What are you machining?

Morrisman · Oct 13, 2024

Brad93 said:
I'll show you wasteful next week. 150mm solid cast iron bar into a 3mm wall bearing sleeve. Criminal. I'm trying to find a supplier for the Cast iron EZE-Sleeves they have in america

When I worked in the machine shop one job was 6” diameter locking rings, 5 1/2” bore, acme thread, from 316 stainless. I used a trepanning tool, like a parting off tool but curved for clearance, and cut the centre out of each piece. They were maybe an inch thick and it cut okay.

First dozen or so I went halfway in from each side, but it was time consuming, so I tried a single cut straight through from one side, until I could feel it getting towards the end, compound slide would suddenly get easier to turn, and I’d back out before it came loose and locked up. Then I’d knock the centre out with a hammer. Then we had freebie chunks of 316 stainless for some other jobs.

Jelly_Sheffield · Oct 13, 2024

Brad93 said:
Aye that's spun cast. Problem is we use so many different sizes of bearings it is in some ways easier to start with solid. Ideally we'd have some deep face grooving or trepanning tools to recover the core of the bar. It's something i'm looking into.

The EZE-Sleezes are cast iron, possibly spun, but premachined to suit common metric bearing sizes.

If you're doing similar sized jobs often enough to justify the time investment, it's fairly straightforward to make insertable trepanning tools inexpensively in-house.

There was a guy who goes to my local pub who recently retired from running a one man deep hole and trepanning shop, made all his own tooling from a particular style of carbide insert and heavy wall tube.

He did actually post some how-to videos before he retired, but I can't find them again right now.

The upshot was he would:

• get some tube of approximately the correct size,

• mill two or three flutes down the outside,

• let in a section to clamp indexable lathe tools with countersunk screws level with the top of the flutes (because it's cheaper to replace them if an insert breaks deep in a cut),

• then weld a cap on the back with a BSP 3/4 I tapped hole for coolant,

• weld a toolholder on, either a large square bar to clamp in the Toolpost, or an MT7 to fit the powered tailstock on a turret lathe,

• for really long jobs he had a additional fixed steadies on most of the lathes with the bearings at 90° to the normal orientation to support the tool whilst starting a cut.

I think the key information which I'm unable to remember is which insert geometry he'd found most reliable.

Most days he'd have 3-5 lathes running with automatic feed trips, slowly chomping away at big trepanning jobs, whilst he was doing finish boring ops on "the good lathe", making up new tooling, or doing office stuff...

ukracer · Oct 13, 2024

Jelly_Sheffield said:
If you're doing similar sized jobs often enough to justify the time investment, it's fairly straightforward to make insertable trepanning tools inexpensively in-house.

There was a guy who goes to my local pub who recently retired from running a one man deep hole and trepanning shop, made all his own tooling from a particular style of carbide insert and heavy wall tube.

He did actually post some how-to videos before he retired, but I can't find them again right now.

The upshot was he would:

• get some tube of approximately the correct size,

• mill two or three flutes down the outside,

• let in a section to clamp indexable lathe tools with countersunk screws level with the top of the flutes (because it's cheaper to replace them if an insert breaks deep in a cut),

• then weld a cap on the back with a BSP 3/4 I tapped hole for coolant,

• weld a toolholder on, either a large square bar to clamp in the Toolpost, or an MT7 to fit the powered tailstock on a turret lathe,

• for really long jobs he had a additional fixed steadies on most of the lathes with the bearings at 90° to the normal orientation to support the tool whilst starting a cut.

I think the key information which I'm unable to remember is which insert geometry he'd found most reliable.

Most days he'd have 3-5 lathes running with automatic feed trips, slowly chomping away at big trepanning jobs, whilst he was doing finish boring ops on "the good lathe", making up new tooling, or doing office stuff...

It would be great if you can find links to those videos etc.

Jelly_Sheffield · Oct 13, 2024

ukracer said:
It would be great if you can find links to those videos etc.

I will try.

I have also seen another vid of the same thing from a guy (also in Sheffield), so I will see if I can dig up his as well/instead.

Maker · Oct 13, 2024

Jelly_Sheffield said:
If you're doing similar sized jobs often enough to justify the time investment, it's fairly straightforward to make insertable trepanning tools inexpensively in-house.

There was a guy who goes to my local pub who recently retired from running a one man deep hole and trepanning shop, made all his own tooling from a particular style of carbide insert and heavy wall tube.

He did actually post some how-to videos before he retired, but I can't find them again right now.

The upshot was he would:

• get some tube of approximately the correct size,

• mill two or three flutes down the outside,

• let in a section to clamp indexable lathe tools with countersunk screws level with the top of the flutes (because it's cheaper to replace them if an insert breaks deep in a cut),

• then weld a cap on the back with a BSP 3/4 I tapped hole for coolant,

• weld a toolholder on, either a large square bar to clamp in the Toolpost, or an MT7 to fit the powered tailstock on a turret lathe,

• for really long jobs he had a additional fixed steadies on most of the lathes with the bearings at 90° to the normal orientation to support the tool whilst starting a cut.

I think the key information which I'm unable to remember is which insert geometry he'd found most reliable.

Most days he'd have 3-5 lathes running with automatic feed trips, slowly chomping away at big trepanning jobs, whilst he was doing finish boring ops on "the good lathe", making up new tooling, or doing office stuff...

Not Dave Wilks by any chance?

Jelly_Sheffield · Oct 13, 2024

ukracer said:
It would be great if you can find links to those videos etc.

Boom!

Couldn't find the first guy's videos, but the second chap still has a dormant YouTube channel with a bunch of good stuff: David Wilkes on YouTube

He uses W-shape inserts (I guess WPMX/WPMT/WBMT for clearance angles, but he doesn't say), whilst the other chap used some kind of dedicated "Turn, Face, Drill, Bore Insert" like a Multi-Turn or QCMT

Some footage of one of the setups I'm talking about in action, here at 17:21

~~And some footage and commentary on making a new trepanning tool on the same video at 44:40~~

Edit: Wrong video, This vid gives a good overview of him finishing the key steps in making up a new tool.

I assume the two blokes either trained at the same place or worked with the same people at some point, but it's possible they both independently arrived at the same idea because it's a neat solution to the problem.

Jelly_Sheffield · Oct 13, 2024

Maker said:
Not Dave Wilks by any chance?

He was the second guy I was thinking of, you posted just as I was finding his videos.

oldbikedavey · Oct 13, 2024

Mostly , today , it has been a bit of old chair leg being thinned down to produce a suitably narrow runner core and pouring bowl for the sand casting of aluminium in Petrobond ...
Could quite get fond of using that wood turning lathe.

Brad93 · Oct 13, 2024

Jelly_Sheffield said:
If you're doing similar sized jobs often enough to justify the time investment, it's fairly straightforward to make insertable trepanning tools inexpensively in-house.

There was a guy who goes to my local pub who recently retired from running a one man deep hole and trepanning shop, made all his own tooling from a particular style of carbide insert and heavy wall tube.

He did actually post some how-to videos before he retired, but I can't find them again right now.

The upshot was he would:

• get some tube of approximately the correct size,

• mill two or three flutes down the outside,

• let in a section to clamp indexable lathe tools with countersunk screws level with the top of the flutes (because it's cheaper to replace them if an insert breaks deep in a cut),

• then weld a cap on the back with a BSP 3/4 I tapped hole for coolant,

• weld a toolholder on, either a large square bar to clamp in the Toolpost, or an MT7 to fit the powered tailstock on a turret lathe,

• for really long jobs he had a additional fixed steadies on most of the lathes with the bearings at 90° to the normal orientation to support the tool whilst starting a cut.

I think the key information which I'm unable to remember is which insert geometry he'd found most reliable.

Most days he'd have 3-5 lathes running with automatic feed trips, slowly chomping away at big trepanning jobs, whilst he was doing finish boring ops on "the good lathe", making up new tooling, or doing office stuff...

The problem is time.

The company I'm working at twice a week the work is stacked up, i'm looking to buy sleeves in to save time.

Jelly_Sheffield · Oct 13, 2024

Brad93 said:
The problem is time.

The company I'm working at twice a week the work is stacked up, i'm looking to buy sleeves in to save time.

That makes sense, if there's a commercial product that's mass manufactured, it will probably be cheaper than putting you own time into it, as well as more efficient.

Brad93 · Oct 13, 2024

Jelly_Sheffield said:
That makes sense, if there's a commercial product that's mass manufactured, it will probably be cheaper than putting you own time into it, as well as more efficient.

Exactly.

It's time consuming drilling and boring big holes. We do have a Spade drill for the big semi cnc lathe but i haven't figured out any of the programming side yet

Jelly_Sheffield · Oct 13, 2024

Brad93 said:
Exactly.

It's time consuming drilling and boring big holes. We do have a Spade drill for the big semi cnc lathe but i haven't figured out any of the programming side yet

When you get to it, that probably will make something of a difference.

The BTA type (with carbide "cheeks" to register on the wall of the hole like a gun drill) in particular can give crazy fast MRR if there's enough power to support it, but the more recent designs of "conventional" spade drill aren't far behind now.

Johnnybravo · Oct 14, 2024

Jelly_Sheffield said:
When you get to it, that probably will make something of a difference.

The BTA type (with carbide "cheeks" to register on the wall of the hole like a gun drill) in particular can give crazy fast MRR if there's enough power to support it, but the more recent designs of "conventional" spade drill aren't far behind now.

A spade drill will always be a slower alternative than trepanning and extremely power hungry. I did a job a couple of years back that involved putting a 76mm hole through a 40mm thick blank of En3b. My homemade trepanning tool was using less power than a 35mm U drill and going through in less than 45 seconds. Did 500 of them before changing the tips. And loads of forum members benefitted from all the slugs !

minimutly · Oct 14, 2024

Morrisman said:
When I worked in the machine shop one job was 6” diameter locking rings, 5 1/2” bore, acme thread, from 316 stainless. I used a trepanning tool, like a parting off tool but curved for clearance, and cut the centre out of each piece. They were maybe an inch thick and it cut okay.

First dozen or so I went halfway in from each side, but it was time consuming, so I tried a single cut straight through from one side, until I could feel it getting towards the end, compound slide would suddenly get easier to turn, and I’d back out before it came loose and locked up. Then I’d knock the centre out with a hammer. Then we had freebie chunks of 316 stainless for some other jobs.

One of the model engineering suppliers used to sell cast iron bar - 17ton iron I think it was called, some years ago mind. I can't remember the supplier though..