Dormer 108 Drill Grinder Resurrection

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krv3000:
all I can say is brill :thumbup:

awemawson:
Thanks for the kind words chaps :thumbup:

Well that gauge still hasn't arrived, but I've been playing a bit - I've even successfully sharpened a 9 mm drill :ddb:

However, the protrusion of the drill, which is what the gauge is for, is set by moving the 'tailstock' in or out along a square bar, and it's ever so fiddly as the clamping is with a hex key, and you run out of hands :bugeye:

So I decided to make some knurled clamping screws this morning which have made the setting up far easier. Simple turning and knurling exercise - I 'loctited' screws into blind tapped holes, then parted the screw head off. I'd really have wished to use brass for the one that bears directly on the male / female centre but nowhere could I find a 2 BA brass screw of suitable length, and I was too lazy to thread a bit of brass!

I think long term I'm going to make some form of screw advance for the tailstock, as it's not the most subtle of adjustments as it is.

awemawson:
Seems to work - this is an abused 13 mm drill I just put through the machine. I still need to experiment with web thinning, chisel angles, and varying the relief.

awemawson:
To operate this grinder, the drill is clamped between jaws, a calculated amount ground off, then the wheel is backed off to let you remove the drill, rotate it 180 degrees, then grind to the same point on this second flank.

To do this reasonably accurately there is a 'stop collar' that can be clamped to physically stop the movement at a particular point, however it's very hard to not over run as the feed handle has much mechanical advantage so it can slide the collar - certainly not precise enough in my opinion.

In the later model the feed handle had a 'friction fit' collar carrying a pointer that could be rotated to show zero, and give you a positive indication that you were where you want to be. No such collar and fidicule line on this one.

awemawson:
I may well modify the machine along those lines in the future, but as a test I decided to rig a dial gauge up to show me when I'd 'arrived'

I have had a magnetically mounted Mitutoyo one that I rescued from an EDM machine I pillaged for spares - it was used to show cutting progress like this one on my own EDM machine, but it was in a sorry state, with a bent needle

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