Thread: Efficient options for making larger holes on the lathe

Recently I had to make up a couple of steel sleeves - 60 OD, 49 ID, and 100 long.
Some hollow bar would have been nice, but I didn't have any, so they were made from 65mm solid bar. Biggest drill I've got is 32mm so there was a fair bit of boring involved, and it took me roughly an hour per sleeve to rough them out.
For context, my lathe is a 14x40" Takisawa, with 3HP motor, and 3MT tailstock.

Got me thinking about more efficient options for making these larger holes to reduce the amount of boring.
Apart from the obvious one of a larger twist drill, there are other options such as carbide spade drills, U drills and annular cutters etc.

Interested to hear what methods you guys use or have tried and rejected.

Steve

I trepan holes in plate occasionally but 100mm long at 50mm is a bit tough for that without building a tool. Annular cutters are also a solid choice.

There was also a cool drill made by someone in Australia that used chunks of hss with extra relief as a piloted spade drill kind of like a big adjustable counterbore but I can't remember the name.

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50mm depth annular cutters are reasonably cheap, and would just get the 100mm going from both ends.
Moving up to 75mm depth cutters seem to be a quantum leap in cost from what I can find online. I've watched a few of Stefan Gotteswinter's videos where he uses smaller diameter ones very successfully on the lathe.

I know the tool you mean - but the name escapes me also. Someone posted about them last year IIRC, but I can't find the thread.

Steve

We trepan a bit at work with custom made trepanning tools made by Sandvik, sometimes I grab the smaller trepanned slugs of 4140, 4130 etc from the scrap bin.

This one is 400 long by 105, I won't bring home any more this size, it's been a real PITA to have around home
IMG_1068.jpg

Hi Guys,

A long time back I used to trepan disks 4" inches in diameter out of 1/2" thick aluminium plate, a real pain, I did several hundred of them, more recently I've used an annular cutter to make maximum use of material, certainly less wasteful than drilling.

Originally Posted by caskwarrior

There was also a cool drill made by someone in Australia that used chunks of hss with extra relief as a piloted spade drill kind of like a big adjustable counterbore but I can't remember the name.

I assume this is what you are talking about.
https://www.practool.com/super-drill.html
https://www.practool.com/online-shop.html

Some of them will only cut 25mm deep(and the cheapest only up to 40mm dia)

Their videos don't seem to be loading for me. But they have one on you tube
https://www.youtube.com/watch?v=a-jQXtJMv6Q

I have one of their hose clamp tools. Nicely finished piece of kit.

I have had the second one in Stustoys' link above, i.e. the one which can bore up to 50mm holes. Bought it many years ago. I doubt I'd use it more than once every couple of years. They have their limitations, e.g. they require a 1/2" pilot hole, practically they are best used for through holes, they are expensive for what you get, and it is fiddly to set them up to bore an accurately sized hole using the gauge supplied. HOWEVER they are quick to set up for boring approximate sized holes (to the nearest 1/16th inch), work very well in the lathe as well as the drill press, and can replace numerous hole saws on jobs suited to their limitations. I've never regretted buying one.

Frank

Originally Posted by NedsHead

We trepan a bit at work with custom made trepanning tools made by Sandvik, sometimes I grab the smaller trepanned slugs of 4140, 4130 etc from the scrap bin.

This one is 400 long by 105, I won't bring home any more this size, it's been a real PITA to have around home

I doubt I'm alone in saying I'd like to dig in your scrap bin....

Have you tried using the HP of the lathe to reduce your time or has the 3HP been exhausted?

Originally Posted by OxxAndBert

Got me thinking about more efficient options for making these larger holes to reduce the amount of boring.
Apart from the obvious one of a larger twist drill, there are other options such as carbide spade drills, U drills and annular cutters etc.

What's wrong with the obvious one? Sometimes the simplest answer is perfectly good....
U-drills are awesome, but they like consistent (CNC) feed and through coolant to work best, especially on deep holes. They also need a lot of power as the size increases.

If you wanted to drill a 100mm hole I'd understand, but for 50mm it's almost not worth the effort IMO, just get a 45mm drill and call it a day

larger twist drill is the most economical way to go, Udrills and carbide tipped twist drills are $$$ and dont play nice in manual machines. spade drills would also be out of the relm of a hobby budget.
What tooling were you using? what speeds, feeds DOC? I reckon it would take me about 10 mins to rough that out from 32mm on our 400X1100 chin hung manual lathe at work 25mm Tpmt boring bar, 650RPM 2mm DOC .25-.3mm/rev.

Originally Posted by pipeclay

Have you tried using the HP of the lathe to reduce your time or has the 3HP been exhausted?

I haven't run out of HP when boring, and I know there are things I can do around that to speed things up.
I really need to scrape the cross slide as it has some uneven wear and the usual issue where snugging up the gib to remove play makes it bind at the ends.
Pretty sure a couple of decent size positive rake boring bars would be a big improvement too.

Originally Posted by elanjacobs

What's wrong with the obvious one? Sometimes the simplest answer is perfectly good....
U-drills are awesome, but they like consistent (CNC) feed and through coolant to work best, especially on deep holes. They also need a lot of power as the size increases.

If you wanted to drill a 100mm hole I'd understand, but for 50mm it's almost not worth the effort IMO, just get a 45mm drill and call it a day

Nothing wrong with it, just interested to find out if there were other practical options that might be better - if you don't ask you don't find out

Steve

Fair enough. Once you get past 3", I reckon there's more to be gained, but even then you need big power to drive the tool and vast amounts of through coolant to keep it happy in deep holes.

This guy does serious trepanning with shop made tools in all sorts of nasty materials https://www.youtube.com/user/userwl2850/videos

Yes, I’ve been watching his channel for quite a while now. Very cool.
A few years ago he made a 3” trepanning tool for a fellow YouTube creator.
Given that the inserts are around 12-15mm across the cutting face 3” is about the smallest you could practically go I’d think.

Steve

Originally Posted by snapatap

larger twist drill is the most economical way to go, Udrills and carbide tipped twist drills are $$$ and dont play nice in manual machines. spade drills would also be out of the relm of a hobby budget.
What tooling were you using? what speeds, feeds DOC? I reckon it would take me about 10 mins to rough that out from 32mm on our 400X1100 chin hung manual lathe at work 25mm Tpmt boring bar, 650RPM 2mm DOC .25-.3mm/rev.

Thanks for that - gives me a benchmark to work with.
I was using 680RPM, 1mm DOC, .13mm/rev with a 20mm WNMG boring bar - no coolant.

The WNMG tool definitely isn't good for boring, particularly with C1020.
I only picked it up at the time as I didn't have a decent size bar and thought I'd try and stick with the WNMG inserts as they were working well for outside turning with >1mm DOC.
I've since read that for boring on a manual lathe you're best to stick with positive inserts. The couple of smaller CCMT bars that I've got work well.
I've been tossing up whether to stick with the CCMT and a bigger bar or try the TCMT.

Apart from the cost side - what are carbide spade drills like on a manual machine? If they work well then it might be worth picking a couple of used ones up (at the right price).

Steve