The Craftmans Shop > New from Old
Yet another Beaver resurection (TC20F)
awemawson:
Excellent that you found it.
I'm reminded of once years back when I was called in to a fault at the CEGB National Control Room at Park St SE1. (*) We had two suites of Argus 500 computers, a main and a standby monitoring the grid network, and smoke was coming out of the Burroughs 2 mByte fixed head disk on the stand by side. They were on separate phases running off a huge battery bank and invertor set up. They had a high resistance neutral bond, so one suite was getting about 150 V AC and the other something like 350 hence the smoke. Fortunately only a fan but you see even the best people can get it wrong !!
(* all moved to Winersh near Reading now)
JeffK:
Well I guess its been a while since I last posted,,,, been busily :D making parts with the Beaver :D I finally discarded FAPT and figured out how to program the machine without it. Apart from a few issues with tooling and getting feeds and speeds right all was going really well with until the CRT went 'Ping'. I managed to source a replacement LCD monitor at a cosy and everything went back to normal.
Then the other day I was trying to cut an acme thread. I had done this before and had the program I had used previously successfully so was a bit puzzled when the end product was more like a series of razor blades than a nice square acme profile :scratch:
I tried a few things, bought a new insert holder etc but to no avail. Finally figured out the spindle encoder was slipping :Doh:
To retrieve the missing grub screw that held the encoder shaft in place I had to disconnect the encoder and pull the whole drive wheel off. Retrieved and re-secures all of the bits and all seemed to be well except now when I use MDI mode the feed works perfectly but when running a program the machine stalls on the first line where there is a feed command - even on programs which worked perfectly before.
eg. If I enter G01Z-3F0.01; in IPR feed mode in MDI it will work fine but if I enter the same line in a program the program stalls at this line and will not execute the command.
I am pretty sure disconnecting the encoder has messed something up either in the spindle synchronisation or just with the parameters - the question is what? :scratch:
Any ideas would be most welcome as this one has had me stumped for days and despite reading manuals etc I have not come up with anything useful yet.
cheers
Jeff
awemawson:
Bad luck Jeff. Mines a Siemens control unlike your Fanuc, but I seem to remember that the encoder has an index pulse once per rev as well as the quadratue A & B pulses. Could it perhaps be missing.
A ‘scope job I think.
JeffK:
You may be right but I wondered if just disconnecting the encoder could create an issue? May have to go out and buy a scope to check it with as I don't have such a beast. Got by over the last few months with a simple multimeter (believe it or not!!). The thing that confuses me is why everything worked ok before I disconnected the encoder but now doesn't. If I had inadvertantly broken a wire or something in the connector surely MDI would not work? Unless I am unlucky enough to have damaged the actual encoder (I was pretty careful with it). Any recommendations for a decent scope?
cheers
Jeff
awemawson:
s/h Tektronix scope off eBay They are robust and professional. You don't need a particularly high spec one.
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