rwillett

Santa has arrived with a late delivery. 2 x 500g of 44AWG and 42(ish) AWG. I suppose this means I need to get my act in to gear and get the stepper motors working properly.

I'd forgotten that about Fry and Adams, they were heavily into IT. As an aside the company I worked for as a sandwich student (do they still exist?), brought something like the 2nd Apple Lisa in the UK when it came out. I worked doing research in formal methods and the dept next door had the Lisa. It was wonderful but I recall that if you dropped the calculator into the wastebin it crashed the OS. Not to be outdone, the dept I worked in brought a few Xero Dolphin workstations and a laser printer. I think they were £25K each at the time and ran Interlisp-D. Thats when I first encountered Lisp and loved it That works out to be around £100K now, so around £400K for three workstations and a printer. Rob

Nice but inaccurate nod to Douglas Adams FTFY

Damm, misremembered that, though technically a panther is just a black leopard. However I will claim that I didn't want to get sued by Douglas Adams estate rather than my memory is failing me I can now say that it saved me two £15 stepper motors, two DRV8825 drivers, a CNC board and an Arduino (though the latter is more difficult as it's more isolated), total of about £30. It's almost paid for itself.

Whilst I've not made a lot of progress over the weekend, beyond what I put above, I have started to understand more about the Vref potentionmeter on the little driver sticks. These drivers slot into the CNC board and controll the stepper motors. You can control the stepper motors directly from an Arduino but its better to control the drivers and let them control the stepper motors as thats what they are designed to do. The Arduino was designed to allow physical components called shields to slot on top of the board. These shields provide additional functionality such as Ethernet, WifI, Real Time Clocks, stepper motor drivers, connections to sensors and so on and so on. I'm using a sheild called a CNC shield, see below which is really just a simple way of adding in stepper motor drivers which are the four chips around the side. CNC Shields are about £2-£3 each and are made in bulk. CNC shields have no programming capability, they just present a simple and uniform way to get stepper motors connected. You access the stepper motors using a standard and uniform coding libraty as well on the Arduino. So instead of making complex calls to pins and timers, all of that complexity is abstracted away. Thats the theory anyway However to get the stepper drivers to work, you have to do some low level coding to enable the stepper motors which appears in documentation that is hidden in a file cabinet in a cellar in the local planning office with the stairs removed, the lightbulb out and a sign saying "Beware of the Panther" on the door. It's only two lines of code, but it's an important two lines of code as nothing works without it. Once thats done, you can connect your PSU up to the blue terminals on the bottoms left. The input is 12V to 36V which is way beyond USB so a dedicated PSU is needed. I used this as an excuse to buy a decent bench power supply This little beauty has one key feature. I can restrict the amount of current that can be drawn. So I set it to 12V and 1A plugged it in and immediately the CNC board and stepper motors started to whine. It turns out that the DRV8826 stepper motor sticks have a little potentionmeter on the top that determines the maximum current draw. I initially set this to 1A so I didn't blow anything up. I didn't understand how this worked so decided to keep increasing the allowed current to see what happened. I got to 12V 4A and still nothing worked. Turns out that the potentionmeter was allowing around 8A per driver to be pulled and if I didn't have a decent bench power supply, I would have fried both driver sticks and the stepper motors. I only really noticed I had a problem when I touched the heat sink and promptly burnt my fingers. So I put a multimeter on the potentionmeter centre point through a screwdriver and a crocodile clip, and the black to ground and turned Vref down to 0.6V from 3V. The whining stopped and the stepper motors started to work. Also the temperature dropped to non burning temperature. The moral of this story is "Dont mess with things that you think you understand but really don't, because it could be expensive and you literaly do get your fingers burnt". Thankfully I didn't blow anything up, and the only damage was my singed fingers. I can see the burnt marks now. Now I have the pots turned down, time to see if my Arduino coding actually will work and drive real stepper motors as opposed to simulators. Rob

Sam I had seen Voronoi stuff before and promptly forgot all about it. Its very organic shaped and almost Gaudi like. Thanks for reminding me about it. The fact there is a F360 generator is great and once I finish the pickup winder, I'll look at using this again. Since I've now been converted to glue for PETG bits, I don't have to worry about flat sections and stuff like that for bolts. I'd love to see your pedalboard with this as well. <hint> The pickup winder is still progressing. Spent most of Sunday evening trying to understand the Vref potentiometer and how it works on a DRV8825. Thanks Rob

So after putting up the bathroom mirror, changing lights, sorting out the clock in my daughters bedroom, taking dog for walk, paying my tax to HMRC, I finally got around to doing some work on the winder. I now have a case for the Arduino, screen and keyboard. I have ordered a mechnical 4x4 keyboard to replace the membrane one but got a 3x4 by mistake so a new one is on it's way. Whilst the membrane keyboard works, it's vile to work with. The gorilla tape just holds it down as I have no idea what the glue would do to it, probably dissolve it. I've attached the lead screw mechanism to the plywood base and am working out how to get the motor that loops the bobbin as square as possible, hence the set square. I would have this all powered up, but the bench power supply came with no cables apart from the mains supply, it needs 4mm banana plugs and do I have any? No! The lead screw mechanism was a little tight as the screws that mount the linear bearing on each arm, were probably out by 0.25mm. Not a lot but thats enough to put friction in the system. So I'm reprinting that with a fraction more leeway in the screw holes to allow it to settle down. This lead screw mechanism is critical and it needs to be as smooth as possible as it moves back and forth as the bobbin rotates. The area at top left is reserved for a dedicated PSU once I work out what the power consumption is. Thanks Rob

There's seven bids on it, so somebody is interested in it.

Odfly enough I did think about that but a simpler model. I have rejected the idea though

It means that I have the basis of the controlling software for a winder. As far as I know, there is no code around for doing this, so I wrote my own, I know that people use electric drills and similar to do windings, but I wanted anything I did to be defined. I'm not very good mechanically so Id rather write software that does things for me, as thats easier for me.I have nothing but admiration for people who can make things creatively. So if I can make this work (note the word if) and they sound OK, it's repeatable. If I want to make a pickup with 10,000 loops of AWG 44 wire or 5,000 loops of AWG 42 wire (thicker than AWG 44), it's a matter of changing the Wire Width parameter and the number of loops. The software should do the rest automatically. If I want to make a thicker bobbin or thinner bobbin, thats just a parameter change. I now have the CNC shield setup, added the stepper drivers, DRV8225, set up 1/8 microstepping, I have a 60V/10A bench power supply but now I just realised I don't have any jumpers to fit the stepper motor wiring to the CNC shield. These are DuPont connectors. I can make them, I even have a kit, but I hate making them, Sod it, Mr Amazon to the rescue. £10 for 6 of them, I only need two (at the moment), so a bargain. Everybody uses their own connectors Rob

Managed to get the IDE working on my Mac. Didn;t have to download any drivers from an obscure Chinese web site. That was never going to happen Copied all the code across to the IDE, compiled it, uploaded it and blow me down with a feather it works. No drivers setup, but I now have working keypad, screen and Mega 2560. That was rather painless. Suspect the CNC shield and stepper motors will be a lot more hassle.

Everything is possible. The easiest way is probably to create a file externally that has all the motor actions, basically the same as a gcode file for 3d printing. The looping motor just loops, an external source with a lot of memory (Raspberry Pi comes to mind), connects to the USB port and sends down the stepper motor commands for the lead screw motor to move it along the X axis, perhaps a step or two extra left or right or take a step out. The most difficult thing would be the connection from Pi to Arduino and keeping the timing right. Other options include making the bobbin with angles so that the top of the bobbin could have a wider diameter to the bottom or the middle is thinner or anything really. As I'm 3d printing the bobbins, that fairly easy. No idea if it makes a difference though. Perhaps this is V3. Rob

Randomisation is not in V1. Scatter winding appears to be how Fender wired these things, basically hand wound trying to make it near but with imperfections. At the moment my focus is getting anything down, neat is a bonus. If the winding pattern can be reduced to a function, then everything is easly possible. What you are describing above is what I would call typewriter winding (just made that up), you wind to the end and then instead of winding back carefully and slowly, you move the wire back quickly to the start and then wind across. There are loads of ways to skin this cat, I could do randomisation and capture this in a stream of data that is sent off the Arduino. I could inject random data into the Arduino from an external source that is precaptured. I have a TrueNas file server here with a lot of free space, so capturing data and storing it is not a problem. There's a number of options to consider but I'm not ready to do that yet. I just want to get something working and try it out. I am going to have to make a test bench guitar for these pickups (6 and 4 string) so might quickly take the 3d printed guitar design and just print the absolute essentials (bridge, pickup and neck modules) and attach it to a plank of wood. Another thing to add to the list Rob

Since my last update, I have now written most of the software and it works (for some value of 'works') with the simulator. I've now just about reached as far as I can go with the simulator, there's probably going to be some hardware issues to resolve now and the only way to do that, is to get the hardware built and the code uploaded. I'm now going to use a Mega 2560 Arduino rather than a UNO as it has more pin outs. I'd literally run out of pins on the Uno and was struggling to put all the bits I wanted. I had a Mega 2560 sitting around doing nothing so thats now the base. It also gives me far more code space to program in and save stuff in. I've got a CNC Shield as that sits on top of the Mega 2560 which saves vauable real estate, I'll only use two stepper drivers at the moment, though I can use four. I might use a 3rd for tension control of the wire but not yet. The CNC shield takes 12-36V and a bench power supply is on order (60V/10A). Stepper motors can take a lot of amps, I suspect I won't need this sort of output power, but it's nice to have a lot of head room just-in-case. The menu interface is quite good (even though I do say so myself), I can create sub-menus but so far haven't needed it. I can use a 4x4 membrane keypad to enter integers, floats and select from lists. I'd love to be able to find a blank 4x4 keypad, or one where I can change the keys to be what I want them to be. I'll have to use sticky labels at the moment, but as these keypads are about £2 each, not a problem. So next steps are: 1. Working out how to do microsteps on the stepper motors. The reason for this is that there is a ratio between the number of loops that the main pickup winder motor makes and the number of turns that the lead screw turns to ensure that the pickup wire moves across the bobbin so that the pickup wire is evenly placed. I know some people might want randomisation but thats V2 of the firmware. These microsteps appear to be controlled by the CNC shield and setting jumpers (!). if I can move from 400 steps per singe revolution to 800 or 1600 steps, then I can get the ratio between the two motors to be higher and closer to an integer. Thats good 2. Putting everything onto a thick A3 plywood base. I wanted to use a larger base as that reduces the angle that pickup wire moves through as the bobbin is turned. If the bobbin is very close, then the angle subtended gets closer to 90 degrees. Imaging your finger wagging at 10 times a second going through 90 degrees vs at 45 or 30 degrees. I might be worrying about nothing but lets see. I have printed most things including guides to position everything accurately. I have all the hardware to do it, just been away and its bloody cold in the garage here in North Yorkshire. 3. Work out how to build an Arduino dev environment on a M series Mac. I have a simulator but not a clue how to actually prgram an Arduino on a Mac. Last time I did this, I used a Windows laptop. I might still have to yet. I really want to built it around Emacs but suspect thats not going to fly. 4. Get it installed and get the firmware properly debugged. 5. I have a couple of cheap bass pickups I've brought, so will gently take them apart and see if I can replicate how they are made. My knowledge of magnets is limited but I'll start reading up over the next week or so. 6. Buy some 42AWG wire. I'll start with the thicker stuff first. 7. Work out how to fit bump stops in case everything goes out of control. There are pins on the CNC shield for this, its mounting them thats the challenge. Thats probably enough to go on for the next week or so. I still have to start work on my 3d printed bass but thats on hold whilst I get this working. Rob

I can't say I like the pickguard, it looks like that had a load of material left over and just used it up. However the rest of the package looks the sort of guitar that Disaster Area would play. All it needs is a little black button saying "Do not press" on it, oh anda large black spaceship. Rob

Thanks for the information. That sounds about right for me. Any suggestions on makes or models please. Happy to spend £50-£100. Many look identical and possibly are. Are there good ones and bad ones anymore? Or all are pretty good?

Hi I'm looking for a decent bench power supply to test my Arduino pickup winder. I'm a coder, not a hardware engineer (I'm not even sure I'm a coder these days but hey ho). I want to get a bench power supply to test everything out for the arduino and a couple of Nema 17 stepper motors. I've brought this type of dedicated psu's in the past like this (this just shows the type and isn't one I have brought). https://amzn.eu/d/76ekIkm But I keep putting off buying a bench power supply that's a bit more flexible so I can test things work and then get the right dedicated PSU at the end. I don't suspect I'd need anything too big, but I have a number of projects with three stepper motors in mind and they can draw 2A each. So 30v and 6-10 amps seems the right size but beyond that, no idea. I look on Amazon and get very confused so any recommendations welcomed. Thanks Rob

It is truly beautiful...

Now that is a thing of beauty... Just looking at the kids college funds, approx two years, they can always get jobs. Rob

Hawes and the Wensleydale dairy are great. The courtyard don't make cheese and to be honest I don't think they ever will. But what I do know. Nothing.

I like cheese but I wouldn't travel that far. One option we have for the bash could be takeaway pizza from Rind.

Luke You are clearly very close. My daughter works at Rind next to the cheese shop

You might live in Yorkshire and still be nearly three hours away. We're on the border of North Yorkshire, Lancashire and Cumbria. My kids go to school in Cumbria and we drive through Lancashire to get there.

Diary vs dairy....