Oh Blimey I bought a CNC Lathe !!!!

[awemawson]

Adev that's definitely not recommended in large quantities. At the very least you need to pour the concentrate into a flowing stream of water / coolant or it will tend to float and add to your tramp oil problems by hiding in non turbulent areas. Remember that the reservoir is the base of the swarf conveyor, so there is no large accessible tank to mix into, only the upper surface of the conveyor belt. The bulk is inaccessible and below.

Now if I had had a 45 gallon drum to hand I could have mixed it in that as you suggest, but I didn't ! It is quite important to get the concentration reasonably accurate, firstly so that you know you have the right mix for your tooling and rustproofing, but also so that you can monitor it over time and know what's happening. Industrial production practice would be to measure the refractive index and acidity daily and trend it on a graph, but I'm not going that far!

Anyway MSC have done the decent thing and refunded me.

[AdeV]

OK, in that case.... fill with water, turn on swarf conveyor to get good sploshing motion going, add concentrate?

Understood about the concentration - interestingly the stuff I use reckons anything from 5-10% is good, I usualy mix it 2ltrs oil to approx 23 ltrs water ( a convenient barrel full).

[awemawson]

5% is usually good for grinding and that's what's in my surface and also my cylindrical grinder. As you go up in the cutting forces you need a higher concentration all the way up to 10 or 11% for heavy machining stainless steel or HT steels in the hard state.

Incidentally the swarf conveyor goes at a slow crawl, so not much stirring there !

I've been experimenting with the various canned cycles in the control - amazingly sophisticated - today's play has been around the 'roughing cycle'. You can define a finished contour on your part that is the shape your final pass with your finishing tool makes, then call up a 'roughing cycle' that makes multiple passes getting closer and closer until your finishing allowance is left.

Two slight detours on the way. Firstly it seems that although 'absolute positioning' moves in X refer to the part diameter, 'relative  positioning' refers to radius  so:

G01 X25.00 put the tool on 25mm diameter or actually X=12.5

whereas
G01 X0
G01 U25.00 puts the tool on 50mm diameter or actually X=50  (U being the way relative X moves are defined)

Confusing until you know, and it's nowhere in the book of words that I can find 

Second detour involved the tool setting microscope. It has specific co-ordinates stored in the control so that tool offsets can be calculated from its known position. Well they were slightly wrong so I couldn't achieve correct diameter work, until a bit of head scratching and adjustment of the pre-set location 


Next onto the threading cycles for a bit of fun 

[lordedmond]

 Slowly slowly catchee monkey

getting there , guess you are up to full working condition now with all this posting when you should be resting



Stuart

[mattinker]

I'm glad to see you onto details most of which escape me!

The end in sight, what's next!

Regards, Matthew

[awemawson]

Thanks chaps for the support - should be signed off (or is it back on?) in a couple of weeks - hooray I can drive again.

Anyway back on topic.  I cut my first thread today 

It may only be simple but it took a long time coming 

This is the first 'real' operation sequence since I got the lathe running. First I cut the profile of the thread, which is 20 mm o/d by 25 mm long with 45 degree lead in and lead out, cut from 25 mm mild steel stock. Then I cut the thread itself, which is 1.75 mm pitch using a 'partial' thread form insert as that was the only one I had on a tool holder! Then profiling was an exercise in "G96" roughing cycle following a defined profile. Then the thread was a "G76 thread chasing cycle"

Made my head spin understanding all the parameters but we seem to have got there!

Only slight down side is that I've had a few 'trip outs' on the axis drives - no real rhyme or reason and so far they've always reset, but there's something lurking there still 

Anyway on a more positive note have some pictures, and a video will follow as soon as it's uploaded

[lordedmond]

that looks a fine thread ( I mean a well curt thread ) was it on spec ?

better get down to chasing those pesky bugs , but I fear that you may well have a few more to sort the more you use the beast


Stuart

[mattinker]

Those moments when it all works, those moments are special...................

Regards, Matthew

[awemawson]

Here's the video of the screw cutting. The 'roughing' and 'finishing' tools are in fact the same tool as the roughing tool I had mounted fouled on the 45 degree chamfer nearest the headstock.

I'm using 'constant surface speed' machining so if you listen hard you can hear the spindle changing speed with the diameter of the cut.

[awemawson]

that looks a fine thread ( I mean a well curt thread ) was it on spec ?

better get down to chasing those pesky bugs , but I fear that you may well have a few more to sort the more you use the beast


Stuart

Stuart, well it's what I aimed for  I don't think 20 mm x 1.75 can be a standard by any means. The pitch is as right as I can measure it, and the o/d is dead nuts on at 20 mm as I specified, whereas if it was being made for proper the o/d would be slightly under nominal size. Thread form is down to the insert, but looks ok in comparison to a thread gauge. I've bought a new set of metric full form inserts, but didn't want to mount them and wipe them out whilst learning 

Andrew

[BenH]

I just had to read all of this, crikey there is some work involved so far. Great read though and very interesting thanks

[RussellT]

 

Russell

[Pete.]

Great vid Andrew!

BTW is there a problem with the seal on the tool turret? It seemed to be leaking coolant from the back of the rotating head after it switched to the threading tool, so much that the coolant feed was only dribbling.

[awemawson]

Sadly yes Pete, the rotary seal is leaking. It's retainer seems to have rusted at one spot but the way to disassemble isn't immediately obvious.

The relatively little flow on the threading tool is more due to the fact it's tube has been badly squashed and is 'on the list' - it's only 6 mm steel pipe threaded standard 6 mm - the seal only leaks badly on high pressure coolant. Several of the tools have no tubes and those not used are not yet blanked off so coolant is going all over the place.

[vtsteam]

Wooooohhooooooo! A widget!!!

 



nice lookin one, too!

[awemawson]

Thanks chaps - it's only simple stuff really but takes a lot of working out 

I've been experimenting with alternatives places to mount the camera, as where it has been isn't the best angle. Problem is where it is is the best for keeping out of swarf and coolant.


This is a rather unsuccessful re-siting of the GoPro camera on the inside of the lathe cabinet door. Far better viewing angle but as I suspected too much in line for coolant splashing. I deliberately "re-cut" the thread previously videoed so that no swarf was produced - I suspect if I did a real cut the swarf would destroy the Gopro outer casing lens in short order

Perhaps I need to make one of those spinning disk windows that they have on Lifeboats and trawlers - and make a good supply of spare window disks. (hey can you get CDs as see through ?)

[John Stevenson]

Perhaps I need to make one of those spinning disk windows that they have on Lifeboats and trawlers - and make a good supply of spare window disks. (hey can you get CDs as see through ?)

Or speak nicely to someone who has a laser and a big stack of clear perspex.

[awemawson]

Well John that's a jolly good idea 

I was thinking of you today as I stuck those laser cut labels on the machine this morning.

[chipenter]

When you buy blank CD's on a spindle they usually have a clear disk top and bottom for protection .

[awemawson]

Good point Jeff - thanks.

I've tried another approach:

Here the same machining sequence is being filmed through the window in the machine sliding door. Hand held as I had no suitable mount. Again not ideal but at least the window tends to clear - this one may be worth pursuing.

[redshift]

What about mounting on the angle bracket thingy behind the chuck?
Regards
Dave

[awemawson]

Dave, that's the mount for the tool setting microscope - it has a door that flops down to keep swarf and coolant out of the mounting as it's only used when the lathe is not rotating. It has a nice convenient VDI30 socket which is tempting to use but I want to keep the inside un-violated !

[awemawson]

Yesterday I rolled my sleeves up and got down to trying to sort the intermittent axis servo drive fault I'd been having. Analysing the error reports the drive was saying that it had lost contact with the controller.

This perhaps, maybe, perchance, just could be poor connections somewhere thought I clutching at straws. I noticed that under the cooling unit there was quite a significant pool of condensate on it's drip tray. Also the inside of the cabinet was rather clammy to the touch.

I came to the conclusion that the chiller was perhaps set to come on at too low a temperature, and was blowing damp air around. Mopping up and resetting the chiller to come on at a higher temperature was the next action.

I also dismantled the various boards of the servo drive, and all the interconnection plugs and sockets to the controller, and put them back together with a tad of contact cleaner spray, ensuring everything was screwed back firmly.

So today's mission was to perform a 'soak test'. I left it cycling round the program making and re-making that poor old 20 mm screw thread for getting on for three hours. So far the fault hasn't raised  it's 'orrid head above the parapet, and I'm keeping my fingers crossed, but making no assertions !

This soak testing meant I had to be there twiddling my thumbs so I got on with something else described here:

http://madmodder.net/index.php/topic,9180.msg101132.html#msg101132

Andrew

[lordedmond]

if it pokes its head up shoot it with a 12 g both barrels that should fix it


when I was working as a sparks at the iron works intermittent faults cause us more that one nightmare when is a continuous process plant thats in trouble , think pipe casting and blast furnaces , they cannot be stopped without  costing a fortune , think back tho it was a lot worse at the bank 40 million in five mins downtime that mdd you sort it out


Stuart

[awemawson]

Tell me about it! We had computers controlling Llanwern, Port Talbot, and Ravenscraig, so 'just going off line for half an hour' wasn't going to happen !