Replies to This Discussion

Permalink Reply by Ellison Chan on August 8, 2012 at 7:33am

Ok folks I added the survey link and my description of what the servo vs stepper system is up top of the discussion.  Monroe, and RD, please correct or add any info you wish up there for everyone to see.

Here's the link again to the survey created by Franco:

http://www.surveymonkey.com/s/2SRRRWT

Permalink Reply by Franco Scipioni on August 9, 2012 at 11:51am

Here are the poll results and responses as of today. It's quite interesting that its 50:50 at this point. For the most part, most of the reasons for choosing one or the other have to do with price, accuracy, power, and other reasons that have already been discussed, but there are some that are less obvious and It's cool to get these responses and see different perspectives. Unfortunately, it looks like this poll is inconclusive thus far :( If there are more responses I'll post them too :)

Poll Results as of 8/9/12 @ 3pm ET

Stepper Motors: 39.1% with 9 votes
Servos: 39.1% with 9 votes
Another Solution: 21.7% with 5 votes

Other solutions:

1. Servo controller with a stepper motor (ex. QuickSilver Controls)
Reasoning: Best of both worlds... lower cost compared to straight up servos, yet with similar performance.
2. either ,but want encoders
Reasoning: want feed back in machine. repeatable positioning. dont want to have to find zero point if power is lost or machine overloads and trips circuits.
3. I'm too ignorant to have an opinion! (lol)
Reasoning:but if the cost difference is "not too much" I would prefer the higher quality option.
4. Servos with Positional Encoders
Reasoning: Reliability
5. Depends on users needs
Reasoning:Either will work fine but depends on the user budget and what the user hopes to do with the machine. Build the mechanics of the machine first. Then determine the forces needed to move the parts. Then determine the forces needed to cut the desired materials.

Reasons for choosing Stepper Motors:
1. A printer can place a small dot of ink on a page with reproduced accuracy, using steppers and opto feedback (simple disc) and it is the cheapest, why use servo's?

2. Price. Just need upgrade ability to servos in the future.

3. Servos aren't precise enough to correctly control velocities of the various CNC axis

4. Lead time, it's off the shelf. Ultimately I want servos but I'd rather have a machine than wait years

5. I am doing light work with wood an aluminium.

Reasons for choosing Servos:

1. Quality over price

2. Much more Power

3. more power and precision, looking for pro grade CNC

4. Accuracy

5. Servo Feedback with encoders provides better reliability. Machining can be both accurate and precise allowing for more exact replication of models. In woodwork designs (and other projects), multiple products can be made with more certainty that they will all come out the same.

6. closed loop vs open loop. I know that this would be pricey..

7. more experience with them

Permalink Reply by Ellison Chan on August 9, 2012 at 11:59am

Thanks, Franco!

Permalink Reply by Ellison Chan on August 9, 2012 at 12:17pm

The boards seem to be open source, but the code is not.  We'll have to make our own code.

Permalink Reply by Franco Scipioni on August 9, 2012 at 6:45pm

Fantastic! Thanks Monroe. Anxiously awaiting for a response!

Permalink Reply by R. D. Starwalt on August 10, 2012 at 5:52am

The *initial code* for the Elm Chan board (pre UHU) is available - I downloaded it.

Looking over the history of this board, I believe the Elm Chan came first.

Then Uli (German developer) improved the code and made it a popular project.

Uli sells the programmed chip for 5 to 10 Euro, shipping included.

He has sold/shipped over 5,000 of the chips. The current version is 3.0

Permalink Reply by Ellison Chan on August 10, 2012 at 10:07am

Invite him to join this group.

Permalink Reply by Ellison Chan on August 10, 2012 at 10:20am

No biggie, we'll have fun programming it ourselves.

Permalink Reply by R. D. Starwalt on August 10, 2012 at 6:50pm

Elm Chan <-----Click there, scroll to the bottom of the page. 'Firmware' is what you are looking for. Note the original date of the page at the top in the header...

Permalink Reply by Allan C on August 11, 2012 at 2:59pm

Hi Everyone, I'm In.

Happy to help in anyway I can.

I have a software background.

 

Permalink Reply by Nick S on August 11, 2012 at 7:47pm

Hi All, new to the group and have just read the history. Sounds great.

I'm based is Aus so a little challenge but happy to help where I can as I have a long background in electronic construction and design from my defence days.  Put me down as yes.   Looking at the servo version for me I think.

Permalink Reply by Ken Kroeker on August 12, 2012 at 9:24am

I'm interested. Currently looking at building a cnc router for wood and Al in a 18 in by 36 in cutting area, but 24 by 36 would be ok too.  I have a cnc mill, so can proto parts if necessary.

Is there a working spec somewhere with drawings?  I use Alibre and draftsight for CAD.

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