[gthlm]

Cliff,

I went against your advice and bought that hurco 4th on ebay, beat the price down a bit though!

Anyway, turns out it was a good buy I think, it's in pretty good nick, used but not abused! Mechanically smooth and tight, servo motor is good, haven't checked the tach or encoder though.

I want to fit it on dad's bmc25 (serial # BN9-009-060 if it's any help, already rigged up for the 4th - hydraulics and all), we discussed it before if you recall and thought it would be a direct fit. What I mean to ask is what are the chances of getting a cable from hurco? Or failing that, would you be able to assist me in making one up? It came with manuals inc. wiring diagrams but I've nothing for the machine side.

The amphenol connector on the unit is peculiar, and is damaged slightly. I'd like to replace it but can't find anything like it. Any suggestions on that?

Photos:







Cheers, Gregor

[bloke]

Gregor,
How are ya, fella?
It's funny you should mention this as at the start of the week, and due to having a bad back at the moment, I tidied my desk up a bit and found the original drawing for the J+S tables.
The connecting cables (they called them umbilical cables) were a pain in the backside to make (I did all of them for the last couple of years we did the J+S tables. Those connectors are hideous to work with and I'd recommend replacing the ones you have with Amphenol connectors. The originals used a specially made adaptor for Anaconda conduit fittings and I doubt you'd be able to get them any more.
If you went Amphenol, I'd put a straight PMAfix fitting in the motor box on the table (28mm conduit available from R.S.) then replace the cabinet fitting with an Amphenol socket (MS3100A 28-11S should do it nicely). If you struggle finding a supplier for that, do a searh for a company called Temar - they do Amphenol stuff and they hold those sockets under this number: DMS3100A28-11S. If you ask for a plug to suit and a straight, threaded backshell for it, they'll sort you out.

The cabling was simple enough to sort out and I can let you know the pinouts and a recommended new layout for the Amphenol socket.
Does your machine have a servo amp and dual axis card in it for the table?

[gthlm]

Cliff, I'm well thanks, yourself?

Firstly, dad and his machine are 300 miles away and I have to take a holiday whenever I want to tinker with the thing, so the more I can get figured out in advance the better!

The machine came prewired for the 4th, a/b dual axis in place, servo amp in the cabinet, air/hydraulic unit mounted too. Only thing missing was the table!

The amp is an odd looking thing, I haven't ever examined it closely, but it's an open board with no enclosure, mounted down at the bottom left of the cabinet. That's all I can remember about it off the top of my head. I'll get him to take a photo of it.

I will do as you suggest and get replacement connectors.

Hope the back doesn't keep you out of action for too long.

Thank you very much for your help mate.

[bloke]

I'll dig you some wiring out on monday and see if I can PDF it as it is in the old diazo copy form (like I said, it's the original copy so it's a bit old! Could you PM me an email address to send it to as I can't find yours?
Have a good weekend!

[gthlm]

PM sent.

I don't even know what diazo copy is? Must be before my time!

My weekend will be spent killing myself trying to meet monday's deadlines, hope yours is better!

[bloke]

I know it's on old process we used to use years ago for copying drawings done on what looked like tracing paper. You'd feed the sheets in along with another sheet of yellow copy paper and then back feed that on it's own through the proceesing fluid.
The whole process stank of ammonia!
Here's a bit of a linky: Whiteprint - Wikipedia, the free encyclopedia

Edited to add: Cheers for the mail address, I'll get something sorted next week for ya!

[gthlm]

Cliff,

Well, after all that it turns out the old git has HAD the right cable all along. Came with his machine. I suppose I should talk to him more often!

Anyway, I'm going to be sending it up to him soon so I expect I'll have some more questions. I do know for a fact the rotary axis encoder resolution setting has been reset because I had to replace the memory board batteries a year or so ago.

I have a few mechanical questions about the unit that I wonder if you might be able to answer.

What type of oil do you put in it and where does it go? There is no sight glass or obvious filling point but I can only assume it's supposed to run in oil?

Is it possible to adjust the graduated ring with the calibration block in relation to the spindle? The chuck sits at a random angle when it's at 0 degrees.

I'm beginning to wonder if this is not in fact the actual 4th axis missing from his machine. Apart from being the same colour, they both arrived covered in the same phenolic dust that they had clearly been machining!

[bloke]

Don't you just love it when that happens?!
The old J+S rotarys were just greased normally. If you want to check yours for grease, take out the hydraulic fitting in the table (keep an eye open for the aluminium seal in the bottom of the hole) and then undo the outside line of screws on the back of the table and the whole brake unit will pull out. From there, you'll be able to see the worm/wheel and check it's umm.. errr.. greasiness.
If you want to adjust backlash on it, there is a small clamping plate on the bottom with four M6 caps that you can slacken slightly and then adjust the eccentric using an 8mm key in the hexagon in the centre. If you remove the name plate cover you'll be able to turn the worm (Ha! the worm has turned! Sorry about that, I couldnt resist) by hand and "feel" the meshing you have.
Just a side note, if I remember correctly, when you tightened the four M6 caps to lock it up again, it nearly always made the meshing tighter. The best thing I found was to pinch the M6 caps slightly before adjusting and the effect on tightening them had little effect then.
The booster for the table shouldn't be set to anything above 50 PSI on the gauge as it could burst the brake out of the back of the table (this was both ugly and expensive).
As far as I recall, there was no way of moving the graduated ring - that was just how they arrived from J+S.
Keep us posted, fella!

[gthlm]

Spot on as usual Cliff!

Was pleased to see the innards are immaculate with just the 'right amount' of nice clean grease covering the worm and wheel.

I see what you mean about them being small for the size of table though. However it won't be working hard where it's going.

Thanks for the tip about the booster. I will make sure and check that carefully before it's plugged in!

I will probably hardwire the cable at the motor end as you suggested and do away with the damaged socket. Hopefully I'll be able to keep the one on the machine as I got a price for the socket/plug you suggested and was 'slightly taken aback'



Thanks, Gregor

[bloke]

One more thing, Gregor. To bleed the hydraulics for the brake, there are two little plugs on the back of the table that let the air out. They are at the top when the table is stood on either of the mounting faces. I think they are 1/8 BSP if I remember correctly. Obviously, you only need to do the uppermost one for the face it's sat on.
Should only need doing the once after taking the hose adaptor out.

[gthlm]

Thanks Cliff, I did wonder about that at the time and was going to ask you, but I forgot about it.

BTW, I have an unrelated question that doesn't warrant a new thread; What is the likelyhood of being able to get our dcx32 with a big plus spindle? Or HSK100 maybe?

I'm looking at a job that might end up being regular, that would be the better for something more solid than the basic 50 taper interface.

We spoke to Steve Turner about it this afternoon, but my boss asked me if I could get your opinion too, knowing that you've been quite involved with that model.

Thanks mate, Gregor

[bloke]

I'll see what I can find out for you. I'm not sure what other options are available for sure.
If I remember correctly, they were going to be available with a variety of different spindle types including a 5 axis model.
I'll get back to you on this!

[gthlm]

Cliff, at last I have the rotary hooked up and all is working except the rotary parameters were lost when the batteries died and the encoder counts are wrong. Do you happen to know the correct encoder resolution and the max speed?

Cheers, Gregor

[bloke]

Should be 2000 counts / degree and I think 6 RPM.

Gregor, go to bed!
G'night, fella!

[gthlm]

Haha yeah it was a late one last night, still I could say the same to you!

Anyhow I was back to messing with it this morning. By the trial/error/calculator method, it turns out the correct resolution is 1426 counts/degree which seems a bit random but I took it four full turns in one direction and it seems accurate and correct. Also I have the max rpm at 4, more than that causes motion errors during rapids, but I really don't know what that one should be at all. When calibrating I get an a axis servo alarm if it has to travel too far (more than quarter of a revolution - ish) to the calibration marker. After it's cal'd though it seems to work fine.

Another minor curiosity is that it does not move very smoothly using the mpg. You have to watch closely but you can see turning a bit irregularly when you are turning the mpg quite steadily. Seems to work fine on auto though.

Any thoughts on what I've done so far, the servo fault when cal'ing or how to set the max speed correctly?

Cheers mate!

[bloke]

It sounds like you have a dirty encoder. If it's run really slowly in program, does it jump at all? It sjould always find a marker in less than 4 deg.

[gthlm]

Well Cliff, I followed your advice and opened up the encoder, but found it not dirty but broken in several pieces! How it was working at all I have no idea...



The encoder is made by Litton and I'm going to look for a replacement but I don't have particularly high hopes of finding one, more likely a new motor will be called for. Do you have any leads for finding an encoder?

Thanks, Gregor

[bloke]

Gregor, I've sent a mail to your fastmail account.

[fasto]

Gregor I don't know what Bloke's got up his sleeve, so I will just mention that all encoders are about the same. If you can source a 2000 PPR encoder (if that's the proper resolution) with a marker pulse and get it to fit on the motor's shaft you will be fine.
I'd imagine that any number of outfits catering to the CNC conversion crowd would have such a device available.

One other possibility that I ran into is a program that will print the encoder graduations using a laser printer. I don't exactly recall where I saw it; I will look if you would like.
Here it is, Codewheel Generator, though I'm not sure that it will do 2000 PPR as it seems more geared towards the jog wheel type encoders.

[gthlm]

Aaron, thanks for your suggestions. I was unable to find a suitable replacement (1000ppr, 1/2" hollow shaft mount) but with Cliff's help we got a hold of one and he helped me set it up.

Here's the first test piece: