Here is a list of all the postings Sam Stones has made in our forums. Click on a thread name to jump to the thread.
|Thread: EMI from electric shavers etc|
With apologies to everyone, I think Robert is correct Neil.
Close the thread.
If anyone wants any further information from me, I'd be happy to go via the message board, even direct email.
Best wishes to all, and keep safe.
Not so Desperate Sam
Steve, it was Victor Kiam. I read his book back in the 80's.
Not only buying the Remington company, he used various ploys to gain easy access to ball games.
A fun read.
PS - I can see you're working late!
Never having taken it apart, I can imagine it having a segmented copper commutator and carbon brushes.
In the early days I used contact-less types where the armature rocked back and forth at mains frequency.
There was a perforated steel foil between skin and chopper blades. Then along came the various rotary heads.
Thanks for your post.
Edited By Sam Stones on 25/03/2020 01:35:48
Thanks Emgee. Yes, that occurred to me shortly after I posted.
If anyone tells me to "Keep your chin up", they might care to measure the distance from their neck to their collar bone. Mine's less than 15cm.
Edited By Sam Stones on 25/03/2020 00:40:24
Many thanks for your very prompt and sensitive response Michael.
Being a rather thin-skinned specimen, and given little time for shaving during NS square bashing I went ‘all electric’. That was in ’56, so I’m pretty set in my ways.
Just read your post Chris - Thank you too.
I now realise that members who truly understand screening for EMI, may justifiably refrain from comment.
It was worth a try.
From Monday, I shall need to stay a sufficient distance from certain devices that radiate EMI.
In particular, this applies to my use of a mains-powered shaver, which occasionally produces smells akin to sparking electric motors (ozone? etc).
On the basis that testing the razor near an ‘off station’ AM radio setting indicates EMI, I’d like to discover if sufficient shielding could be achieved by wrapping a large proportion of the razor in aluminium foil, and perhaps covering that with cling film.
Is this a viable solution?
I’d appreciate any positive comments.
Growing a beard would not please SWAMBO
Thanking you in advance.
|Thread: Astro-skeleton clock project|
If you are already feast your eyes on this project, then you need go no further.
Otherwise, take a look here **LINK**
I also make especial note of their switch from weight-driven to Constant Torque Motor Springs.
Their (what appears to be) innovative (EDM wire cut) spring attachments is yet another gob-smacking (brilliant) approach.
Sorry if I appear biased.
Would it be rude of me to mention their exclusive use of cycloidal gear-tooth profiles?
|Thread: Closing the chapter on meshing|
Neil wrote … Pah, Sam, it works which is what counts
Thanks Neil, and well spotted.
Had I been more observant before cutting my own clock teeth, I could have taken the easier route of a radiused cycloidal addenda. Instead, mine were a botched up involute, a recollection from night school perhaps.
I’m sure too, you know better than I that, as with ordinary wheels (which were originally square until the corners wore off), most of the Antikythera gear teeth appear to be triangular and nothing like cycloidal. At least that’s how Chris of Clickspring has cut his Antikythera teeth.
Martin, Thanks for the prompting re force vectors. I couldn’t think of how to apply the potential variance between entry and exit friction. Maybe I’ll fire up the laptop and ponder some more.
With no intentions of appearing gender biased, I was brought to my senses by what appears to be a sign of the times when MS Word underlined in blue my use of the word ‘gentlemen’.
So I tried gentle men, and guess what, MS Word responded with the instruction to use ‘gentlemen’!
And all I wanted to say was ‘Gentlemen, Thank you for your interest and contributions!’
Any tin hats to spare?
In a former life of suffering endless report writing to which I was never fully tuned, we were encouraged to create a title that more than adequately posed the issue.
With a prompt from earlier, (good onya Michael) here’s my effort …
In clock making, how does the sweet-spot equate to the theory of cycloidal gear-meshing?
Before I reply to the above responses while risking repetition and appearing smug, my experience of clock building is a one-off skeleton clock designed by Mr John Stevens. I drilled the pivot holes into the plates before I made the wheels and pinions. Although I eventually owned a copy of ‘Watch and clock making and repairing’, by Mr W J Gazeley it was already too late to apply the recommended method of depthing.
Well may you shudder at the ugly tooth shapes I generated. Here’s the evidence …
… but it worked and they are not even cycloidal or involute.
Well, the clock ticked unaided first time around.
John, Jumping ahead, I would have been in deep poo had I been fitting ball bearings, and the clock didn’t work.
Thanks Michael on at least two counts. I forgot to mention that I had returned to applying the theory to the 290-8 wheel/pinion pair in the Wilding large wheel design, while continuing blindly to follow the BS 978 data. This latter item along with the Swiss Standard NHS 56702, 3, and 4 was presumably, developed with a great deal of cerebral input with an eye on economy. The A, B, C of tooth addenda you highlighted just adds further to the complexity of surpassing practical depthing with a theoretical solution. Also, your observations put succinctly as always, address what I’m getting at.
Roy, I fully align with your comments, if only I had more than CAD.
Martin, At a theoretical level, cos that’s all I’ve got, I imagine ‘ideal meshing’ to be a sort of sweet spot where, subjectively, the transfer of energy is both smooth and efficient. How it’s achieved at a theoretical level, I can only imagine the requirement of a high degree of complexity.
Doesn’t the variable level of friction (from [tooth] entry to exit), further complicate a definitive solution?
This, to some extent, repeats the questions – Is there (likely to be) much of a detectable difference between the theoretical pivot centres as per the standards and those for the sweet spot, wherever the latter may be?
What allowance for tooth wear is necessary? I’m really out of my depth (pun?) here.
Finally, an apology is required in that I failed to notice that the Swiss standards actually show a full (semicircular) root radius.
Apologies to those not-into-clocks.
As with previous threads, I based the geometry of this wheel/pinion layout upon BS 978: Part 2 see…
In the previous threads on pinion/wheel meshing and depthing, I took it that the ‘optimum’ condition of meshing would occur when the respective PCD’s touched. Using CAD, (for the time being my easiest option), I decided to ‘go deeper’. An actual depthing exercise may prove this wrong.
Without truncating the tips of the wheel teeth or deepening the pinion teeth (to weaken them even further), the limit to closing the gap (from optimum) was 0.445mm when the wheel teeth bottomed out.
Having ducked the many hours of a full run through the fifteen pinion steps as before, my adjusted starting point revealed that at 0.4mm (0.045mm short of bottom), the trailing edge of the next wheel tooth was contacting the pinion tooth next in line.
For reference, the yellow dots indicate where contact is made, and where jamming may occur.
As a slight deviation, members may question the reason for ignoring root radii. Seen on the left of my illustration, un-radiused pinion teeth are so much weaker. Not only are they thinner at the root but the sharp notches invite premature failure. Even the (seemingly token) radius of Swiss Standard NHS 56704 appears insufficient.
I welcome your answers.
Edit - There was no smiley face in my original
Edited By Sam Stones on 02/03/2020 23:57:27
2nd edit - attempted to remove smiley face!!!
Edited By Sam Stones on 03/03/2020 00:00:59
3rd edit - Smiley face removed.
Edited By Sam Stones on 03/03/2020 00:02:48
|Thread: Spring's a-coming|
I feel sorry for the puppy too Steve.
Normally in southern Victoria (Australia) as we enter autumn (which is supposed to begin 1st March), lawns (and most other ground cover) have turned a brown crispy mess with little to mow but dust.
Reflecting upon previous years, I’ve only needed to water the garden two or three times in the whole of summer.
|Thread: Cutting a clock fusee using the Turnado turning system|
Having checked the box for bookmarking this thread, I've just found it didn't work.
With nothing more to say other than good luck with the rest of your fusee Ifoggy, I'll sign off.
All I had available (in the 70’s*) when turning the fusee for John Wilding’s skeleton clock with lever escapement (and room for a pony), was the taper-turning attachment.
It was a relatively simple exercise to mount the curved template to the slide bolted to the back of the machine, seen here but set for taper turning.
The follower was a ball race secured to the cross slide (with its leadscrew removed).
At the same setup (without removing the workpiece), it was a simple matter to cut the groove. Light pressure applied to the ‘front’ end of the cross slide was all that was needed while the saddle was engaged to traverse. The top slide, set to 90°, provided the depth of cut.
On the down side, the curve was specified as a 2” (two inch) radius. There was no mention in the text about calibrating the curve from the main spring performance.
*Mr John Stevens’ clock design was first published in five issues of Model Engineer commencing in February 1972. Vol 138, issues 3434, 3435, 3437, 3438, & 3439.
|Thread: Is this an improvement?|
Is that much different to my using CTRL-C of the graph and then CTRL-V(ing) into Word?
That's what I did and the only way I could think of doing it.
Having said that, I discovered that I had no difficulty with my earlier attempts while dealing with those extended Meshing threads.
This is a tired old 84 yo brain down here.
Thank you for spotting my frustration. Your edit is much appreciated.
Rather set in my ways, I've never used Powerpoint as an editing tool.
Re your PM, it's 5am and I'm still waking up and haven't got around to reading it. Actually, I was in the middle of responding to comments in this thread including the addendum radius issue.
Time to finish my cuppa tea.
PS Just read your PM John. Thanks for the thought, I'll reply by (direct) email.
Edited By Sam Stones on 20/02/2020 18:02:32
Tell yah wot ... split three times ... it's taken me twenty-five minutes to get this b******y graph into the thread.
Cobbled in Excel, it went into MS Word where I prefer to edit, and then into Photoshop, before becoming a .jpg file and palatable for this forum.
Now, if you haven't lost interest, you'll have to go back to the text on the previous page. EDIT Now on same page,( Jason)
Edited By Sam Stones on 20/02/2020 01:23:49
Edited By JasonB on 20/02/2020 08:01:49
My back-step is in regards to velocity ratio. I had become rather tired of attending to all the manual (CAD) iterations and abandoned the exercise when I got around to messing with lantern pinions.
In that case, I retained the number of teeth, the lantern pinion having 8 (eight) pins (leaves) meshing with the John Wilding’s 290 tooth large wheel. The teeth of the latter being of conventionally accepted cycloidal design.
Consequently, I can only show what was happening where Mr Wilding’s pinion was cycloidal not a round pin.
The graph shows that the velocity ratio (theoretically 290/8 = 36.25:1), gradually increases to almost 40:1 as a single (large wheel) tooth makes its transition. Then, as the ratio gradually decreases, surprise, surprise, the ration drops (from 38.77:1 to almost 36.25:1) as the next pair of teeth/pins meet.
I'm obliged to split this thread a second time ...
Before moving on to the now, quite clearly, ancient trunnion concept, it seems appropriate to reiterate a (perhaps) minor issue. This cropped up towards the middle or final exercise of meshing (read messing) with cycloidal clock teeth in a CAD simulation. With an appropriate warning, the extent of my verbosity can be unearthed here …
Would you mesh with this? Some thoughts on cycloidal clock teeth
Meshing with Lantern pinions - Part A Another slice of CAD, and how cycloidal clock teeth might mesh.
Meshing with lantern pinions - Part B Due to my zealous output, I have been 'advised' to split the original thread.
I agree Phil.
Some sort of torque/friction relationship?
I’m beginning to think in addition, that even the tiniest amount of lubricant needed for each end of the pins (even minimal), might eventually migrate onto the wheel teeth.
Are there dry (or non-migratory) lubricants suitable for clocks?
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