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| A Low Profile CNC Tool Height Setter. |
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| Tweakie:
--- Quote from: Noitoen on June 17, 2012, 11:39:37 AM ---You can use a piezzo disc from a buzzer as a sensor mounted on some spring suspension just to act as a little over travel damper, with a little metal disc glued to the piezzo. Anything that touches the sensor will generate a voltage spike to be amplified and generate the home reset pulse even if the tool pushes the damper springs. --- End quote --- Hi Noitoen, Thanks for the suggestion but I am not sure of the performance of piezzo with relation to slow probing rates - it is my understanding that the voltage generated is tightly related to speed of impact but I will certainly try one and observe the results. Tweakie. |
| Tweakie:
--- Quote from: philf on June 18, 2012, 04:26:28 AM ---Thanks Tweakie, Mine has an overtravel of 2mm but hopefully I never need to worry about it. In operation I can't see any movement at all. When I first set mine up I didn't realise the significance of some of the numbers in the macro and entered a number less than than the height (then 30mm) of my height setter. The 2mm of overtravel soon disappeared followed by the "ping" of another 2mm carbide cutter as it tried to bury itself in the top of the plate. :doh: After cleaning up the plate the setting gauge is now only 29.74mm! :beer: Phil. --- End quote --- Hi Phil, Sorry to hear about the 2mm cutter. It may be of interest but for my setup (probing at 200mm/min) the over travel (assuming a decelerated G31 stop) was calculated at 0.0543500044871 (d=v^2/2a) then adding the operating distance of 0.0037 indicates that a total over travel clearance of 0.0058mm should be allowed for so I am reasonably confident that 0.5mm should be more than enough. Only time will tell. Tweakie. |
| Tweakie:
--- Quote ---How repeatable are microswitches? I'm guessing they must be reasonably repeatable as my machine uses them as both limit switches, and reference marks, when setting itself up. It had occurred to me if they were good to, say, 0.01mm, they'd make an ideal tool height setter without having to worry about conductivity. --- End quote --- Hi Ade, I suppose it all depends on the quality of the microswitch but it is certainly worth a try. Tweakie. |
| AdeV:
--- Quote from: HS93 on June 18, 2012, 08:07:11 AM ---Ade would this do, Knowing you you probably have half a dozen already http://www.machine-dro.co.uk/z-axis-dial-tool-setting-gauge-aluminium-body.html --- End quote --- Hi Peter, Nice find, that's definitely something I would use. But at nearly 70 quid including contribution to the Chancellor's beer fund, I think I might try adapting a dial guage... Nice bit of :proj: for me anyway. And if I get bored, at least I know there's a commercial option! I've got a couple of old Mercer 10ths dial guages which I briefly tried to use on the lathe, before discovering that trying to chase down 0.0001" in an 80-year-old 10" 4-jaw chuck mounted to an 80-year-old lathe was a bit like trying to nail jelly (aka Jello) to a ceiling; they've been sitting quietly in the cupboard waiting for a project, this will be ideal :) |
| Tweakie:
This is my 'over-travel' limit switch, well there are actually 3 of them but they are wired in parallel and operate on the 'first home' principle. The total thickness, including the PCB is 2mm and it fits below the contact plate assembly in the base of the probe and operates a machine limit in the event that the G31 probing routine fails. That's the theory, only time will tell. Tweakie. |
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