Copyright 2011. figNoggle Designs.

7x10, 7x12, 7x14 Mini-Lathe Information

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  2. DRO
  3. CNC V1 - CNC V2
  5. HOW-TOS

On to the CNC conversion. without DRO, it would have been extremely time consuming to get repeatable points. anyway, it's the x and y axes for now. the z axis is going to get a ballscrew deal. check out version 2.

x axis coupling. i decided to mount the x axis stepper motor on the left hand side of the bed. the acme screw had a deal for the power feed.

update. it's difficult to get 100% parallel alignment as i found out when running the motors at higher speed/accel. the motor would stall and make nasty noises. so i cut down the right end of the coupling to allow more angular clearance. i also ordered a flex coupling that should allow up to 15 degrees.

here's the pulley for the y axis getting modded for mounting onto the handwheel. haven't seen anyone do this one yet.

note that a washer will need to be fitted to deal with the backlash adjustment.

update. the pulley itself can be machined down so that the washer is not needed.

mounted. nice.

onto the to pulley contraption for the y axis. basically, i DID NOT want the motor sticking out too far like the sterlingsteele mod. a pulley system seemed ideal. (actually i had considered sticking the pulley underneath the base!)

here's the housing of the stepper motor being made.

here's the plate that mounts to the baseplate. note slots for adjustablility.

here it is cleaned up and mounted to the y axis plate.

the completed x and y axes.

update. this is version 1 of the conversion. version 2 of the conversion can be seen here.

here's a test of the CNC setup with mach and turbocnc. lots of adjusting to do.

a brief clip of x-y. need to work on settings. 1st attempt. with mach2.

click for clip

this is actually the 1st attempt. i used turbocnc with default settings. this sounds bad. listen closely.

click for clip

2nd attempt. started dialing in the settings and made my own g-code file for a small rectangle thing. mach2. not saying one is better than the other. out of the box, mach2 is nice.

click for clip

here's the computer and controller inside a rack mount 2U case.

inside. note the wiring and xylotex controller.

here's the faceplate. not the best work (a cnc-cut one would have been much cleaner)

results after dialing in backlash and motor setup.

umm, what's the deal here? is it due to the paper moving around when the motor stops and switches directions or is it a backlash artifact?

oops. it WAS the y-axis bronze leadnut.

here's a 1.5" dia. circle with the backlash artifact. 0 backlash compensation in X and Y in mach2.

i had covered the adjusting bolt with the dro holder. i drilled the hole to expose this and tightened it.

no changes in backlash compensation. here's what happened after the nut was tightened. the same 1.5" dia. circle. much better.

ok, you can see that scale does matter. the smaller circles show more of the backlash artifact while the larger circles show less.

a brief clip of the concentric circles being made.

click for clip

next, the Z axis

slight distraction here. roughing end mill versus 4-flute end mill. notice the finish. also, you really can take a whole bunch of material per cut with the roughing end mill. get some.

assembled ballscrew assembly. the ballscrew was turned in a 7x10 mini-lathe and threaded for 3/8"x24. you'll see why later.

assembled z-axis motor assembly. this was quite a simple way of doing it, though it didn't seem like it at first.

the side brackets are being made. tip: using index cards for stacked parts is a great way for making sure they're gripped tight. note that part of the design calls for a slot for aesthetics and functionality.

the brackets are complete. note the chamfer for the column. there was an "oops" moment when i chamfered the wrong side of the bracket.

here are the brackets positioned. note: the column is 3.930" inches wide (in case you were wondering)

update. i've heard from other people that milling 4" in the y-axis is not possible. it is possible. it's gets really tight at the extremes of the milling operation but it is possible.

update. version 2 of the z-axis brackets have become easier to machine and smaller in size.

this reminds me of something.. figured it out!

all done! here's the first pocket cut made. still need to learn mach's coordinate system stuff.

see the z-axis move up and down. ok, not the most exciting clip, but there's only one other clip on the net that i've seen of the z-axis conversion MOVING. click for clip

here it's actually milling in 3D! you can see my conversion working.

click for clip


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