[philbur]

Spot on, but is anybody listening, I hope so.

Phil

There is a lot of good advice on what is best, like for example ballscrews over acme, or servos over steppers, but for you newbs you have to remember there is a big difference between "better" and "unacceptable". We don't make that distinction enough here, and while debating finer technical points of things people get the idea one or the other is actually bad or undesirable. In many cases the differences are so slight when dealing with a small machine, especially one that isn't run continuous production duty. Things like wear will usually take years to appear on the nut for an acme screw setup, and the nuts are trivial and a few dollars to replace. Running proper nuts, actual screw wear is unheard of in any reasonable time scale. Even then IT is trivial to replace and only costs ten bucks. I'm not about to argue that ballscrews aren't nicer to have, I use them too, but are they really a big deal to insist on for a first hobby mill? Usually not, which is why most hobby mills don't have them. Most of their advantages don't even apply on small CNC mills, while their problems still do.
I guess my point is that while debating some of those differences, a newb looking for a first machine can get very confused and get scared away from options that are perfectly safe and reasonable ones. Sometimes even optimal choices for them, simply through the magnified fear of one of its style of part. Especially with the commonly seen fear ingrained by misleading (to be polite) servo sales literature of buying anything that doesn't have servos. This often drives newbs to spend way more money than they needed to on the drive system and be able to afford less of an actual mill in the end because of it. As well as they often don't even wind up with a true servo system in the first place, or even worse a cheap brushed system inferior to steppers in the first place. In any case a more fragile and complex system, usually the last thing they needed.
Take most of this stuff with a grain of salt. There is a solid reason the lower tech systems are still out there, so don't fear them. Quality of the system and its suitability to you needs are far more important for you to focus on than some specific type of part, regardless of how many buzzwords get thrown in.
It's Cost/Benefit you should be looking at, and just like with tuning cars, its the last couple horsepower that cost more than all the rest combined...

[Crevice Reamer]

....I like to have the manual access on the machine. I don't want to have a computer on all the time....

The best way to accomplish this on a ballscrew machine is a MPG, or Manual Pulse Generator. With a hand-held pendant like this, you can have FULL manual control without the computer.

http://www.candcnc.com/MPG101.htm

CR.

[Harryman]

Very nice synopsis Crevice Reamer! Quite right, that should get stickied somewhere.

I agree with Stepper that the price/performance value for some of the more expensive components like ballscrews, doesn't make them worth it for many hobby type mills, nice to have, but not necessary. Sort of like the difference between a Porche and a Toyota Camry, if you just need a car to commute with, a Camry will just work fine. If you need a Porche though, you need a Porche.

kwyrbndr, if you have already done some work in tool steel and AL with your manual Sherlines and are happy with their performance, then by all means, buy the motors and electronics and get cnc'ing with them, it'd be the best way to go with your budget. If you're planning on something like making lots of metal molds however, you'd want to look at something a bit beefier. Sherlines are a little underbuilt for harder materials so you will have to go slow and with light cuts.

CAD software is expensive, but it is true that you get what you pay for and even more so with Jewelry specific CAD software. The more expensive ones like Matrix, 3Design and ArtCam are easier to learn, quicker to use and you'll get product out and ROI faster. There's lots of examples and discussions about CAD Jewelry software and hardware at www.3dcadjewelry.com if you want to check it out.

[loboy]

hello,

I have upgraded my Sherline 2000 mill to CNC using the 3-Axis SideStep CNC Stepper Motor Driver Kit from PROBOTIX.

The process was fairly simple and took me a weekend to go from no CNC, to 3-axis CNC. I made sure I had all the parts for both the the mill (motor mounts) and the electronics before I sat down.

I had to purchase a bunch of components, like limit switches, an E-stop button, a case, wire, panel mount DIN connectors, fuses, and the such to make a rack mount case and 3 cable assemblies. I spent $309 on the kit, and I spent another $300 on parts to make a nice custom case, which I can upgrade later if I wish.

While waiting for the parts to be delivered I designed the front and back panels of the case. Once the parts arrived I machined the panels for the components, and then assembled everything. Once my case was assembled I tested the 24 volt power supply, then I adjusted the drivers. Then I spent some time testing everything with the stepper motors unattached.

Once everything was tested I attached the motor mounts and the steppers. On my Sherline 2000 mill, I just had to tap 2 holes on the Z-axis to attach the motor mount. The steppers that came with the kit were dual shaft, so I was able to re-attach the hand cranks and still have manual control. I had to ground flats on the shafts, so the couplers in the motor mounts would key correctly.

Once everything was assembled, I spent time adjusting and tuning the system. There is nothing like seeing for the first time your mill doing rapids. Right now I have an accuracy of .001". I run the steppers in half-step mode, giving me 400 steps per revolution.

The whole process was very enjoyable and I learned a lot putting the entire system together, and was able to build a system that was exactly what I was looking for. My one piece of advice would be to sit down and diagram the entire system, with all the components you will need.

[Crevice Reamer]

A note on the subject of limit switches with stepper motors:

FIRST, Different tools have different heights. This makes it almost impossible to limit lower travel of a Z axis without also limiting your tool choices. Most mills don't NEED a lower travel limit switch on the Z axis.

On a SERVO system, If the servo hits the end of travel and stops, it will keep on trying to go until it quickly overtemps and destroys itself. So limit switches are ABSOLUTELY NECESSARY on a servo system.

On a STEPPER system, if the motor reaches end of travel and stops, it will simply stall. There is no danger to the motor unless it is traveling at a very high rate of speed. So in a conversion without ballscrews, the speed is most likely to be low enough to forego the use of limit switches.

Mach3 allows the set up of "software limits" which perform travel limiting quite adequately without added complexity.

CR.

[cyclestart]

If you need a Porche though, you need a Porche.

Nonsense.

You may need a 3/4 ton truck. You desire * a Porsche. Chasing precision for it's own sake is no bad thing as long as you're aware that's what your doing, It can be a desire thing.

*Unless you need to pick up women. There the Porsche has few equals

[philbur]

Yes but if you need to go round corners real fast you will NEED the Porche.

Phil

Nonsense.

You may need a 3/4 ton truck. You desire * a Porsche. Chasing precision for it's own sake is no bad thing as long as you're aware that's what your doing, It can be a desire thing.

*Unless you need to pick up women. There the Porsche has few equals

[Ron111]

Any links to info on the New Gecko 540 board?

Thanks,

Ron

[Crevice Reamer]

Get your coffee and snacks ready and settle in. This will take you awhile:

http://cnczone.com/forums/showthread.php?t=51083

CR.

[Crevice Reamer]

Any links to info on the New Gecko 540 board?

Thanks,

Ron

Latest info with pics and manual on this page, post #892:

http://www.cnczone.com/forums/showth...462207#post892

CR.