Wandering round a car boot is always fun as I try to spot metal items that can be repurposed or even used as a source of raw materials and this old ‘gut buster’ hand drill just lay there waiting for me!
It had interesting two speed gearing, allowing hand cranking from either side and a huge bonus was the potential to drive it from both sides simultaneously even if it was at different speeds – but what I hadn’t realised was the fact that the hand cranking went in opposite directions! Also, the drive spindles were staggered due to the gearing with the ‘fast’ one being nearest the chuck end of the drill.
So I set about mounting it horizontally on a steel baseplate with a couple of oscillating cylinders driving either side. A cast iron bar-bell weight was attached to the main chuck spindle for a flywheel.
As it slowly came together it started to look a bit boring and so I decided to make entirely different power cylinders for each side…
The oscillating side driving the fast gear came together quite quickly but the other side was going to have full power double acting slide valve operation which was quite a bit more complicated. It required an eccentric to operate the slide valve. This would need to be on the inside of the crank to avoid a fancy crankshaft, this led to me realising that the cylinder and valve block would need to be arranged similarly. Big headache. The eccentric and crank would also stick out a mile on an unsupported shaft, not good.
Having wasted many hours on this daft layout I chucked the finished cylinder etc. into the bin and opted for a return to plan A using basically twin oscillating cylinders. It looked a bit like a metal grasshopper.
On testing with air pressure it became clear that as this old drill never had proper bearings, the whole thing was full of frictional drag. Nothing could be done about it apart from increasing the power piston sizes and allowing for higher steam/air operating pressure.
Another setback was the backlash in the gearing, it made a heck of a racket and that together with noisy conrod bearings created a right old cacophony.
So it slowly came together but it somehow didn’t look right, drills don’t lay down.
I decided it should be mounted vertically, the natural position for drilling after all, and I found a length of thick wall 20mm stainless tube to use for the pillar. Not ideal but all that was available.
The drill complete with flywheel and steel chassis plate was heavy, too heavy for the pillar and I looked at ways of lightening it…
The original drill body was amply strong enough and it didn’t need another baseplate/chassis! So this was also chucked in the bin and the drill with new twin cylinders was attached to my (too thin) vertical pillar.
Next some kind of stand was needed and I found a rusty car brake disc for the job. Under power it wobbled!
On showing pictures of my lovely almost completed MkI air powered drill to Jane she said, with typical feminine logic, ‘does it drill?’
Oh dear! 🥴
MkII, or, why-ever did I decide to stand it up ? 😖
Hand drills simply don’t need to rise and fall in a controlled manner and now having turned it into a pillar drill I had to arrange for it to slide up and down requiring a major change.
Well I suppose it kept me busy during the Covid lockdown…
Bernie's Engines 