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  #81  
Old 09-07-2020, 08:18 AM
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Quote:
Originally Posted by dikman View Post
0.01 mm! You've got to be happy with that.
Oops, typo.. 0.04mm, that's what it seems... when turning the knob I can feel when lead screw engages inside the nut.
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  #82  
Old 10-07-2020, 07:47 AM
dikman (Richard)
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That's still pretty good, given that wherever you've got mechanical couplings it will be almost impossible to completely eliminate backlash/play.
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  #83  
Old 10-07-2020, 08:08 AM
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Yes, I am happy with this, especially when comparing with original situation, when there was a hole in aluminium and steel shaft turning inside..

Actually, cross slide is sort of better (almost no backlash but tighter), this is due to the way nut is attached to the slide (with screw), so when tightened, nut is also rotated a bit (as allowed by screw.. which is then hold tight),
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  #84  
Old 22-07-2020, 11:02 AM
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Caliper ready for installation...
Now I need to drill/tap couple of M3 threads on the cross slide to fix it in place.
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  #85  
Old 08-08-2020, 09:25 AM
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Done...
Also, yesterday I received measuring strip (it is 600mm long PCB with capacitive encoder pattern), it works with Chinese caliper reading head.
I plan to mount it under the apron for X-axis.
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  #86  
Old 08-08-2020, 03:10 PM
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Is there no end to you creative drive ? Rhetorical

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  #87  
Old 08-08-2020, 03:20 PM
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I am just bored :-)
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  #88  
Old 31-10-2020, 06:31 AM
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Smile Installing DRO

After having both calipers installed some time ago (pic 1), I decided to go one step further: more sophisticated DRO with some math (radius-diameter conversion + some memory functions and calibration of tool position).
The idea was to use Arduino UNO for reading both calipers and display on LCD with buttons for commands.

For sketch (Arduinian for "f/w") I found couple of examples on web, but I had some initial problems with pin terminology (Arduinians are strange folks with some strange ideas of how to name things). After some fiddling with the code I have basic functionality to use with my lathe.
For level converter between caliper 1.5V logic and Arduino 5V logic I used cheap converters from ebay (LV needed to be dropped from 3.3V as suppied from UNO by means of series diode to achieve better output voltage span).

Pics 2, 3 are showing working circuit (here one caliper is used for both inputs so the displayed values are the same).

Next step is to mount the processor and LCD with buttons in the metal box and wire the whole thing to the lathe.
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Last edited by bojan; 31-10-2020 at 06:45 AM.
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  #89  
Old 31-10-2020, 07:32 AM
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Caliper mounting details.
Both of them are as far away from tool as possible, but still easily visible by lathe operator.
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  #90  
Old 01-11-2020, 01:21 PM
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Command box with buttons..
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  #91  
Old 14-11-2020, 02:14 PM
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Installed...
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  #92  
Old 14-11-2020, 03:52 PM
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Very neatly done

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  #93  
Old 14-11-2020, 06:45 PM
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Quote:
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Very neatly done
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Thank you, yes it turned out nice...
For caliper connectors I decided to go with this design (from Thingiverse).

With first prototype I just soldered wires directly on caliper PCB, but this could damage the board... so perhaps connector is better idea (and hopefully reliable enough).
And, if anyone is interested, code (still under development) is attached as well.
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Last edited by bojan; 23-11-2020 at 11:28 AM.
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  #94  
Old 20-11-2020, 07:27 AM
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Finished. Tray for swarf and 300mm DRO strip in place, all functional.

Now, I have to start using it :-)
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  #95  
Old 22-11-2020, 08:26 AM
alval (Alan)
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It looks good and functional but too clean 😊, unfortunately once you start using it youíll find other things to modify 🙄. Things will annoy you, like swarf over the back so you make a larger guard, having to move to get to tools so make an accessible holder for quick change tool holders, another for centres. The list goes on but its all good. At least now you can make things, in between you can tweek things. Mines been going for twenty years, thinking of trying to make it variable speed now, so the tinkering goes on and on and ........
From the other stuff Iíve seen you put on here, youíve got it covered.
Al
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  #96  
Old 23-11-2020, 11:44 AM
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I cleaned it for presentation :-)
Yes, tweaking/adjustment things is always necessary before start of making anything..
BTW, I updated the code a bit, however there are still couple of details I would like to fix before I will be satisfied - one of them is the consequence of keypad multi-functionality.. I have to implement adequate de-bouncing to this essentially analogue keypad.
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  #97  
Old 23-11-2020, 01:49 PM
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I like the way you used a diameter symbol instead of a "Y" on the Y axis. Unambiguous. No second guessing when you're busy.
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  #98  
Old 23-11-2020, 05:14 PM
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Quote:
Originally Posted by bojan View Post
one of them is the consequence of keypad multi-functionality.. I have to implement adequate de-bouncing to this essentially analogue keypad.
Dont know what language you are using there, Im sure the debouncing Im thinking of has nothing to do with the one youre talking about 😂.

This is a picture of the archaic (literally coming off the arc) motor control system on my lathe, it only allows for forward and reverse, with a timer when switched off so I cant immediately reverse. 40-50 years old. Hence why Im looking to convert to variable speed, if this dies not sure Id find the parts to repair.

With your variable speed do you find you still have the torque on low speeds? Ive heard varying accounts on this, using slower speeds on larger diameters tending to bog down. Its not an issue on the geared system.
Al
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  #99  
Old 23-11-2020, 06:03 PM
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Yes, this is pretty old.. no electronics whatsoever.
The term "debouncing" is used to describe the behavior of the push button switch.. because electronics is much faster than closing contact of the mechanical switch, it detects every "bounce" and interpret them as multiple pressing of the switch.. which leads to unwanted behavior of the system.
In my case, "Up" and "Down" buttons have two functions, depending on previously pressed or not "select" button. So, when I press "select" then say, down, it executes first command (setting ref for Y axis) and immediately after that it executes diameter Ý or Y. So I have to slow down the buttons somehow so only first command is executed. Not a big deal but it could be annoying.



This lathe has brushless permanent magnet motor, so it is supposed to have speed proportional only to applied voltage. But in practice, torque is significantly lower at very low speeds because of coil resistance (I can stop the chuck by hand) but I think it is not a big problem (unless perhaps cutting the thread on big diameter).
The better solution here would have been a speed controller with encoder and feedback (interestingly, this lathe has encoder, but it is used only for speed display). Maybe this will be one of my future tweaks :-)
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  #100  
Old 23-11-2020, 09:28 PM
alval (Alan)
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Might have to have a rethink, cant have it stall when turning 6 inch cast iron flywheels for my model engines. Low speed high torque is required. I suppose if it aint broke I should keep using it, been working fine for me for twenty years. Just annoying i have 8 speeds, 4 high 4 low. The two used most are high low and low high (as luck would have it) so I have to pull the belt off and change a gear quite a bit. Its worked til now, and Ive got it down pat like a speed change. Just wishful thinking I suppose and getting lazy.
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