Here is a list of all the postings Joseph Noci 1 has made in our forums. Click on a thread name to jump to the thread.
|Thread: Determining/measuring sub-micron displacement|
Chaps, it was not my intention to stir the pot so badly...I am certainly not upset with anyone here!
Perhaps I do share some of the blame however- I indicated I am trying to measure the displacement, when I suppose what is really needed is to find a way to show that the detection 'accuracy' is 'good enough' to within limits so small that the actual value of the deflection does not matter. In other words, for a edge detection probe, one would probably be safe to assume a deflection of less than 0.01mm is acceptable, since we rarely work to better than that anyway. But if I can achieve better than 0.005mm, then that would be really good. If the actual value lies somewhere between 0.001mm and 0.008mm, it is still really good, but not definitive - but perhaps that does not matter to be able to use the probe definitively.
So my absolute requirement statement was poorly put and I apologise..
That said, I went and made a mechanical 'magnifier' - a long arm, pivot one end, micrometer at 600mm from the pivot, and my probe at 30mm from the pivot, so a 1:20 reduction of Micrometer anvil motion. This is not perfect of course, working in an arc, etc, so the linear movement at 30 mm is not true....but its good enough!
Set up in the mill and tested with a 0.01mm indicator, and then a 0.001mm indicator ( of dubious nature..)
Then I set the probe in the mill and tested that for contact - I do believe my contact displacement is less than 0.0005mm, maybe even 0.0002mm...Judge for yourselves..
The device in the mill, turned 90deg to check Z axis of the probe:
Using a 0.01mm indicator-below: (note, arm multiplier = 20)
Fist row - Dial and Mic at Zero.
Second row - Mic plus 5div x 0.01mm = 0.05mm div 20 = 0.0025mm at indicator
Third row - Mic 25 divisions = 25 x 0.01mm = 0.25mm div 20 = 0.0125mm at indicator.
Dial appears to be under-indicating by 0.002mm maybe?
Mic moved in 1mm, div 20 = 0.05mm, Dial shows 0.05mm - correlates OK.
Now using a dubious 0.001mm indicator:
First row - Dial 'zeroed' at 30, Mic zeroed at 11mm,
Second row - Mic moved plus 20div = 20 x 0.01mm = 0.2mm div 20 = 0.01mm
Dial moves from 30 to 40 = 10 div x 0.001mm = 0.01mm - correlates with Micrometer.
Then fitted the probe - see contact point with lever in photo below.
Photo below shows probe OFF, Mic = 0
Second row shows probe on - contact made, Mic = 1/2div (maybe?) = 0.01 / 2 =0.005mm
0.005mm / 20 ( lever multiplier) = 0.00025mm movement at probe tip...Believe it or not!
Similar tests were done in the Z plane with the test lever on its side - similar results obtained!
Yes, that would confirm the moment of contact detection, but still not give an indication of any related ball deflection. Its a little complicated in this instance since the ball is oscillating in a rough sphere @ 3.9khz, so electrical contact will occur at the same time as oscillation damping - but I would still not have determined if there was any deflection of the ball, and how much...
I am building a 20:1 reduction lever to be actuated by a micrometer and see if I can find my microns that way!
Played a bit in the workshop with this again. It will not be possible for me to measure accurately the actual deflection required for detection - as Kiwi Bloke said - chasing microns is hard! just brushing against the test setup causes detection to come and go in my setup - micron(s) are really small!
I put the probe in the 3jaw on my Emco V10P. Gently clamped a micrometer in the tool post and tried with the anvil against the ball to see in a 'rigid' setup if I can actually see any movement of the thimble line from zero.
The lightest touch on the thimble is enough to cause/remove detection, and being very gentle, holding my breath, I can 'just' sense some thimble rotation to make/break detection, but cannot see any line movement on the thimble with a x3.5 loupe.
I moved the cross slide so that the micrometer anvil just touches the ball and shows contact, and locked all slides - fiddly to lock cross slide while ensuring that contact is 'just' made, but got it right. Then I 'tapped' my right forefinger nail against the tool post and each tap would break contact, removing finger re-made contact - the lightest of taps! See the video link...
I have a strong suspicion the contact detection deflection is WELL into the sub-micron region!
Thank You for your Kind offer Michael. I would really like to take you up on it, but shipping tween Nam and the World is so expensive - Unless by 'mail' and a lot of that sort of mail parcel is simply 'lost' in Johannesburg - So I tend to only use Fedex/DHL air ship - a 1kg parcel from London to me is around 120 BP...
Andy_G : I have a Chinese 0.001mm indicator, but it is not great. The spring is quite weak, and there is a 'lube' in the pushrod tube that causes stiction so its presently useless..I have stripped it and its soaking in alcohol...Hopefully it is improved once assembled and will give it a try. The concentricity ( going to be another measurement problem - the probe can only be set as good as the measuring indicator..!) is set by means of 3 grub screws - see photo.
Can be set very close to null - the bigger problem is how to drill the hole in the ball on the probe tip - if that is off axis, its a mess..
Am looking into the optical route - a laser pointer with a pivoting mirror, etc - just not sure how to relate dot-on-the-far-wall displacement to the small mirror on a lever rotation, etc - seems like moving the measurement problem somewhere else is all...
Duncan, at first I also thought backlash was the issue - however it cannot be - screwing into contact with the ball is fine, then unscrewing, if there is backlash, should show greater thimble rotation than there actually is anvil travel. But that is not evident - During retraction contact detection is lost with no discernible graduation alignment movement on the thimble even with a loupe in the eye! If there was discernible graduation movement, then one could question the actual measurement since backlash would consume some of that linear movement.
I think Kiwi's excellent suggestion of flexures is the way to go - much easier to quantify the magnification ( or reduction) ratios, and driven by a micrometer drive gives the initial accuracy.
The requirement in terms of your observation might seem trivial, but in the context on my final question, how to do this in my amateur setup, it still offers no solution other than perhaps purchasing such a mechanism - Not really a workshop solution?
I posted in my CNC lathe thread a little on an edge finder/probe I am playing with. Turns out it is very sensitive in detecting contact with an object, but I wish to quantify that somehow. I wish to try measure the deflection of the ball at the instant where detection of the contact is made. A crude attempt in the DRO fitted mill gave very promising results, but not definitive. The DRO is a hi-spec glass scale type, with readout in 0.005mm resolution - note, not accuracy, just resolution. Moving the probe to detect contact, zero the DRO and then retract till no-detect and the DRO shows - nothing..no movement detected. I repeated this at a dozen different DRO positions, moving towards and away from contact, etc - the DRO never registers the movement that results in a detection or loss thereoff.
I tried with a micrometer, screwing the anvil up to the ball till contact, and then retract till no contact - the amount of unscrew is so small it shows nothing on the micrometer scribed position line movement...
I was wondering if Foucault measurement concepts ( such as for lens accuracies) might somehow be used - but not really applicable. My current ideas are around making a differential screw setup to improve on the micrometer concept - a differential screw with 1mm and 1.1mm pitches ) doable to some extent on my lathe with ELS, but at those dimensions maybe even the lathe leadscrew variation will mask the results. Averaging over a few settings of the differential screw length may help? And even a 0.1mm per screw rev gives 0.001mm with 1/100 of a turn - difficult to determine that as well. - Maybe a combination of a metric and imperial thread, sort of 1mm and 1.01 mm pitch!
The probe tip vibrates at around 3.9khz - in a resonant oscillator circuit, which relies on feedback from a pickup point on the piezo disc generating the mechanical vibration. The probe and disc are part of the mechanical load, setting the resonant frequency. A LC tuned circuit forms the 'tank' of the oscillator and ha a high circulating current in the tank ( tens of milliamps) . The feedback from the Piezo disc is adjusted so that the system only just oscillates. Then the slightest mechanical contact causes heavy damping of the resonant circuit, and oscillation stops - I then detect the drop in current in the coil and know we have made contact.
How do I in an amateur workshop measure this? I guess I don't need to know that it is '0.3um' - sort of less than 1um would be good enough..!
0.4grams on the ball results in detection:
Piezo Disc showing the little feedback finger with red wire attached.
Edited By Joseph Noci 1 on 01/04/2022 09:43:37
|Thread: What adhesive - that shrinks when it sets - do you recommend for melamine laminate sheets?|
All PVC glues ( most of the white wood glues) shrink when curing, but all tend to cure by water evaporation - Gorrilla glue does not shrink - it expands, as do most polyurethane glues. However these glues cure process is triggered by moisture - very little moisture is needed and is 'consumed' in the process - there is no residual moisture left in the bond, so you would not have a problem with trapped moisture . However.... It can expand 2 to 4 times the applied thickness, bonding impervious surfaces, but pushing them apart...
Perhaps a slow cure epoxy and clamping the boards together, or laying them flat and weighting them?
What is the application?
|Thread: CNC Lathe Scratch Build|
Thanks John and Jeff.
Finished off the probe as far as I want this prototype to go - It really works well. Fitted an LED so I have a visual indication if I use it on a manual mill. Connectors for these items are always an issue - I hacked in a USB-2 connector - use two pins for power and one for the open drain to ground output to Linuxcnc for probe contact. When I do the actual one for the lathe it will be permanently mounted on the cross slide and a different format. The proto in the images is great for the mills.
It is REALLY sensitive less than 1gram activates it fully, and oblivious to machine vibration, etc. A crash ( it happened..) of 4mm overrun pops the Piezo disc out of the tri-point holder with no damage - refit it and recal ( runout) and all works fine again! Of course this is only valid in XY - Z would kill the piezo disc!
The USB connector pcb - held in place against a rebate by the spring seen below, when the rear shaft and cap is fitted.
Business end of the USB connector
A section of snap-off blade shows how sensitive the unit is. The blade weighs 1.37grams and one end sits on the eraser so the weight on the ball is maybe 0.7grams or so.
And while its powered it sits and sings quietly at 3.9Khz...
Edited By Joseph Noci 1 on 24/03/2022 16:52:42
Not really a continuation of the Lathe itself, but related since I am pursuing touch probing concepts for the Lathe.
Most 3D touch probes work on the principal of a lever (the ball attached to the end) moving a tri rod contact from 6 balls, all items electrically in series, so when one rod breaks contact with a ball, the touch probe has made contact.
Some DIY attempts have used a Piezo sounder disc attached to the touch probe, and relies on high gain amplifier detecting the voltage spike from the Piezo when the probe 'strikes' the workpiece. These have various measures of success - contact must be 'definite' - slow approaches require very high gain in the amplifier which then requires deep filtering to prevent machine vibration detection etc...
I went another route - used a piezo disc, but in a closed loop oscillator so the probe ball tip 'vibrates' ultrasonically. The disc holder is critical - the piezo disc domes in and out during oscillation, so supporting the disc is normally at 2/3 its diameter. I supported it on the periphery at 3 small points, zero deg, 120deg, and very critical, 220 deg, NOT 240deg. 240deg gave a probe tip up/down motion only, almost no side motion. Moving the 3rd support caused the tip to oscillate up/down and circularly, ie, the tip oscillates all over inside a sphere around 0.003mm larger than the ball on the tip...This was measured with a Laser inteferometer at the local Mining Mineral analysis labs..!!
The piezo disc is a common buzzer disc, with 3 contacts - GND, main contact and feedback contact. The oscillator runs from 1.2V and the feedback is set so that is just oscillates reliably between 0deg C and 50degC. The slightest contact with the ball in ANY plain stops the oscillation. This cessation is detected within 3 oscillation cycles ( @3.9KHz = 0.7msec) . Deflection of the ball at cessation after 200 to-and-fro runs is around 0.008mm in horizontal, and 0.006mm in Z.
It works a darn treat!
The assembled probe and its bits below.
The PCB - engraved on my PCB router..
The Piezo disc from the rear - with the disc holder beneath it - left.
The disc with probe, fitted to the holder supported by the three points.
Electronics on the rear of the disc holder
The jig used to located the probe on the disc when soldering it in place.
Left, main body with Z springs
Right, disc and holder atop the Z springs
View of the probe tip and drilled ball - also the disc holder
Setting tip runout - 1/2 div @ 0.01mm div guage.
This one for the Mill, another for the lathe - a different shape to fit an arm on the ATC...
Edited By Joseph Noci 1 on 23/03/2022 17:10:52
|Thread: Large Scale Heat Pumps|
Hopper, you are quite right!
I fall foul of my own zeal and fanaticism, losing focus on the size of the 'other' evils!
Still not sure how to go collar our Lions with an electric car...
No doubt that burning oil is worse, but I despise the mentality that approaches fossil fuel eradication by painting any such eradication bright green.
A 3MW turbine blade is typically 50m long, weighs around 12,500kg and costs around $300k to make - lasts 10 to 20 years. 2 million waste blade tons/year - approx 150 blades per year - They don't stack well, and 'land fill' is a misnomer - when dumped they don't fill any holes any where - they are dumped and occupy huge areas of land - mostly in the deserts where they are out view, and its that mentality that then kicks in - out of sight, out of mind...
Each turbine takes around 200 to 250 liters of lube oil, lasting 12 to 18months. Where does that oil go? Refine it and put it in cars? That is around 87 million litres of oil every 2 years from the current world estimate of 350,000 turbines operating.
Electric cars suffer from the same mentality - where do all the hugely increased requirements in copper, lithium and all the really toxic rare earth metals come from? A vast majority of the raw material stem from 3rd world sources. Copper, about 20% from USA, the 77% from Chile and Peru - the latter are so far out of view of the clean green West that the ecological mining disasters developing there are out of the western minds.
Lithium, highly toxic - for all the Green Batteries...Here we must look at reserves versus production - Australia I today the largest Lithium producer - because its reserves are easily extracted. China is about 3rd or 4th in production. But as for reserves, Chile has the worlds largest - in fact, 80% of the world reserves are within Chile, Argentina and Bolivia. And we all know the great ecological track records of these nations. While West looks the other way - as long as in our 1st world cities we can be clean and green.
And what happens when all the Green West's wishes come to fruition - no more petrol or diesel, Car manufacturers not making vehicles with internal combustion engines anymore - what happens to Africa and other 3rd world nations? Namibia is a country with only 2.6m people - when travelling from central Nam to the North, you plan your route according to Fuel stops - distances of 500km to 1500km abound, some fuel stops are 400km apart. 90% of roads are unpaved, 40% REQUIRE of-road vehicles - Central Africa is worse, and it gets worse further North. Food and materials travel by road in these countries. Trains do NOT star. And roads are BAD.
So what happens - The Nambian country and desert becomes a dumping ground for the famous Green Electric car, while it waits for Charging Stations to spring up? Seems they cannot provide enough in the UK for even the few electric cars running about there, let alone in Africa and Namibia.
Or does Africa ( and the Australian outback..) become a permanent receiver of western aid and food packages...
Mind you, failure of road transport in Nam would do wonders for the Desert here - no more idiots tearing up the desert plains, the Lichen fields, etc...One would just not be able to go and see the clean fields either..
Burning oil is not the answer and must go, but the head-in-the ground attitude of eliminating it at all cost is even worse.
Interesting reading -
Hopper , re wind turbines, in fact regarding all the 'green' power concepts that have the world by the short and curly's...Seems to me wind turbines are another way of putting today's (new) problems on a train headed to the future, problems to be resolved by our kids or their's...
Wind turbine blade life is supposed to be 20-25 years, but stats show that blade lifetime is more like 10 years, taken across the world. Those blades are massive, do not decompose in the elements, are not repurposed/recycled to any tangible extent anywhere - simply landfill for future generations. Current estimates of blade waste is around 50,000 tones in Europe alone. If current 'land-fill' process continue, expect an accumulated blade waste of 40Mton by 2050, with an annual blade waste generation of 2Mton by 2050..
The only present re-use concepts focus on shredding, which is hugely power hungry, and shredder blades are replaced after 4 turbine blades are shredded...Typical shredder blade weigh in at 380kg per blade, 3 blades in a shredder. They weigh less than 100kg when they are replaced - hope they collect that metal dust for re-use..!
The blades first have to be sawn into chunks that can fit the shredder...
Lots of 'innovative' ideas - use them to make roofing ( and fill the gaps how??) , build bridges ( how many bridges can one build??)
Else burn the composite blades, like in Brazil....
The blades are really big - longer than a 747 wing half...And the chord is as wide a 3 to 5 people tall...And each one releases 7 to 10kg of really noxious fumes into the atmosphere in its manufacture while curing.
My rant for the day
Edited By Joseph Noci 1 on 20/03/2022 12:13:09
|Thread: Adjustable Y tram for Emco FB2 mill|
I understand - I did not have that problem on my FB2's - A test bar in the spindle morse taper run up and down with a dial gauge fitted to the column showed less than 0.008/0.01mm delta, so the head is nicely parallel to the column on my machines. Shimming the column perpendicular to XZ sorted my tramming issue.
However, unless I am misunderstanding the issue completely.... I trammed Y on my FB2 by shimming the column base mounting at the 4 attachment bolts that fasten the base to the XY axis base. Simply add shim stock to under the top bolts to tilt rearwards, or under bottom bolts to tilt forwards. Much easier, and keeps the head square on to it's tilting ring.
|Thread: Another mystery object|
I am a well seasoned Google Searcher Michael, but you seem to have SuperUser status! How do you find the many gems you do???
|Thread: Shaper tooling.|
Here is my home made version
|Thread: How to remove a SMD resistor|
Is the resistor broken/open cct? Do you need to fit a different value? If you need a lower value, put a suitable value in parallel - easier than removing the present one. If you need a larger value....
|Thread: EMCO 150mm Rotary table with Stepper motor indexing|
Backlash will remain an issue...It can be adjusted 'out' but that is not finite. The worm can be set snug up against the wheel, but absolute backlash depended on many factors here. The worm must not move axially in its mount - the worm 'thread' is not perfect and nor is the worm wheel teeth. Worm wheel concentricity may not be perfect either. The result is that you may eliminate any backlash at some setting and then find the worm binds at some wheel rotation, or is loose at others. The EMCO table is very well made, but I do find the aforementioned occurring around the wheel periphery, albeit with very small backlash - maybe 5 minutes of arc or so in places
So I guess the question is ' what is near zero'...?
I use the table always in one direction only, and for hobbing always in the 'pull' direction, ie, so the wheel is also pulled against the worm by the hob 'threading' action. Hope that makes English sense.
Edited By Joseph Noci 1 on 25/02/2022 07:39:45
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