What size drill

In the same way as you would not screw a bolt into a hole with chips in it, you don't unscrew a tap with chips behind the cutting bit*. As an Apprentice, one job We had was tapping out 4 Ba washers, 6" long "machine tap" (4"+ core diameter over top of cutting area) in the pillar drill, hold washer in pliars, push upwards on to tap, repeat until a pile of washers two inches thick was on tap. Then remove the tap and shake washers off. Repeat ad-nauseum.

* Turn metal upside down and shake chips out.

Frank

Good mouning, lots of free addvertising on here for DORMER DRILLS !! I worked for a drill manufacturer in sheffield ,we were a competiter to Dormer for many years , selling to the same custumers ,FORD and BL to name two plus all the other engineering supliers there were at the time . Not much to chose in quality of tools same machines and same staff because it was comon pratice to move from one to the other . Like most things today you only buy the name. Dormer are made in Mexsico now and Presto Tools in China . Tell you what though I bet Guring Drills are still made in Germany Stewart

I thought the Dormer drills were made in Brazil, at least thats whats on mine and their taps in Sweeden.

Out of interest to the OP my 3.3mm Dormer A022 series measures 3.28mm at the end of the shank

May be , I looked on the web to find out were , the point is , its not here any more ,its the name you buy . As stated on here the shank will be smaller for clearance ,but when you get to the end of the flute the turnings wont be able to clear so in practice thats the depth to drill. Stewart

Stewart, as far as I know Guhring and Walter "Titex " are still made in Germany. I recently bought a new Titex 14.25mm Ø and it says " Germany " on the shank. It doesn't say Made in Germany just "Germany" These days it's well nigh impossible to be sure of where a product is made A lot of famous firms like to keep that part secret .

Edited By Raymond Anderson on 10/09/2016 08:44:00

Just been informed that a lot of Guhring gear is made in " Wisconsin " with the Metric and higher end gear still in Germany. Like I said you are never sure. Incidentally, all me Titex drills bore bang on size, and just measured the new 14.25 and it measures 14.21 at the end of the shank.

Nobody has mentioned that with straight fluted taps you have to be sure the chips are not packing the flutes. Wrong lubricant (or none) is another problem. Spiral fluted taps have much to recommend them.

Similarly, yes you can bore beyond the spiral depth of a drill, but common sense dictates that frequent withdrawal to clear swarf helps a lot!!

It is interesting to note too that the shanks of most drills beside being smaller diameter than the fluted section, are not made of HSS but of a softer, more flexible grade of steel welded on to the end of the HSS blank. You can easily turn the shank of a 3/4" drill bit down to fit in your 1/2" drill chuck if needed.

I have turned shanks of large drills down, but I always assumed that the shank was a soft form of HSS.

Do you know that they are welded on extensions?

Ian

I too have always read that the shanks are unhardened HSS rather than welded on materail

No, don't know for sure. Just remembering what I was taught as an apprentice 40 something years ago. The old grey cells, well they could be unreliable. And manufacturing techinques could have changed I suppose. HSS is not as exotic or expensive as it used to be, so it might make more sense these days to make the whole drill out of HSS but harden only the working section.

I do remember being taught to grip the drill in the chuck leaving plenty of gap between the end of the flutes and the chuck jaws so the unhardened section of shank would be allowed to flex and so would not snap the drill bit off at the weld. Maybe it was just a toolmaker's old wives' tale.

Edited By Hopper on 12/09/2016 05:46:11

Edited By Hopper on 12/09/2016 06:02:51

PS from what I remember, I was told the HSS section and the carbon steel shank were welded together using friction and or pressure welding, ie forcing them together and rotating them in opposite directions. Going back a long time now though.

Well I just had to find out if I was remembering right. Couple of interesting videos on Youtube about drill bit manufacture. A couple of the older firms, Titex and Dormer, mention welding a softer section on the shanks of their drill bits. Others seem to just use great coils of HSS wire to spit the drill bits out like cookies.

Mention of it at 3:12 in this video

The whole video is worth a watch, 1967 manufacturing technology seems so primitive today.

This one is more modern, showing rolls of 1/2" HSS like wire being fed into CNC machinery. Friction welding the HSS section to the carbon steel shank is shown at about 2:10. Interesting stuff.

Hi Further to the discussion on drill manufacture .If we look at what's known as a Jobber drill 1/64 - 1/2 " and metric up to 13mm these are solid HIGHSPEED STEEL (HSS) not welded ( hardened for about 2/3rds of it length) Next you have what would be known as a par shank ( a drill up to 3/4" I think) with a parallel shank of 1/2" solid HSS not welded . Then we have taper shanks starting at No1 MTS through to No 6 MTS , used to be Carbon shanks welded to HSS . As the cost of welding increased and machines developed, it was more cost effective to make No1 and No2 MTS from solid HSS . A point of interest ,the smallest drill might be a number drill through to say 6" MTS and everything in between going up in 1/64s or metric equivalents , that's quite a range of drills to stock and a lot of money not making money ,the accountants didn't like it , and as they say that was the beginning of the end.

Stewart

There may have been one or two other reasons as well Smiley face in a strange place (what y gunna do). Stewart