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Member postings for John Haine

Here is a list of all the postings John Haine has made in our forums. Click on a thread name to jump to the thread.

Thread: Advice on milling machine purchase
19/01/2021 16:28:52

If you definitely want CNC I would recommend getting a s/h Denford Novamill though they are hard to find and you may need to upgrade the electronics.

Thread: Drilling crankshaft hole
19/01/2021 14:18:52
  • Machine base flat
  • Mount base to vertical surface (angle plate so valve port face is uppermost and as level as you can get it (probably by eye) - machine port face flat.
  • Also machine upper end of crankshaft bearing boss flat.
  • As accurately as possible, by eye and whatever measurement equipment you have - or by reference to drawing - set drill over centre of crankshaft bearing boss
  • Centre drill, drill through and ream for shaft.

But it does depend on what equipment you have available.

Thread: Lathe Tool Height
18/01/2021 16:30:13

Tangential tool and/or QCTP. Use a height gauge for setting.

18/01/2021 11:34:16

Garden suppliers have packs of 0.5mm aluminium strips about 10 x 30 mm used for glazing clips between panes in greenhouses. They are very useful for packing lathe tools, clamps etc.

Thread: IDEAS PLEASE ?
17/01/2021 12:58:35

A, no idea. B resistance or spot welder. C doorstop. Or one of those!

Thread: The romance of silver and gold
16/01/2021 23:09:32
Posted by Keith Hale on 16/01/2021 13:02:26:

The Incas hoarded much silver and gold. You couldn't leave the planet without it.

.....

Keith

Taking lots of gold and silver with you must make it harder to lift off...

Thread: Digital Height Gauge Recommendations?
16/01/2021 12:27:58

Keep a small supply of batteries for your gauges. Allendale sell them.

16/01/2021 10:53:59

Just to put a contrary point of view. I have a tall "dial type" mechanical height gauge that get's used on the surface plate. It's the type that has a rack and pinion to set the height with a big knob, the dial shows mm by 0.01 mm, and there are resettable mechanical "digital" counters for whole mm both up and down. Height is about 50 cm. Very nice but use with care since it is easy to actually lift the base slightly when using the knob to put the pointed on the reference of measuring surface. Also much too tall to easily use on either mill to get the material height datum.

I have two short digital gauges, one is a Wixey type made really woodworking to set saw height, the other I made from a short capacitive scale (and is even shorter that the Wixey). Why two? Well one is left and the other right handed, so I can use at either end of the little CNC mill table without having to try seeing over the back of the mill. Being able to easily set the gauge to zero on a reference surface is also a boon. I wouldn't be without any of them.

Only problem with the Wixey is that the base is aluminium so very light. It came with a little magnet in the base to stick it down to a wood saw table, but you can imagine what happens to that on a mill! Once you get a bit of swarf stuck on the magnet a bit proud, you start getting odd zero errors, so the magnets came off.

Thread: It Is A Steam-Engine... Using the term loosely
13/01/2021 21:55:33
Posted by Nigel Graham 2 on 13/01/2021 21:42:18:

........

Recently my local paper gave a splendid diagram showing how the heat is harvested for a household ground-heat pump: fluid circulated through a large array of pipes at shallow depth below the garden. I thought, unless I am missing something, you need only school-level physics to see the obvious flaw.

.....

Given the number of such systems being installed, do share.

Thread: Another Arduino-controlled pendulum clock
12/01/2021 16:25:48

Peter, you can get an approximate idea by using the Arduino itself. You can record the time of a "tick", for example when you detect the pulse from the coil using the "micros()" function and remember it until the next "tick" when you subtract the new time from the previous one and remember the new. The difference will give you the period (or semi period) measured in 4 us increments with an accuracy somewhat limited by small changes in software execution time and of course the Arduino clock. You'll have to output the data somehow, the easiest is to use the Arduino serial monitor. That needs a PC or at least something like a Pi in the workshop. One approach could be to use a Pi without a display of keyboard, running the Arduino IDE (version available for the Pi), and controlled using VNC from your PC via your Wi-Fi. The Pi comes with VNC server and the client is free from the web. No need for your pendulum to beat seconds.

Thread: capacitor droppers and power factor
12/01/2021 10:09:38

The brown tubular thing looks like a power resistor to me.

Thread: Arduino Pendulum Clock Design - Comments Welcome
11/01/2021 15:09:03

Thanks Dave - that web page is a find, thanks Michael as well. I'm amazed to find that R can also calculate AVAR (though I shouldn't have been I suppose).

Thread: Collet chuck for workholding on the mill
11/01/2021 14:35:43

Had I possessed an 8mm collet for my ER40 collet block I could have used that, but I don't. Even then I have an alignment key (tenon?) in the chuck base, so probably easier to do it this way. I did use the block in the vice to hold the part for cross drilling before parting it off its 0.5 inch parent.

11/01/2021 11:52:01

I thought this might be useful to someone. I needed to hold a small cylinder of brass to mill a transverse slot across one end - this is the top block of a new pendulum. But how to hold it for milling? I mounted the brass in a Myford collet in the MT2 chuck that screws on to the big bore spindle.

img_20210111_104222451.jpg

This is the chuck clamped down to the mill table with a silver steel rod to get the cross-hole aligned. But how to get the axis of the collet aligned with the spindle?

img_20210111_103542994.jpg

So I put 10mm collets in the mill and the chuck, and gripped a bit of 10mm ground steel in each before tightening the clamps.

img_20210111_103556028.jpg

Then zeroed the X and Y axes on the DRO. Now I could get the axes back in line using the table feeds. As always it took longer to work out what to do and set up the work than do the job.

Thread: Arduino CNC
09/01/2021 14:36:52

I use GRBL on a Uno for my X axis power feed. Also has a Bluetooth interface and is controlled by GRBL Controller from my phone.

https://www.model-engineer.co.uk/albums/member_album.asp?a=53829

Thread: A not-so-new Pendulum formula
09/01/2021 10:28:51

It's worth noting that for practical clock pendulum amplitudes, say up to 10 degrees, the difference between the AGM formula and the usual "A^2/16" approximation to the circular deviation is very very small: 3.3 usec for a 1 second period and 10 degrees. I've done pendulum simulations for the order of amplitude used in "Clock B" and compared them to simple formulas based on the same approximation with virtually identical results.

Where the AGM really is useful is for methods where you need to quickly compute elliptic integrals. One example is designing very selective LC filters, where there are formulas for the component values that incorporate elliptic integrals. Once you needed to have extensive tables of these, but now they can be calculated more accurately in a few lines of code.

Thread: Another Arduino-controlled pendulum clock
08/01/2021 17:14:24

Alan, that's very interesting that you're using the Mini - what batteries do you use and how long does it run please?

08/01/2021 10:26:11

jh5_schematic.jpg

In case anyone is interested here is the schematic.

08/01/2021 10:19:36

Latest timekeeping results.

clock_8january21.jpg

This shows readings over the past 10 days since setting the two correction counters to 132 and 92. One odd thing I've seen is that every time I upload new software with changed counters, even though the clock doesn't actually stop swinging it takes quite a long time (days) to settle down. In the plot above the blue error curve was steadily increasing but the rate of increase seeming to flatten off, so 3 days ago I reset the seconds hand (just using the control switch which inhibits dial impulsing, removing 24 seconds of accumulated error. Since then the error has built up to 2 sec, but this includes some due to my accidentally jogging my desk (the clock sits on the desk in my study). The clock has a "half-second" pendulum so the SW divides by two to drive the dial, and normally you see the dial advance on the same half-swing each time, in this case it was L->R. But then I stood up yesterday and accidentally jogged the desk since when it has been incrementing on R->L, so I think there's been at least a half-second extra input to the displayed time and possibly more as the pendulum settled down. I also display the temperature at the time of the reading, I'm not convinced that there is any obvious correlation but haven't yet done a regression analysis. Ignore the grey line. Anyway, I think the regulation is getting there, and I already rely on the clock when I just want to quickly know the time.

Thread: Arduino Pendulum Clock Design - Comments Welcome
06/01/2021 17:43:19

Oops! Sorry, I should have thought. I'll try again.

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