Slow Monster rebuild

utopia · 03-09-2017, 10:12 AM

On the drilling ...
I've struggled for years using thin machine oil (or cold tea, even) as a cutting fluid for steel but last week I threw off my scroogeish behaviour and bought a small bottle of proper cutting fluid from Machine Mart. The difference was marked. Well worth the cash, I reckon.
On cutting speeds, most DIY market small pillar drills run way too fast. Mine has never, ever been on anything above its slowest speed for anything .. and I've owned it since the 70s. I have even cut larger sizes in aluminium by turning the chuck by hand. I'd advise trying slower.
Strictly speaking, it is bad practice to open out holes using an ordinary, two-flute drill. Ideally you should use a three-flute or "core" drill. The three flutes give the drill support much like a three legged stool, whereas the std drill will tend to chatter on its two flutes. Of course nobody has any core drills to hand, but the theory still applies.
And on the drill sharpening ... do you do this yourself ? Its a pretty skilled job to do it "offhand", without a clever gadget. Getting the angles correct and equal, sufficient rake behind the cutting edge etc is quite tricky. I sharpen mine by hand, but I was shown how to do it properly years ago as an apprentice. Well actually, I was shown how difficult it is and advised not to do it, but I'm too cocky for that.
Dormer used to produce a little handbook for engineers on the ins and outs of drilling .. maybe it is still available.

03-09-2017, 10:12 AM	#11
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,545	On the drilling ... I've struggled for years using thin machine oil (or cold tea, even) as a cutting fluid for steel but last week I threw off my scroogeish behaviour and bought a small bottle of proper cutting fluid from Machine Mart. The difference was marked. Well worth the cash, I reckon. On cutting speeds, most DIY market small pillar drills run way too fast. Mine has never, ever been on anything above its slowest speed for anything .. and I've owned it since the 70s. I have even cut larger sizes in aluminium by turning the chuck by hand. I'd advise trying slower. Strictly speaking, it is bad practice to open out holes using an ordinary, two-flute drill. Ideally you should use a three-flute or "core" drill. The three flutes give the drill support much like a three legged stool, whereas the std drill will tend to chatter on its two flutes. Of course nobody has any core drills to hand, but the theory still applies. And on the drill sharpening ... do you do this yourself ? Its a pretty skilled job to do it "offhand", without a clever gadget. Getting the angles correct and equal, sufficient rake behind the cutting edge etc is quite tricky. I sharpen mine by hand, but I was shown how to do it properly years ago as an apprentice. Well actually, I was shown how difficult it is and advised not to do it, but I'm too cocky for that. Dormer used to produce a little handbook for engineers on the ins and outs of drilling .. maybe it is still available.