Member postings for John Haine

The Nano can run vanilla grbl but not the offshoots mentioned, but vanilla works fine for straightforward 3 axis milling. For CAM and simple CAD I use CamBam which is quite cheap and excellent for most purposes. Lots of people using grbl use UGS as Huub mentioned.

David, congratulations on the new machine. When you say Arduino interface, what do you mean exactly? To the best of my knowledge there is no Arduino based controller that is compatible with Mach3, Arduino cnc is usually based on grbl or a derivative and there are a number of "g code streamers" that can be used with them. One mentioned here recently is I think Openbuilds Controller.

https://software.openbuilds.com/

https://software.openbuilds.com/

Edited By John Haine on 28/08/2023 22:25:14

I think that must be an aluminium or steel tooling plate?

The actual locus of the bob is a "prolate trochoid", not a cycloid. Woodward shows that the radius of curvature of this for small angles is greater than the circular path of the bob with no roller. This means that the "lift" of the bob for a given deflection is less than for a circle, whereas for a true cycloidal path it would be greater. In fact the circular deviation of a pendulum with roller suspension is greater rather than less than normal. Others have confirmed this numerically. Unless one could hang the roller on a magnet this means that there's no point in roller suspensions in an attempt to reduce circular deviation.

Another point is that for compound pendulums (which all real pendulums are to a greater or lesser extent), it can be shown that there is no path the bob could follow that will be isochronous. There are some schemes to correct for circular deviation over a small range of angles, of which the most successful was probably the Fedchenko suspension spring. Or one can try to control CD to gain other benefits which is what Harrison's circular cheeks do.

Andy, I wish you hadn't posted this! Now I'm thinking about upgrading my cnc to use esp32!

Well for completeness it was in HJ August and September 1994.

Intriguingly, he shows that if the roller rolled below a flat rolling surface it could work.  Very strong magnets might do the trick, but then the rest of the pendulum would have to be non-magnetic to avoid magnetic forces interfering with gravitational.

Edited By John Haine on 27/08/2023 07:41:55

This has been analysed by Philip Woodward but alas doesn't result in isochronism. I could dig out the reference if interested.

It's worth looking up Harrison's tin whistle compensator for fine tuning.

My Nome has a stepped hole in the Bob with a ledge. Upper part of hole is 10mm, lowere about 14 fro memory. No need for a square step, just use ordinary drill.

One "feature" of the current site which keeps annoying me which I don't recall having seen mentioned is the behaviour of "More Latest Posts". If this feature is retained it would be great if it actually showed a list that didn't include all the latest posts at the top - i.e. just the ones that dropped off the list.

Its teeth will probably not have side clearance so not operate very effectively as a face mill. As Thor suggests, give it a try? Nothing to lose.

Any web browser can open a file on your local storage just as easily as one from a web server provided it recognises the file format.

You have 3 blocks each of which may be in the stack or not. The sum of the heights is

A*10 + B*20 + C*25

where A B and C can be 1 or 0 depending on whether you use that block or not. ABC forms a binary number, which can go from 0 to 7:

000, 001, 010, 011, 100, 101, 110, 111

For each you can easily compute the total height and enumerate the possibilities. A 2 minute spreadsheet gives:

0 0 0 0
0 0 1 25
0 1 0 20
0 1 1 45
1 0 0 10
1 0 1 35
1 1 0 30
1 1 1 55

Jason, you mention png but I trust that other file formats will teh supported for attachments? Every other forum I use allows a range, and for us in particular pdf, xls, txt, would be very useful. That would also allow for example software in .txt format (to share useful programs) to be attached.

**LINK**

I'm sure there are 🇺🇸 stockists.

Renaissance Wax

Well that will be quick and easy won't it? No alternative to one at a time as far as I can see.

Bateman has flat top bracket and no clamp. My Arduinome had clamps but I recently slackened those off as I suspected the pendulum might be slightly out of plumb.

Compared to my Helmholtz coil configuration your magnets are rotated 90 degrees. Also thinking about the force lines from each magnet, as the other end is in contact with the rod the flux may be "bent back" at the hot end, how will they interact with the coils?

I'm probably late to this party but had a sudden thought today. Though the measurements I did on the Sharp opto interrupter showed impressively low (sub micron) repeatability, I just realised that the emitter wavelength is 950nm, nearly 1 micron, so arguably whatever one does in the optical system will not I think improve the results.

I have a big bore S7 with vee belt drive to the spindle and the countershaft runs in bronze bushes.

The period would decrease very slightly, but the cycle-to-cycle random variation would be very small unless there was a lot of noise affecting it (for example support vibration).