameter as the across-the-flats measurement of an 8 mm Nyloc nut is drilled into the bottom of the MDF drum with the nut then being “gently hammered” (is there such a technique? ) into place.
As shown in Picture 11, the final assembly, from the top down is: – 1 large plain washer – 1 shake-proof washer (to grip the top of the MDF drum) – the centre spindle itself – then hold the top of the spindle firmly in the vice while screwing the drum with the nut in place until the shake-proof washer has bitten into the upper surface of the drum. So far this seems to hold quite firmly with no tendency to loosen off.
While looking at the web I did seen one idea whereby a car windscreen wiper motor was coupled to the raise/lower handles of the pillar drill by means of a wooden eccentric crank! Frankly, I thought the idea was a bit too reminiscent of Heath Robinson for me, but clearly my drum sander set up is not as good as a proper rise and fall drum sander - but cheaper!
So far however it works well and it’s proved easy enough to clean the abrasive. The Axi Tools block of crepe rubber works well, as does a tip I got early on after joining this Forum (a length of rubber – not plastic – hosepipe). And it’s not difficult to undo the 2 retaining screws and invert the abrasive so that top becomes bottom and vice-versa.
So there it is folks. This seems to have created some interest already, before the 3rd part and this one was even posted, so thanks to everyone for their interest so far.
If this helps anyone else then I’ll be very pleased, and if anyone has any questions I’ll be happy to answer as well as I can.
But I really don’t think there’s anything here beyond the capabilities of the average “bodger” – and from what I’ve seen on this Forum, the majority of members are well above that standard!
All the best to everyone, I’ll post any further news after I’ve had a chance to use the whole set up for a while (and have made a couple more sanding drums and perhaps another drill hold down).
AES
Like much else here, the drilling hold down clamp is based on several designs I’ve seen on the net. I made no attempt to copy any particular model, just took several ideas and combined them. The basic dimensions are 200 mm (8 inches) long overall x 30 mm (11/4 inches) wide x 50 mm (2 inches) high to the clamping area. See Pictures 2 (Pt 1, clamp in use), 20, and 21 (below). It’s made from 2 laminations of a red-ish hardwood (VERY heavy and very hard - sorry, I have no idea what species, it came from some scrap I found on a building site). I just sketched the curves free-hand direct onto the wood, and cut the semi-circular “clamping button” free-style out of the rest of the piece. Before laminating the 2 halves together (screws and 5 minute epoxy) I roughed out the roughly 80 mm (3 inches) long slot for the clamping bolt and finished it with a sandpaper-wrapped dowel after the epoxy had hardened. The clamping T bolt and knob came from the Axi jig kit and the nominal OD of the threaded part of the bolt is 4 mm (3/16 th inch). The 2 pieces of scrap aluminium sheet are simply to retain the clamping button in place while tightening and loosening the clamp. So far it seems to work fine on the few jobs I’ve drilled on the new table. I may make one more the same, or based on my usage, may vary the design a little. I guess a second one will be needed, but another advantage of an add-on drilling table is that standard G cramps, Kwik-Grips, etc, are easier to use than with only the original cast iron table.
The sanding drum was one of the simplest jobs. 3 x 66 mm (25/8 th inch) diameter x 21 mm (3/4 inch) thick MDF wheels cut from scrap with the hole saw; glued together and trued up on the (metal working!) lathe.
During a discussion on the UKW Forum, I posted that I thought a section of bike inner tube glued to the resulting drum would be a workable idea, but another member posted that perhaps this rubber would be too thin. Quite by coincidence I found a better substitute in my local Aldi – a roll of self-adhesive contoured “rubber” about 3 or 4 mm (3/16th inch) thick. I think the stuff is intended for use as a non-slip base for tool chest or kitchen drawers, but so far it seems to be fine as a resilient surface on a sanding drum. The roll is seen on the LH side of Picture 22, and the finished drum with the material applied is shown in the centre. To be sure of adhesion I gave the bare drum a coat of clear varnish after sanding, followed by a coat of contact adhesive before applying the Aldi self-adhesive rubber material.
Originally I cut normal paper-backed abrasive as sand paper for the drum, but found that it tore quite quickly. So instead I cut up a 150 grit sanding belt which is cloth-backed (it came from a defunct belt sander), and this seems to work better. The abrasive is retained on the drum by means of a vertical radial slot cut with the band saw, in the middle of which a suitably-sized vertical through-hole is drilled. I quickly found that the width of this slot and the position of the hole is quite critical – the slot should be just slightly wider than twice the thickness of the abrasive, and the hole must be positioned mid way along the slot, between the OD of the drum and the inner end of the slot. The abrasive is retained by 2 screws, one below and one above the drum, making sure when securing the abrasive that the screw goes between the 2 thicknesses of abrasive, so forcing the abrasive firmly into the slot.
You can see my original effort in the picture, which was a mistake - I drilled the screw hole right at the inner end of the slot. Therefore when inserting the screw the ends of the abrasive weren't correctly forced into the slot. Stupid mistake! I had to drill the screw holes bigger, insert a length of dowel, then re-drill the screw holes into the correct position (midway along the slot).
The drum centre spindle was already shown in Picture 11, but here it is again:
A simple machining job with a lathe, but by no means impossible without – I have only owned a lathe for 2 or 3 years! The basis is an 8 mm (3/8th inch) diameter coach bolt, 100 mm (4 inches) long. The mushroom head and the short square part of the shank is sawn off and then the remaining plain shaft is threaded 8 mm for a short length. A 50 mm (2 inch) length of 10 mm MS bar is then drilled and tapped all through 8 mm. This is fully screwed on to the new thread and secured with Loctite thread locker. Finally an Allen-headed 8 mm bolt is screwed into the free thread remaining in the bar and turned down to 10 mm if necessary, also using Loctite to be sure it is locked firmly. This dodge simply extends the length of the original coach bolt, which was the longest I could find.
The other (threaded) end of the bolt is now dealt with – simply by turning down approx 10 mm of the original approx. 20 mm threaded length. The newly machined dia should be a nice fit into the ID of the below table support bearing.
Finally a short hole of the same diameter as the across-the-flats measurement of an 8 mm Nyloc nut is drilled into the bottom of the MDF drum with the nut then being “gently hammered” (is there such a technique?
) into place.As shown in Picture 11, the final assembly, from the top down is: – 1 large plain washer – 1 shake-proof washer (to grip the top of the MDF drum) – the centre spindle itself – then hold the top of the spindle firmly in the vice while screwing the drum with the nut in place until the shake-proof washer has bitten into the upper surface of the drum. So far this seems to hold quite firmly with no tendency to loosen off.
While looking at the web I did seen one idea whereby a car windscreen wiper motor was coupled to the raise/lower handles of the pillar drill by means of a wooden eccentric crank! Frankly, I thought the idea was a bit too reminiscent of Heath Robinson for me, but clearly my drum sander set up is not as good as a proper rise and fall drum sander - but cheaper!
So far however it works well and it’s proved easy enough to clean the abrasive. The Axi Tools block of crepe rubber works well, as does a tip I got early on after joining this Forum (a length of rubber – not plastic – hosepipe). And it’s not difficult to undo the 2 retaining screws and invert the abrasive so that top becomes bottom and vice-versa.
So there it is folks. This seems to have created some interest already, before the 3rd part and this one was even posted, so thanks to everyone for their interest so far.
If this helps anyone else then I’ll be very pleased, and if anyone has any questions I’ll be happy to answer as well as I can.
But I really don’t think there’s anything here beyond the capabilities of the average “bodger” – and from what I’ve seen on this Forum, the majority of members are well above that standard!
All the best to everyone, I’ll post any further news after I’ve had a chance to use the whole set up for a while (and have made a couple more sanding drums and perhaps another drill hold down).
AES
