Aussie Lapidary Forum
LAPIDARY => Tips and Gadgets => Topic started by: RoughCreations on July 10, 2021, 06:35:46 PM
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Thought I would start a thread for the recent fitting of an encoder to my Facetron faceting machine by MakkyBrown beers.
I'll do a recap to cover some of the early preparations.
A key component was required - Makky CNC-milled an alloy housing/adapter suitable for a Facetron using the dimensions I supplied (shown below). The adapter was designed to suit an Avago Technologies AEDM-5810-Z12 5000cpr encoder.
Dimensions used for CNC-milling of adapter:
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-140521131105.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9598)
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-140521131149.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9599)
Here you go. Currently, I've made the recess 24.68, which allows about 0.07mm for a slightly uneven circle polygon. Hopefully that is enough and sanding is not required. Will cut from 10mm plate, recess is 4mm deep. Hole will be adjusted so 6mm shaft slides in with as little pay as possible so the mount can be used to align the shaft extension. After the glue on the shaft sets pull off the mount and drill the hole slightly larger before gluing the mount on.After fitting the shaft extension you can check it for run out, if ok go ahead and fit the encoder if not then I won't have to buy a replacement for my machine.
I've made the recess 4mm deep, 3mm for the bearing and shaft and an extra 1 mm for glue squeezing when the shaft is fitted.
Your OD is probably 31/32" or 24.604mm
Should work, I'll see if i can cut it on the w/end.
MB
(https://aussielapidaryforum.com/forum/gallery/9/medium_5704-140521185549.png) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9600)
Here it is in the flesh:
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-100721175528-96822167.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9683)
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My machine under anaesthetic, ready for some elective surgery (surgeon MB) in southern Tasmania:
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-100721180517-9687134.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9688)
You can see the catheter has already been inserted:
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-100721175527-96811036.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9682)
Black Dextone epoxy-based adhesive was used to achieve this step. You can just see a little fillet around the shaft bottom edge. Note the alloy adapter was in place when the shaft was glued to centre it correctly, this a is crucial step and without doing so would result in the shaft being badly mis-aligned.
I will state here that no drilling or dismantling of the machine was required, so the modification is reversible (but I'm certainly not going back!). At first I found it a little hard to accept the concept of gluing, as I am more of a dismantling, drilling and tapping kind of guy. However, following on with the same analogy, I see this as keyhole surgery rather than open-heart surgery. The components aren't coming off anytime soon, this black stuff sticks good. There's no physical load on the encoder or adapter, and components are very lightweight. The metal surfaces were lightly sanded to allow the epoxy to better anchor with the raised metal grain, and then surfaces were cleaned with alcohol to remove any finger grease etc.
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I take it that this will give you a digital display of the angle of the quill. Something that can be used as a stop, but also record the angle of the facet. For example, if the facet was 43.25deg and you later spot a problem with it, you can go back to 43.25deg and fix it. That would be brilliant.
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I take it that this will give you a digital display of the angle of the quill. Something that can be used as a stop, but also record the angle of the facet. For example, if the facet was 43.25deg and you later spot a problem with it, you can go back to 43.25deg and fix it. That would be brilliant.
That's pretty much it in a nutshell. It effectively negates having to put up with play in the mechanical drivetrain from quill to indicator. No squinting at an indicator dial graduation either, you can choose how to display the encoder information (numerically or graphically) by writing some not too difficult code, or get someone else to write it for you.
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I forgot to mention this bit, a small alloy collar with centre hole drilled the same as the shaft (6mm). I think it was used to help with the shaft alignment whilst gluing (the most critical step). MB could probably add some more details here.
MB Edit : Yes, it is an alignment tool that fits snugly into the encoder base plate and kept the small shaft centered and vertical while gluing.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-110721110130.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9690)
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The alloy adapter glued with Dextone to the Facetron side arm. The black plastic encoder base plate has been screwed to the alloy adapter. The gluing was successful as the shaft run-out appeared minimal with slow manual rotation - within the encoder's installation parameters.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-100721175528-96831856.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9684)
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Encoder internals and housing snapped onto the baseplate, a tiny allen key locks the shaft to the encoder hub wheel.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-100721175529-9684457.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9685)
The encoder wiring harness (five wires) are connected to the encoder by a Molex KK type? push in connector (Broadcom HEDS-8903 connector). The ferrite ring seen here on the cable was later removed.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-100721175530-96851061.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9686)
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Connected to display box. Note that the LCD screen is a little dead in some areas, I have a new screen to replace it with. The black button is the on/off, the green button is the calibration button.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-100721180516-96862221.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9687)
The calibration button is pressed when the brass dop extension is laid flat and parallel as possible with a straight and true alloy backing disk. This then becomes the 90 degree reference value for the encoder and is stored in the EEPROM.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-130721130647.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9693)
The cable ties seem a bit crude, but they work well and haven't got in the way of cutting so far.
Amateur Gemstone Faceting Vol 2 is the unofficial "licence" required to undertake the Tom Herbst inspired faceting machine encoder modification project.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-110721114520.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9691)
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Wow, looks the goods RC! You'll have to post your first stone when you do it. By the way, I know it's been a while but do you or Makkie want the specs for the saw blade holders for the Facetron? I'm home now and can measure them for you.
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Bought that book by Tom a while back so I could fit an encoder to my machine. I think he dedicated 23 pages on the subject, anyway way over my head and never attempted to fit one.
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I agree Frank, it is not something I would have tried on my own, even with the book. The fact that MakkyBrown did the install for me, by documenting it, I hope this encourages more people with some technical ability to give it a go.
I think I will do a bit of a breakdown of what's in my display box next, and how to upload code to the micro-controller.
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Wow, looks the goods RC! You'll have to post your first stone when you do it. By the way, I know it's been a while but do you or Makkie want the specs for the saw blade holders for the Facetron? I'm home now and can measure them for you.
Appreciate the offer, but it's all done now:
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-250321090527.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9382)
MB, (bless his soul once again) machined the saw holder up out of perspex for me.
I have already cut some stones with the encoder, it is very user-friendly to use, and my pavilion tiers meet beautifully, and are so pointy now!
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I have recently rebuilt my encoder box to learn more about micro-controllers generally, and also enable me to add more lines of code to perform extra functionality, and have a bit more room inside to put things that are not really necessary, lol. The Nano board in my original box was reaching its limits in some areas, but still managed to do the basics just fine. Everything except the screen was bought at Jaycar.
My Parts:
Back and front of screen, black screen bezel mount and Uno Wifi 8266 board.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-300721170354.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9707)
In progress:
Uno Screw Shield (green screw terminals not really necessary except for proto-typing), white polyethylene chopping board insert, screen underneath. By using the Uno form factor shield, the wiring can be soldered to it, but the board can be removed easily - it just pulls off and pushes back on.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-230921103719-97322365.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9733)
ST7920 128 x 64 Screen wiring:
My soldering needs a little improvement, but it tested OK. I can provide the wiring details I used if anyone is interested. I later added a trimpot to Vo pin to control the screen contrast.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-230921103720-97331330.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9734)
All wired up:
Completed encoder box with 8266 chip board. The little square hole was cut to enable me to access the micro dip switches underneath if required, but I haven't used the Wifi functionality of the board yet. You can see the connector on the shield for the encoder wires (red-white-green-black-black). The encoder cable is removed in this picture.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-230921103717-97302451.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9731)
Front view, in action:
Red button stores the current angle in the EEPROM, it then becomes the Target Angle. The angle shown in large font is raw and un-smoothed. The Smoothed angle and the progress bar don't change until seven encoder readings in a row are exactly the same (about 0.5 seconds) - I find this works well for me. The black button currently does nothing, the knob does the screen contrast, and there is another button underneath to calibrate the unit (not shown).
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-230921103716-97242499.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9730)
I can't help myself, I'm experimenting with yet another board:
An ESP32 board in Uno form-factor this time, quite powerful, and still under $20. The other smaller board is a DC-DC converter to provide a cleaner input voltage to the board (taken from original box from MB). The GPIO pin outs are laid out quite differently on the ESP32 board.
(https://aussielapidaryforum.com/forum/gallery/9/medium_112303-230921103718-97311820.jpeg) (https://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9732)
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Bump for jcricket.
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Bloody hell RC, do you actually do any faceting these days or are you having too much fun with the electronics!? I will expect scores of >98 in any future competitions.
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Bloody hell RC, do you actually do any faceting these days or are you having too much fun with the electronics!? I will expect scores of >98 in any future competitions.
Not quite as much faceting as I have done at certain times in the past. I get bogged down with many stones, being too much of a perfectionist maybe. I get halfway through a stone, notice something I think that needs fixing, then go back several facet tiers. The cycle repeats and it takes ages to finish a stone, assuming that I don't lose interest.
It has surprised me how much I have enjoyed working with microcontrollers since MB showed me how. I have worked as an application programmer in the past, but programming a physical device is way more interesting imo.
I also believe that faceting is an example of a rare hobby where you *can* actually blame your tools! This means any devices that promise to improve precision and repeatability will get my attention - encoders fit into this category.
RC
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See link below to download specification sheet for the encoder used in the Facetron modification:
https://aussielapidaryforum.com/storage/AV02-4926EN_DS_AEDM-55xx_2015-06-04-706336.pdf
RC
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I know your pain RC, the last stone I did was something like 330 odd facets, had to repeat the pavilion after a slight miscalculation with the height of the stone, I ran out of stone before the culet!
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Just bringing this topic back so it's convenient for me to look at.