Member postings for Russell Eberhardt

Well, there are a few. There is a paid version.

The free version restricts you making designs public on line (as read only), it also lacks FEM which is unlikely to cause you a problem. If you need FEM it is available in Freecad and used to be available in F360 but I'm not sure if it still is.

Russell

For a beginner I would recommend Onshape as the easiest to learn. It is free and runs in a web browser so no complicated installation needed and it works under any operating system. It has just been upgraded and comes with a series of online courses called the learning centre.

Russell

My ancient system is giving a maximum jitter of 25uS and I am happy with the maximum step rate. I have no need for particularly fast movements.

Might the GPU of the Pi 5 take load off the processors and improve the latency over the model 4?

Russell

Russell

Well, my current cnc system runs LinuxCNC on a single core 3.2 GHz processor. Yes. the parallel printer port does cause some timing issues but I found the reduced step rate needed to prevent lost steps was still fast enough for me. I would imagine the four cores at 2.4 GHz of the Pi 5 should beat my old computer.

Russell

Thanks, one of those should do the trick.

Russell

Looks like a good candidate to replace the Dell computer I bought second hand 10 years ago for my CNC build. Can the raspberry Pi version of Linux CNC emulate a parallel printer port for my driver electronics?

Russell

Yes, I had an air to air heat pump, otherwise known as reversible air conditioning, installed seven years ago. It is a dual split unit with a maximum heating output of 5.4 kW. Living considerably south of Inverness the cooling is essential in summer. COP for heating is about 5 at outside temperature above +7 C but drops to about 3 below -7 C as a result of the defrost cycle. With the prevailing wind coming off a mountain range over 2000 m elevation I expected to have to use our wood burner for supplementary heat but it hasn't been used for years.

I would expect more recent models to be yet more efficient.

Russell

For anyone interested in sustainable energy it's worth reading the book Sustainable Energy - without the hot air .

Link is to online version free to read.

Written by the late Professor Sir David McKay of Cambridge university. It might be a little out of date now but the logic and simple maths are still very relevent.

Russell

I find this style are often more useful in confined spaces:

Russell

Just been doing a bit of thinking about solar panels. My weather station records incident solar radiation. Here, in the south of France during the winter solstice the maximum I recorded was 335 W/square metre at 12:49 pm on a sunny day. The average over 24 hours was about 50 W/m2. Now the conversion efficiency of solar panels is about 15 to 20 % so I would be getting, at best 10Wh of electricity. Depending on your lattitude in the UK you would be getting about half that (on a sunny day).

How big is your 300W panel?

Russell

I've always pronounced it as "jib" but perhaps I'm just talking gibberish.

I wonder if there is a north/south divide in the pronunciation? I was brought up in southern England.

Russell

The run out you need to achieve depends entirely on what you intend to turn in the collet chuck. In general, if you are turning, say a 1mm diameter pivot on the end of a piece of 2 mm pivot steel you will need much better alignment than if you are reducing a piece of 20 mm bar to 3/4 inch.

Russell

Yes, turned the spindle nose female for a good fit on the register after turning the screw thread a little on the loose side. Then turned the taper with it fitted to the spindle.

Russell

But they have the disadvantage that there are more places where run out can occur . Never had any problems with my homemade screw-on type.

Russell

Make them from steel and then apply Abbey Blue Gel as used for gun barrels. A couple of applications should give a nice dark blue colour. Fix the colour by wiping with oil or waxing.

Russell

The o-ring cross section should be such that it is compressed slightly between the bore and the bottom of the groove. It should be slightly loose in the width of the groove. The diameter of the o-ring should be such that its ID is close to the bottom diameter of the groove.

Good luck finding the correct size.

Russell

They are not magic numbers. They come from a bit of mathematics.

See for example **LINK**

Russell

Easy way to measure pendulum Q is to set it to swing freely and count the number of periods it takes for the amplitude to fall by 21%. Double it to get the Q. Expect a value of around 10,000 for a good clock pendulum.

Russell

Edited By Russell Eberhardt on 08/08/2023 18:05:17

Perhaps they are impregnated with a fine abrasive of different grades?

Russell