Build new 25X49 CNC router?

[jeffmorris]

I built a 17X20 overhead leadscrew CNC router following plans from Solsylva. Is it possible for me to build a new 25X49 CNC router following plans for a 25X37 CNC router using parts from my 17X20 CNC router, especially the Z-Axis carriage? Should I use belt drive or two stepper motors for X-Axis leadscrews? Which wood is best for the frame?

[CarveOne]

Originally Posted by jeffmorris I built a 17X20 overhead leadscrew CNC router following plans from Solsylva. Is it possible for me to build a new 25X49 CNC router following plans for a 25X37 CNC router using parts from my 17X20 CNC router, especially the Z-Axis carriage? Should I use belt drive or two stepper motors for X-Axis leadscrews? Which wood is best for the frame?

I built the Solsylva 25x37 and made quite a few changes to it as I went. How much of your original parts you can use depends on whether they were common parts used on both Solsylva plans and which changes you want to make on the larger machine.

If all you want to do is lengthen the x, y, and z axes it will be only a matter of calculating the extra lengths and adding it to the original part lengths in the plans. If you change lead screw diameter it will affect bearing size and hole sizes in the bearing mounts as well as possibly affecting the location of the holes in the bearing mounts. New pulley part numbers will be needed also. I had to figure this stuff out as I built mine since I changed the leadscrews from 5/16" to 1/2" diameter.

Dual steppers on the x axis will cost a bit more than the pulley and belt drive shown on the plans. Not sure if the cost difference gains you much in performance. Have no experience with it. It would require a fourth stepper motor, fourth controller (or four axis controller board), and a shaft coupler.

I would guess that the z axis is physically not compatible with the gantry dimensions but the skate bearings and a few other hardware parts may be reusable.

As for better wood than pine 2x4 lumber there are many options. You can make the equivalent of 2x4 lumber by laminating two pieces of 1" x 3" poplar, oak, MDF, or a good grade of plywood. The red oak I used for the 25x37 cost me around $90 and I'm very happy I spent it so far. Looks good and is very stiff. Check out the older posts in my CNCzone build log "CarveOne's Solsylva 25x37 Router Build" and the customer photo section of the Solsylva site for machines that are using red oak. Poplar is not quite as stiff as oak but is lower in cost and harder than pine. Carriage bolt heads won't sink into it as deeply as they will in pine when the nuts are tightened. Poplar and oak also don't warp as easily as pine.

CarveOne

[jeffmorris]

I want to make the Y-Axis gantry on the new CNC router fit the Z-Axis carriage. I may have to modify the parts for the new CNC router so that parts from the old CNC router fit. I want to make the frame for the new CNC router out of aluminum rectangular tubes. What about maple wood? I don't like the home-made idler pulley and is it possible to buy one?

[CarveOne]

Making the gantry beam fit the existing z axis assembly should be easy enough to do and it makes sense if the beam is made rigid enough.

Hard maple ("rock maple" is very dense and well, rock hard. It is used for flooring and aircraft propellers. ( I have some very expensive quilted maple that is fairly soft.) Hard maple would work well for a cnc router frame I suppose, though it can be expensive depending on your source.

I didn't like the Solsylva homemade plastic coupler idler design either, but after I made it and skimmed the surface true in my lathe it has worked very well. It measures 1.075" diameter after skimming. If the plastic coupler had a thicker wall I would have made a shallow recess for the belt to run in. I could make some press-on or glue-on flanges for it though it seems it's not needed. No signs of splitting after 10 months.

http://www.sdp-si.com and others have flanged timing pulleys and idlers. Some of the idlers have needle bearings. You will need to find the proper outside diameter, shaft diameter, and belt width part that will work for your machine. A non-bearing timing pulley will work if lock nuts are put on each side of the pulley and are left loose enough that the pulley turns freely on the support bolt. I would try to use one with integral bearing if possible. The belt will want to wander side to side a biton the idler as the direction of rotation is reversed.

CarveOne