Recent Posts

Pages: 1 ... 8 9 [10]
91
New from Old / Re: The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
« Last post by awemawson on June 17, 2018, 04:39:01 PM »
Pekka,

There is a  pair of external terminals on the PSU labelled "Power Supply OK" - they are not connected, but of course may also be routed internally to the backboard of the logic crate. They seem to be a N/O relay contact that closes a second or two after the PSU is powered up. Certainly they change state when the 'Reset' button on the PSU is pressed then revert to the closed state after a second.

Of course I have no idea whether relay open or closed is the good state, but as with no mains they are 'open', the likelihood is that 'closed' is 'OK'
92
New from Old / Re: The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
« Last post by PekkaNF on June 17, 2018, 02:30:29 PM »
.....
I wanted to prove the PSU was OK but only the +5 volt output had test points. I was fairly sure that it also was supposed to put out +15 v and -15 v.  Pulling the PSU apart it's only output connector is a three row  96 pin Eurocard type. I was surprised to find that mains for the 240 volt rack fans is routed via this connector. Inside I found a pair of 15 volt regulators confirming my suspicion, and also a Ferranti Uncommitted Logic Array - in a PSU for goodness sake WHY ?
....

If my memory serves right S5 135/150 series simens PLC rack had somewhat similar looking PSU module. I once had trouble with it. I was chasing non responsive CPU-card, when in fact the problem was "power good" sort of signal from PSU module. There were some handshake signals with busscontroller card/cpu/psu, it was not clear without consulting the technical manual, which we luckily had. If I remember right cpu had enough power to do post startup check and then fiqure out not to talk to bus, because status from PSU was not correct. It was all pretty odd to have some "logic" on the PSU, you might think that it just posts "power good" and that's it.

Not sure if this is relevant, but that was my personal encounter.

Pekka
93
Project Logs / Re: Building a New Lathe
« Last post by vtsteam on June 17, 2018, 01:24:42 PM »
And here's he finished bore gauge. The slot allows me to drop it down over the boring arbor and test the bore without taking apart my setup. I was a little apprehensive putting a slot in the gauge, in case there were internal tensions that would change the OD's, but measuring after slotting (and letting the gauge cool) showed the diameters were still spot on.

So I stamped both sides of the gauge with their dimensions, and we're ready to continue boring the journals.

94
Project Logs / Re: Building a New Lathe
« Last post by vtsteam on June 17, 2018, 01:20:49 PM »
Then I sawed a slot close to the finished diameter on my bandsaw. I probably could have left it there, but decided to clean up the slot on the mill:

95
Project Logs / Re: Building a New Lathe
« Last post by vtsteam on June 17, 2018, 01:18:17 PM »
I turned the gauge to 2.440" on one side and 2.430" on the other. Sorry I don't have any photos of turning, but if you're interested, John (Doubleboost) posted a fine video on youtube awhile back showing the process of bore gauge making (his ER32 lathe chuck video).

I'm adding an additional touch to suit my particular headstock boring setup here -- first drilling the gauge 3/4"

96
Project Logs / Re: Building a New Lathe
« Last post by vtsteam on June 17, 2018, 01:12:47 PM »
Getting closer to journal size, it was time to make a bore gauge. I found a scrap piece of aluminum 2.5" in diameter. The bearing measured (on my calipers) 2.4395". Not that they are accurate to a half thou, but I've been using it consistently, so parts should match.

97
New from Old / Re: The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
« Last post by awemawson on June 17, 2018, 01:11:54 PM »
A little bit more progress today:

I wanted to prove the PSU was OK but only the +5 volt output had test points. I was fairly sure that it also was supposed to put out +15 v and -15 v.  Pulling the PSU apart it's only output connector is a three row  96 pin Eurocard type. I was surprised to find that mains for the 240 volt rack fans is routed via this connector. Inside I found a pair of 15 volt regulators confirming my suspicion, and also a Ferranti Uncommitted Logic Array - in a PSU for goodness sake WHY ?

Soldering a pair of 'wire wrap' square gold plated pins to my test probes I was able go along the crate back board and find the 15 volt lines powered up, so that's looking good.

Then I turned my attention to some of the card retaining screws that had sheared off. They are M4 but have an extended outer part with a hand grip, and a turned down section to retain them in the card. Drilling tapping and Loctiting replaced the sheered threads.

Then it was a case of 'hunt the battery' The one in the back of the monitor was easy - it's an SL2770 and RS Components carry it. However the one on the little RAM card proved more elusive. The original is in far too bad a shape to take reliable measurements from, but eventually I found an image on the web that revealed all - it's an SL886. There are two versions, one with pins and one with pads, and the original and the image I found don't help the diagnosis, so I will wait until the replacement card arrives to see which before I order.

Strangely the data sheet for the SL886 give it's weight as 21 grams, and my ruptured one weighs EXACTLY 21 grams despite all that death and destruction that it has oozed  :scratch:

Apart from posting pleas for help on Practical Machinist and CNC Zone that's about it for today.
98
Tools / Re: Edgwick lathe
« Last post by Biggles on June 17, 2018, 12:54:30 PM »
Hi and welcome Faz, larger machines tend to be cheaper than Myfords at the low end. i expect Edgwick/Harrisons etc now days to be around the 1k mark if they are reasonable and with some chucks/tools etc. unless they from a dealer who will probably apply VAT. Having said that there is one dealer online forget his name, who doesn't have VAT.

George
99
Gallery / Window / glass camera mount
« Last post by David Morrow on June 17, 2018, 12:37:21 PM »
A friend of mine lives in a high rise apartment and nearby, there is another tall building undergoing a slow motion demolition - about 2 years. He bought a camera that could be set for time lapse photos and mounted it to his window with a suction cup mount - same suction cup as many dash cam's. The problem was that the suction was only good for a few days, maybe a few weeks. Putting the camera back in the exact same spot and angle was almost impossible when the suction was lost. I suggested that we make a mount using rare earth magnets - half the magnets attached to the mount, and the other half on the other side of the glass. The window was single pane and that made the distance between the magnets much smaller. We made the mount to use 8 magnets on each side but found that 4 was the safe minimum and 6 magnets stuck like the proverbial to the blanket. He ended up using all 8 because he already bought them. To say that this mount was solid when mounted on the window is an understatement. The camera was attached to the window mount with a Ram arm and Ram ball.

This is the mount being tested on one of my kitchen cabinet doors.




100
CNC / Re: DDCSV Support Forum
« Last post by 71taa on June 17, 2018, 11:31:04 AM »
Pages: 1 ... 8 9 [10]