Hello all. Great site here though there are a bit too many forums to choose from so please pardon me if this is the wrong one.

I'm a hobbyist looking for to get some sort of CNC solution up and running on a budget. My needs are pretty much exclusively PCB milling. I intend to do a lot of double sided circuit boards and the big board houses simply cost too much (or take too long) to be practical.

While I'm good with software and electronics, I'm not very good with mechanics. I was wondering if there was any sort of complete CNC kit that I could buy and put together for a reasonable amount of money. The kit should include the table and all the mechanical pieces necessary to put together a working CNC mill. I don't want to have to cut anything or create any holes myself: it should be possible to simply screw the thing together, add motors and electronics and dremel and be done with it.

Is there such a beast out there? I've been looking for quite some time but haven't found anything that quite fits the bill. Most of what's out there seems to be either complete professional CNC machines or complete DIY stuff. The machines tend to be expensive and I just don't feel that I'm ready at this point to do the complete DIY solution. I'd like to have all the mechanical parts worked out so that I can just add motors, electronics, etc.

It should also be pretty small, tabletop size. Since I'll mostly be doing small PCB's I don't need a whole bunch of space for this.

Thanks in advance.

Try (mikebeck.org). Assembled controllers or kits available.

Try (mikebeck.org). Assembled controllers or kits available.

Are you referring to this: http://www.mikebeck.org/router_info_click_to_page.html

?

Be careful when shopping for kits. Many, including the one in the link above are not complete. Some are missing all of the pricey parts.

John

Be careful when shopping for kits. Many, including the one in the link above are not complete. Some are missing all of the pricey parts.

John

I believe thats very good advice. It's unclear in a lot of kits what is actually included.

How about the Zenbot CNC machine (link: http://cgi.ebay.com/ZENBOT-CNC-ROUTER-ENGRAVER-mill-PCBs-engraving_W0QQitemZ190232869535QQcmdZViewItem?hash=item190232869535&_trksid=p3286.m14.l1318).

I know a lot of junk is sold on ebay but that machine actually looks pretty good. It certainly looks better than something I could make myself in a reasonable amount of time/cost. I also like the fact that the seller is very clear about what is included and what's not (stepper motors are) and that you can actually return the thing if you're not happy with it. Plus I just recently bought a Dremel I could use with this. Any opinions on this machine for a beginner on a budget? Keep in mind that I would mainly (perhaps only) use this for milling PCB's.

yea it is a fairly safe machine, and if you check his seller feedback you can see how other customers have fared. just make sure it would work the size of boards you need.

That ZENBOT is a nice looking machine. I wonder why they don't include the stepper driver/power supply. One thing I don't like is the Dremal tool. I built my first machine with a Dremal and quickly changed it for a trim router. Much better selection of bits available for the 1/4" collet.

It will take full 3D CAD/CAM software to do what's shown in the videos.

John

If only want the mechanical components for a small router/engraver I would suggest http://www.widgitmaster.com/

Eric is a retired aerospace machinist who makes very precise aluminum gantry routers as a retirement job.

Search for widgitmaster on this site and you'll find some of his customers for references.

You can bolt on stepper motors and wire up a controller yourself by selecting components from Gecko, PMDX, and other vendors. Or you can buy a CNC motor / electronics package from HobbyCNC, Keling, or others.

That looks very nice but it's $1095. I'm a poor student so such prices are out of my range. The ZenBot comes with stepper motors for $550.

Just wondering, why are most of these thing sold by individuals, not companies? I'm not saying that means that the quality is lower, it just seems strange that no company is willing to produce a hobby level CNC mill for a good price (sub $1000).

That's a very good question that I can't answer authoritatively.

My guess is that CNC is far too complex to offer a low-cost product that will be profitable for large companies. This leaves an opportunity for smaller companies that focus on one particular area or niche and for individuals offering more comprehensive offerings.

Just take a look at all of the posts made by new CNC users who are confused, over their heads. Now imagine you were running a company that had to pay tech support staff to assist these people use your product.

They are very different machines. It may be useful for you to buy a lower cost machine to get your feet wet. This is what many of us do by building our first CNC using skate bearings, allthread, and MDF.

It's too early right now, but if you can wait a few weeks this may be a promising purchase for your needs:

http://lumenlab.com/estore/home.php?cat=272
http://www.lumenlab.com/forums/index.php?showtopic=25411&st=100&p=286890&#entry286890

Do you have a sense of the precision you'll need for your intended application?

Yes, a low cost machine is really my only option. Like I said though, I don't have the time or mechanical skill (yet) to try to build my own so I'm looking to buy as much as possible.

The lumenlab micRo you link to looks good but I'm not sure that it looks any better than the ZenBot. It's hard to say though since I can't really find any pictures of the machine as a whole. I guess I'm asking: is there any advantage over the Zenbot that I should wait a few weeks for?

Precision is somewhat important. Like I said, I'm going to be doing double sided circuit boards. They're not going to have tiny traces or anything like that, I just don't want to purchase a machine designed for machining huge parts when I just need mostly small circuit boards. It should be able to comfortably do circuits like this: http://youtube.com/watch?v=SlGcgQJRncc (look at the last few seconds of the video).

The lumenlab micRo you link to looks good but I'm not sure that it looks any better than the ZenBot. It's hard to say though since I can't really find any pictures of the machine as a whole. I guess I'm asking: is there any advantage over the Zenbot that I should wait a few weeks for?

Precision is somewhat important. Like I said, I'm going to be doing double sided circuit boards. They're not going to have tiny traces or anything like that, I just don't want to purchase a machine designed for machining huge parts when I just need mostly small circuit boards. It should be able to comfortably do circuits like this: http://youtube.com/watch?v=SlGcgQJRncc (look at the last few seconds of the video).

I don't know anything about the Zenbot machine other than what's in the eBay listing, a very little IRC chat, and one or two web pages apparently created by a Zenbot customer using the previous design of their machine.

I don't think it's fair for me to say which machines are better or worse than others. All I can give is my opinion about what's important and suggest some options you haven't looked at. Since I don't do PCB work, my opinions probably aren't all that helpful to you. It sounds like you're pretty close to deciding on the Zenbot machine. If you're looking for someone to talk you out of that or affirm your decision I'm the wrong person. In the end, buy what you feel comfortable with just make sure the vendor can support their products.


Hopefully someone else will jump in with other opinions. (Any one else out there tempted to jump in and criticize my oversimplified explanations please apply your energy more directly to help hexdump rather than being an '41 73 73 68 6f 6c 65')

If I were buying a pre-built machine I'd want to know more about the linear bearings and drive system.

It's unusual to use a belt drive on such a small machine; be sure you're satisfied that the minimum addressability is adequate for your application.

Stepper motors typically have 200 steps per revolution, meaning they can be positioned every 1.8 degrees of rotation. This positioning can be interpolated or smoothed using a micro stepping driver board, again with trade offs. The drive system the motors connect to use those steps to move the cutting tool (and/or the table) There are many different designs for drives. None are absolutely 'good' or 'bad', they each have benefits and limitations.

Machines this small more commonly use drive screws which provide a built-in gear reduction. A 10 thread-per-inch drive screw will move the tool an inch when the motor turns 10 times. Even using full steps, this gives 2000 steps per inch, resulting in a high degree of addressability (and additional torque) by trading off fast movement. A belt drive works differently, trading off some addressability for fast movements. Depending on the belt drive design you may end up with fewer than 200 steps per inch reducing the theoretical ability to position the tool at an exact location. Then again, for some applications this could be adequate. If your application doesn't require high addressability then a belt drive may be a good solution, particularly if it's well designed.

Note that addressability isn't the same as accuracy, the two are complementary properties. Accuracy is the result of the design, materials used, manufacturing processes, and many other factors.

Speaking of design, the X&Y bearing design isn't discussed in any detail on the web site. From the little I've read (this (http://www.linuxcnc.org/irc/irc.freenode.net:6667/emc/2007-08-16.txt), this (http://axis.unpy.net/01188338604) and this (http://axis.unpythonic.net/01188441458) ) the previous design used hardened ways and nylon or HDPE bearings on X&Y. The new design apparently uses ball bearings on square steel tubing. Does this new design have any provision for adjusting the bearings?

I suggested the Lumenlab micRo after reading your comments about price and concern about buying from a person rather than a company. It's not shipping and I have no experience with it but it will likely be a bit cheaper than the Zenbot. Lumenlab is new to CNC but has been around for a while supporting hobbyists building DIY video projectors. They have an active support forum.

Maybe THIS is what you need:

http://www.kdntool.com/_sgt/m2m3_1.htm

CR.

Take a look at the fireball. Sounds like it will suit your need perfectly. Around $1k for a turn key setup wo software. Here are some sites:

The fireball site:
http://www.fireballcnc.com/machines-and-kits/v90-interceptor.html

Retailer that sells turn-key kits:
http://www.probotix.com/

A user that mills very fine double sided boards:
http://millpcbs.com/

I don't know anything about the Zenbot machine other than what's in the eBay listing, a very little IRC chat, and one or two web pages apparently created by a Zenbot customer using the previous design of their machine.

True, the information about it is very scattered at best. A good support community to turn to is important for a beginner like myself. The ebay feedback is good but that's not really saying much these days.


I don't think it's fair for me to say which machines are better or worse than others. All I can give is my opinion about what's important and suggest some options you haven't looked at. Since I don't do PCB work, my opinions probably aren't all that helpful to you. It sounds like you're pretty close to deciding on the Zenbot machine. If you're looking for someone to talk you out of that or affirm your decision I'm the wrong person. In the end, buy what you feel comfortable with just make sure the vendor can support their products.


Hopefully someone else will jump in with other opinions. (Any one else out there tempted to jump in and criticize my oversimplified explanations please apply your energy more directly to help hexdump rather than being an '41 73 73 68 6f 6c 65')

If I were buying a pre-built machine I'd want to know more about the linear bearings and drive system.

It's unusual to use a belt drive on such a small machine; be sure you're satisfied that the minimum addressability is adequate for your application.

Stepper motors typically have 200 steps per revolution, meaning they can be positioned every 1.8 degrees of rotation. This positioning can be interpolated or smoothed using a micro stepping driver board, again with trade offs. The drive system the motors connect to use those steps to move the cutting tool (and/or the table) There are many different designs for drives. None are absolutely 'good' or 'bad', they each have benefits and limitations.

Machines this small more commonly use drive screws which provide a built-in gear reduction. A 10 thread-per-inch drive screw will move the tool an inch when the motor turns 10 times. Even using full steps, this gives 2000 steps per inch, resulting in a high degree of addressability (and additional torque) by trading off fast movement. A belt drive works differently, trading off some addressability for fast movements. Depending on the belt drive design you may end up with fewer than 200 steps per inch reducing the theoretical ability to position the tool at an exact location. Then again, for some applications this could be adequate. If your application doesn't require high addressability then a belt drive may be a good solution, particularly if it's well designed.

Note that addressability isn't the same as accuracy, the two are complementary properties. Accuracy is the result of the design, materials used, manufacturing processes, and many other factors.

Speaking of design, the X&Y bearing design isn't discussed in any detail on the web site. From the little I've read (this (http://www.linuxcnc.org/irc/irc.freenode.net:6667/emc/2007-08-16.txt), this (http://axis.unpy.net/01188338604) and this (http://axis.unpythonic.net/01188441458) ) the previous design used hardened ways and nylon or HDPE bearings on X&Y. The new design apparently uses ball bearings on square steel tubing. Does this new design have any provision for adjusting the bearings?


All good information here. I greatly appreciate it.


I suggested the Lumenlab micRo after reading your comments about price and concern about buying from a person rather than a company. It's not shipping and I have no experience with it but it will likely be a bit cheaper than the Zenbot. Lumenlab is new to CNC but has been around for a while supporting hobbyists building DIY video projectors. They have an active support forum.

The LumenLab does have an advantage in that it seems like a community-supported project. I certainly have no problem trusting them, it's just a matter of the machine not existing yet...perhaps it would be worthwhile to wait...

Maybe THIS is what you need:

http://www.kdntool.com/_sgt/m2m3_1.htm

CR.

I've looked into that. It certainly seems very professional and nice but $1k is a bit much for me at this point.

Take a look at the fireball. Sounds like it will suit your need perfectly. Around $1k for a turn key setup wo software. Here are some sites:

The fireball site:
http://www.fireballcnc.com/machines-and-kits/v90-interceptor.html

Retailer that sells turn-key kits:
http://www.probotix.com/

A user that mills very fine double sided boards:
http://millpcbs.com/

I've looked at that one and contacted the seller as well. He says that the V90 probably isn't that great for PCB milling. The site you link to (http://millpcbs.com/) is by a user of the F90, which is no longer sold by Fireball but was better for PCB work (according to the guy I contacted at Fireball CNC).

So, at this point it's a matter of waiting for the ZenBot (sold out) or micRo (not yet available) or saving up some money until I can get that converted Proxxon. Suggestions?

If you are comparing the V90 to the ZenBot, then you will have similar results with milling PCBs because they are both flying gantry machines. True, that the F90 may have been more suitable for PCB milling with it's moving table design, but that is apples and oranges.

You can get good results with the V90. It's a matter of how much time you are willing to take to dial in the table. The F90 also requires a lot of patience. Having the right engraving bit, finding the perfect feed rate, and figuring out how to level the PCB substrate to the cutting path is the key to good PCB milling.

>Len

check this package
http://www.kelinginc.net/CNCNEMA23Package.html
Ready and plug controller
http://www.kelinginc.net/ControlSystem.html

One of the emc2 developers purchaced a zenbot..

http://axis.unpythonic.net/01188338604
http://axis.unpythonic.net/01188441458
http://axis.unpythonic.net/01215190154

sam

Keling,

This thread is about hardware, not electronics and motors. Perhaps you linked to the wrong page. All I saw there were motor/driver kits.

>Len