DIY CNC Machine How Hard Can It Be?

[D from BC]

[quoted text muted]

Well, motors are like cavemen. They are not so smart. For a stepper,
there are four coils and you have to turn on A-C for n micro-seconds,
then B-D for another n micro-seconds. You have to keep doing that
until you reach the target. How you find the target is the difficult
part, usually machine visions or some other feedbacks.

You don't want steppers for CNC. They put steps in the work. Slopes and
curves come out all rough.

Nobody "in the business" uses steppers.

DC is easiest and probably cheapest. 3-phase AC permanent magnet
synchronous is mostly current practice.

Cool! The best motor type!
D from BC

 

[D from BC]

You need to tell them how fast, too, unless all you want to do is drill
holes, when only the Z feedrate *really* matters.

If you want to mill slopes and curves, velocity is all-important.

I plan on using a 100W laser mounted on the CNC.
To start off basic..I'm just going to have a fixed motor velocity.
However, I think to be kind to the mechanics, I think I should include
acceleration/deceleration motor control.
It might be rough for a CNC tool head to race across a 8ft of table at
full speed and instantly come to a screeching halt on target within
100 microns.
Let's say I'm using positioning feedback (optical or magnetic encoders
<<hopefully that's the right term)
....I'll probably need a routine that makes the motors "creep up" to
the target XY position.
That's going to be some creepy code

So the machine moves like this.. ( Imagine the sound )
zzzzzzzipppp rrr XY1 RRRR zzzzzipppp rrrr XY2 RRRR zippppp rrrr XY3
RRRR

rrrrr = deceleration
RRRR = acceleration
zzzzzipp = fixed rate motor velocity

Does it show I'm a newbie at this and I'm just making it up as I go
along
D from BC

 

[D from BC]

Happy birthday to you.
Happy birthday to you ..

Has anyone touched a nucleus?
D from BC

 

[Rich the Philosophizer]

Happy birthday to you.
Happy birthday to you ..

Has anyone touched a nucleus? [/QUOTE]

I've opened my Root Chakra, and felt the Kundalini flow through me. Does
that count? ;-)

Cheers!
Rich

 

[Fred Abse]

Cool! The best motor type!

Take a look at what Baldor have to offer. Not exactly cheap, but in the
low range as prices go for this sort of kit. They do RS485 interfaces, PCI
servo cards, and a whole slew of motors, AC & DC from a few amps up to
quite big stuff.

www.baldor.com (IIRC)

 

[Fred Abse]

I guess many precision tool makers are not "in the business". That's
why I can't buy the right tool. They keep telling me what I want is
not what I want.

But what they happen to have at the time?

 

[Chris Jones]

You can safely extend that to all motors.

I guess so, but the delusion that timing doesn't matter seems to be more
common amongst users of stepper motors.

Chris

 

[joseph2k]

IBM assembler H - HCF command (...halt and catch fire). Next...?

Many many years ago i saw a list of interesting assembler opcodes like RMXG
-- randomize memory execute garbage

 

[D from BC]

I've opened my Root Chakra, and felt the Kundalini flow through me. Does
that count? ;-)

Cheers!
Rich

That's the electrons in your lunch.
D from BC

 

[Jonathan Kirwan]

Many many years ago i saw a list of interesting assembler opcodes like RMXG
-- randomize memory execute garbage

Probably something like these:
http://gdl.msu.edu/~vanhoose/humor/0112.html
http://ruthless.zathras.de/fun/top-secret/NewOpCodes.txt
http://www.pvv.ntnu.no/~steinl/vitser/aseembly.html
http://monster-island.org/tinashumor/humor/opcodes.html

The real problem is having enough memory for the 'convert to unary'
instruction.

Jon

 

[MooseFET]

No, that was a real 6800 instruction.

Many many years ago i saw a list of interesting assembler opcodes like RMXG
-- randomize memory execute garbage

 

[Colin]

D from BC wrote:

On Sat, 16 Jun 2007 20:13:07 GMT, Ecnerwal


I hoped that putting a smiley after the "Too much?" ...it would be
taken as a joke.
Sometimes I like posting a question without an achieve check because
things change... This is news...What's new?..What's the latest coolest
most modern up to date solution? I mean...I'm afraid if I go too far
back in the achieves I'll learn about making fire
D from BC

SteelTailor portable CNC cutting machine
More info: www.steeltailor.com

 

[D from BC]

SteelTailor portable CNC cutting machine
More info: www.steeltailor.com

That's cool Arrrrff! Arrrrfff!
D from BC

 

[henryhaozq]

To Make Better Portable Flame/Plasma Cutting Machine

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6. spare parts supplier of Chinese "Spaceship Shenzhou V"

Competitive products:
1. Step/Servo Motor of CNC Cutting Machine
2. Step/Servo Drive of CNC Cutting Machine
3. CNC Cutting Controller(System)
4. Portable CNC Cutting Machine (Flame/Plasma)
5. THC (Torch Height Controller) of CNC Cutting Machine
6. IBE (Nesting Software)

Please forgive and understand if my email bothers you.

Anyway, I hope we can build a long-term and friendly trade cooperation and your business is better and better.

I'm looking forward to meet each other at next ESSEN Welding & Cutting Fair or our company in the future!

Thanks a lot. Have a nice day

Sincerely.

Henry


Overseas Trade Department
Beijing Start Microstep Control Technology Co., Ltd., China
Tel: +0086-10-88909273
Fax: +0086-10-88909271/77
www.startsh.com
Email (MSN): [email protected]
Skype: henryhaozq