drilling brass?

[dickieto]

hi irving
i usually take the sharpness off of a drill by holding a sheet of wet and dry on a flat surface with a little light oil on it and rub the cutting edge untill the sharpness is off of it,
i also push the drill bit into some soft soap for lubrication,may seem a bit mad but it seems to work for me in brass.
Tom

[Peter Griffin]

Irving

Thats what I mean't the cetting edge needs to be removed as in Robin's picture.

[Robin Hewitt]

Just had a thought.
Mentioning no names, I bought some cheap Jobber drilll bits on ebay, supposedly 'quality' items.
After the first 2 sizes snapped on the first hole attempted the rest went in the bin.
Maybe your trouble is naff drillls and what you really need is a Dormer?

[irving2008]

Strangely I nearly bought some cheaper jobber drills, then changed my mind and got some dormer ones off eBay... twice the price, but probably last more than twice as long. The current drills are from a drill set from one of the usual sources...

[Wobblybootie]

OK, I give up ... what's the difference between a 'jobber' and a Dormer' :confused: ... I think a 'jobber' is supposed to be L =10 X dia (when new) but any more and I am lost ... If I want to drill a 7mm hole I grab a 7mm drill bit ... Yes I know my lack of engineering knowledge makes me a Neanderthal knuckle dragger ..

[cropwell]

I thought you might be interested in some special purpose drills
From left to right
45 degree hole
next two for corner drilling
middle one for approximation drilling
three on the right are straightened flute, for when you just want to unwind

Dont ask me how they happened, they aren't mine. Mine just break !

[BillTodd]

Irving,

I was thinking about you method of backlash removal; It might be worth arranging things so the bulk of the thread is pushed or pulled towards the handle of the cross slide, rather away from it, since most turning is external and the cutting force will be in that direction.

[irving2008]

Bill,

The plan was that the screws would be on the side away from the handle so they can be adjusted from the outside, and this would be the shorter 1/3 of the nut (approx) as per diagram

[BillTodd]

Bill,

The plan was that the screws would be on the side away from the handle so they can be adjusted from the outside, and this would be the shorter 1/3 of the nut (approx) as per diagram

So, your adjustment screw will squeeze the threads? If so, it means that while outside turning the force will be taken via the adjustment screws to the cross-slide. I modified my Southbend in a similar way except, the adjustment screw were threaded into the split portion (I simply sawed part of the way through the nut) , so the adjustment separated the parts IYSWIM.

[irving2008]

i see what you mean, and i was going to do it that way, but i was told there was a risk of the nut splitting if i did this (being old brass) - the amount of backlash is significant... it might need quite a gap!

What I had planned to do is saw it with a fine saw, then reassemble and check the backlash. then mill a small amount off the fixed portion such that when the screws are done up its a little overtight.. then shim it back. Its only until I can make the new nuts and screws so only has to last another, ummm, year or so... these have lasted 100y already!