The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)

[awemawson]

No nor do I Pekka - it's very odd 

I can see why the finishing cut approaches slightly beyond centre to eliminate any possibility of a pip, but not 6.6 mm ! The program is set up to move the tool tip allowing for tip radius, so I don't see  ANY reason why there should be material other than the 'finish allowance' left to machine.

OK the 30 degrees approach has solved this particular issue, but I'd like to understand the generality

[cnc-it]

You are welcome Andrew  Probably with it being a different version of FC but mine defaults to 30 degrees lead in and lead out on turning and milling. You can set up all these things before hand by using the manufacturing tab then the machining attributes tab 

[awemawson]

Oddly John, when I go into the Manufacturing -> Machining  tab it is set to default to 30 degrees, so goodness only knows how it got set to 0 degrees when processing that simple dome . . . life is full of these idiosyncrasies 

[awemawson]

Time to re-wire the lathe and the associated bits of infrastructure wiring !

Today I was experimenting with threading programs - I've not actually got a threading tool mounted yet but wanted to prove that the inbuilt threading cycles work. (they do  ) They use the same position encoder that is involved with the axial spindle stop function (M19) that I still haven't got working (*) and to get a good finish whirl away at maximum spindle speeds using loads of power.

Well I managed to trip the 32 amp type C breaker that the 3 phase is sourced from, and the SY flexible cable to the machine was distinctly HOT ! - not unexpected, the 27 kW spindle motor is the main load and at full tilt accounts for 48 amps at 415 volts three phase. The SY cable being 2.5 mm csa is only rated at 24 amps !

So I'm going up to 6 mm csa SWA cable rated at 53 amps, and will upgrade to a 63 amp 5 pin interlocked socket and plug (Looking for one of each if you have them skulling about !)



(*) I've made contact with a company who have two of these lathes of a similar vintage, and although they don't actually use the axial positioning M19 facility know that it is embodied, and are happy for me to go and poke around and see if I can find out what enables  it.

BTW these two lathes are used intermittently making parts for Merlin engine rebuilds  so a visit should be extremely interesting  anyway.

[cnc-it]

Sounds like a shop tour coming on..great to see some British made machines are still making parts..

[awemawson]

Today the bits arrived to mend one of the Powered Tools. I'd diss-assembled it a few days ago, revealing a pair of rather nice opposed pre-loaded taper roller bearings taking the main load, and a needle roller bearing supporting the drive shaft, with seals at both ends.

The taper roller bearing was seized solid and the rollers rusted , so I assume the the seal at that end had failed. However the (rather expensive looking) slim taper roller bearings were in good order.

I'd had a bit of a mare getting the old taper roller bearing out - drifting from the outside was the only way but the angles were too steep. I thought about making a puller and slide hammer, but looking on eBay I could see that it just wasn't worth the effort. A nicely cased set of bearing inner extractors and slide hammer were mine for £18.90 including post. OK Chinese but probably no worse than I'd have made myself, and they will come in handy in the future. The extractor worked faultlessly, needle bearing outer removed so I could measure up, and an online order placed which is what arrived this morning.

1st September today so first I had to cut the field hedges with the Twose Fail (not allowed to do it before 1st Sept, and this time of year things very quickly get too wet to put the machine on the ground. A few hours later - (I hate driving the flail tractor, it bounces all over the place!) and I'm able to get back in the workshop and re-assemble the Powered tooling.

Simple enough - gently tap the well oiled seals and bearing back into place, lubricate it with high melting point lithium grease, pop the shaft and collet chuck back in and tighten a few screws -" job's a good 'un "

I've decided not to modify the drive dogs on the powered tooling to suit the lathe, but rather to modify the lathe to suit the powered tooling. My logic being, these Baruffaldi tools are quite rare but do surface at times, whereas the genuine Beaver ones I've never seen and probably never will. So when the time comes I will remove the lathe tool drive shaft and dog and make a replacement longer one to fit these tools.

[awemawson]

...continued

[awemawson]

I had a free couple of hours this morning, so I decided to attack the second Baruffaldi Powered ER32 collet chuck. I'd taken the precaution of ordering two sets of oil seals and needle roller bearings so should have been equipped for war !

Taking this one apart revealed that the needle roller bearing was actually in very good condition, but the pair of opposed taper roller bearings were locked up solidly. They slide onto the shaft and are retained and adjusted by the usual nut arrangement that would usually have a tab washer or some other device to stop it unscrewing.

This one looked to have been attacked with a cold chisel mangling the nut into the shaft thread. Problem was, the shaft has a 36 mm hex flat behind the collet nut thread, and the closer nut thread is greater than 36 mm, so any spanner would need to be thinner than 9.5 mm to fit. All my 36 mm spanners are big fat things, so the job took a slight detour into making a spanner.

I decided rather than make a conventional spanner shape, I'd make a plate that I could firmly grip in the vice, as it would also support the shaft as I worked on it.

Usual thing, draw it in Autocad, push it though SheetCAM, cut it on the plasma table using MACH3 - and again as usual the Plasma Table did an excellent job. A minimal bit of clean up with a file and we were good to go.

So, into the vice and now I can use the hook spanner to good effect unscrewing the nut - by this time the bearings had freed up and were turning smoothly. I'm running out of time (Need to be presentable for a BBQ with friends for lunch) so I will leave removing the YL-TIMKEN-X-32006X bearings for inspection later. But I did find that they are available on the web at £14 each)

. . .to be continued . .

[seadog]

Looking at the nut and the cut-out at the top of the thread, it looks to me as though peening is the correct method of locking it, just not done very neatly in this case.

[awemawson]

I think it's been reworked previously, and as you say the peening has not been done very neatly. The nut is 28 mm x 1 mm pitch, which doesn't seem to be a common one (other than on scooter clutches !). I'll probably re-use the original, but re-making would be reasonably easy.

[seadog]

All you need is a CNC lathe and it'd be a doddle...

[awemawson]

It's actually a simple enough job on a manual lathe and mill (had to do one on the Tractor Flail Mower rebuild) but I'll probably re-use the original.

Now back from the BBQ (where the host / hostess were embarrassingly serving my pork and sausages!) and have managed to knock the bearings off the shaft - they look at a first inspection to be fine but I can't get too involved as I'm still in my glad rags !

I'll give them a good wash out in the morning with spirit and see i they still seem OK, in which case it's just a 'put it back together' job 

[seadog]

"I can't get too involved as I'm still in my glad rags !

I'll give them a good wash out in the morning with spirit and see i they still seem OK."

You should have put your overalls on then...

[awemawson]

Driven out of the house by Vanity Fair on the TV I took refuge in the workshop and re-assembled the powered tooling.

As expected the bearings on examination proved perfectly serviceable, so with a bit of lithium grease and application of the broaching press it was re-assembled. I used the existing M28x1 locking nut: examining the male thread on the shaft the 'damage' was actually an intentional scallop taken out to receive the deformed nut as a locking device. Adjusting for 'reasonable' drag and pre-load brought the nut up remarkably close to where it had been, and I secured it with three pops with my large centre punch (inherited from my Grandfather who was a mill wright)

Stealing an ER32 cap nut from some spare tooling for my Beaver Partsmaster made the job complete. Just the 90 degree one to tackle some time in the future.

[awemawson]

The other day when I was experimenting with threading cycles, the motor was accelerating to max revs and decelerating, all very impressive, but doing it a few times I managed to trip the 32 amp three phase breaker in my workshop distribution panel. Also feeling the 2.5 mm 5 core 'SY' cable that fed he lathe, it was distinctly warm  hot 

When I came to power the machine up 'just one more time' there was a big bang and a puff of smoke from the cable clamp on the 32 amp plug. Investigation showed that the insulation of the cores had softened, bringing the wires into intimate electron passing closeness 

Now using this feed was always an interim solution, only intended for initial testing - I'd intended to upgrade. Obviously now was the time ! The 32 amp type B MCB was wired to the 32 amp Commando socket in 4 mm 'singles' cables in ducting, rated at 32 amps.

So I hatched a plan - running 6 mm Steel Wire Armoured (SWA) cable (rated 53 amps) round the workshop ending up on a 63 amp Commando Plug & Socket thence running in 6 mm SY flexible cable (rated 42 amps) to the machine. But also to upgrade the breaker to a 50 amp 'Type D' motor rated one.

I put out a plea for cable and plugs and sockets, but to my embarrassment found I already had cable rescued during the site clearance for the Tractor Shed, and a box of 63 amp commando plugs and socket that I've no idea where they came from  (plonker as I'd already ordered some on ebay)

So getting it all together needed a few things. The big Commando Plugs use 'PG29' threads or Panzergewinde threads (*) and my SWA terminations are M20 x 1.5 mm standard conduit so an adaptor bush was needed. No local electrical factors carried them, so I made one on the manual lathe. The cable , socket and plug are beefy things needing a hefty mounting plate, so I cut one on the Plasma Table.

Then threading massively stiff SWA cable round the over crowded workshop and fixing it required much emptying of shelves etc and quite a bit of ingenuity - that stuff is alive and just waiting to pounce and knock expensive tooling over when you're at the other end of the coil up a ladder and unable to stop it 

Anyway, cable up, entry made into the Distribution box, and made off across steelwork trusses to where a pair of empty holes were just asking for a mounting plate to be bolted on for the 63A socket.

Meanwhile I fixed a 'riser' from the machine up to socket level (made from pedestrian barrier bits - thanks Pete) and found a way through various internal ducts and cabinets to minimise the external cable run, fixing to the ceiling of the main electrical box using sticky Ty-Wrap pads reinforced with a nut and bolt to prevent pull-off. (again thanks Pete for the pads). I also fixed a short bit of Din rail to take terminations for the Earth and Neutral  cables as this machine had none (I ALWAYS run a neutral when wiring, even to wall switches - you never know when you'll need it!)


(* https://en.wikipedia.org/wiki/Panzergewinde )

[awemawson]

It always amuses me when making PG threads, which I've had to do a few times for Commando Plugs & Sockets, that all the dimensions are metric, until you come to the thread pitch, which is 'turns per inch' - 16 in  this case 

So a plate got cut out from 9 mm steel, painted and bolted up with the 63A socket on it. The SY cable was pulled through the internal ducts and threaded up the 'riser' protected by an anti chaffing shield, then fixed to the main electrical box roof, made off to the Main Machine Isolator and plugged in.

. . . the moment of truth . . no putting it off . . . time to throw the switch Igor 

Now I had been concerned if any damage had been done, as just after the initial tripping and my attempt at a re-start, the main transformer had been making alarming humming noises, presumably running on only two phases. Hence my concern 

So, switch on, power up the controller, home the axis's - all well so far - try and home the Tool Turret - cycle starts but never ends  The dreaded Tool Turret 

Actually it was simply an internal breaker that had tripped, presumably when 'two phasing' - reset it and all was well.

As a matter of interest I put my Fluke clamp ammeter on 'peak amps' - 90.5 for a very brief time, but usually about 20 per phase

[awemawson]

For peace of mind I ran the threading program several times over and over, then measured the temperature rise of the 6 mm 5 core SY cable, and the 4 core SWA cable. Both had gone up by only 7 degrees, so unless I go into mass production of widgets 24/7 I reckon I'm in the safe zone. Both cables are rated up to 70 degrees C and they only got to 30.

While I was in the measuring mood, I put the clamp meter on the DC armature drive cable from the KTK Mentor to the 27 kW Mawdsley spindle drive motor. 109 amps peak  But well within spec

Then I measured the average on phase one of the 415 volt three phase input - only 18.8 amp - but peak 90 plus as above

[awemawson]

Indulge me, and bear with me as I try to sort a few things out in my head regarding tooling 

I'm getting tied in knots trying to set up tooling in Featurecam to match what I have and also to produce workable code, but there are just too many variable

Firstly, this is a single turret slant bed lathe, with the turret BEHIND the spindle - Featurecam details an Upper and a Lower turret, so I assume that the upper one is relevant.

Then (Obviously) the spindle can be programmed to turn Clockwise or Anticlockwise

Then tools can be Left Handed (LH) or Right Handed (RH).

Now the turret Tool Holders come in two flavours so that when using a LH or RH tool, the reference surface passes though the centreline of the turret to allow the correct tool height to be set, and for left handed tooling the spindle needs to rotate CLOCKWISE, and for (inverted)right handed tooling the spindle must rotate ANTICLOCKWISE.

Only the left hand version keeps the force downwards into the bed as in a manual lathe, but the turret and slide arrangement are so massive I don't think that this is an issue unless VERY heavy cuts are taken.

OK fairly simple so far, BUT, each tool in the Tool Crib is defined for CW or CCW rotation, and the M codes for these are embedded into the Post Processor, CW being M03 and CCW being M04

All well and good, but setting all these sensible values FeatureCAM has the spindle rotate in the wrong direction  Easily changed in the Post Processor coding by swapping M03 & M04 but it's very odd to need to do it.

Having sorted all that, programming a normal right handed thread produces a left handed thread 

Now I have a feeling all these oddities revolve around the choice of turret (Upper or Lower) - but as soon as I select the other turret the program refuses to allow me to pick the correct tool as it swears blind that the tool is intended for the opposite rotation - argh, my head hurts 

Have some tooling pictures

[seadog]

Maybe their interpretation of what is left or right handed is not the same as yours or mine?

[DICKEYBIRD]

It should be that M3 causes the spindle to rotate clockwise as viewed from the rear of the spindle or chuck & M4 the opposite direction.

I know you British folks drive on the left side of the road but do your clocks run backwards as well?

[awemawson]

Milton, this lathe, and other ones I had (Traub, Denford Mirac, etc) , definitely rotates clockwise looking from tailstock to chuck for an M03

Seadog, the trick I was taught re handedness is imagine  a pair of hands held in prayer. The tips of the fingers on the LEFT hand point right so that is a LEFT HANDED tool and vice versa - it works for me !

OK in Featurecam, using the UPPER turret, swapping the M03 and M04 around, and using inverted right handed tools for threading produces sensible code and right handed threads when asked for - but my head still hurts !

[seadog]

I agree with your interpretation of handedness, it's the standard as far as I'm aware. It seemed like that might be a possibility without having to use any brain power (reducing by the day) to analyse what you'd said.

[awemawson]

Milton, maybe this IS a UK thing - googling does throw up several pictures of M03 being clockwise from behind the head stock as you say. But most certainly the Beaver is the other way round as is the Denford Mirac

. . . .more oddities . . 

I suppose it follows a mill spindle where the clockwise rotation being M03 is looking down the spindle.

Also if you think of a conventional manual lathe, top of the work comes towards you for 'forwards' and away for 'reverse'

. . . I'm more confused than when I started !

[PK]

I'm sure I'm telling you how to suck eggs, but I've re read your post and you didn't explicitly say that you would normally put tools in a rear turret 'facing down', ie the chip curls on the floor side of the insert, not the ceiling side. M3 is then clockwise from the rear of the chuck  etc....

[DICKEYBIRD]

Milton, maybe this IS a UK thing - googling does throw up several pictures of M03 being clockwise from behind the head stock as you say. But most certainly the Beaver is the other way round as is the Denford Mirac

Surely Beaver didn't convince Siemens to reverse the Beaver lathe control's spindle rotation away from the world standard M3/M4/M5 conventions just for their machine?

I work with British luxury vehicles every day and have run across some  really strange things (to my American way of thinking) but in the end there's usually an ah-hah! moment where the engineers' logic soaks in & it all makes sense...sorta.

What about you John/cnc-it...what say thee about this from your Beaver experience?  Another British other-side-of- the road thing?