Search found 1740 matches

by John Hasler
Sun May 30, 2021 2:14 pm
Forum: Milling Machines
Topic: Fixing the electrics in my old German mill Ruhla 250/710
Replies: 63
Views: 2692

Re: Fixing the electrics in my old German mill Ruhla 250/710

Make copious notes so that you refer to them when it goes wonky again in the future.
by John Hasler
Sat May 29, 2021 4:06 pm
Forum: Milling Machines
Topic: Fixing the electrics in my old German mill Ruhla 250/710
Replies: 63
Views: 2692

Re: Fixing the electrics in my old German mill Ruhla 250/710

We call that the smoke test. Possible scores are working machine = 10, nonworking but no smoke = 8, some smoke but fixable = 6, flames that go out when you cut the power = 4, call the fire department = 0. I've done it many times on all sorts of electronic and electrical stuff and never scored worse ...
by John Hasler
Fri May 28, 2021 7:45 am
Forum: Milling Machines
Topic: Fixing the electrics in my old German mill Ruhla 250/710
Replies: 63
Views: 2692

Re: Fixing the electrics in my old German mill Ruhla 250/710

liveaboard wrote:
Fri May 28, 2021 2:10 am
got it, thanks for the clarification.

But with 230v coil voltage, don't I need capacitors rated at 230+ ?
I somehow got the impression that you had a 24 V control transformer. Yes, the snubber network components must be rated for the coil voltage plus a comfortable margin.
by John Hasler
Thu May 27, 2021 10:34 pm
Forum: Milling Machines
Topic: Fixing the electrics in my old German mill Ruhla 250/710
Replies: 63
Views: 2692

Re: Fixing the electrics in my old German mill Ruhla 250/710

Measure the resistance of one of the relay coils. That's Rcoil. Connect a resistor equal to Rcoil/2 in series with a .47 uF capacitor. Connect that series combination in parallel with the relay coil. Do that for each relay. Use 1/4 watt resistors and 100 volt or higher ceramic capacitors. Or connect...
by John Hasler
Thu May 27, 2021 10:14 pm
Forum: General Discussion
Topic: The dumb ideas I get sometimes
Replies: 18
Views: 828

Re: The dumb ideas I get sometimes

No taper. Tilt the rotary table and use a radius endmill. No need for a sine table either. For a non-critical 2 degree angle shims will do.
by John Hasler
Thu May 27, 2021 9:35 pm
Forum: General Discussion
Topic: The dumb ideas I get sometimes
Replies: 18
Views: 828

Re: The dumb ideas I get sometimes

I'd use my rotary table and an end mill to add draft.
by John Hasler
Thu May 27, 2021 11:50 am
Forum: Milling Machines
Topic: Fixing the electrics in my old German mill Ruhla 250/710
Replies: 63
Views: 2692

Re: Fixing the electrics in my old German mill Ruhla 250/710

Your relays will be fine. A transient protector in parallel with each coil could lengthen contact life.
by John Hasler
Tue May 25, 2021 7:53 pm
Forum: Milling Machines
Topic: Fixing the electrics in my old German mill Ruhla 250/710
Replies: 63
Views: 2692

Re: Fixing the electrics in my old German mill Ruhla 250/710

You would be surprised at the transients that ate generated with stopping and starting motors. Takes a recording scope to see them....cannot measure them with a meter. all they gave to do is pull in a contact for an instant and cause a control circuit to engage and latch when you do not want it. He...
by John Hasler
Sun May 23, 2021 8:14 pm
Forum: Milling Machines
Topic: Fixing the electrics in my old German mill Ruhla 250/710
Replies: 63
Views: 2692

Re: Fixing the electrics in my old German mill Ruhla 250/710

Those old "Selenium" type rectifiers would fail over time. The new bridge rectifier will work much better. Also, wear gloves when touching the selenium rectifiers. They are considered to be toxic. There's no hazard in touching elemental selenium (besides, the plates you can touch are just heat sink...
by John Hasler
Sat May 22, 2021 8:30 pm
Forum: Lathes
Topic: Show us your lathe!
Replies: 484
Views: 203779

Re: Show us your lathe!

If you can't find proper way oil chainsaw bar oil has similar properties. While you are looking for the right stuff, though, oil it up with whatever you've got.
by John Hasler
Tue May 18, 2021 2:25 pm
Forum: General Discussion
Topic: Parkerizing
Replies: 5
Views: 1730

Re: Parkerizing

I have used a heated tank. The process goes much faster with heat and I think that the resulting coating is thicker. I don't usually bother, though. I just leave the part in for 3 or 4 hours, sometimes overnight. I'm not usually concerned about appearance (I'm doing parts for my power hacksaw now) b...
by John Hasler
Tue May 18, 2021 10:58 am
Forum: General Discussion
Topic: Parkerizing
Replies: 5
Views: 1730

Re: Parkerizing

I've had good luck making steel and cast iron machine parts rust resistant (though not rust proof) with phosphoric acid. I clean the parts with acetone and then soak them overnight in 10% phosphoric acid (I use dairy milkstone remover). Make sure the parts are fully submersed and exposed to the solu...