Since we may be contracting 3rd party to make PCBs and supply parts for the CNC, I'd like to gauge how much real interest there is in buying one of these machines, when we're done.
Keep in mind that this is not a commitment, just think to yourself to see how serious you would be, and comment yay or nay.
Update June 8th, 20122:
Ok, just counting heads. So far it's 17 people. Let me know if I missed anyone.
My personal budget for this is $1000-$1200, so any higher, and I'm out, but of course would continue to do my best to get this done for everyone!
Here's a list of "yays" so far (again no commitment assumed):
| Dany Thivierge |
| Monroe |
| Ellison Chan |
| Kevin Bouchard |
| Eric Tweet |
| Eoin |
| yovio |
| John C. |
| Fred |
| Ruwan |
| Raversspesh |
| 924aussie Alan |
| Terry |
| arashi |
| Dave C |
| Nick Joyce |
| Andrew Adams |
Drive System Survey
Franco Scipioni has set up a survey to gauge interest in which system we want to have on the system.
Access the survey here:
http://www.surveymonkey.com/s/2SRRRWT
To summarize:
Servo System:
- has rotational encoders to allow exact motor control
- position encoders, so that tool head can be positioned precisely
- uses DC motors
- requires development or use of a custom circuit board to drive the motors
- more expensive solution
Stepper System
- no rotational encoders, so will not allow exact motor control
- position encoders, may still be possible
- uses stepper motors
- no custom circuit boards needed, motor systems easily available
- cheaper than servo system
Replies
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
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
Here is a quick survey for gauging interest on steppers vs servos for the prototype. You can state why you chose that, define a specific stepper or servo, or just add any comment you want. It should display results after you vote and I'll post the "why did you choose this" comments after a number of people have responded.
Click here for stepper vs servo!
Sounds great. I'll volunteer to be the accountant, and keep track of funds sent to Monroe, or whomever is needing the money. We'll have to work out the logistics. Maybe we can start a discussion for keeping track of the contributions, where I can post balance sheets.
I'll contribute to the test fund too! And I like Monroe's idea to keep a running balance sheet.
Ok, Back from vacation! :) Happy to see that we are making progress in the CNC area. Slow but still the project is still alive. Monroe, did you start to build the prototype following Kevin drawings? Would love to see the wood version of it!
When do we need to make a decision on the control boards and other parts? Let's pick something and move on, I see too many projects always waiting for the perfect planet alignment and never getting done. I appreciate all the inputs and hard work that was put in this so far but I want us to be able to have something before end of the year. Would be nice to be able to craft stuff for holiday season! hehe
An interesting project and you can count me as another IN.
Have been looking at something like this for a while as a workshop need but the cheap ones on line are just that.
If this thing will be capable of doing light alloys, then it has real uses.
Ok Ellison,
There has been no repsonse to my email from the fellow listed in the frame with the SMD UHU pcb. I am not sure how long we should wait and suspect the Gerber files in question were given up to public domain by this time. There was not a disclaimer on the page regarding maunfacturing rights. I am still plodding along with Eagle and getting better but the issue again is having the device package needed to be correct when the program is asked to make a pcb.
On the other hand, do you think your contacts could use a 'rough' Eagle schematic of the UHU? If they polish it up, it is better than starting with a blank screen.
Count me in for sure.
I'm new and desperate to fit in, so I'm game..... I'll post any questions AFTER I read the post though. Actually I've been kicking around on the internet "researching" a CNC build for years. Maybe this will get me started. Be nice to buy the wrong bolt for a critical screw that ends in a complete redisign with a bunch of guys instead of by myself. Will there be a monthly support group for anyone who participates? And some sort of documentation to show my wife that this thing is real and should work when we are done would be nice too.
Where do I sign?
Christopher
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