new and interested

[PaulD]

Hello all, I'm new to this forum and am interested in building a CNC router. I am a retired diemaker/machinist/woodworker and have worked in robotic welding. I have access to good sources of materials such as 8020 rail ( I designed machines and robot end effectors with the stuff). Can weld well, and have access to a machine shop.

My questions are; Other than reading extensively and learning what is contained on this site, what driver programs would be recommended? Is there a step by step plan available?

I'm thinking about a 4' x 4' working surface. I do have some specific uses in mind to dovetail with another business I am starting.

How does one calculate the size of the drive motors? I assume that bigger is better. I always liked MORE POWER! and always hate when a machine is under powered. I suppose this is related to the size of the router?

Are some of you folks doing inlay with these machines? Nuf for now.

[debetto]

Hey Paul,

I am new as well, and I cannot speak from actual experience yet (I just started my build: http://www.cnczone.com/forums/showthread.php?t=68720), but I can share what I have learned from all the lurking around that I've done.

I think, for our purposes, steppers in the mid 300's up to high 400's in in-oz torque rating are sufficient. Go for bipolar parallel configuration, and make sure that the capabilites of the motors are put to use by using matching drivers and power supply, i.e. if you have a 3.5A motor, use a driver capable of at least 3.5A and a voltage about 20 to 25 times rated voltage (or more precisely, voltage that is equal to 32 times the square root of motor inductance in mH). The power supply should be capable of supplying 2/3 the current rating of 1 driver multiplied by the number of drivers at close to the max voltage. I would be using Keling steppers, Gecko 251's, CBC4PC breakout board, and a DIY power supply for my build.

As for software, Mach 3 and EMC2 seem to be popular. Mach runs on Windows but is not free. EMC runs on linux and is shareware.

This is what I have learned so far, and I want to stress that I got this all from reading, not actual experience. I hope that it helps point you in the right direction, but I am sure there are others out there who can give more detailed/better info.

debetto

[PaulD]

Thanks for the reply debetto, I'm a long way and a lot of learning before embarking on this project. I am very fortunate to have a scrap steel yard near by that often has 8020 extrusions and lots of other aluminum scraps from industry. I have a good relationship with the guy who runs the place so I just have to ask him to keep a lookout and call me when he has the stuff. I'm kind of sick thinking about some of the parts I've seen there that would be suitable for these types of machines. I seem to remember seeing a pile of ball bearing linear bearing sets with the slides. I hate to think about some of the machines that were scraped out from the plants I worked in. Oh well, there will be more. Another source has lots of electronic equipment for pennies on the dollar. Once I figure out the electrical end I'll have to watch and see what turns up.

I'm nowhere near electrical minded. I'm a gear head. But my former engineering partner is a whiz in the electrical department and I'm sure he will help me out. We both recently retired so I'll have to figure out something to barter for his services.

I have autoCAD to design with and run a dual boot winxp/linux ubuntu system. I will have to find out how the linux based software compares with the other available programs.

What are you planning on using your build for? I have been thinking about several options for the power head. It seems it would be fairly easy to have several options when it comes to the spindle. A high speed air pencil grinder might work real well for fine detail work. There are some that run in the 100,000 to 300,000 rpm range. I have several routers but may just pick up a new one to dedicate to the machine.

I would think that ball bearing linear slides would have less resistance than the plastic linear bearings. I used to have several engineering books that listed all this kind of stuff as well as 8020 catalogs. I gave them away when I retired. danghit.

I really like the shopbot buddy with the stick attachment. That seems to a good design for limited space. I wonder how hard it is to figure out the programing for the 4th axis?

[johnmac]

From what I have found out, design software for more than 3 axis gets real expensive. (at least for me!)

John

[debetto]

Hi PaulD,

I plan to use my router to make giant scale rc plane kits, both traditionally built-up balsa and ply, and composite ones as well--although I don't have much experience with the latter.

I am using 80/20 for the frame and CNCRouterparts.com parts for the mechanics (linear carriages, bearing blocks, etc.).

I have the table and gantry bolted up, but it is more of a trial fit for now. http://www.cnczone.com/forums/showthread.php?t=68720. I should be making a whole lot more progress after the holidays.

Lookign forward to the start of your project.

debetto