Problems with Steel

[willray]

I no longer use Slocomb drills for anything other than on the lathe when intending to turn between centres Instead I use spot drills. I was recommended to these by the late John Stevenson when I used to correspond with him. They are excellent and have much smaller lands than Slocomb drills.

Before everyone starts misusing "Land" as the term to for the chisel edge on the web of a drill bit, please:

Viking Drill Bits : Drill Terminology

The land is the non-cutting space between the flutes - bassackwards of the structure of firearms-rifling (though consistent with "the land is the stuff that wasn't cut away).

As an aside, Viking drill bits seem pretty decent for the money.

 

[L98fiero]

Before everyone starts misusing "Land" as the term to for the chisel edge on the web of a drill bit, please:

The land is the non-cutting space between the flutes - bassackwards of the structure of firearms-rifling (though consistent with "the land is the stuff that wasn't cut away).

The Viking definition of the land is a bit ambiguous, Kennametal-Greenfield has a better one, or not. So how wide is the land on their drills? Seems they've also called the margin, the narrow cylindrical area behind the leading edge of the flute, the land.

 

[SmithDoor]

Sad to see.
I hope everyone is ok.

Dave

Hi Goldstar,

Like you as an old timer, I also usedtools which had been passed down to me from father and grandfather. but unfortunately I had a devastating garage/workshop fire which destroyed all of my tools and machinesas well as my sailing dinghy and 2 Triumph Stags one of which I was rebuilding. So as you see I had to re equip after rebuilding, fortunately I had very good insurance which was some compensation and was able to completely replace almost everything. The main road past my bungalow linking to the M1 was blocked for 4 hours by 2 of the three fire appliances which attended. I alsways reccomend that folks check their insurance policy as some only offer small amounts for contents of detached buildings, around 2 -5000 pounds whereas mine included full replacement costs. Was I glad that I hadn't gone for those 'cheaper home insurance' offers.

My own old gold watch passed down from my grandfather (a Benson, a present when he retired) is still working and I wear it occasionally to remind me of him in place of my own Rolex.

View attachment 118981View attachment 118982View attachment 118983View attachment 118984

The bottom left picture is the remains of a Boxford CSB on stand with splashback.

TerryD

 

[willray]

Like you as an old timer, I also used tools which had been passed down to me from father and grandfather. but unfortunately I had a devastating garage/workshop fire which destroyed all of my tools and machinesas well as my sailing dinghy and 2 Triumph Stags one of which I was rebuilding...

I feel and share your pain:

Yes, that was the 30-inch model.

Fires suck. Don't do it.

 

[L98fiero]

I feel and share your pain:

Fires suck. Don't do it.

Did you find out the cause of the fires?

 

[Tim Wescott]

Another side note is how to drill a ROUND hole in sheet metal. Often, when you drill sheet metal the hole will come out almost triangular, a way to prevent that is to put a small patch of cloth under the drill, it should be 2 or 3 layers thick depending on the cloth, and drill through that. When it was shown to me there was no rationale behind it just that it worked but I think the idea is that it supports the drill point as it goes through the sheet.

Inneresting. I discovered by accident that if I back up a piece of sheet metal with a piece of wood on the drill press, I get a nice round hole.

In fact, it's so accidental that I only just now realized that's why my holes come out nicer on a drillpress than when I'm drilling freehand!

 

[willray]

Inneresting. I discovered by accident that if I back up a piece of sheet metal with a piece of wood on the drill press, I get a nice round hole.

The reason that you get non-round (roughly reuleaux-triange shaped, actually) holes when you try to drill sheet metal with a 2-flute drill, is because it's energetically favorable for one cutting lip to "dig in" and stop, while the other cutting lip pivots around the stationary one, cutting a 2x-drill-diameter arc, as compared to both cutting lips to cut at the same time. The moving lip then catches and the formerly stationary lip starts cutting, and the drill walks around a 3-lobed path, alternately sticking and cutting.

The reason that drilling into a piece of wood (or at least a reasonably solid one) creates rounder holes, is because the drill is no-longer supported at "only one point" along the length of the flute - even if one lip tries to dig in to the wood, that flute describes some portion of a spiral along its length into the wood, so it does not form a distinct pivot point like the drill biting into sheet metal does.

One working hypothesis about the "use a bit of cloth between the drill and sheet metal" process, is that the cloth naturally wedges itself into the flutes, filling them up and limiting the depth of chip that each cutting lip can grab - kind of like the action of rakers on a chainsaw chain.

 

[SmithDoor]

That was great lathe.
If I had I would rebuild it back to life.

I have done rebuild from machine tools to engines fire to floods. The worst is flood I had take everything apart. Sand was in ever nock and cranny

Dave

I feel and share your pain:

View attachment 118989View attachment 118990
Yes, that was the 30-inch model.

Fires suck. Don't do it.

 

[Hrcoleman66]

My late father, many years ago, was modifying a small box trailer to carry a small dinghy. He went to the local hardware three times to buy the same drill bit because he was convinced that the sheet steel of the mudguard had a hard spot and he was blunting the drill. Eventually, he asked me to have a look. The first thing I did was to check that he had the drill running the right way. Of course he'd had it running backwards.

But seriously, how small are th holes you are trying to drill? Are you 'Pecking" to allow the chips to break and evacuate from the hole as the drill progresses? Because if you are not, the chips will jam in the flutes of the drill, create friction and over heat the drill.

I doubt that it's the fault of the steel. Even "cheap chinese" steel as others have called it, is not that bad. India made steel maybe...

Cheers,

Hugh

 

[IanN]

I have worked over 40 years in steel. We drill thousands without cutting oil in A36 steel.
If has problem it was drill bit.

Dave

Hi Dave,

I realise that you have already decided that I am wrong, but just give it a go - try using cutting fluid

Al the best,
Ian

 

[IanN]

Yes that's true, but using too much pressure causes more wear on the drill margins and dulls the drill quickly. Also can cause the point to "walk".

Hi,

In the Cain/Walshaw book "Drills, taps and dies" referred to by Norman there is an interesting set of notes (in Appendix A in my copy of the book) regarding some measurements of drilling feed forces made by Walshaw.

Not directly relevant to this point, but useful insight and worth a look

Ian

 

[IanN]

:
Always start with a centre punch mark,
:

:
I now use 4 facet sharpening ....
:

TerryD

Hi Terry,

Second point first - four facet drills - I agree 100%. The best aspect of the four facet form is that the chisel point of the normal twist drill is changed to a true point and so there is no need for the use of a centre punch

Your first point ("Always start with a centre punch Mark") I would qualify by adding "if accuracy is not important"

All these things are relative, of course, but the centre punch is the work of the Devil and the tool of the blacksmith - it has no place in precision work. Think of the sequence followed when marking, centre punching and drilling a precisely located hole:

Step one) Mark hole location - there will obviously be a tolerance/error in the measurements and marking, so the marked location will not be the truly intended location of the hole.

Step two) Locate centre punch in crossed scribed lines (which we know already have an error) and introduce Mr Hammer in to the equation. There are three possible results:
1) The resulting punch mark will be perfectly placed on the line intersect.
2) The punch mark will be miss placed, but by an amazing stroke of luck the error in the dot location perfectly cancels the error in the marking out
3) The punch mark will be miss placed and add further error to the error in the scribed lines

Let's be honest - 1 and 2 will not happen and you now have a centre mark even further from the desired location.

Now the centre mark crater - this could in theory be a perfect conical depression, but in reality is asymmetrical and so will push the drill slightly off the punched centre. Situations 1, 2 and 3 above apply again, and as a result the actual drilled hole location is even further away from its intended place.

Centre punching ok if you are drilling holes in gate hinges.

Al the best,
Ian

 

[goldstar31]

Sounds remarkably like George Thomas- Model Engineers Workshop Manual

 

[GrahamJTaylor49]

Talking about center punches being the tool of the devil and "Mr. Hammer" causing even more problems, has any one tried the
"Dankroy" optical center punch ? I bought one at the Model Engineering show at Wembly Conference Centre many years ago
and have used it with terrific results ever since. Used as directed one cannot help but get a perfect center punch on the scribed lines.
Just make sure that the scribed lines are in the correct place.

 

[goldstar31]

Talking about center punches being the tool of the devil and "Mr. Hammer" causing even more problems, has any one tried the
"Dankroy" optical center punch ? I bought one at the Model Engineering show at Wembly Conference Centre many years ago
and have used it with terrific results ever since. Used as directed one cannot help but get a perfect center punch on the scribed lines.
Just make sure that the scribed lines are in the correct place.

I bought one - or similar at Harrogate- moons ago
I recall that there was a free offer of re-pointing it

 

[minh-thanh]

A little more of my experience :
I always use cutting fluid in steel and stainless steel drilling
At least with a little oil
I find it difficult to drill steel or especially stainless steel, mostly due to the heat generated during the drilling process (If the drill bit, drilling speed, pressure ... is correct, the drilling still generates quite a lot of heat. )
Maybe it's my habit, or feeling, I always use a little oil when drilling in aluminum and It seems that drilling is easier

 

[clockworkcheval]

Two comments 1) for longer holes in tougher material like stainless I prefer 6 facet drills. You basically grind additional facets on the 'shoulder' at the outer diameter of the cutting edge, thereby relieving the forces on the hardest working part of the drill 2) for aluminium I always lubricate with something light like WD40 to prevent the build-up of a spot of aluminium on the cutting edge.

 

[goldstar31]

Heaven knows why but I don't but my son wants to restore a left hand Citroen Deux Chevaux.

Ok, I did a English City and Guilds when I was a Manure student and got distinctions and became a Certified Welder( note the Malapropism)! Ah well!
What I used to remove spot welds and to make a hole for 'plug welding' using my Mig welder was a spt welding removing drill. They are pretty hard bits- and not unduly expensive.

Of course there is the usual prattle about work hardening but today's -- or possibly yesterday's high strength alloyed steels instead of the traditional phosphorus mild steel. Of course these niobium steels did not work harden under the oxy acetylene torch but cracked.

Thoughts for the day? Well I DID say that I wasn't an engineer

Norman

 

[ranger]

A few years ago, before I retired, I had to repair a stripped thread in a mild steel bracket. Drilling out to the next size up, M10 x M12, the tap felt as though it would break, drilling to maximum tapping size, new tap, threading compound, oil, nothing made any difference. My friend, a toolmaker gave me a pot of ‘cream’ his late mother had for a skin condition, ‘ e45’ I think?
I tried it, it was like tapping into butter. I’ve used it for drilling and tapping threads into stainless steel as well. Apparently ‘Swarfega’ handcleaner works well for drilling into hard steel and stainless. I keep what’s left in the pot for machining operations in difficult materials.
Doug.

 

[goldstar31]

In all probability the 'cream'-- hand or face???? is 'lard oil'

I use refined lard oil as my cutting fluid

HTH


Norman