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saxonhawthorn
10-12-2009, 11:10 AM
Hello People,

I'm a retired software engineer and like many who have spent their working lives pondering the invisible workings of processor internals, I feel the need now to make things with my hands as well as my head. So I have bought a 7 x 14 mini-lathe and of course I already have a decent bench drill, and I'm currently in the happy process of fitting out the rest of my tiny workshop.

Now it's clear from this site that CNC holds attractions for many hobby machinists, but can somebody explain to me why? Surely CNC makes sense only if you're going to make products in quantity on a production basis? No doubt I'm missing something here, but may I ask "What exactly are all these CNC wood and metal routers going to make in such quantity that it's worth all the trouble and expense of going from manual machining to CNC?"

Looking forward to being enlightened.

Ian in Banbury :confused:

ptjw7uk
10-12-2009, 11:39 AM
I think there is more than one answer to this question.
First I think saying cnc is only good for production runs is wrong in concept, it can make single items quicker and easier than by manual means.
The manual method will entail the production of jigs etc to get the required shape and jigs again are usually in the realm of production whereas the cnc jig is the drawing program.
Why use a machine at all most things can be made by hand tools and lots of effort, but if you like tools make a cnc mill or router nad then you can make even more tools.
Most people on the forum are doing it as a hobby or as an idea to make money etc. Its ones imagination that wins in the end and if you have to justify it then dont do it just go down the pub.
It all depends on whether its the journey you enjoy or just the destination, I for one enjoy it all and am not at all sure it will do what I want in the end but I'm not going to stop because I cant see the end in sight!
Besides I like tools using and buying, making them, I have the belief that some day I will use them in earnest(well thats what I tell thye misses)

peter

saxonhawthorn
10-12-2009, 11:55 AM
Thank you Peter. It's the same excuse I use to my wife when she complains that when she opens her broom cupboard now, lots of metal bar stock falls out!

I understand the point you're making though; the journey is part of the fun, and if the destination turns out to be somewhere nice, that's a bonus.

But thank you too for a point I hadn't considered, namely that it's quicker to make a single part by CNC than by manual methods. That hadn't occurred to me. So perhaps you can answer another question which follows on from that, namely "Which CAD?" AutoCAD is a good commercial product but hopelessly over-priced for hobby use. Whis is the most popular CAD/CAM amongst the users of this forum? Is there such a thing as a concensus?

Ian

CraftyGeek
10-12-2009, 01:22 PM
I've recently finished my MDF machine - I enjoy designing things on a computer...I have done so even before the cnc machine. I also enjoy making things - now I have the cnc machine it allows me to design more complicated things & then make them with an accuracy that I could never have done before with hand/machine tools....at the end of the day its another workshop tool - but a very versatile one that does also speed up the building process.

Mine is purely for hooby use & my own enjoyment - if at some later stage I find that I make something that I want to sell, then I have the capability to make more of them easily.

saxonhawthorn
10-12-2009, 01:43 PM
Thank you. I'm beginning to get the drift. I have used CAD for designing PCBs for about twenty years and I certainly wouldn't want to go back to the early days of PCBs when I had to draw tracks by hand on to the board using a paintbrush. So I can understand the improvements which come from using CAD for machined parts.

I probably approached this subject from the wrong end. The right place to start thinking about it would seem to be the CAD, and THEN the CNC follows naturally from that.

(Which probably means I should find and migrate over to a CAD/CAM thread.)

Regards,
Ian

tribbles
10-12-2009, 01:51 PM
For me, the attraction is four-fold.

Firstly, I design on a computer, so being able to just tell the computer "Take this, and make it" is fantastic - I don't need to print anything out.

Secondly, I can get a significant amount of accuracy that I wouldn't have been able to get manually. I'm designing a car body, and it's expected that a manual process would be, at best, 3mm from side to side. The computer's accuracy is significantly higher than this (I'm aiming for 1mm, but I know that it should be able to get much higher).

Thirdly, it's repeatability - if I need to make 1 'doodah', then manually it would be doable. If I needed to make 10, then it would be a bit laborious - 100, and I'd get really tired of it.

Finally, it's automatic - I don't need to watch it do its thing over many hours, so I can get on with other things while it's doing its thing.

ptjw7uk
10-12-2009, 02:24 PM
The software side of things is a big problem in that you will unless you start to sell items never make up the large cost of the software.
So what are the options, cambam do a free version which I have used and is reasonable for whta I want to do at the moment. Then there is Flashcut CNC3 which loads and can create gcode for free see http://www.mycncuk.com/forums/showthread.php?t=896&highlight=software post 5 by JohnS
This will get you most of the way down the learning curve.
I have Autocad Lt but it will not run on my Vista machine so I have to transfer dxf files to the vista machine so much for progress. Looking at the new Windows7 professional which will run a version of XP but needs a clean install so I'll just wait as this is a hobby and not a bottom less money pit.
Just had a dya of more learning the ins and outs of cnc in that the software used with my controller Easycnc2 has an engraving function taht I have been playing with. For small print it appears to be OK but as I wanted bigger the curves to letters was a bit lacking so, I tried the Cambam text and it was a lot rounder flowing output, So produced the gcode and input it into easycnc2 and run it in emulate wtf it was producing great swirles all over the place?
Had a look on the web for an emulator, found one download and run it text was great. Loaded the code into the mill and produced great swirles as per the emulator. Quick email to CDE produced the fact that there was an option for G02 and G03 code in that for arcs there is an option to do them in absolute or incremental fashion. Put a tick in the box and the text is now OK.

You just have to take it one step at a time!

Peter

saxonhawthorn
10-12-2009, 04:39 PM
Thank you Tribbles. That's a very comprehensive and persuasive set of arguments! :)

Tom
10-12-2009, 04:45 PM
can somebody explain to me why?

For me it's the same, the pleasure and freedom of being able to design something that doesn't necessarily have many straight lines in it. It's a bonus that you can make 2 or 3 in a similar time as it takes to make one (make one, sell one, give one away). My machine has only been running a couple of weeks, and isn't truly finished, but I'm loving CNC so far - if you can imagine it, you can make it!


So perhaps you can answer another question which follows on from that, namely "Which CAD?" AutoCAD is a good commercial product but hopelessly over-priced for hobby use. Whis is the most popular CAD/CAM amongst the users of this forum? Is there such a thing as a concensus?

My workflow at the moment is ProgeCAD Smart -> Cambam plus (still in my 40 trial startups) -> EMC2. This is fine for 2D and 2.5D cutting. The programs import and export via DXF.
ProgeCAD Smart is basically the same as autocad, and free for non-commercial use. http://www.progesoft.com/en/smart-2009

Later I'm going to get more into 3D forms (I have a very specific project to make a wedding present for some good friends), and have started to learn Blender (a pretty steep curve). Again export via DXF, but I haven't tested Cambam like this yet...

I don't know about a consensus though! :)

In summary, if you need to find some critical views on CNC, you probably need to try a different forum!! :smile:

saxonhawthorn
10-12-2009, 04:51 PM
Peter, thank you for the CamBam tip. I hadn't heard of it, and it looks interesting. You're certainly right about the cost of software, and I'm amazed that hobby users can afford stuff like AutoCAD at all (unless of course they hoist the Jolly Roger and sail off into the sunset with a dodgey copy).

I'll take a look at CamBam tomorrow. I suppose if all else fails I could actually write some CAD/CAM code myself; but I'm not very good at visualising things in 3D, and the thought of debugging 3D trig makes my head spin.

saxonhawthorn
10-12-2009, 05:03 PM
[quote=Tom;9740]
if you can imagine it, you can make it!

Tom, that has to be the quote of the week. :)

It was seeing all the hardware bits on eBay that set me wondering what the attraction was? But as you and others have pointed out, it's clearly the ease of CAD design that most attracts people to CNC, and I can understand that.

I think tomorrow (and probably quite a lot of tomorrows) will now be spent reviewing CAD packages. Then once I have found one I'm happy with I'll start thinking about bolting steppers on to my lathe.

Ian

ptjw7uk
10-12-2009, 05:41 PM
Hi Saxonhawthorn,
Have a look at this one (free) http://doublecad.com/Download/tabid/1128/Default.aspx at bottom of page the free one.
I just remembered I had loaded it and have just tried it, looks OK but like any of the others will take time to look around, spent 10 minutes trying to find the ortho button.

Peter

jonm
10-12-2009, 09:26 PM
hi
have you heard of the cnc toolkit,a plugin for gmax which is a free version off 3ds max , can make toolpaths from objects made in gmax, and generate g code all for freehttp://www.cnc-toolkit.com/
a manual for cnc toolkit can be downloaded here http://www.cnc4free.org/

saxonhawthorn
11-12-2009, 12:16 PM
Thanks for the link Peter. I have downloaded DoubleCad, but I hope the product itself was not written by the person who wrote the download form. It demanded from me a company name I haven't got; then even worse, demanded that I tell them the most-used CAD packages in my non-existent company, offering me a list to choose from, most of which I had never heard of and none of which I have ever used, without even thinking of giving me a "none of the above" exit from the input loop.

This is an appalling way to write any code. I spent 25 years writing software for a living, and one thing I learnt from that is that more than half your code space (and programming time) is taken up by exception and error handling; i.e. when the real world (or the end user) doesn't do what you think it's going to do. I shall look with interest at DoubleCAD, but I hope it's error handling is better than that on their web site!

In the bath this morning (which is where I do my most productive design work) an approach to the expensive software problem occurred to me which I need to experiment with. It may be of interest to others here, and if so I'll post details when I've tried it. Won't be until after Christmas though; too much needs to be done in the workshop first.

Ian

saxonhawthorn
11-12-2009, 12:32 PM
My word! You gents are all extremely helpful. The http://www.cnc4free.org/ link is a very useful one Jon, and seems to have the right philosophy for me now that we have to live on my meagre pension, namely: "If it costs money, we don't do it."

But looking at some of the lovely things people have made, I must say I am beginning to get the CNC bug :)

Ian.

Robin Hewitt
11-12-2009, 06:39 PM
Are Alibre still doing their $99 offer? That was the bargain of the year. Of course I got referred to a UK dealer who wanted 99, but I knew the Yanks wouldn't turn away my $99 if I pressed on regardless.

My old AutoCAD no longer works now I have to go Windows 7, looked up the replacement and blenched at the price. Searched el webbo for AutoCAD look alikes and ProgeCAD for 220 looks the best bet. Anyone tried it?

CamBam is good, I sent him the money. You have one minor hurdle to leap before you can start stacking cuts down the left hand side of the screen, perhaps not quite as intuitive as the manual thinks. Having to redefine the tool every single blooming time is a pain in the butt and somewhat fraught.

Smiler
14-12-2009, 07:59 PM
I make the odd sign or plaque now and then but the real reason was this: (and I saw this quote on a CNC site somewhere but it stuck)

"to make something with my hands that can make something I could never make with my hands"

And that's the real reason, I'd have loved to have been a carpenter but I'm hamfisted where chisels/planes etc are concerned BUT I'm good with CAD and decent at 3d modelling and frigging amazing with a welder. Bish bash bosh, one CNC router and I can now carve wood better than the artist guy who lives in the next valley, faster and better quality too and I don't even own a chisel.

Jeff.

Robin Hewitt
14-12-2009, 08:42 PM
I knew I'd arrived with files and saws when my metalwork tutor was asked for someone to copy a security key. With a whole college to choose from he picked me. I cut it out of mild steel on a bench pin, got 40 Bensons and she said it worked better than the original which slightly worried me. I thought it would work the same. Maybe she was just being kind :whistling:

I was taught well for 3 years. I can make most anything by hand (so long as I can find my +4.0 close up glasses for the fiddly bits). OTOH CNC is much easier if you can live within the constraints of 2.5D and radii on internals :beer:

saxonhawthorn
15-12-2009, 11:36 AM
Gentlemen, you have converted me! I am now gathering the bits and pieces to make a CNC pick-and-place machine for populating PCBs. I couldn't even estimate the number of PCBs I have built by hand over the years, but now I'm looking forward to leaning back in my chair and watching a robot do all the work.

After that will come the various robotics for machining die-cast cases, fitting the PCBs in them, and testing the end product. Time scale to be in production is six months, but for the first time in my life there are no commercial pressures on me so if it takes longer, who cares?

By the way, surveying the CAD scene there seems to be plenty of 2D and 2.5D software around at sensible prices, but there doesn't seem to be so much 3D. How important / useful is 3D? Do people here use it? If you do, could you live without it?

My grateful thanks to all who have responded so magnificently to a stupid newbie's questions! I now understand your enthusiasm for the subject. :)

Robin Hewitt
15-12-2009, 12:13 PM
I am now gathering the bits and pieces to make a CNC pick-and-place machine for populating PCBs.


Now that is a subject dear to my heart. Are you doing SMT or conventional? Do tell more :beer:

Robin Hewitt
15-12-2009, 12:21 PM
By the way, surveying the CAD scene there seems to be plenty of 2D and 2.5D software around at sensible prices, but there doesn't seem to be so much 3D. How important / useful is 3D? Do people here use it? If you do, could you live without it?


3D requires an extra axis or two and the maths gets complicated once you stray beyond tube cutting.

OTOH you can do a lot of 3D with a 2.5D machine, if you can figure out how to turn the part over without losing position and avoid overhangs.

saxonhawthorn
15-12-2009, 02:04 PM
Robin,

SMT. It's smaller, neater, and I won't have all those flippin' pig-tails to cut off.

I haven't made up my mind about applying the solder paste yet though because I have never worked with lead-free (sshhhh.....) and I don't know the preferred method: silk screen or a dab from a syringe. Silk screening would be quicker, but probably less controlable for the tiny dots. But I'll have to ask the paste manufacturers.

Otherwise I can't really see any insurmountable problems. I have bought a beautifully machined large worm and wheel for the robot arm major axis, and an equally well made tiny worm and wheel for the component pickup head horizontal rotation. (OK I'm cheating, and I should have machined them; but I'm a beginner, and hobbing those gears is something I'd need to get some practice with).

Ian

tribbles
15-12-2009, 02:30 PM
I've been doing SMT for quite a while now, but all manually (for three reasons - size, component availability and not having to drill so many damn holes). Not sure if I do the volume for a CNC machine yet though!

I thought that for solder paste you really do have to do a kind of silk screen (at least a mask) - although I suppose it would be possible to use a very small paint brush for some of the pads!

Robin Hewitt
15-12-2009, 03:19 PM
I haven't made up my mind about applying the solder paste yet though because I have never worked with lead-free (sshhhh.....) and I don't know the preferred method: silk screen or a dab from a syringe.

The paste mask is usually thin brass stretched tight on a wood frame so you can place it slightly above the pcb. The paste dries out to unworkable pdq, at least the cheapies I have tried do. There was some bod lasering paste masks out of Mylar, I forget the details.

Problem with CNC is you either hand feed it or pick from the reel and then square it off while it's on the vacuum head. If you were in no particular rush, squaring might be easiest as a seperate put down.

Have you found plans for this gizmo?

A crummy worm will work because you can go for limited rotation and spring it. An elbow arm is fine if you set the position for every component manually, it's repeatability rather than precision.

saxonhawthorn
15-12-2009, 06:09 PM
Plans? What are they? I've never had any plans for anything! In 25 years of writing commercial software I never even once got a specification from a customer. They always wanted me to tell them what they wanted.

I hadn't thought of brass as a screen. Not a bad idea. Not sure if I can afford a laser powerful enough to punch it though. I'd have to etch it.

I envision picking up components from the reel with a vacuum head on a robot arm, then holding them over a camera with some vision recognition software to square them up (that's where the tiny worm & wheel come in) before plonking down on the pasted-up PCB.

I bought the large worm & wheel (18) because - like Mount Everest - it was there. I didn't have any particular use for it, but I had a hunch I'd find one. When it arrived I was really delighted with the quality, and I'm sure it will be adequate for the job.

As regards Tribbles point about volume: yes, and I can indeed rattle out boards manually at a rate of knots if I have to. But now that I'm liberated from the shackles of somebody else's factory I'm planning new products which I intend will go well, and anyway somebody's got to give the Chinese some competition! Once you've got a production line set up of course, it's easy to switch from one product to another. You just load the appropriate product code, and away you go.

Ian

Robin Hewitt
15-12-2009, 06:48 PM
I don't think you have to laser your own paste stencil any more than your assembler would, there's a ready made industry out there. First hit on Google...

http://www.smtstencil.co.uk/?gclid=CPS9ref92J4CFU0A4wodF1p6rA

Don't think you need a worm for the rotation, a dinky stepper will easily microstep anywhere you want, with no load mirostepping really works!

Is an elbow arm really the best solution? As soon as you locate over a camera you can't "teach" the arm and you are back to positioning by co-ordinate :naughty:

Tom
15-12-2009, 06:52 PM
Sounds great! Here are some plans.... (tee hee)

YouTube- Gigabyte Mainboard Factory

I've been in a board manufacturer before, and this is the method that they used:
Screenprint solder paste (stainless screens), 3D vision system to check for paste registration (and volume), pick and place machine(including pick, scan to check orientation, rotate to correct, and place)(as in the video above), then another vision system to confirm, and finally the reflow oven. You could obviously skip the pre and post paste vision systems (what I saw was pretty high volume).
If the boards are small, consider processing them joined together then do a final op (punch, or route) to separate into individual boards.

It sounds fun! I'm looking forward hearing all about it!

saxonhawthorn
16-12-2009, 12:24 PM
Blimey Tom! That machine was going pdq. My only experience of automated board manufacture was at Sony forty years ago. We built a factory in Wales for making TV sets, and at 10k each the pick-and-place robots were the most expensive machines in the factory. But they went at a stately plodding pace compared with the clip you posted. Quite an eye-opener. Thank you very much for the benefit of your experience.

Yes, I'm not planning to manufacture TV sets! My boards will be quite small, so I'll place several on one sheet and route them out.

Ian

saxonhawthorn
16-12-2009, 12:38 PM
Robin,

Actually, I thought about this in bed last night, and grinned when I realised the answer. CNC! All I need to make holes in the solder mask is a CNC drill. I'm fairly sure the CAD outputs a Gerber file that will either do the job as it stands, or will do so if I just fiddle a bit with the hole sizes. But thanks for the link to that mask manufacturer. I've made a note of them, just in case. The price is certainly right. As a general rule I like to keep as much as possible in-house, for both cost and quality reasons. But sometimes it can make sense to contract out.

And yes, it's true that I don't really have to use a robot arm. I could just as well do it by 2D XY positioning. But that's just a tad boring, and I have to have a challenge in it somewhere to keep up my interest. Besides, a robot arm will impress the hell out of the customers; and although it's irrational, in real life that's an important part of getting contracts. :) Then I can make vids like the one Tom posted!

Ian

saxonhawthorn
16-12-2009, 12:59 PM
Robin,

About micro-steppers.... when I mentioned using an arm I was working on the assumption that the minimum angular resolution of a bog standard stepper would be 1.8 degrees, and to get anything better I'd need a worm. Was that assumption wrong?

Ian

tribbles
16-12-2009, 01:50 PM
Microstepping does do in-between steps, but you lose torque.

The controllers I'm using will (supposedly) allow the motors to be controlled to 0.036 degrees (10000 steps per revolution) from a 1.8 degree motor.

Normally you'd get half, quarter and eighth stepping (0.9, 0.45, 0.225 degree steps).

Robin Hewitt
16-12-2009, 03:19 PM
The perfect current for stepper motor coils would be two sine waves 90 degrees out of phase. Simple drivers approximate to it, pukka drivers try to create it. Intermediate points are a bit springy but rotating a component is a no load situation so tiny changes in angle are possible if your driver is willing and able :beer:

irving2008
17-12-2009, 11:05 AM
The perfect current for stepper motor coils would be two sine waves 90 degrees out of phase. Simple drivers approximate to it, pukka drivers try to create it. Intermediate points are a bit springy but rotating a component is a no load situation so tiny changes in angle are possible if your driver is willing and able :beer:

For this requirement, where full rotation isnt required, i guess, but accurate partial rotation is, I wonder there would be mileage in a purpose built sinewave phased driver rather than a stepper driver as such? The load is small but not zero.. presumably you'd be rotating the suction head which would have a vacuum tube attached which would give some tangential load.

saxonhawthorn
17-12-2009, 12:26 PM
Irving,

"presumably you'd be rotating the suction head which would have a vacuum tube attached"

Correct. And you are also correct that I am thinking in terms of designing my own driver board - mostly from sheer habit, but also because that way I end up with exactly what I want (or alternatively, have only myself to blame if I don't). I'm planning to spend time thinking through this project over Christmas (although I have the wife in bed with 'flu at the moment, and I'm therefore having to do all the running around town that she normally does) and because of family commitments little will actually happen in terms of either hardware or software until Q2 of 2010; but by then I expect to have thought through all the details and be ready to move quickly once I start in the Spring. I'm looking forward to it greatly now, because almost everything I do has a processor and a PCB in it somewhere, and to be able to knock those out quickly and easily will be really useful. I'll post pictures and circuits when I get there.

Ian

irving2008
17-12-2009, 12:48 PM
Look forward to seeing the outcome of your deliberations....:idea:

I am mentally picturing a 'Wallace and Gromit' scenario...

Wallace sitting at his PC designing the board, and ceremoniously pressing a big green button, activatiing a robot arm (complete with shirt sleeve and oversized cartoon hand) which picks up a blank piece of PCB, places it in a CNC PCB router which cuts the board, then the arm picking it up and placing into the SMT placer, and then again into the solder oven, and finally (with singed fingers and a 'boing' sound effect) putting it on Wallace's desk!:heehee:

I'll get back to work now.....

Robin Hewitt
17-12-2009, 01:30 PM
Correct. And you are also correct that I am thinking in terms of designing my own driver board - mostly from sheer habit, but also because that way I end up with exactly what I want (or alternatively, have only myself to blame if I don't).

You probably won't believe this but I think I have to mention that you may be making beginner's mistake. I won't be saying, "I told you so", but you can assume that :naughty::rofl:

Yes, you could gain vast extra control by making a seperate computer to interface Windows to your machine, but you would do well to stick with commercial stepper drivers and PSU.

Given the price of a humble MSD542 it really isn't worth the nightmare of trying to recreate it :eek:

saxonhawthorn
17-12-2009, 06:13 PM
Robin,

Er.... hrrumph! I have to live on a pension now, and our house rule is "If it costs money, we don't do it."
I just checked the price of an MSD542 from Motion Control Products (http://www.motioncontrolproducts.co.uk/product_info.php?products_id=3): it's 47.12 presumably plus vat, and presumably I'd need one per motor (you're right that I'm new to CNC).

However I'm not new to electronics, and I have more oscillators, scopes, and logic analysers than I have benchtop real estate to put them on, and for me it's not a nightmare at all. I haven't yet designed or costed up making a multi-channel controller, but my instincts tell me that by the time I've bought four or five MSD542s I could have built many more myself and probably saved quite a few bob into the bargain.

But "He that putteth on his armour ought not to boast as he that putteth it off." I'll do it first, and then boast. :)

Ian

irving2008
17-12-2009, 06:42 PM
Robin,

Er.... hrrumph! I have to live on a pension now, and our house rule is "If it costs money, we don't do it."
I just checked the price of an MSD542 from Motion Control Products (http://www.motioncontrolproducts.co.uk/product_info.php?products_id=3): it's 47.12 presumably plus vat, and presumably I'd need one per motor (you're right that I'm new to CNC).

However I'm not new to electronics, and I have more oscillators, scopes, and logic analysers than I have benchtop real estate to put them on, and for me it's not a nightmare at all. I haven't yet designed or costed up making a multi-channel controller, but my instincts tell me that by the time I've bought four or five MSD542s I could have built many more myself and probably saved quite a few bob into the bargain.

But "He that putteth on his armour ought not to boast as he that putteth it off." I'll do it first, and then boast. :)

Ian

Ian,

As a hardware designer turned software engineer and one who much prefers to build rather than buy I would dearly love to agree with you. However unless your bits box is very deep you are unlikely to deliver something of the functionality of the MSD542 for the price. I built my stepper drivers based on a very long-toothed design using the L297/L298 chipset and the parts alone for 3 axes came to over 70. While arguably that was cheaper, I could have bought a DIYCNC System 3 for 90 for the same functionality and that doesn't come close to the capabilities of the MDS unit.

So I sadly have to agree with Robin, who I know to be no slouch for going down the "create your own" route (having seen the injection moulding rig he built, and his nearly finished plasma cutter - is that running yet?), that your limited funds are better applied elsewhere.

saxonhawthorn
17-12-2009, 06:43 PM
Irving,
:)
"They said the thing couldn't be done!
"With a smile, I went right to it.
"I tackled the thing that couldn't be done....
"And I couldn't do it!"

Ian

saxonhawthorn
17-12-2009, 06:52 PM
Gentlemen,

I am, as you know, a complete beginner in CNC. I need to read the spec sheets and think through what's required, and until I have done so I'll defer to your greater experience.

But not the least valuable aspect of DIY is that at the end you know that you know exactly how it all works. I cannot live with bits of engineering in which there is the slightest fuzziness in my mind about how it works. I just have to know, and the only way to know that you know is to do it. (And until you have, you cannot possibly teach anybody else how to do it either, which is something to be considered at the senior end of the age spectrum).

I have an utterly boring meeting to attend all tomorrow morning: but then I'm looking forward to getting stuck into some spec sheets.

Ian

Robin Hewitt
17-12-2009, 07:01 PM
I just checked the price of an MSD542 from Motion Control Products it's 47.12 presumably plus vat, and presumably I'd need one per motor

Gary has them for 33 + tax but I can see you feel driven to try :whistling:

It may look good on paper, but the 542 microcode is probably based on what actually works, rather than what should work. The best you can hope to make is the 542 prototype which probably ended up in the bin.

Confidence is that feeling you get just before you understand the problem :heehee:

I started out with home brew, then went to 542's, then fitted drivers that plugged straight in to the mains and rectified it. You can never have enough volts :beer:

ptjw7uk
17-12-2009, 08:49 PM
saxonhawthorn I think you are in for a long long learning path as you have not yet arrived at the foot of the cliff.
My cnc conversion has almost been finished and now I am onto the software and that is just as hard as the mechanical side of things, there is just so much to learn.
The information on the subject is a bit thin on the ground and harder still i dont know what to look for in the books etc.
I like you like to do evrything but when I looked into the making of the stepper drivers I balked and bought a box already made so I could concentrate on my mill and oh boy was that a baptism of fire. The only machining I had done was the odd hobby done whilst at work but now I have to buy the tools myself and there are so many! and possibly more I havn't heard of yet.

Peter

irving2008
17-12-2009, 09:57 PM
But then again, thats half the fun of it! I, like Ian, prefer to know exactly why something works, but I came to the conclusion some time ago its better to focus on the non-commodity stuff, on the grounds that enough people know about the other already...

Ian, if you go over to the CNCZone.com and look for threads from Mariss or about Gecko drivers there is a good, warts n all, thread documenting the development of a new driver from scratch through to a production item...its interesting but painful reading....

saxonhawthorn
18-12-2009, 07:37 AM
Gentlemen,

"I think you are in for a long long learning path as you have not yet arrived at the foot of the cliff."

Of course, but that's exactly what I enjoy about engineering, and especially electronics and software. There's always new stuff to get my head into. Would you deny me the pleasure of doing what I enjoy most? (well, second most ;) I have spent years programming Intel processors, and if you can program Intel there's not much else in this vale of tears to terrify you. I have also had to decipher spec sheets in Japanese, and more recently Chinese. Where there's a will, there's usually a bored girl in a Chinese take-away who's happy to do a bit of translation over a plate of noodles.

Now, you're certainly right about all the tooling needed to turn out quality work on today's power tools; but this is just another argument for not spending what I don't have to on electronics. And there again: where I can make the tooling myself, I shall do so.

Irving, yes I have had a quick look at CNCZone and have seen the threads on Gecko. I'll read more at the week-end.

But I have to chuckle:- I entered this forum with people applauding the task of automating PCB manufacture. Now the roles have reversed, and you're all trying to disuade me from doing it!

Come on gentlemen! Where's the spirit that began the world's Industrial Revolution in England? Where's that can-do attitude that built the Empire? Ask an Aussie if he'd rather buy off the shelf or build his own? Nine times out of ten he'll roll up his sleeves and do it himself. (And incidentally, have you noticed that for several years now all the constructor articles in Practical Electronics have been written by Australians? It was a British magazine for decades, but it's now written by Aussies, and the online edition is distributed by a Brit living in America.)

If I were still employed in Industry I'd normally go for an off-the-shelf developped-and-debugged item every time, simply because the commercial environment almost never leaves time to re-invent the wheel. You just buy what's needed and cost it into the project, because the customer wants ten thousand off delivered at a thousand a month starting next Wednesday. But I'm not in that environment any longer. I'm a free man again; my time is my own to spend as I please; and it pleases me to learn about designing stepper drivers. There are not many areas I haven't explored yet, and in all my working life I have never met a technical problem I couldn't solve. Now I'm looking forward to doing this.

And I will.

Ian

irving2008
18-12-2009, 08:55 AM
Ian,

I applaude your sentiments and your will-power... if I had the time I'd probably approach things a different way as well...

I look forward to your efforts with interest and I am happy to help where I can, as I know other will be too (not that I should think you will need it).

regards,
Irving...

Tom
18-12-2009, 09:21 AM
Gentlemen,
Where's the spirit...

...in all my working life I have never met a technical problem I couldn't solve. Now I'm looking forward to doing this.
And I will.


Hear, hear....

It sounds like you will massively enjoy the project, and that's the only justification you need to start it. I won't be able to help with electronics, but I look forward to reading about it, and learning plenty... Bolt-together modular machines is what I (and many others on the forum) have done. It will be a refreshing change...

Onwards and upwards! - do keep us up to date with developments...

Now, you've made me thirsty for tea and English cake.... I'm going to boil the kettle.... :)

Robin Hewitt
18-12-2009, 11:56 AM
But I have to chuckle:- I entered this forum with people applauding the task of automating PCB manufacture. Now the roles have reversed, and you're all trying to disuade me from doing it!

Au contraire, I'm totally selfish and want you to succeed with as few pre-conceived notions as possible.

I don't want you getting bogged down recreating things that are of no use to me, I want you to come up with novel solutions to old problems so I can pinch your ideas, fix your mistakes and make a better one :rofl:

saxonhawthorn
22-12-2009, 11:52 AM
My Dear Robin,

When I have totally exhausted my energies on stepper drivers, please feel entirely free to brief me all about those old problems which need novel solutions, and with a glass of Christmas cheer in my hand (or probably more like Easter cheer by the time I get there) I shall enjoy nothing more than cranking-up the little grey cells.

FWIW I was taught workshop practice fifty years ago by one George Stevenson, grandson of the man who invented the railway. Everything he made - in any medium at all - was both beautiful to look at and perfectly efficient. Genius ran in the family. I'd encourage anybody who hasn't done so to take a look at the Stevenson linkage for reversing a steam engine: it's a perfect example of a brilliantly simple but elegant solution to a very real and practical problem. That's the kind of approach to engineering that has inspired me all my life, and I'm never content with anything I have made until it reaches that same high standard. I don't always reach it but I try, I try.

A very Happy Christmas to all here. May your swarf never tangle and your bearings never jangle.

Ian