Why CNC?

[saxonhawthorn]

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....roducts_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]

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....roducts_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.

[Robin Hewitt]

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

[ptjw7uk]

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]

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....