Not Your Traditional Musical Box

[JasonBModerator @jasonb]

It is not just the supermarkets and department stores that put out Christmas adverts, check out this one from DMG Mori.

Note the worm wheel cutting, does not look to be a difficult task as discussed in another thread!

[Nigel Graham 2Participant @nigelgraham2]

Obviously it’s part of DIGI-Mori’s advertising but very impressive.

No coolant on machining the aluminium. Presumably the alloy and the tools are such they will co-operate in that manner.

The wormwheel cutting is so rapid it’s hard to identify the method. Is it a form of spiral milling with a tool akin to a horizontal-milling cutter, or a variant of gear-hobbing?

I like that two-chuck principle for the parting-off. Perhaps something we might adapt for our modest conventional lathes, using a chuck on a free-rotating spindle? Like a revolving tailstock centre but gripping the work instead. I’ve an idea I’ve seen it suggested.

Nifty laser-cutting for the treble-clefs!

[Andrew CrowParticipant @andrewcrow91475]

CNC has changed a bit since I used to have to write programmes and input everything manually about 40 years ago, very impressive.

Nigel,

I think there was something recently on this forum about a revolving chuck in the tailstock, unfortunately short term memory stops me recalling which thread it was in.

[JasonBModerator @jasonb]

Nigel, the process is known as Gear Skiving

That is not laser cutting but a laser 3D Metal printer where the laser melts successive layers of metal powder onto the revious layer to build up the 3D shape. You can see them pull the job out of the powder when it is done.

Some of these demos they cut dry so you can see what is going on although some machines use IPA which you would not really see.

As to the revolving chucks, the CNC machines they are on will often do further machining to the cut off end while the work is in the right hand chuck, they are not just to catch the work being parted off.

Certainly some people us e arevolving tailstock chuck quite a lot, good way to support long items while you set up a fixed steady or simply if the item is hollow and has a bore too big for even a cone ctr.

[JasonBModerator @jasonb]

Now my YouTube feed is going to give me a whole load of these videos. This one from Horn the cutting tool people – don’t throw that swarf away! Interesting how slow the feed is for the final cuts to get that mirror finish so much for those that say these tools need to have a decent chip load to work.

[Andrew CrowParticipant @andrewcrow91475]

Being one of those sceptics who have doubted the use of carbide inserts on model making machinery, probably due to long past experiences, have thanks to you been partially converted to modern tooling.

I have for many years used a KNUX tool for turning brass and bronze but the ground tips for these are almost impossible to get now, so on your advice I use tools with **GT inserts for turning and milling non ferrous with excellent results.

However, I won’t be throwing away all my HSS just yet.

[Nigel Graham 2Participant @nigelgraham2]

Jason –

Interesting! I’m not sure I quite understood it, but skiving seems somewhere between hobbing and gear-shaping (meaning by the latter, the progressive type by which the tool and gear move slightly for each pass as if finished wheel or wheel-and-rack in mesh.)

Ah – the initial laser operation did look to me more like cutting, but I did wonder what all that powder was afterwards.

I recalled an item a while ago about revolving tailstock chucks, on here or in the magazine, but could not remember what or where. A revolving chuck in a conventional lathe’s tailstock will not do much more than support the work (and soon show any misalignment!); but if the rotation can be locked it might allow something like drilling or counterboring the parted-off face from the live chuck.

 

We often see remarks on here that carbode inserts can only work at high speeds but I don’t recollect much about chip load, apart from ensuring it is not so low that the tool merely rubs. I have not found speed all that important for finish, but given the bewildering variety of insert characteristics if I obtain poor finishes it’s more likely I’ve chosen the wrong insert, or selected an inappropriate feed-rate, for a metal of dubious provenance! (Rusty, so it’s steel…)

[Tony Pratt 1Participant @tonypratt1]

I also manually programmed CNC machines back in the day but the advent of CAD/CAM has made the process fairly easy these days and stuff which was impossible to manually programme years ago is now just a routine operation.

Tony

[Clive FosterParticipant @clivefoster55965]

Concerning carbide cutting abilities the world moves on but received and published (magazine) wisdom remains largely the same. Internet and social media outpourings don’t help as they tend to multiply the repetition of the our date.

This antediluvian penguin reckons data fossilisation in teh amateur world settles at around 5 to 10 years in from the novel latest and greatest thing initially hitting the boarders of affordability and driving down into plausibly general use under the right, limited, conditions.

Certainly back in the day a major point of carbide inserts was to exploit the hot strength for heavy, hot swarf cuts going down to size in as few passes as possible. Easier cutting on hot surface leaving awesome finish on a part almost too hot to handle needing heat expansion to be taken into account when checking size. The old fart still has a few that have my massive, by most Home Shop standards, S&B 1024 working hard to get the best from them. The SouthBend Heavy 10 I had before, excellent a machine as it was in its own right, being quite overmatched.

Apart from the steadily declining cost per edge the big change I’ve seen over the years is in the steadily improvement of robustness, particularly against chipping. This modern strength has allowed sharp, small tip radius, inserts to be routinely made that are effective at very fine cuts without worrying about loosing the edge. Back in the day there was a very real risk of prematurely retiring an expensive edge due to chipping from careless manual entry in to the cut or ill constrained chatter. Found that out the hard way when trying an insert that worked well on a Colchester Triumph 2000 at work on the Heavy 10 and destroying it in nothing flat when when a gnarly bit in the material drove the job into into serious chatter. So glad I blagged, rather than bought, it. SouthBends magnificent plain bearing, cam lock, spindle on the late model Heavy 10 was well stiff enough for carbide loads but the relatively lightweight top and cross slides weren’t. Good enough for mirror finish and 10ths thou accuracy with well sharpened HSS but not strong enough for older style carbide.

Clive

 

[parovozParticipant @parovoz]

Just for reference with discussions on tooling and feeds etc. These videos are shot with coolant OFF so the ‘punter’ can see the work in progress. Coolant blast is normally used for at least chip clearing.

 

All the best and happy Christmas.

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