Member postings for Iain Campbell

Martin,

Never worry about the toy appearance about some of these things. There is not a single electronics engineer I know, myself included, who does not feel a certain child-like glee from making a microcontroller turn an LED on or off. It's the hardware equivalent of software's "Hello World!". They're useful for debugging things, too, not just software, but hardware and the link between the micro and a PC.

And as Jason points out, controlling the toys is usually little different to controlling the big stuff - it might be an LED now, but add a relay and it's power to the motor of a CNC Miller tomorrow, you know?

Give **LINK** a try as a source for things. They do a lot of Arduino.

Jack

Misunderstanding understood... er... you know what I mean! He he! And again, I completely agree about beginners and dabblers. They sometimes get the bug and turn into experts which encourages others to dabble - and that's no bad thing, at all.

Iain

I guess I came from the other direction, albeit enforced. I got into PICs because the small company I worked for at the time had a project in need of a micro but couldn't justify the expense of what I had been using previously (Siemens C505's, 8051's etc). Dev kits for them, especially software environments, were very expensive at the time (late 90's) and the project couldn't bear the cost of a £5 or £6 micro for the quantities we would be building.

Then I remembered an article in a model R/C aircraft mag about using PIC's for servo mixing and I had a look at them. Our distributors were a bit snobbish about PIC's ("you're a company, not a hobbyist!!" ) but the financial constraints of a small business meant a hobbyist outlook was definitely the best way to go - cheap dev kits, free software development system, cheap parts that were easy to get, and as you say, a lot of beginner stuff out there that made my learning curve very steep, but very short (and yes, it was just me doing the work). I went from knowing very little about PIC's to building and programming relatively advanced things within a week, pleasing my boss no end (an accountant, not an engineer). I guess that experience means that, like you with AVR's, I'm forever hooked on PIC's.

Had that servo mixer article used AVR's instead of PIC's, though, I'd have probably used them instead. Flip of a coin, eh?

Iain

Edited By Iain Campbell on 10/11/2014 12:23:53

Neil,

Why "PIC (spit!) or AVR (swoon!)"?

It's not a prelude to a debtate on the pros and cons between them - they often turn heated if you look at electronics forums! They seem comparable in terms of offerings, performance, price, etc., and as I've never used AVR's, I'm genuinely interested in your thoughts.

Cheers,

Iain

Edited By Iain Campbell on 10/11/2014 10:53:12

Jack,

I know and I completely agree. If you read the rest of what I wrote, you'll see that I did say I've been using PICs for years and have enough knowledge and kit for them that I can't justify using Arduinos, hence "But I can do that with a PIC...". You'll also see I did say they were great for people who were just starting out and didn't have knowledge of things like PICs, AVR's, Stamps, etc.

As for software bloat, I'm not talking about the PC but on the chip itself. To be so easy to use and accessible, there must be a level of auto code generation used by Arduino dev system, right? Auto code generation is never the most efficient of things. And if you need a cross assembler as well (writing in C needs one, which Arduino provides) then it can get worse. Cross assemblers are notorious for adding extra steps in the chip's code that are not really needed. This all takes up memory and processing time. Not an issue for the OP's application, but may be a problem for more complicated projects.

Jack, I think you've taken my post and assumed I'm anti-Arduino. I'm not. Far from it, I like them a lot. They are extremely useful and they are perfect for people starting out. I know many electronics engineers who use them for prototyping because of the ease of development and I would look at using them myself, if I didn't have the kit for something else already - hence my second post in this thread ( I was pricing up while finding links for this thread... well, I am a geek, and geeks can never have TOO much dev kit! )

Iain

*Cross assembler: translator between high level languages like C/BASIC/ADA, etc., and assembly/machine code.

Neil - I KNEW I wasn't the only one trying to resist spec creep urges! Liking the LCD idea!

Assuming the targets are not fairly heavy, and assuming ease of putting it together is more important than cash, you can get stepper drivers pre-built and tested from Ebay for Arduinos (or anything else for that matter) for a few quid each. L298N based drivers are popular. Get an Arduino board as well and simply connect them together - Arduino to driver to motor (OK, there's a bit more to it than that, but not much more). There is bound to be some tutorial for the Arduino to control the motors, similarly for adding buttons and doing some timing. And then off you go.

If you have a search on Google for "arduino with 3 stepper motors" there's plenty to look at. Adafruit and SparkFun are two sites with plenty about Arduino and stepper motor drives. In fact, this page **LINK** is a good starting point. Sparkfun are based in the US, but there's a UK equivalent called Cool Components and both will sell you the bits, too.

And as an ex-shooter, I like the end use, too

Iain

An interesting thread, this.

I've never used an Arduino but when I've looked at using one, I frequently find myself saying "But I can do that with a PIC**F**..." If PIC's aren't meaty enough for the job, then it would be a Raspberry Pi. So far, I haven't yet justified splashing out on Arduinos when I have PIC's and Raspberry Pi's around me, you know? That said, I've been using things like PIC's for years and maybe a little set in my ways (the wife would definitely say that!).

I also suspect that things like Arduino and PICAxe can suffer a little from software bloat. The micro on it's own can be used as a real time control (within limits of it's computational speeds, of course) as they can be told to do something and nothing else. Can you do the same for Arduino or PICAxe? Having never used them, I don't know.

Saying all this, however, I like Arduinos and PICAxes. If it can make life easier to get something working, then it can't be a bad thing especially if you don't need a lot of experience to do it. And I've seen both Arduinos and PICAxes used in the flight controllers of Quadcopters - so they're definitely not to be sniffed at if they can keep track of 4 rotors and a Gyro.

As for the original posts - yeah, Arduino can do that (though I doubt FFT can be done if the chip is on a par with PIC's). The problem you may have with using an Arduino is one of spec creep - will you be just satisfied with what you say in your post? Or will the inner geek in you start to show a bit and make you think "Wouldn't it be good if it could...?" in which case, I doubt it would be long before an Arduino isn't good enough! C'mon, who doesn't do this???

That's usually my problem - hence why I'm re-learning Python to programme a Raspberry Pi to do something I originally had a PIC18F doing in assembly!! I had this idea that it would be good if it could process G-Code as well as control steppers... and then, if it could do that, how about converting from DXF first... over a network... and USB... and a touchscreen showing predicted tool path... and spindle speed control... and... and... and...

Anyone know a good place to get Cray supercomputers cheap??? I think I may need one!

Iain

Gents,

I had thought of reverse switches as the only lathes I've used in the past also had them. I guess I thought they were the norm.

But regardless of that, an NVR switch definitely sounds like a damn good idea. I don't want it potentially starting up on it's own. And if they exist with keylocks on them, so much the better. My kids know not to go in the garage (usually locked anyway) to get near it, but as they get older, they'll no doubt get more adept at unlocking doors. A locked switched would prevent temptation getting the better of them - especially if the key stays in my pocket!

As for the pessimism (Martin) believe me, where electrickery is concerned, it's pessimism shared. I've seen the lathe running, but one look at the connections and there is no way it'll run again until I've sorted it out! Bare connections on the motor and no switch between it and the mains - not having that! I'm also thinking of a plexiglass shield for it. As you can see from the pics, it's rather open and is full of wood dust. I'll clean it up (or replace it in a manner more consistent with my day job... don't ask! Expensive and unnecessary geekiness that I'm trying to resist!) and then shield it from swarf.

Once again, thank you for the advice.

Iain

PS. I thought I had posted a response but it never seemed to appear. If it has and I can't see it, apologies for the duplication.

A quick question: can you recommend the best place to get a decent switch for it and what to look for when buying one? I'm thinking a forward/off/reverse type. I've seen loads on Ebay, but instinct keeps stopping me from buying, for some reason.

Thanks again,

Iain

Jason,

Not necessarily. If the gear is ferrous, the change in magnetic field can be enough to activate them... might need some conditioning before measurement, amps etc., or careful thought about the size of teeth on the gear - the bigger the teeth, the more change in signal. The sensors used on ABS are very often Hall Effect devices.

Iain

Instead of paper, can you mount a gear anywhere on the shaft? Place the IR emitter one side, the photocell the other (photo-transistor may be better) and use the teeth to break the light beam between the two. You'll get more pulses than you do currently, but the PIC shouldn't be too difficult to reprogramme for that.

An elegant alternative is a Hall Effect sensor looking at the teeth of a gear. No worries about light reflection/absorption, etc.

Iain

I've used plenty of CAD packages in my time, mainly for electronics (the day job!), ranging from the free to the insanely expensive.

The trade off between price and performance is my prime consideration and so far, I have to say DesignSpark is the one for me. For electronics, the price-performance beats everything else - some packages are better but aren't worth the extra cost, you know?

For mechanical, again DesignSpark is the one I go to. However, if the open source community behind FreeCAD sort out the limitations, bugs, and gaps in it's feature list, I might be persuaded to move back to that instead. It reminds me a lot of SolidWorks and could be extremely powerful once it's fully featured.

Iain

I did use FreeCAD for a while but the lack of certain features like drawing over JPEGs and converting to 3D (AutoCAD can do it) plus a difficult interface and sometimes very buggy code, I got fed up of it. I could easily learn Python and extend it, or get involved in the community and go from there... but that's a lot of hassle when I'd rather be making stuff instead of improving software. A shame, because it has huge potential. Maybe in a few years...

I've gone over to Designspark Mechanical (a collaboration between RS and SpaceClaim), instead. Has a feel much like Google Sketchup but from a mechanical persepctive. So far, it's been able to do everything I've needed, more so than FreeCAD, and is very intuitive. The only downside it is limited in output formats, but Step files are one format it does do.

Iain

Thanks for your responses, gents.

I did wonder if the lack of leadscrew was down to optional extras, but I'm just learning about lathes at the moment so I was open to the possibility it was a different type of lathe. The lack of screwcutting facility isn't an issue as I don't really intend to try that yet. If I did, some have already suggested thread chasers as an alternative - one even suggested it was a better alternative to leadscrews, but I wouldn't know. I'll get to know the thing first before trying stuff like that.

I probably wouldn't go to the effort and expense of fitting a screw to this one, though. I think I'd rather spend the additional expense on a lathe with it already fitted - factory fit is usually better than retro fit after all. But for now, it suits my needs - once cleaned up, of course!

Washing machine motor?? I laughed when I read that (sorry!), but it makes perfect sense. Cheap, readily available, plenty of grunt - more than a lathe this size needs. If the motor in mine needs replacing, I'll look at that first, I think.

Thanks again for the help. It is very much appreciated. I know a lot more about it than I did before, so thank you.

Iain

Hi,

This is my first post on here so please forgive me if it's the wrong place to post this. It seemed a logical place given my knowledge of lathes - yes, you guessed it, a newbie!

Anyway, I've been after a lathe for a while but have often been priced out on places like Ebay, GumTree, etc. And I could never afford anything from more knowledgeable outlets. I always thought I'd need to work on anything I get and that proved to be the case.

I found on Ebay what was described as a Perfecto model maker lathe. It works and turns, but does need a lot of restoration work. The motor is filthy with wood dust (previous owner was into woodworking so this became surplus to his requirements), but it seems OK. It does need a proper switch... the motor is wired to a plug, and that's it!

Reading up, I found out that they're similar to Myford ML2/3/4. However, rust, dirt, and general neglect aside, the one thing that puzzles me is the fact that every search I've done online for information shows that Perfectos, and indeed the similar Myford's, all have leadscrews for power feeds. This one has no leadscrew/power feed at all, at least that my novice eyes can determine. It does seem to have the castings to take one, except they haven't been drilled out. It also seems to have superfluous gearing underneath the headstock which would, I suspect, be used for the leadscrew had it been fitted. Also, everything I've seen shows the Perfecto sticker on the headstock with a serial number... I haven't found serial number at all, yet, let alone where you would expect to find one.

I have many other questions about it, including an interesting lever at the side of the chuck that seems to engage another gear, and various things that I think may be missing.

But my main question is, does anyone know exactly what this lathe is so I can find spares if needed, or just simply know what I have?

By the way, forgive the clamps in the photos holding the lathe up. The motor and pulleys pull it over to one side, so I used the clamps to keep it upright until I get a bench for it.There are more photos in the album "Perfecto (??) Lathe" on my profile.

Many thanks for any help anyone can give me.

Cheers,

Iain