U drills

[pressbrake1]

I use u drills on the Devliegs in cast iron , seem to use less power than twist drills in iron and I can use relatively high rpm.

Not any fun on a manual lathe in steel as you can’t be near it though I have a job where I have a u drill in the dsg tool post so I punch through without messing with centre drill then offset on the dro to finish bore much like a cnc

If you really want insert tooling get a spade drill but as a hobbyist do you really want to bother

 

[Brad93]

What lathe was that?

Harrison Alpha 1800S

22% spindle load

 

[pressbrake1]

good job shop machine until bed wears then they kill lead screw ball screw nuts

 

[Brad93]

good job shop machine until bed wears then they kill lead screw ball screw nuts

It's worn by the chuck, it's done cast and spray work with no maintenance.

Shame really im really starting to like it

 

[Brad93]

Looks like they don't even make anything as big as the 1800S now.

Swing over bed 800mm
Spindle 35hp
120mm spindle bore
2m between centres

Must of been a fortune new, it's got all the sizes of steadies and three jaw/four jaw. I think they bought it used

 

[fizzy]

All i can say is good luck

Just spotted ABom79 using a huge one on his American pacemaker lathe. Similar size and weight to my Holbrook. Maybe a tad lighter. Less HP I think as well.
Coped very nicely.
I am not in his league of course but I was going to use much smaller ones.

 

[Erie Fred]

Just spotted ABom79 using a huge one on his American pacemaker lathe. Similar size and weight to my Holbrook. Maybe a tad lighter. Less HP I think as well.
Coped very nicely.
I am not in his league of course but I was going to use much smaller ones.

The video shows an allied spade drill.
Not an insert drill that your OP linked to.
Different animals.

Did you change to the spade drill ?

 

[pressbrake1]

Just spotted ABom79 using a huge one on his American pacemaker lathe. Similar size and weight to my Holbrook. Maybe a tad lighter. Less HP I think as well.
Coped very nicely.
I am not in his league of course but I was going to use much smaller ones.

As above said it’s a spade drill which is positive rake .
U drills big rpm and feed

 

[pressbrake1]

And u drill needs Morse taper adapter which is expensive. Then any vibration will dislodge mt

 

[Rrobson]

I have used spade drills countless times with hydraulic drilling equipment. They have HSS tips and are very forgiving. Don’t need as much power as the ones your looking at as they don’t need to speed and feed rate. They could be a better option as one drill spreads over a range, although the inserts aren’t cheap.

The biggest I drilled with one was a 4” UN8 fastener in one go, straight to tapping size. Something like 103mm spade, 60 rpm with a 0.002” feed rate. Slow and steady through a number of T41 fasteners.

 

[pressbrake1]

I have used spade drills countless times with hydraulic drilling equipment. They have HSS tips and are very forgiving. Don’t need as much power as the ones your looking at as they don’t need to speed and feed rate. They could be a better option as one drill spreads over a range, although the inserts aren’t cheap.

The biggest I drilled with one was a 4” UN8 fastener in one go, straight to tapping size. Something like 103mm spade, 60 rpm with a 0.002” feed rate. Slow and steady through a number of T41 fasteners.

I’m a fan of spade drills .

 

[Brad93]

U Drills need to be mounted to the carriage really.

As Clive said doesn't matter what size MT, the action of cutting can dislodge it which will wreck either the tang of the adapter or your tailstock barrel. They ideally want coolant too or you're gonna be burning up inserts on anything other than iron.

The harrison alpha at work has a Parat toolpost with a dedicated boring bar toolholder in which is mounted the U-drill.

Theres no compound on the lathe it is a solid toolpost.

Small things but all add up to rigidity.

Have a look at the data for a King drill in CAST IRON.
38mm dia.
0.4-0.16mm per revolution
800-1600 RPM

 

[MickeyW]

Not used them on a lathe, but many moons ago when I was in the toolmaking shop we used them for putting in holes in plates for guide pillars, normally in the 30-40mm dia range. They would plunge through P20 at one heck of a rate with chips and coolant going everywhere. It would have been a decent brand of tool, probably Sandvik or similar, and run on a fairly sizeable Huron mill.

 

[mmcengineer]

You might be better served with a spade type insert drill , they seem to be much happier in manual machines, I know plenty of the manual machines here for doing big stuff will drill happily with the minimum of fuss
index drills ? mileage varies on these mainly use them in CNC lathes where the coolant is doing a good job of ejecting the chip one day they cut lovely the next they can get to be a real PITA (plenty of reasons for the variability )

 

[fizzy]

So what are the main differences between a spade drill and a U drill? I suspect the tips are far more expensive on a spade drill?

 

[fizzy]

Looks like they don't even make anything as big as the 1800S now.

Swing over bed 800mm
Spindle 35hp
120mm spindle bore
2m between centres

Must of been a fortune new, it's got all the sizes of steadies and three jaw/four jaw. I think they bought it used

And a D1-11 chuck

 

[Erie Fred]

So what are the main differences between a spade drill and a U drill? I suspect the tips are far more expensive on a spade drill?

yes, you have shown both styles.
The spade is in your video.
The "insert" of the spade style is a chunk of HSS and you re-grind them.

 

[Rrobson]

The only issue with re-grinding a spade drill insert is you quickly loose the geometry of the cutting edge. Also, they are challenging to grind without a soft wheel, most of them are usually a cobalt HSS and thus are quite hard.
Inserts are quite expensive but hold an edge well.

They are much more forgiving with a machine that isn’t totally fixed and rigid though, as HSS doesn’t chip like carbide. They also come in various ranges, so one holder will do various sizzled holes. As said you don’t need the high speeds and feeds associated with carbide either, they work down to a couple of thou a rev. And due to the lower speeds and feeds, you don’t need as high pressure to get them through the work. Our drills were 6hp which was enough for drilling straight up to 4” with a 3/4” pre-drilled bore

They also chip differently, although the spades do have chip breakers built in which usually work quite well.

 

[Erie Fred]

The only issue with re-grinding a spade drill insert is you quickly loose the geometry of the cutting edge. Also, they are challenging to grind without a soft wheel, most of them are usually a cobalt HSS and thus are quite hard.
Inserts are quite expensive but hold an edge well.

They are much more forgiving with a machine that isn’t totally fixed and rigid though, as HSS doesn’t chip like carbide. They also come in various ranges, so one holder will do various sizzled holes. As said you don’t need the high speeds and feeds associated with carbide either, they work down to a couple of thou a rev. And due to the lower speeds and feeds, you don’t need as high pressure to get them through the work. Our drills were 6hp which was enough for drilling straight up to 4” with a 3/4” pre-drilled bore

They also chip differently, although the spades do have chip breakers built in which usually work quite well.

For the OP's low usage, he can send them out for a proper re-grind.

 

[Rrobson]

My experience of them is extensive re-grind is not really an option. To make a decent job of it would require removing a good 1/4 off the height to allow the features to be re-ground. But doing so will impede the holes for fixing it into the holder and it may fall below the end of the holder.

Have a look at the image below

Below the cutting edge as we look at the insert is curved to give a slight negative rake to aid cutting action and swarf evacuation, and the cuts along the face break up the swarf so it comes off in pieces rather than long strings. If you grind them you loose the rake and the cutting edge moves closer to 90 degrees which makes it incredibly difficult to drill.

You can tickle them once or twice but major grinding to reinstate the rake reduces the strength of the tool. Plus the chip breakers need reinstating too.
Considering they cost £40-£100 each a professional re-grind isn’t going to be cost effective. You’d be better tickling them yourself. Although you find once you’ve done so they don’t perform nearly as well as they did with the titanium oxide coating on them…

Softer stuff will be a different story but the stuff I used to drill it wasn’t worth messing about trying to regrind them. Once they were spent they were binned.