Soon to build a CNC router

[justin22885]

i am planning a build sometime later this summer of a CNC router.. and ive been looking up various ideas, techniques, mechanisms, i havent decided on a linear motion system just yet.. or a drive system for that matter.. ball and leadscrews seem to be the most popular..

Z axis.. since theres not much of a need for a full support system, i might just use ball bushings and a steel pipe or rod, supported on the ends, but the X and Y axis is where im looking for more information on linear motion system

does anyone have a fully supported X and Y axis rail system of low cost, but reasonable accuracy? im looking to have an X travel of about four feet, and a Y travel of 2.5-3 feet, obviously accounting for the size of the size of the pieces resting on them i would need to add about a foot or so to the overall length of the rails..

and about the drive systems, im either going to use a typical threaded rod and some sort of a nut.. but ive also been looking into belt drives... possibly bicycle chain.. has anyone used these last two methods? and if so, what sort of accuracy and cost were you enduring?

[rjfurness@bigpo]

Hi Justin,
have a look at the Sosylva plans by David Steele. I think they fit what you are looking for in terms of size and probably lower cost. I am doing a build thread on building his smallest machine in this forum.

My next machine will go for the full ball screws and linear rails solution I think using belt drives. I have visited a guy who lives near me and seen how he has done it, so it helps me make the decision.

Regards
Jason

[justin22885]

where do i find these plans?

[rjfurness@bigpo]

Hi Justin,

try here. I found him using by coming across his name in some threads and googling it. The plans are very good quality and easy to read if you take your time.

http://solsylva.com/cnc/cnc_plans_home.shtml

Jason

[justin22885]

i really like the style with the lower recessed table, using the gantry without legs riding on the elevated rails... they say the belt drive model costs no less than the twin leadscrew/rack and pinion model.. so i feel inclined to go with something like that instead.. but id need to learn more

[justin22885]

ya know what? im mostly worried about the X axis since its going to bear the most weight.. i think im going to get a short steel rod.. and some metal pipe from the hardware store.. slide off a chunk of the metal rod.. slide it tightly into the pipe and glue in with JB weld so i have something to hold the pipe when i drill and drive screws through it to make a supported shaft.. i can get open 3/4" ball bushings for about $9 each.. four of those and JB weld them into a flange.. maybe a little drill and tap here and there to make sure theyre secure.. and thatll be my X axis sliding assembly...supported rod and ball bushing, total cost should be about $50...should be able to do the full frame and X axis setup for $150 motor included.. Z axis assembly will be unsupported and both Z and Y axis will use a size smaller rod than the X.. so all motors included, MDF to build the structure, the pope, bushings.. should come out to about $300 with motors included... with an MDF table.. with the motor out of a cheap 2 1/4hp plunge router and i should be good to go for wood.. what do you guys think of that setup? i have the plans for the structure.. normal looking one with the x axis movement being on legs, probably a single lead screw underneath.. later on i can just upgrade those rails to a more purpose specific linear assembly and upgrade the threaded rods to ballscrews