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

[RodW]

Rod,

The motivation was to get it back 'as was'

Yeh, I got that and its a credit to you that you slavaged a machine and was able to restore all of the failed electronics

Rod,

and anyway there are some massively powerful servos and spindle drives on this beast that would cost a fortune to replace.

LinuxCNC should be able to control the existing motors on these kinds of machines. I certainly agree it would not be viable if you had to replace the motors.

So save that idea for when you buy the machining centre to go with the lathe.   

People so often think of the limited  I/O parallel port breakout boards with home built CNC but with LinuxCNC and Mesa, this can be infinite plus support most of the control panel features and handle encoders and resolvers. There are different options for running servos but even the $200 Mesa ethernet connected 7i76e I use has 32 inputs, 16 outputs, 5 step generators, 4 analog inputs, 2 Mpg inputs, spindle encoder plus an option to add 2 more similar daughter cards before you venture into the onboard smart serial RS422 interface that allows you to daisy chain a whole host of other I/O options.

[naffsharpe (Nathan)]

Rod, I love your new word. " Slavaged" has to be the best description of refurbishment/rehabilitation of a machine I've ever heard !  Nathan.

[awemawson]

Be kind to him, he's an Australian, and spends all day upside down tangled in the corks from his hat 

[RodW]

I wasn't sure if Andrew savaged his machine or salvaged it so I had a bet each way 

Its hard to get  a good supply of corks these days. Far too much wine in screw tops down here! I think I better go and open one seeing its Friday night here...

[awemawson]

I've not been convinced that my setting up of the turret was actually spot on. I suspected that checking the turret rotation setting using a flat lathe tool mounting position and adjusting to be parallel to the X  movement wasn't sufficiently accurate, so I made up a test piece.

I turned an accurate 10 mm spigot on a bar end and left it in place in the chuck. Then on my manual lathe I drilled and bored and reamed an accurate 10 mm sleeve in a bit of brass hex.  then with a 10 mm dowel pin mounted in a 10 mm end mill holder in tool position #1 offered the two together. If aligned properly the sleeve should slide from one to the other when the X axis is set to zero.

Well as expected it didn't - it was out in X as well as height - so a repeat of turret adjustment was called for.

It was my intention to sweep a DTI round the inside of a VDI 'tool hole' in the tool disk, but much to my surprise I found that the holes are intentionally not round

[awemawson]

Never mind, I have a boring bar holder with a nicely finished 50 mm outer diameter, so I could sweep round the outside of it just as well as in internal hole. 

Then there was a slight detour making a rigid DTI holder to go in the chuck and off I went tweaking turrets again!

But first I roughly marked the quadrant points on the 50 mm diameter, as judging them from the odd angles that you are forced to use isn't easy.

So repeat of the previous exercise and setting it went pretty easily, tapping the tool disk slightly to get an exact centre position. The X error as displayed at this point was -0.197 mm which can be corrected by applying a 'grid shift' by entering half the error in microns into a parameter - or so the procedure said 

I went all over the place, error increasing, error unchanged I was going scatty, until it dawned on me - the measurement and error correction values are being measured using a system that already has  (wrong) compensation applied. Starting again having set the compensation to zero all went to plan in a matter of minutes. Of course in the factory they go onto the commissioning floor already with zero in the parameter so no need to mention it 

So, remount the tools, reset all the tool offsets, remake the 10 mm spigot and try again. SPOT ON - the sleeve slides nicely from dowel to spigot when X=0  . . . . phew

[nrml]

Any updates on the Renishaw probe?

[awemawson]

It supposedly was going to be posted on 19th Feb but nothing has been received. I emailed PK on Tuesday 5th asking how it was sent but as yet I've received no reply.

All very frustrating   

[tom osselton]

So what is the purpose of the 3 mm ditch in the turret any ideas?

[awemawson]

I'd love to know Tom. The only pictures a bit of Googling gives me seem to show circular pockets on other manufacturers tool disks. 

I've posed the question on the Practical Machinist Forum so hopefully someone with more experience than I will give us the answer 

[PekkaNF]

That pocket shape is interesting...If I needed to quess possible logic behind that shape:
* Round hole with loose fit shank would give a line contact, while that pin on the front or other feature indexes it and prevents it from turning there would be tendency to "rock" about that single line contact.
* On the other hand V-groove would give a two line contacts for a round counterpart----maybe this round pockect odd relief woud serve the same function in economical execution.

Never seen this construction, but if that serves other purpose I keep mine in mind...least I think it might come handy

Pekka

[awemawson]

I've just spent a couple of very frustrating days bottoming out a fault on the lathe.

Symptoms: Turret clamp solenoid not clamped. It EVENTUALLY turns out to be a simple bad connection on a Sub D 37 way connector used on the  input array, this pin takes the 'clamp request' from the SMCC subsystem conveying it to the controller that should then act on it, clamping the turret.

Along the way I've had to replace the vastly expensive Euchner 'unclamped' switch as it couldn't reliably be set - this thing works on 10 thou movement to switch!) - fortunately I'd had issues with it before and had bought a 'pre-emptive spare'. And I've discovered that certain cables are incorrectly marked differently at each end, with wires for 'clamp' and 'unclamp' being interchanged in a couple of places, but 'end to end' the errors compensate and it works in the correct sense !

So the thing that the fault is on is a Klippon 068386 terminal block. It probably only has a dry joint on it's pcb but although I'd hoped to solder the pin in situ - it's all enclosed. Only ebay one is in the US and although reasonably priced the postage is ridiculous.

I've wiggled the connector into a working position, and the machine is running as I type this, but of course it needs fixing. If I can't source a spare I'll pull this one apart - bit of a pain as it has about 40 cables screwed into it !

[redshift]

Will this sort your problem
Regards, Dave

[awemawson]

Dave, thanks so much but I've just found one in Holland 

[redshift]

No problem

[awemawson]

I started out this morning with the intention of removing the wires from the Klippon Block for input array #3 one by one, and numbering them and replacing to avoid confusion. I had the choice of cutting off the boot lace ferrules, slipping on small number sleeves and refitting a bootlace ferule, or using a larger diameter number sleeve that would go over the existing ferrule, and hold them in place with clear heat shrink tubing. I choose this later approach. The replacement Klippon block isn't due until next week.

By the time I got half way through the process I thought, blow this, leave the wires off and see if you can attack the Klippon block with a soldering iron. Someone on another forum had told me that the orange plastic of the blocks is in two parts, the sides clipping together, and if unclipped the PCB is released.

So, all wires off, and released from the DIN rail, sure enough with a bit of persuasion the sides came off letting me see the solder side of the PCB for the first time. To my amazement every single pin of the 37 way Sub D connector had a neat little skirt of solder about 1/2 mm off the board - the whole lot were dry joints So the 'solder to pin' junction had stood the test of time, but the 'solder to PCB' junction had failed. I assume that these were flow soldered originally - perhaps the PCB cleaning wasn't up to scratch  (But the joints for the terminal blocks were fine)

Careful application of a bit of flux along with flux cored solder and soldering iron, and I remade all the joints. All passed a continuity test so I re-assembled the block, re-wired it in the machine and crossed my fingers.

All was well, she fired up like a champ and passed the tap test ("Tap with screwdriver handle in the manner of a reasonable man")

It does beg the question what is the state of the other four of these blocks - but then, I'll have a spare arriving next week 

This exercise did at least give me an excuse to try my new Chinese "Heat Proof Silicone Soldering Mat", and I must say it's actually pretty good - saves my desktop drawing surface, and is thick and pliable enough to stop things skidding about as you work on them.

[nrml]

Is there enough wriggle room to pull open the other blocks for inspection without disconnecting all the wires? Isn't it worth sorting out while you are still working there for future peace of mind?

[russ57]

Is that soldering mat like the silicon BBQ/grill mats? Although direct from China might be cheaper anyway..

Russ

[awemawson]

NRML: in a word no, and then yes in that order!

The DIN rail that they mount on is right at the top of the cabinet, and the connected wires are too short to get the unit off while still attached.

However I do intend to work my way through them starting with the extreme left one this morning. Some are quite sparsely wired so should be easy, but #5 at the extreme right is fully populated so will be time consuming.

Russ: not seen the B&Q mats so can't comment. This was £11 inc postage.

[awemawson]

So I cracked on and attacked the leftmost Klippon block - IP1 - moderately populated with 14 wires needing labelling and 5 pre-numbered that need mapping.
It took two hours end to end and thankfully all tested OK on re-assembly. Oddly there was a link on pin 16 but the PCB track looked OK and tested OK. The soldered joints didn't look too bad but I re-did them anyway and also left the mystery link in place - maybe the track has a hairline crack?

Can I face doing another one just now - mm - have a coffee and a think 

[hermetic]

Andrew, could you rig up some sort of tester to put, say, 1 to 2amps through each connection to see if it broke down,, that would show if you had any more dry joints. Possibly the action of pushing in the plugs helps to cause this problem? What a pain! You could of course leave it as is, because you would know where to look in the event of another failure, but also considering the job or worse that the failure might cause damage to.................I think my autistic nature would make me check them all too! Good luck!
Phil

[hermetic]

actually, looking at those tracks, maybe 500mA!

[awemawson]

Well Phil, I cracked on and did IP2 Klippon Block.

Only one pin that looked possibly suspect, but of course I re-soldered them all. This one was a bit of a pain to do as several terminals had multiple cables entering them. There was the "bugger" moment when re-wiring it I found that I had two white wires BOTH labelled #30. I remember now that that was when the Postman arrived  Easily sorted with the circuit diagram and a meter. Cable #29 now CORRECTLY labelled 

Then there was the heart stopping moment when testing and the machine refused to jog. Looking for a wiring error I found I'd left the 37 pin cable unplugged - plonker 

Tested OK eventually - so that's three out of five done. Depending on how good lunch is I'll try for another later !

[awemawson]

On a bit of a roll, I went straight ahead and attacked the first of the digital output blocks OP1. Relatively lightly populated only having 13 wires needing labelling, the rest already bearing sensible numbers, and no complications of 'two in a hole'

All went well, the soldered pins looked absolutely fine, but of course I soldered them anyway. Re-assembled it - re-wired it and all tested OK - phew !

. . . on to the next (LAST  ) one before I crack  !

[awemawson]

So after an absolutely marathon session un-wiring, labelling, soldering, testing, and re-wiring Klippon 37 way terminal blocks all five are now done. 

The last one, OP2, wasn't too bad. Although pretty well fully populated all but eight wires had sensible numbers on them. Once out an inspection showed that one pin was a bit suspect at the extreme end of the socket, but of course I soldered all 37 then tested them for continuity. All well when re-installed 

So hopefully that has shaken out a few failures down the road and improved reliability markedly. It was only the IP3 block that show a gross error with virtually every pin moved off the board. Strange really as the cables to the D37 sockets are all well secured to the cabinet and not apparently straining the connector