pre drilling for holes

Help Support HMEM:

tornitore45

Well-Known Member
HMEM Lifetime Supporter
Joined
Jan 17, 2009
Messages
941
Reaction score
182
There is some seriously wrong with that drill bit.
The cutting edge are ragged
The flutes have a terrible finish.
The metal smear behind the lands indicates the they were not releaved for clearance. And that is the worst offense because rubbing and galling generate heat more than rough edges and flutes.
Let's face it Dormer of fake, whether it missed several manufacturing steps by accident in a quality plant or is a cheap imitation of a drill the result is the same. A poor drill like that may work on some plastic or Styrofoam but should never come near metal or wood.
I am really curious to see what the response from Dormer is.
 

goldstar31

Well-Known Member
Joined
Feb 20, 2010
Messages
2,675
Reaction score
730
Location
Twixt Tyne and Tees
I can't see a firm as big as Dormer bothering about one bad drill which is only worth a few dollars.

I would send the guy an apology and a generous sample of drills-- and start living again.

I got mixed up with a rather large problem- a damned sight bigger than this - and my bank sent me a couple of vouchers worth £50 in all to buy my grandchildren some pizzas.:D

For the record, I'm a shareholder of the bank and if I had played awkward had access to the bank's annual general meeting!

Life if I may remind, isn't the dress rehearsal it's the once only affair so let's move on.o_O

Norm at almost 90!
 

ALEX1952

Well-Known Member
Joined
Jan 17, 2018
Messages
70
Reaction score
17
Location
SCOTLAND
If the knee of the machine is to be used as a method of feed as suggested previously, lock the quill as it can still pull it through.
I think this method is a terrible and potentially dangerous idea, as it can bring your face nearer the work piece if you have to bend to do the feeding. I have never seen this used in a professional environment. Discuss!
 

chrsbrbnk

Well-Known Member
Joined
Jul 25, 2007
Messages
127
Reaction score
29
Drilling with the knee is a reasonable approach just really sorta slow, might want to clamp the work down , might want to wear safety glasses, and of course clamp the quill. might want to keep your hair out of the fray too. Drilling under power feed is ultra common in the professional shop and for all intents and purposes the same as cranking up the knee or the tailstock on the lathe. just easier to keep the feed constant. its pretty easy to give too high a feed rate when drilling out very small amounts leading to tip failure.
while I was working we would find brand new drill bits with messed up cutting angles once in a while you would get a whole dozen that were soft .
best test sharpen the messed up bit and try drilling again that will show if its the bit or material or practice
 

tornitore45

Well-Known Member
HMEM Lifetime Supporter
Joined
Jan 17, 2009
Messages
941
Reaction score
182
The method suggested was for special situation where the manual feeding can not guarantee a constant feed rate.
Specifically it was suggested to remove a broken tap with a carbide bit.
The irregular fracture and the tap flutes will bounce the drill or end mill chipping the fragile carbide edge if the operator arm is all that define rigidity.
In that case one has to proceed at glacial speed anyway.

My mill has no knee, the head moves down, the practice is safe but is used only when the alternate feeding method is troublesome because of the bouncing.

Knee type milling machine usually have a fine feed crank operating on the quill.

As anything in life danger and risk can be controlled or pursued.
 

Wizard69

Well-Known Member
Joined
Mar 9, 2013
Messages
1,369
Reaction score
277
Nick you need to learn how to learn from those that know more than you.
Mountains of experience say you are wrong, why do you insist in defending something wrong?
By the way, from the point of view of the reamer cutting into the hole the geometry is essentially the same and that is why a drill bit can cut into a hole slightly undersized just like a reamer. The difference is that a reamer has multiple flutes keeping a better center and cutting a rounder hole, something a drill bit may not do because is allowed to wander, but that difference is meaningless to the issue at hand.
I’ve have had this issue happen to me and have seen other suffer in the same way. If you don’t like the term tool abuse we can call it something else. In general drill bits will tear up the margins when you try to drill close to size. Yes drills made with better steel might tolerate it better but the fact remains it is hard on the drill.

As for the steel I’m not certain it is low carbon. It could be structural steel with a hard spot for all we know.
 

Wizard69

Well-Known Member
Joined
Mar 9, 2013
Messages
1,369
Reaction score
277
I learned this approach from an old tool and die maker. In the right materials you are at a greater risk of shattering a diol or damaging it from Quill feed as you can control for cork screwing and other effects. With the quil clamped and feed coming from the knee a drill bit would have to grab enough to lift the knee before anything bad happens.

Frankly using the knee for drill feeding can be ideal in the right situation. There ware problems though, the lack of feedback being one, so maybe not a widely used technique. As for your face where is your safety glasses and shielding.

If the knee of the machine is to be used as a method of feed as suggested previously, lock the quill as it can still pull it through.
I think this method is a terrible and potentially dangerous idea, as it can bring your face nearer the work piece if you have to bend to do the feeding. I have never seen this used in a professional environment. Discuss!
 

xpylonracer

Well-Known Member
HMEM Supporter
Joined
Dec 23, 2010
Messages
281
Reaction score
65
Not all mills have a quill on the vertical function, the first mill I had was a Victoria U1 universal horizontal machine, the vertical head fitted to the rear dovetail and was driven from the 3MT horizontal arbor drive, this gave double the spindle speeds of the horizontal function.
The vertical head was a hefty lump but had no quill although it could rotated either side of vertical.
To drill or add DOC when milling it was done by using the 10" handle on the knee drive which was low geared and raised 1/8" per rev of the drive, the movement was silky smooth but tiresome on the arm when multiple holes needed drilling.
The Victoria also had a slotting head that was fitted in place of the vertical head, useful and used to slot some gears for my Colchester Bantam lathe.
All of the milling and drilling to make my avitar 5 cylinder radial engine were done on the Victoria.

xpylonracer

http://www.lathes.co.uk/victoria/
 

larryg

Well-Known Member
Joined
Mar 23, 2015
Messages
65
Reaction score
28
Location
Oregon, USA
If the knee of the machine is to be used as a method of feed as suggested previously, lock the quill as it can still pull it through.
I think this method is a terrible and potentially dangerous idea, as it can bring your face nearer the work piece if you have to bend to do the feeding. I have never seen this used in a professional environment. Discuss!
As said above on a HZ mill the knee has to be used if one wants to drill with the vertical head on. On my HZ mill I have power feed on all three axis so powering up to drill is not a problem. I also have an old index #40 mill with only a hand wheel on the quill, no quick handle. There is a lot of back lash in the quill drive so the spindle can drop ~.200" when breaking through or self driving. I use the knee at various times if some precision is needed. In a recent vid from Abom79 he also used the knee for some precision drilling. So it is used at times by various people amateur and professional alike.

lg
no neat sig line
 

awake

Well-Known Member
HMEM Supporter
Joined
Sep 4, 2019
Messages
826
Reaction score
272
Location
North Carolina
It sounds like some of you are using a power quill feed when drilling - ? I'm curious about this, as on my Bridgeport it specifically says not to use the power quill feed for drilling - it is to be used only for boring. Presumably, other types of mills do not have this limitation - ?
 

tornitore45

Well-Known Member
HMEM Lifetime Supporter
Joined
Jan 17, 2009
Messages
941
Reaction score
182
I recall reading somewhere that there is weakness, like a pin, in the quill power feed drive chain that limit the allowed force/torque.
I can see that boring on a BP will always have a DOC less than 3/8" so boring is safe.
 

awake

Well-Known Member
HMEM Supporter
Joined
Sep 4, 2019
Messages
826
Reaction score
272
Location
North Carolina
Bridgeport says 3/8" capacity when drilling.
I could have sworn that the manual said not to use it for drilling, but when I checked, sure enough, the limit is no more than 3/8".

I'm thinking now I must have picked up the "no drilling at all" from reading on the PM forum ... maybe in response to comments about people messing the quill power feed by trying to drill too large a drill? Or something like that. Not sure if someone there said "no drilling," or if that was my interpretation.

In any case, thanks for catching the mistake!
 

Badhippie

Member
Joined
Sep 6, 2013
Messages
20
Reaction score
5
Location
Oskaloosa Iowa
Sorry I am new to posting on this site. It looks like to me this drill bit has been spun backwards. If you look at the pic. The burr I circled would not be facing this way also I circled the relief cut. I can assure you that this bit was spun backwards everyone of us has done it at sometime. The burr is the proof it’s going the opposite direction.
 

chrsbrbnk

Well-Known Member
Joined
Jul 25, 2007
Messages
127
Reaction score
29
in the way back days in the shop if you left your machine running unattended, the jokesters in the shop would off then turn on the quill on backwards so that when you came back and started using it , it would wreck the tool just like that
 

Latest posts

Top