[marc214]

Hello All, this is my first post, so please be gentle.

So I''ve decided to take the step into building my very own 3-axis CNC system and am looking for a bit of advice. I have read through many posts but I'm still unsure of what to do as everyone's build and situation is a bit different.

Okay, so I'm keeping in mind my budget, trying to get the best bang for the buck, without compromising too much.

So I started off looking first for linear drive systems and saw an Ebay ad that was a complete xyz package, 3' x 2' x 1' respectively. ~$280 shipped OBO, it includes what looks like everything needed; rods, bearings, mounts, etc. After pricing out each individual item seperately to others on Ebay, the price seems decent especially since you can send an offer.

Next, I've chosen to go with a 1'2"-10 5 start SS threaded rod for all axis, and anti backlash flanged nuts.

I intend to build a completely mobile gantry to conserve some space as the above dimensions are quite sufficient for any of my intended purposes. I'll more than likely build it with aluminum. I will be using my 2hp rated router that I already have ~10-15 lbs. Of course I'm not too sure what the total weight of the gantry will be at this time.

I'm going to use stepper motors and er lies my next question, what size motors would be sufficient for this type of setup? I'm looking at the cnc kits that keling aka automationtech has to offer. I've decided to go with the Gecko G540 all-in-one solution as the brains. Essentially, would it be over kill to have all 3 motors as NEMA23 size ~480oz, or would i need larger ones?

Also, I've noticed some kits with 1 motor being larger than the other two. Not sure if that's for the x-axis to compensate for moving the gantry, or for the z-axis as it needs to lower/raise the router/spindle. If for the x-axis, should I consider the motor for that to be the only larger one?

That's it for my initial questions. I appreciate any advice anyone can give.

Thanks!
Marc

[mark.simmons]

Glad to see another person asking for basic advice. I'm working on converting my Bridgeport J-head mill to CNC. I've been working on this off and on for a couple of years, having pretty much followed the series in Digital Machinist magazine, starting in 2007, by Peter Stenabaugh. He originally did the design with stepper motors. I have put the whole thing together using 1800 oz. steppers from Homeshopcnc, along with Gecko 202 drivers. What I've found, is that for some reason, if I drive the motors over about 200 RPM, they skip, and then start screaming. I've sent the Gecko 202's back to Gecko to make sure that they're not damaged. I've looked at the power supply on a scope and see that I'm getting a nice clean, almost ripple free, 75.2-75.8 Volts. I'm using Mach 3, and I've tried a couple of different XML files with no difference in motor performance. I've tried changing the windings' phase and this makes surprisingly little difference (which seems odd, just in itself...). I've tried using a BoB from CandCNC (plain vanilla BoB that basically just passes the isolated signals from the DB25 to the Gecko 202's) and just recently tried using a C32 BoB from Arturo Duncan of CNC4PC. Still no difference - I can easily stop the motion from the motors just by applying some pressure against the table for the X or Y axis.

I don't know what's wrong with my system as it is - now I'm thinking that I should have built this with servos instead of steppers. I am hoping that someone out there might be able to give me advice on using servos that will permit me to incorporate encoders for a closed-loop feedback system and provide adequate power on my Bridgeport mill. At this time, I'd be glad to just be able to drive the X, Y, and Z axis; eventually, I'd like to be able to drive my rotary table, a VFD spindle, and a pendant. Right now though, I just need some advice on what motors and drivers people would recommend

Thanks for reading all of this - sorry it's so long-winded.

Mark

[Pader]

Hello folks,
I have been a member of these fora for some 2years when I first became interested in CNC and thought it may give me insight into how to go about building a machine. I am involved in other projects and have a need for building prototypes quickly. I have often felt guilty when receiving emails indicating that I have not been very active, but the truth is that I felt somewhat intimidated by the level of expertise on the site as I was very much a newcomer to the subject, and then only for more or less 'hobby' purposes.

I have almost completed my machine (I have only to complete the electronics side of it) but am coming to the stage where I need to think about software to control it. I have Solidworks for design and Mach3 for control but nothing (other than demos) for the writing of code and tool paths. Bearing in mind that I am very much an amateur, my machine is definitely classifiable as a 'hobby' machine as I am very much limited for space (I built the machine in my living room). If anyone is interested in seeing what I have built, I entered a competition on the 'Instructables.com' web site under the title of 'a good quality CNC machine by Pader'. This rather pretentious title was meant to differentiate between some other submissions using bits of plastic pipe and other less suitable materials on a site that is mainly for hobby geeks like myself so please don't laugh.

To return to the point, my machine has four axis capability (with expansion possibility for a fifth axis) though initially, I will restrict myself to three axes with a possible addition of rotary capability on the fourth. I want to use my machine for light milling including plastics and I have possible future plans to incorporate plasma cutting (I have a small, multipurpose welding and cutting unit) and even 3D printing. I would appreciate recommendations for processing software that is user friendly and intuitive but, most importantly, relatively low cost due to the fact that it will not not be used that often.