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OD turning with a boring bar in a HBM

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
I need to weld up and turn the shaft ends on a large flail mower drum. The drum is too big to fit in my big lathe, but I can get it on my 4" HBM, sweep it in and find center. I do not have a facing slide nor large enough boring head that takes bars. I do have lots of cartridge/insert style boring bars and an assortment of Varilock parts.

The flail drum shaft is 2.5" diameter and I need to reach 8". I'd like to use a 2-3" diameter tool with a carbide insert to efficiently rough the welded up shafts.

Should I just weld something up for this one job or has anyone built a tool with adjustable range for this kind of thing?

Thanks!
 

thermite

Diamond
Joined
Sep 21, 2011
Location
Sol, Terra
shaft is 2.5" diameter and I need to reach 8".


... built a tool with adjustable range

"Range MIGHT be a "freebie"

My first ever tasking, Day One, Galis was a similar "one-off" done with similar Shop-fab methods.

100- Ton crane turntable bearing mounting ring integral with the body.

Reach was about six inches. Could have done easily double that.
Bearing fit was about an inch less.

Diameter 46", outer surface the critical one, but we had inner face to do as well.

Previous shift had set it up and started.

We had near-as-dammit unlimited space to the open INSIDE wall, even more to the OUTSIDE wall, so:

- used a 1/2" burnout leftover bolted to the faceplate

- bolted to that a compound rest borrowed off a 30"-plus lathe. There was our adjustable radial range, no cost nor effort.

- lantern TP, Armstrong/Williams toolholder,

Cleaning up the corncob wudda been Mo-Max (several!) or a Cobra (T1).

Finish - "CPM" Rex 95 (T8? T15?)

Neg-rake Carbolly of the 1960's - all we HAD - the wise didn't take any closer than the tool-crib to corncob stick weld! Rugged T1, rather!

- 11 RPM for that diameter.

- 30 hours? "with care!"

You could need under 10% of that in the cut?

Setup time?? 'bove my present pay-grade..

:)

But yes, it works a treat for a "one-off" if one is but careful not to crash s**t, and patient enough to not get greedy.
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
I have a heavy lathe compound, but it's knackered enough I wouldn't trust it's rigidity/accuracy if a heavy bar was mounted to it and spun at 300+ RPM.

I have a 24" fly cutter made from a solid round cut from 1.5" plate. I might put that up on blocks in a CNC and drill/tap a grid of holes in it, then machine up a mating block with 4 or 6 bolt holes to match the grid spacing. Bore the block to fit a Devlieg cartridge bar or turn the bar to fit a varilock extension.

I gotta finger out what range I've got on the cartidge bars I'd like to see to see if the hole spacing is feasible. But that would probably be a worker.
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
I need to weld up and turn the shaft ends on a large flail mower drum. The drum is too big to fit in my big lathe, but I can get it on my 4" HBM, sweep it in and find center. I do not have a facing slide nor large enough boring head that takes bars. I do have lots of cartridge/insert style boring bars and an assortment of Varilock parts.

The flail drum shaft is 2.5" diameter and I need to reach 8". I'd like to use a 2-3" diameter tool with a carbide insert to efficiently rough the welded up shafts.

Should I just weld something up for this one job or has anyone built a tool with adjustable range for this kind of thing?

Thanks!

I might have something, it's a heavy bar with (IIRC) dovetail fit on the working end that
holds the cartridge (carbide insert)
So you would make a faceplate with a hole close to what you need (radius from C/L)
and then the bar would be able to move maybe 1/2" in/out.

Alternatively, how about a balanced boring set-up ?
Flame cut 3" plate in a large "C", bolt to faceplate, machine pockets to hold your cartridges.
 

thermite

Diamond
Joined
Sep 21, 2011
Location
Sol, Terra
I have a heavy lathe compound, but it's knackered enough I wouldn't trust it's rigidity/accuracy if a heavy bar was mounted to it and spun at 300+ RPM.

I have a 24" fly cutter made from a solid round cut from 1.5" plate. I might put that up on blocks in a CNC and drill/tap a grid of holes in it, then machine up a mating block with 4 or 6 bolt holes to match the grid spacing. Bore the block to fit a Devlieg cartridge bar or turn the bar to fit a varilock extension.

I gotta finger out what range I've got on the cartidge bars I'd like to see to see if the hole spacing is feasible. But that would probably be a worker.

Cartridges are typically seriously short range, but VERY precisely controllable as to using what they have, so THAT part passes the sniff test.

As to "coarse(r) adjustment"?

Think mounting of work to table on a mill.

Introduce a ramp at a shallow angle. Pusher screw. Clamping.

No dovetails nor traverse leadscrew as a general-purpose "permanent" rig would need.

Probably HAVE all the goods you need within arm's length?

Clumsy? Add counter-balance mass? Slow it down? Both? Run HSS instead of Carbide?

You did say "one-off"?
 

gbent

Diamond
Joined
Mar 14, 2005
Location
Kansas
DeVlieg made a range of "L" shaped adapters to hold their cartridges for outside boring. Different holes in the base for rough adjustment. I don't think I've seen ones that would go 8" deep though.

Landis made hollow mill cutters to use in place of chasers for their die heads. Have a 4" lying around?

Maybe search hollow mill for ideas?
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
Cartridges are typically seriously short range, but VERY precisely controllable as to using what they have, so THAT part passes the sniff test.

As to "coarse(r) adjustment"?

Think mounting of work to table on a mill.

Introduce a ramp at a shallow angle. Pusher screw. Clamping.

No dovetails nor traverse leadscrew as a general-purpose "permanent" rig would need.

Probably HAVE all the goods you need within arm's length?

Clumsy? Add counter-balance mass? Slow it down? Both? Run HSS instead of Carbide?

You did say "one-off"?

I try to avoid HSS. The cost of indexable tooling is factored into the rate. Me trying to remember how to sharpen the right HSS bit for the job and touching it up 12 times throughout the job plus carbide speeds and feeds are burned into my brain. I know HSS works, but it's not what I'm invested in.

Every tool I buy or build for this HBM I go at with the mindset of how can I make it as versatile as possible? The machine itself is a swiss army knife and I use it that way. The more I use it the faster I get at setups and it's quickly becoming the money printer of the manual machines in the shop. So if I put a few hours of shop time into making a tool to do this job I'd like it to be real versatile.
 

thermite

Diamond
Joined
Sep 21, 2011
Location
Sol, Terra
Landis made hollow mill cutters to use in place of chasers for their die heads. Have a 4" lying around?

Maybe search hollow mill for ideas?

Point!

One-off, one could maybe fab one out of heavywall faster than find an affordable?

Cartridge for the adjust.
Counter-mass opposite to support higher RPM?

Prolly NOT so fast for earliest passes over built-up weld. But later.
 

boslab

Titanium
Joined
Jan 6, 2007
Location
wales.uk
Outside turning with a boring bar on a HBM was fairly common in work, everything was big, we had coromat bars up to 3” dovetail ended, don’t forget to tighten down the clamp, good thing if it moves the turning gets bigger as the cartridge is thrown out as opposed to internal where welding during lunch to fix the balls up
Mark
 

AJ H

Hot Rolled
Joined
Feb 5, 2019
The Axle Surgeons used to have a purpose-built machine that did this for semis. They'd weld it up and "turn" it back down to the correct size for the bearing races. I can't seem to find any pictures or videos of it. Of course, they patented the process and then started cutting off and welding on new stub shafts instead at twice the money.
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
The Axle Surgeons used to have a purpose-built machine that did this for semis. They'd weld it up and "turn" it back down to the correct size for the bearing races. I can't seem to find any pictures or videos of it. Of course, they patented the process and then started cutting off and welding on new stub shafts instead at twice the money.

It's probably a "Journal Squirrel".
journal squirrel lathe at DuckDuckGo
 

eKretz

Diamond
Joined
Mar 27, 2005
Location
Northwest Indiana
I need to weld up and turn the shaft ends on a large flail mower drum. The drum is too big to fit in my big lathe, but I can get it on my 4" HBM, sweep it in and find center. I do not have a facing slide nor large enough boring head that takes bars. I do have lots of cartridge/insert style boring bars and an assortment of Varilock parts.

The flail drum shaft is 2.5" diameter and I need to reach 8". I'd like to use a 2-3" diameter tool with a carbide insert to efficiently rough the welded up shafts.

Should I just weld something up for this one job or has anyone built a tool with adjustable range for this kind of thing?

Thanks!

I'd make up something adjustable if you can. It sounds like it could come in handy with the direction you're headed. I have used some really big versions of these, but they were pretty primitive. Basically a fabrication that looks similar in shape to the modern versions with linear bolt hole patterns to roughly move a large extended tool holder, then bumping the tool out in the holder for successive cuts. There were different length holders to bolt on for different turning lengths. (Short extensions for a short turned length, longer extensions for longer turned lengths).
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
I drove out to the shop today, and found it.
 

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