pre drilling for holes

[MachineTom]

When I was 14 years old our neighbor put in a swimming pool. Every day I watched the progress, digging the hole pouring cement etc. It being summer I had all day to watch the work progress. Now it came time to install the water slide it was mid August 95 degrees and humid.
I watched the worker drill holes for the anchor bolts, the first bolt hole went fine, but the second made no progress. Thinking the bit was dull the worker replaced it, still no joy. Back to the truck, rummage around, and brings back another. This goes on for 20-30 minutes, the guy is sweating like crazy, and cussing a blue streak. As he seats there looking at the hole with No progress, I walk over and ask why is not using left hand drills for the hole. It's over 50 years since that day, but I still recall the look on his face when he realized the drill was in reverse.

 

[awake]

Running the drill backward - I'm happy to report that I've never done anything like that. Never. Honestly. You can believe me. Really!

 

[kwoodhands]

I'm raising several questions.
The first is whether today's drills need lubrication to avoid damage. I keep seeing warnings about this
Again, about reamers, I always understood that new reamers were machined oversize so that a subsequent re-grind was 'on spec'

Thirdly, I 'm ancient but recall the tale- possibly an old wives one about the competition BEFORE WW2 between the UK and Japan drilling holes and then getting another smaller hole and then another and so on.
Again, my copy of Sparey, the Amateurs lathe book and reference to drilling and then finish drilling. Was Sparey wrong as he made a lot of designs -- which you are all copying.

Lastly, drills heat up without lubrication and I recall that with long carbon spade drills in very hardwood wood that they both expanded and burned and -- went soft in consequence.

I doubt that my recollections are correct. Please comment

Norm

Norm as far as spade drills heating up in hardwoods , you are correct. Not sure if the bits will be annealed and
go soft. I used to get some jobs installing electric hinges and fire exit devices ( panic bars) on wood slab doors where long drilling was required. I kept a 5 gallon bucket 3/4 full to dip the spade bit in to cool it.
Every 3" or so the bit was extracted and dipped into the water. I spun the drill a few seconds to dry the bit before re-entering the hole. I'm guessing that a bore was about 44" or more in length and on an angle from the top hinge mortise to the device near the lock side. The spade bits probably expanded too as sometimes they were hard to extract. Often had to wait several minutes before removing the bit.
I tried various spray lubes , WD-40, BoShield etc. None worked for me. Just cooling the bit with water worked. The bore was started with a 5/8" x 6" auger, then switched to a 1/2" x 6" spade bit in an 18" extension. Finally a machine shop made extension was used to finish the bore.
Nerve racking and tedious job as the set up to bore a long hole on an angle was not easy.
I wound up doing this job for various contractors from Rhode Island to Florida when it was known this job could be done at all. I heard that some attempts wound up with bits going thru the side of the doors.
That is why I never considered using a lamp bit. Much too flimsy for precise work.

mike

 

[goldstar31]

Nerve racking and tedious job as the set up to bore a long hole on an angle was not easy.
I wound up doing this job for various contractors from Rhode Island to Florida when it was known this job could be done at all. I heard that some attempts wound up with bits going thru the side of the doors.
That is why I never considered using a lamp bit. Much too flimsy for precise work.

mike

My long drillings were in woods like cocobolo, kingswood, African Blackwood and Lignum Vitae but my drills were far narrower and possibly longer than yours. Mine were up to 13 inches and never more than 7mm in diameter. Hence, I spent a lot of time extracting and then drilling after flicking the turnings off the silver steel/ key steel rods.
In passing, I should mention that these exotic hardwoods were naturally oily.

Thank you for the input incidentally

Norm

 

[tornitore45]

Again, about reamers, I always understood that new reamers were machined oversize so that a subsequent re-grind was 'on spec'

That can't be true for 2 reasons

1) Reamers are meant to "size" a hole precisely after drilling so a pin or a dowel can slide with minimal play or be pressed in reliably.
2) A reamer has cylindrical ground margins like a drill bit. A reamer cutting action is limited to the small chamfer on the front. If any sharpening need to be done it should be done there.

Drill bits heating up in wood. Spade bits are not usually made with High Speed Steel, therefore overheating can permanently soften them.

Twist drill made of HSS can turn blue and keep hard. Is normal to silver braze a bit of HSS to a shank to make a internal boring/threading bar without affecting the HSS hardness.

 

[goldstar31]

[QUOTE="tornitore45, post: 330085, member: 781

Twist drill made of HSS can turn blue and keep hard. Is normal to silver braze a bit of HSS to a shank to make a internal boring/threading bar without affecting the HSS hardness.[/QUOTE]

If I recall my 'wood boring' days, I recall that drill bits were extended by boring the end with another hss drill and silver soldering a mild steel extension.

As I have done it repeatedly, I must assume that the drill was so- and clearly, that I must entirely disagree with you.

Who also disagrees is the late Leonard Sparey who was the designer of many of the many engines which still appear on this web.

On a lighter note, I recall ex Napoleonic bayonets being used to do the taper bores on The Great or Highland and Half Long bagpipe chanters! You do know that the Irish sent bagpipes to the Scots as a joke-- and the Scots haven't seen the joke yet.

 

[ALEX1952]

Contrary to a previous post reamers are not parallel but very slightly tapered for some of its length and does cut on the flutes or you would struggle to get a finish, this is especially so for hand reamers as you would have difficulty starting them, that's why you are able to enter the reamer into a pilot hole and still end up at size or if desired for a fit slightly under.

 

[ALEX1952]

That can't be true for 2 reasons

1) Reamers are meant to "size" a hole precisely after drilling so a pin or a dowel can slide with minimal play or be pressed in reliably.
2) A reamer has cylindrical ground margins like a drill bit. A reamer cutting action is limited to the small chamfer on the front. If any sharpening need to be done it should be done there.

Drill bits heating up in wood. Spade bits are not usually made with High Speed Steel, therefore overheating can permanently soften them.

Twist drill made of HSS can turn blue and keep hard. Is normal to silver braze a bit of HSS to a shank to make a internal boring/threading bar without affecting the HSS hardness.

on the contrary to a reamers are not parallel but very slightly tapered for some of its length and they do cut on the flutes or you would struggle to get a finish, this is especially so for hand reamers as you would have difficulty starting them, that's why you are able to enter the reamer into a pilot hole and still end up at size or if desired for a fit, slightly under.

 

[goldstar31]

In fairness, probably Torniture. is thinking about machine reamers.
I'm in the School which believes that a properly honed boring bar creates a better finish any way

A comment to Tourniture, I make my boring bars from solid HSS but believe that the best finish is still achieved with carbon steel.

As an aside, I have just resurrected my old Mark1 Quorn tool and cutter grinder as I've got sort of excited and a bit concerned with the introduction of the new Mark3.
And then a kind Scottish gentleman posted me an almost complete set of castings for the Mark 1.

Which all brings me back to drills and Professor Dennis Chaddock who designed the Quorn- from the Deckel to make end mills for his ? V8 and also 4 and 8 facet drill grinding.

Back to topic?

Norm

 

[Cogsy]

If I recall my 'wood boring' days, I recall that drill bits were extended by boring the end with another hss drill and silver soldering a mild steel extension.

As I have done it repeatedly, I must assume that the drill was so- and clearly, that I must entirely disagree with you.

Drill bits (and often even reamers) are not normally hardened on the shank. This would be the only way (in my mind anyway) that a HSS drill bit could drill another HSS drill.

 

[goldstar31]

Sparey writes in his 1996 print of his book 'The Amateurs Lathe' thusly

It is not generally appreciated that the shanks of drills, even high speed steel on
es are left soft, so that they may, in consequence, be turned down to fit small chucks

*********
Another advantage is that they may be turned down for insertion into a drill rod to make extension drills.

As far as I am concerned, I'd be happy to see the matter closed

Thanks to all

Norman

 

[tornitore45]

Given the title of this board contains "machinist" I thought it was implied that the reamer I talked about was a machine reamer or chucking reamer as they are called.

Another reason why drill bit shanks are left soft (well not hardened) is that they are usually held by chuck with hardened jaws. Hard on hard does not grip well at all.

End Mills are hard all the way, but they are held in collet or end mill holder with a positive keying feature.