Author Topic: Servo Driven 4th Axis for CNC Mill (Read 82604 times)

awemawson · « **Reply #100 on:** February 09, 2014, 07:03:49 AM »

Having traversed the front of the machine the 20 mm flexible conduits terminate, along with many others, in the wall of the electrical cabinet.

From there for now they stop on a DIN rail mounted terminal strip, from whence they will be wired to the rest of the machine. Exceptions being the Heidenhain encoder, that goes directly to the TNC355 controller in it's rather special 4 pair twisted screened cable, and also the tachometer output which goes directly to the Bosch servo card in screened twisted pair

awemawson · « **Reply #101 on:** February 09, 2014, 07:06:46 AM »

At long last the pneumatic valve has arrived allowing me to make up a bracket and mount it. I'm glad to say that the brake works very well. In the relaxed state the cylinder is releasing the brake, and when powered it is applied

awemawson · « **Reply #102 on:** February 09, 2014, 07:10:30 AM »

I then could start planning how to physically fix the ends of the umbilical flexible conduits that lead from the 4th Axis to the termination box.

I decided that the easiest thing was to replace the SEM servo motor termination box with a much larger one that could take the Adaptaflex fittings, and also the air fitting, so went too and made a new box:

awemawson · « **Reply #103 on:** February 09, 2014, 07:16:31 AM »

Now that all went very well, I was pleased with the result . . . until I realised that due to the minimum bend radius of the flexible conduit the 4th Axis could not be layed down in 'rotary table' mode

Now I'm unlikely to want to use it as a rotary table, but will want it sat that way for initially mounting chucks and the like, so a re-think was needed. I could have brought the cables out on the rear of the box on the narrower side, but that would have made the 4th Axis too long and the cables would foul on the enclosure door.

I fell back to using the original SEM termination box with the cable emerging 'backwards' so that the curve could be accommodated, and making up a bracket for the second conduit which I had to reduce to 16mm to clear the body of the motor

awemawson · « **Reply #104 on:** February 09, 2014, 07:25:35 AM »

The transformer to drive the Servo motor and card has arrived, and this and that 'wandering choke' will now be mounted alonside the original transformers on the base of the electrical enclosure

awemawson · « **Reply #105 on:** February 09, 2014, 07:28:19 AM »

I still need to mount a contactor for the 4th Axis power, with it's associated MCB, a brake operating relay, and a '4th Axis enable' relay' - these relays are on order and should arrive during next week - but so is the new puppy, so that may delay progress a bit

Watch this space . . . . .

awemawson · « **Reply #106 on:** February 10, 2014, 11:28:11 AM »

Well the relays arrived today, as did another coil of Adaptaflex, but so did this chap, so no more progress for a few days I expect, especially as we are replacing the oil boiler in our holiday cottages tomorrow (Tuesday). This'll be the third (and hopefully the last) boiler I've replaced since we bought this place. (That's the house, the workshop and now the cottages )

Pete W. · « **Reply #107 on:** February 10, 2014, 04:06:10 PM »

Hi there Andrew,

I don't know whether this is

or not:

My lovely but shy assistant suggested, at 50% confidence, he's a Vizsla. (My confidence regarding the spelling is much less than 50%!!

)

John Stevenson · « **Reply #108 on:** February 10, 2014, 04:26:26 PM »

I have seen Andrews other two dogs, absolutely gorgeous, like stroking velvet, unlike that shaggy mad dog I own.

awemawson · « **Reply #109 on:** February 10, 2014, 04:35:59 PM »

Yes Pete, Hugo is a six week old Viszla and is being spoilt rotten on my lap as I write this.

John, sadly Max our 5 year old Viszla, the larger one of the two you saw, died very suddenly in November. So Hugo is here to fill a big gap and has a lot to live up to.

John Stevenson · « **Reply #110 on:** February 10, 2014, 04:57:27 PM »

Andrew,
So sorry I didn't know. It's always a wrench and you say you won't have another but you always do.
We are on No's 9 and 10 of the Old English Sheepdog rescues.

But No 9 is doing my head in, play for England 25 hours a day, mind you if truth be known he plays better than England............

Pete W. · « **Reply #111 on:** February 10, 2014, 05:02:15 PM »

Hi there, Andrew and John,

This is definitely

but here goes,

This is 'Unity', she's a retired guide dog, twelve years old and has been with us just two years and one month.

She's successor to our previous GSD who we lost at six and a half years of age, it took us a while to get over that loss.

We meet several Viszlas while dog-walking in local venues, one of them is wire-haired.

awemawson · « **Reply #112 on:** March 09, 2014, 08:28:59 AM »

I'm pleased to say there has now been lots of progress on the 4th Axis.

I decided that the side exiting wiring was a no-no, and that the use of the original SEM termination box was messy, so I re-made the motor box with rear exiting cables that have to emerge 'upwards' to avoid fouling other things. I also gave the mechanics a lick of paint, that no doubt will all be removed in use !

awemawson · « **Reply #113 on:** March 09, 2014, 08:31:53 AM »

I then wired up the various relays needed:

a/ 4th Axis enable
b/ 4th Axis brake
c/ 4th Axis ESTOP

Wired up the servo card and finished off the external termination box

awemawson · « **Reply #114 on:** March 09, 2014, 08:43:44 AM »

At this stage I was then able to start testing. The system worked, amazingly, but I couldn't get a decent speed out of it without generating 'Gross Positioning Errors' Fairly obviously the servo card needed tuning, and some parameters tweaking in the control. However the good bit was that the gearing and encoder interface was working correctly to give me 360 degrees for a full turn as it should.

I went through the Bosch manual MANY times following their procedure, and try as I might couldn't get the main servo motor spinning more than about 700 rpm without errors - it's max speed is 3100 rpm and I'd initially set it up to max on the servo at 2000 to be on the conservative side.

Many people offered help, both from this forum and others and I thank them profusely, but the break through came the other day, when by chance I was put in touch with a local chap who had installed this type of servo card many years ago.

Long story short - he came round yesterday, and after four hours of tweaking, un-tweaking and head scratching we got it to a very acceptable performance. Servo motor is now reliably able to spin at 2500 rpm giving 2500 degrees a minute on the table.

So to celebrate, last night and this morning I made up the swarf cover and am ready to put it on the machine table and try it for real. That won't happen immediately due to family commitments

Brass_Machine · « **Reply #115 on:** March 09, 2014, 11:52:09 AM »

Wow Andrew,

That looks very nice. Anxious to see the results of all your hard work.

Eric

Pete W. · « **Reply #116 on:** March 09, 2014, 12:27:51 PM »

Hi there, Andrew,

Your project is coming along nicely, exciting stuff.

How is Hugo?

I've actually been cutting metal myself this afternoon, I may get some photos on my thread later.

awemawson · « **Reply #117 on:** March 09, 2014, 04:00:13 PM »

Thanks Eric and Pete for the kind words - it's been quite a journey getting to this point, much more than I'd have expected, but I'm happy so far with the result.

Pete, Hugo is now at least 2 1/2 times the size he was when we got him and he's only 12 weeks now - took him round our field this morning as things are drying out nicely. His 'sister' Cleo decided to swim in the stream, and he plunged straight in. Fortunately he seems to do a good doggy paddle

Off to the abattoir early doors tomorrow (it's half an hour away and I have to be there by 7 am having cajoled the sow to get in, then have to go to the bank regarding some trustee business for my niece so I'l be lucky if I get any play time by the time I've hosed out and disinfected the stock trailer and concreted in the bolts for the new gates (replacements for the ones we lost in the storms) and adjusted the hinges. Hard work this 'retirement'

John Stevenson · « **Reply #118 on:** March 09, 2014, 06:30:30 PM »

At least it will keep you away from the white paint - Yuk

awemawson · « **Reply #119 on:** March 10, 2014, 05:17:20 AM »

Quote from: John Stevenson on March 09, 2014, 06:30:30 PM

At least it will keep you away from the white paint - Yuk

Grumpy old git

It's actually a tasteful shade close to magnolia that was colour matched to the rest of the machine, but it's not a brilliant match !

awemawson · « **Reply #120 on:** March 11, 2014, 10:48:15 AM »

Well after a bit of a struggle I managed to get the unit up onto the milling table. By heck it's heavy. I fitted a bar in the chuck as a handle, moved enough junk out of the way to get my hydraulic pump up table closish, and used a bridge of 18mm mdf to slide it into place.

awemawson · « **Reply #121 on:** March 11, 2014, 10:49:20 AM »

So now it's on the table it needs holding down - I need to make some clamps

If you look closely at this picture, I've added a rear 'brace' to the swarf cover that picks up three of the bolts on the encoder belt box. This was to make it a little more rigid and stop drumming

awemawson · « **Reply #122 on:** March 11, 2014, 10:51:05 AM »

However its not going to happen immediately as these four little piggies that I picked up this morning need dealing with

John Stevenson · « **Reply #123 on:** March 11, 2014, 01:42:03 PM »

OOooo goody, sausages........

awemawson · « **Reply #124 on:** March 11, 2014, 02:08:53 PM »

Quote from: John Stevenson on March 11, 2014, 01:42:03 PM

OOooo goody, sausages........

I've approx 100 kGs of sausages coming back next week from the demise of Martha the sow if you need sausages . . . .

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Author Topic: Servo Driven 4th Axis for CNC Mill (Read 82604 times)