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

[cnc-it]

Worth a try with plastic..if it breaks you can upgrade to steel..nothing lost..wondering though if a heavy cut in steel might sheer the teeth of a plastic version 

[Pete.]

Our demo machines have splined plastic couplings from the 22kw motor to the hydraulic box. Worth a try IMO epsecially if you can beef up the sides and put healthy fillets on the diameter transitions.

[DICKEYBIRD]

Seems pretty simple Andrew; just invent a carbon filament for your printer, whip out a reverse image of the coupler face  in CAD & print yourself an electrode for your EDM.  Easy-peasey! 

[awemawson]

I printed the second (Mk2) version earlier but not had time to try it yet, but also I've put an advert on the Home Workshop site asking for contacts who can cast bronze from an STL model - you never know! OK it's a bit of a cop out, but having lost wax cast myself years back I know the myriad of special bits and pieces you need to scrape together to do it. Also the special plaster has a short shelf life and only comes in big bags !

https://homeworkshop.org.uk/

[nrml]

I've seen a video of someone doing bearing blocks for a CNC router by lost PLA casting and get tolerances good enough to use without further machining.

Your idea of using a plastic printed part as a fuse is quite interesting. You could do a hollow print and fill it with an epoxy and metal mix for greater strength and use it as a semi disposable part.

[philf]

Is there enough meat in the teeth to drill holes for steel dowels for reinforcement? (And perhaps a steel sleeve over the OD below the teeth.)

[nrml]

On mulling over this a bit further, is there any reason why printing this with ABS and treating it like a wax model for casting in bronze but using an excess of acetone to dissolve away the core instead of heat wouldn't work?

[tom osselton]

Or try this

[mattinker]

I printed the second (Mk2) version earlier but not had time to try it yet, but also I've put an advert on the Home Workshop site asking for contacts who can cast bronze from an STL model - you never know! OK it's a bit of a cop out, but having lost wax cast myself years back I know the myriad of special bits and pieces you need to scrape together to do it. Also the special plasster has a short shelf life and only comes in big bags !

https://homeworkshop.org.uk/

It's not a cop out! To make a sand casting, it will need to be divided in two and given draft. This should be easy to do ! I attached a drwing in .png format, I can't see it in the preview.

Regards, Matthew

[awemawson]

I've been put in touch with a couple of firms who may be able to to make a bronze cast from the STL model via the Home Workshop advert.

As an aside I was amused to find when fiddling with the PLA print and the original Beaver drive dog that they tessellate. All Beaver have done is to put a drive dog on the drive shaft that is identical to the Baruffaldi one on the powered tools and presumably make powered tools with fittings like the one I've made. i.e. they swapped which shape was on which !

I've just printed an ABS one that seems quite strong

[awemawson]

Been trying to resolve the 'Turret Unclamped' switch issue where it seems very slow to operate when cold taking up to 10 seconds for the contact to close when the Turret it pushed forwards for a tool change by the hydraulics.

It is a Euchner EGT1/4A5000 'precision mechanical switch' rather than a micro switch or proximity switch as one might have expected. It's end is a ball  that bears on the turret shaft that has a suitable ramp shape so the the switch is made in the unclamped forwards position, and open in the clamped reverse position. I had already removed it, lightly lubricated it's shaft and replaced it, but the symptoms persisted. Putting my meter across it and hand operating to be frank there wasn't any stickiness apparent, so maybe it was just mal-adjusted.

The construction is awkward in that the adjustment collar and locking nut are not 'get at able' when the flange mounting is installed, so any adjustment has to be a long drawn out iterative affair, making a little tweak, re-installing, trying and then removing again for another tweak. The movement from open to closed is microscopic, so that the adjustment took many iterations 

I have tracked down a very expensive replacement but hopefully today's tweaking session will have resolved the issue. Interestingly it's locking ring was by no means tight when I first removed it.

[awemawson]

I set off this morning with the intention of doing a bit of tool setting, then writing a diddy program to incorporate the Spindle Positioning and milling using the powered tooling.

First set back was no spanner to lock the ER32 spindle for tightening - well I had one but too thick to fit, so the usual 'go plasma cut one' - it may look spindly but that 6 mm steel is not mild steel, something much stronger .

Then I'd just got the 10 mm end mill snugged up when visitors descended, and absolutely no chance of tool setting with questions being fired over my shoulder - you need to concentrate to avoid breaking the Renishaw Tool Arm  - I gave up on that !

So I just did a bit of manual milling putting notches at 45 degree intervals round the periphery of  a 1" bar - majorly unimpressive but proves the ABS drive dog will transmit a bit of torque and that the M19 spindle positioning locks on adequately.

.. so proof of concept rather than a major step, and when the dust settles, probably in the dead of night, I'll get back to what I started out to do 

[awemawson]

A few developments today:

Firstly the Ebay seller having failed to sell the Euchner EGT 1/4A5000 precision switch has accepted a more reasonable offer, so that is on the way from the states to hopefully just be a shelf spare and ward off any more 'turret unclamped undetected' issues.

Secondly I've had a very reasonable quote for casting a couple of drive dogs in bronze, so a pair of PLA models went in last night's post to Sheffield.

Thirdly, having a bit of piece and quiet this morning I've completed my cycle of tool setting without breaking the HPA probe - phew.

So on a roll, I decided to see why the remaining powered tool doesn't locate properly in the turret - I knew that something interfered, but couldn't remember what ! It turns out the the Beaver turret has a face mounted swarf guard in the middle that occupies part of the seating plane that the 90 degree tool wants to sit on - as it has an internal gear box it's more bulky than the others.

So there are three possibilities that I can see:
A/ Cut a bit out of the swarf guard - don't like this as it means when the tool isn't mounted swarf can get in
B/ Cut a bit off the 90 degree tool - a possibility as the interfering bit houses a micro positioning feature not used on the Bever turret.
C/ Sit the 90 degree tool on a 3 mm spacer - probably the easiest solution but I'll have to extend it's drive dog to suit.

[awemawson]

I decided that it was time to pull the new cables through for the Renishaw OMM probe that PK is  kindly working on for me.

This needs doing as the existing cables (as previously mentioned) are just draped roughly in place and not in trunking despite there being a suitable run. Another motivator is that I need to re-fit more of the cabinet metalwork that guides swarf and coolant back to where it belongs, and when fitted, the trunking is no longer accessible.

First job - test fit the socket box that I made weeks ago - a bit of adjustment and it's fine 

Then start exposing the trunking and removing as little as possible just to allow me to get a 'pull through' in place to draw in the new cables. I wanted to draw from the rear chuck end cabinet, through the cabinet behind the tailstock, and thence into the duct emerging below the Siemens controller. This allowed me to leave the reel of signal cable uncut and in the rear chuck end cabinet, to await a new piece of flexible conduit that I will install taking it to the place the OMM receiver lives on the left face of the enclosure above and behind the chuck. Currently this cable just hangs in the air unprotected 

Now I have two types of pull through. Very flexible nylon cord intended for pulling 'singles' through round conduit, and pretty rigid fibreglass rods that screw end to end in the fashion of drain rods (but much thinner) - intended for poking wires across ceiling voids. I had to use both, using the rigid ones to get the flexible one into place, which then could draw in the cables. Didn't go too badly considering, but cable drawing is always easier if there are two of you (which there weren't !)

[awemawson]

...cont:


Now I just need to remember how all this tin work goes together 

[awemawson]

After lunch I made off the cable ends on the back of the socket box and mounted it thinking I'd have to leave it at that until I got some flexible conduit for the far end of the signal cable.

But after a bit of cogitating a vague memory of a bit of 16 mm plastic coated steel Adaptaflex tucked away somewhere rose to the surface, so after supper I went hunting. A bit of rooting about in my 'may come in useful' store produced just over 4 meters and it was complete with the terminations - I guessed that I needed about 3 metres so luck was on my side 

One end had a 15 mm bush termination and the other was 20 mm. As I intend to mount a 2" square galvanised 'adaptable box'  on the existing 20 mm fitting on the  chuck bulkhead and these boxes come pre-stamped for 20 mm holes, the 15 mm bush went in the cabinet base. I then pulled the conduit through the bowels of the machine and was able to follow the existing conduit that takes the Tool Setter arm cable and cut it off to length with the battery powered angle grinder. I then swapped the 20 mm fitting from the off cut to the bit being used.

Now as the signal cable is still on the reel, it's important before cutting to reel off enough for the job, but not too much to waste it. So firstly I pushed my flexible 'pullthrough' though the conduit - marked the nylon and then pulled it out as a measure leaving a conservative bit extra.

Then it was a case of  re-threading the pull through from the far end, taping the signal cable to it, and pulling it through. VERY easy to pull the taped joint apart, especially as this conduit follows quite a contorted route, so it was a relief to see the taped joint emerge unscathed.

There was one bit of the plastic sheath of the conduit that had been scraped in a previous life, so I made that good with 'self amalgamating tape' (brilliant  stuff that when stretched and wrapped  bonds with itself into a solid rubber sheath)

So now I'm waiting for the 'adaptable box' to arrive.  It will have a 20 mm hole bored in it's rear face which will be used to mount it when eventually the old cable is removed and the new made live.

But that won't happen until the OMM receiver and probe return from their antipodean holiday when PK has waived his magic wand over them.

[awemawson]

So having got the new cables in the ducting I could make a start on replacing the various panels that I had had to remove to get at it. You may recall that they were a pain to remove entailing making a 1 metre long allen key, and they kept up their reputation going back. Two on the external tail stock end of the machine, and two swarf / coolant guards inside.

I still need to work out how to fix the lower 'L' shaped panel - the only access to screw positions is from underneath. Perhaps they were assembled on a plinth of some sort in the factory 

Then I made off the 24 volt supply to the 2 core cable laid yesterday, and tested it to the socket under the 820T controller

About this time the Adaptable Box arrived, so I drilled a 20 mm hole in it's rear, knocked out one of the 20 mm knockout locations and mounted it on the OMM signal cable conduit awaiting the return of the OMM

[awemawson]

Time to sort out the mounting of the last end panel. Various threaded inserts in both the panel itself and the adjacent panels, but no access to fix or tighten screws.

Initially I reckoned that the two screws on the rear edge of the panel could just about be got at by offering the panel up at an angle, and using the flexibility of it's length to get my hands onto the allen key.

Then it struck me that if strong spring washers were fitted the panels would be clamped but the flexibility remain. In practice I used a compression spring for the joint as per the pictures and it worked very well.

Boring a 20 mm hole in the face of the panel at the front edge gave access to the one screw and threaded insert at that end of the panel, and having made an extended key I was able to do it up nice and tight.

The two vertical screws are inaccessible unless I once more remove the internal swarf / coolant guards, but as it is the panel seems firmly held. If in the future it vibrates too much then I can probably get at them that way to resolve the issue.

So as it is the only visible evidence is a 20 mm blanking grommet showing on the recently fitted panel.

[awemawson]

So why the rush to get the panels back? Well apart from the fact that they are taking up needed space in the workshop, I wanted to bring in one of my newly acquired Versatool cabinets and start tidying the lathe tooling away. Up till now it's been on the floor / work surfaces / anything vaguely horizontal and I'm running out of elbow room.

So in fact both cabinets were forklifted in (they are impressively heavy) lashed together on a pallet, and the slightly more presentable one moved into place at the tailstock end of the lathe.

Then it was a case of  moving shelves vertically to give clearance as they swing, working out a suitable layout and drilling some holes to accept the VDI40 spigots and at least the tool holders are now stored safely 

Much more to go in, but now time is on my side.

I'm working on dismantling the ER32 right angle powered tooling holder which is seized solid and needs a rebuild as did the two straight ones (they were bought described as such). So far I've got all the screws out bar two, which will be left soaking for a few more days in PlusGas. When I'm inside I'll put up a few pictures.

The right angled ER32 holder is probably the most useful of the three, allowing flats and grooving in the Z axis direction.

[awemawson]

At long last the screws in the 90 degree powered tooling head have surrendered and now all are out 

I've been topping up the meniscus of 'Plus-Gas' on them whenever I walked by, and this morning I was down to the last two reluctant ones. Both 4 mm hex sockets in the head, so M6 CSK socket screws. One was so tight this morning that I got a full turn on a good quality 100 mm long allen key and still it wouldn't budge.  The other one started rounding off the hex socket. Often reluctant screws can be freed by a few smart taps on the head, but these were in a slightly recessed situation, and my 1/4" hex drive bits were too short to avoid whacking other precision bits with the hammer. So I turned up a short bar end on the lathe, with a 7.1 mm hole in the end for the hex bit to sit in, and gave the screws a few smart raps with a hammer. They both then meekly unscrewed with no drama 

So the good news is that it's now ready to dismantle without as I had feared, resorting to either drilling them out or burning them out on the EDM machine - the bad news is that I am out for lunch shortly so cannot do it now (I'm told!) 

[awemawson]

So this morning I found a bit of time to start pulling the 90 degree VDI40 powered tooling holder apart. Everything was rather tight with two dowels refusing to let go for a long time. It wasn't until I was nearly there that I discovered that they were drilled and tapped M4 for a slide hammer to extract them which would have been so much easier !

The main issue is the needle roller bearing that supports the input shaft - coolant has obviously entered and it has rusted up.There is an outward facing seal that presumably is the original problem having failed, but at the moment the seal and needle roller bearing are resisting extraction using my slide hammer bearing extractor, so it looks like a few more days soaking in Plus-Gas is called for.

Sadly this means I cannot yet order up the needed bearing and seal until I can make proper measurements

[awemawson]

. . . .then it dawned on me . . I could 'take the waiting out of wanting'  (who remembers where that quote comes from ?) by using my 60 ton hydraulic press.

Although from the rear the bearing doesn't expose anything to press against, the slide hammer bearing gripper when engaged presents the end of it's three fingers, against which a bar could be pressed.

After that it was no contest and out came the needle roller bearing and seal without even a squeak and the press didn't raise a sweat   

. . .so clean up, measure and order  hopefully this afternoon 

[awemawson]

So having ordered up the Needle Roller Bearing and three seals, and having failed to find an 'O' ring 42 mm i/d x 46 mm o/d so 2 mm cord (if anyone knows a source please tell me) rather than twiddle my thumbs I decided to sort once and for all the interference between the mounting face of this device and the central swarf guard on the turret itself.

You may recall that the options were to modify the swarf guard, to modify the tool mounting face, or to mount the tool on a stand off washer and extend it's drive. As the carcass of the tool is now completely dismantled I could check what would be affected were I to slice a bit of it's base off to accommodate the swarf guard, and the answer is NOTHING that I care about  Someone in the future putting it on a genuine Baruffaldi Turret might be a bit hacked off but the cut off bit has no function on the Beaver turret.

A tentative touch with a file showed me that it was mighty tough stuff, but machinable. I had feared that I might have to grind it, but M42 HSS coped OK at low feeds and speeds.

The swarf guard is a nominal 3 mm thick so I needed to remove 3.5 mm of thickness from a 2.5 mm x 5.0 mm area. But first I needed to sink the counter bores for the mounting cap screws by the same 3.5 mm. All went reasonably well, and after a bit of de-burring it's now ready for the bearings and seals and re-assembly.

So far it looks like the risk of buying a seized one might pay off - £24 for bearings and seals - with shipping the three tools (all seized!) were $272 so about £70 each. So about £100 all in for this one. A new 90 degree VDI40 ER32 power tool is pushing £2000 and working ones go for the wrong side of £1000 

OK mucho time spent, but that's the fun part 

[mc]

having failed to find an 'O' ring 42 mm i/d x 46 mm o/d so 2 mm cord (if anyone knows a source please tell me)

Simply bearings have nitrile - https://simplybearings.co.uk/shop/p80828/2mm-Section-42mm-Bore-NITRILE-70-Rubber-O-Rings/product_info.html Viton - https://simplybearings.co.uk/shop/p513418/2mm-Section-42mm-Bore-VITON-Rubber-O-Rings/product_info.html and EPDM - https://simplybearings.co.uk/shop/p84828/2mm-Section-42mm-Bore-EPDM-Rubber-O-Rings/product_info.html

Certainly not the cheapest option, but when you only need one or two, it's cheaper than buying a big bag.

[awemawson]

odd that, they were my first port of call 


... correction - no it was Bearing Boys I went first