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I changed the subject line so it's not so long, more in line with other groups. Hopefully this makes it easier to find things. If there's any issue with this, we can put it back as it was.

Please post sites on projects idea's This just found on small lathes projects http://www.deansphotographica.com/machining/projects/projects.html

The following items have been added to the Files area of the [email protected] group. /5)Charts_&_Tables/8 Hardness Tester.pdf By: davesmith1800 <davesmith1@...> Description: No mark hardness tester Also fun project I have had one since the 1970’s

/g/minilathe/files/5%29Charts_&_Tables For some reason #8 did not downloading to my phone later today turn a real computer and get done. It is on hardness testing I like leaves no marks on finished parts. The biggest cost in the plexiglass tube. Today I use a ?" diameter ball bearing so if drop on floor I can find the ball. At one time I had Rockwell tester but it leaves a mark after testing not good on new parts. It is nice easy useful project too. The Mohs hardness is easier for looking for materials scratch and go with magnic. All do is use like pencil of few type of hardness , magnetic and tape and ready for material hunting. The magnic is good see steel or not and 300 series and 400. FYI Most avoid 400 and it is magnic will work hardened to glass Dave .

Switch Mode Power Supplies have at minimum 20 mS hold-up. In reality they have more, but not necessarily a lot more. I built a factory control system for the DOE way back when and used an unregulated "Ugly" brand power supply for the 24V. BIG transformer, BIGGER capacitors. Worked great. Cheap (for the time). Upper right corner of left enclosure Me working on version 2. I said it was way back in time, there are dinosaurs outside! On 10-Feb-25 20:44, Bill in OKC too via groups.io wrote:

In 1986 I was attending an Army Satellite terminal training class at Ft. Gordon, GA. Had a bad storm that night that shut down our terminal. I'd been writing a letter on the Heathkit. H89 computer when I left for class. Expected it to be shut down when I got back to the dorm. Nope! The filter caps in that power supply were the size of my fists. It was only a transient power hit, but it took down the relatively modern MILSPEC satellite terminal, and didn't touch the monstrous linear old-school linear power supply. Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement. SEMPER GUMBY! Improvise, Adapt, and Overcome. Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first. On Monday, February 10, 2025 at 10:41:09 AM CST, Jerry Durand via groups.io <jdurand@...> wrote: It's what I mentioned about modern power supplies, an inverter welder is a SMPS (Switched Mode Power Supply). It converts the mains power to DC. Then Switches that at a high frequency. This means the transformer is much much smaller. You won't find big iron transformers in these, just small ferrite (a magnetic ceramic) transformers. I remember when these first came out, I worked at a MIL testing lab in the USA. We were amazed but concerned that the output voltage wasn't quite as clean as our big, boat-anchor sized, linear power supplies.

Yep. Higher the frequency the lighter the wiring can be. Back in the day, aircraft electronics were run at 400hz, instead of the 60hz we use in households and industry. Switching would save a lot on expensive materials, but we'd have to remake EVERYTHING! Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement. SEMPER GUMBY! Improvise, Adapt, and Overcome. Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first. On Monday, February 10, 2025 at 10:13:12 AM CST, davesmith1800 <davesmith1@...> wrote: I wonder how make they make inverter welders so light today. It was Aluminum winding onsecondary side now they lighter. Now it is high frequency is about what know. Dave

It's what I mentioned about modern power supplies, an inverter welder is a SMPS (Switched Mode Power Supply). It converts the mains power to DC. Then Switches that at a high frequency. This means the transformer is much much smaller. You won't find big iron transformers in these, just small ferrite (a magnetic ceramic) transformers. I remember when these first came out, I worked at a MIL testing lab in the USA. We were amazed but concerned that the output voltage wasn't quite as clean as our big, boat-anchor sized, linear power supplies.

Higher frequency uses less iron, not copper. It has to do with how much magnetic field the transformer core can hold. Slower frequency means more time to charge the core, so more iron needed. Modern power supplies convert the incoming ac to dc, then convert it back to ac, but at high frequency (up to a million hertz). From there it's back to dc. Sounds Rube Goldberg but it results in a tiny transformer. davesmith1800 wrote:

In the UK the power is 240V, 50Hz. Outlets are often wired in a ring, not just one linear connection. Here we have 220V, 50Hz. On the poles is 3 phase WYE, so 220V from any leg to the common and 380V from leg to leg. A typical dacha (small "country house") is connected to one leg and the common with a 25 amp breaker and RCD (like a ground fault breaker in the usa). That's all the power you get. Because of a series of murky events, we got all 3 phases so have 3 phase power for the workshop, our sauna, and the greenhouse heater. Wiring up the milling machine to 380 volts seemed odd, at that voltage it only has a 5 amp breaker (well, three 5 amp breakers ganged together). I'm still getting used to how thin wire is here, things use half the current and with the higher voltage can stand a greater voltage drop, hence thin wire. One problem with 50Hz is motors and transformers need 20% more iron in them, making them bigger and more expensive. In appliances like washing machines you'll find brushed motors instead of the induction motors the usa uses. Our refrigerator has a tiny brushless DC motor (3 phase with VFD) as we use propane/butane for refrigerant instead of the fluorocarbons we had in California. Propane/butane is more efficient and much lower pressure so refrigeration gear is pretty low power. If we were doing power systems over, probably something like 240 Volts at 100Hz would be good. It would certainly save a lot of iron and wasted wattage. But, at least we're not in the part of Japan where I hear they have 100 Volts and 50Hz, worst of both worlds.

Note that color codes have changed over the years, so you have to match the color chart with the year your building was wired. I hear the UK really swapped colors around. Always check with a meter, I've seen yellow/green used for a live wire. I wasn't expecting that, I had to knock through the plaster to a junction box to fix it. On 09-Feb-25 8:30, davesmith1800 wrote:

Does anyone have a cross reference from usa metal standards to European ones? Like W1 drill rod being U8A (or У8А locally). When I search for metals I keep finding various stainless but not so much of the other grades of steel and aluminum.

The following items have been added to the Files area of the [email protected] group. /5) Charts & Tables for machine work/2drill-tap-chrat.pdf By: davesmith1800 <davesmith1@...> Description: This one I have in my shop hanging in extra large size for easy reading since 1970’s. I also have in my machines binder too. Very handy