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9x20 Lathe CNC conversion

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jumps4

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I took my old 9x20 apart today to start cleaning and converting it to cnc
I took a few pics before i took it apart and noticed the camera said something " no memory card" duuuhhh!!!
So i included the pic from Harbor Freight. this build is going to be bare bones as cheap as possible with parts scavenged off of the mill and what ever else i have around. the motors for this were here on ebay( http://www.ebay.com/itm/3-Axis-Nema-34-Stepper-Motor-880OZ-In-Control-CNC-Mill-/160883445674?pt=LH_DefaultDomain_0&hash=item2575668faa) and the cost for the lathes parts are $484.00 less 1/3 the motor driver and power supply i used for my zx45's 4th axis comes to $319.44. most everything else will be from leftovers from the mill build.
this poor lathe has had an abused life with an owner who had no idea how to even turn it on when he got it " me "
it has been crashed several times and still turns out nice work, but it is starting a new life and probably all new crashes:lmao:
I dont care for the way most 9x20 lathe conversions come out looking with everything cobbled on the front so i'm going to see it i cant find a nice way of doing this without it looking like a box of rocks gobbered to the front of it.
steve

$T2eC16N,!)QE9s3HD)KrBQVCbZsuBQ~~60_57.jpg DSCF0347.JPG DSCF0348.JPG DSCF0349.JPG DSCF0350.JPG image_11332.jpg
 

jumps4

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i have decided on a rear mount on the x axis with a solid coupling and no thrust bearing since the other end of the screw will not be fastened. I dont believe the solid coupling will have an effect on the finish because of the high micro stepping i use there is no vibration. i will see, i may be just making premachined parts for future projects here and have to redo it adding a flex coupling and thrust bearing. here is a pic of a acme screw stepper motor no coupling and they make them ballscrew output shaft also. a mock up of my idea is the other pic but the coupling shown wont be used
steve

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jumps4

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I started on the x axis today , the motor mount was made from scrap so there are a few cuts in it that wont matter ( i said i was going to be cheap ) and i face milled the back of the saddle inline with the dovetails. started cutting out a spacer and thats about it for today my back is at it again. the video is a bit long ( like watching paint dry ) but it shows my redneck riggin to mill the end. the sound in the video is terrible my mill does not sound like that it just humms??
steve
[video=youtube;sZH7xBOZWpQ]http://www.youtube.com/watch?v=sZH7xBOZWpQ[/video]

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jumps4

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i got a few more things done
steve

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Steve;

How long did you make that apron extension? This is scaring me. I can understand it all and I know squat about CNC.


"Billy G" :thinking:
 

jumps4

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bill
i'll measure it to see exactly for you, i didnt want to alter any of the original parts too much so i can return to lathe to manual if i wanted, so it's longer than needed to keep from cutting the end off the screw. all i'm going to change about the screw is mill a small flat on it for a set screw.
a better way would be to make a new screw and run it to the front and put a thrust bearing and even the handle back on for your purpose.
for mine i have to have it cnc to run the z axis so the handle would serve no purpose except something spinning around to hit my knuckles lol
steve
 

jumps4

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I made the coupling but i still have to add the set screws and i stripped a lot of the excess weight off the motor bracket.
[video=youtube;tatV60OwONs]http://www.youtube.com/watch?v=tatV60OwONs[/video]

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jumps4

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i spent all my time in the shop today making a shaft to fit every part perfectly, centered for alignment between the stepper motor and leadscrew.
when it was done it did not look like much but keeping everything perfectly centered, sized and concentric was a measuring and double check project that really took some care to produce. with the 5" long shaft is on the stepper shaft and the lead screw inserted there is less than .0002 wobble. i bored the holes with a boring bar and lapped them to size. the larger part aligns the motor mount to the center of the shaft. I will need this tool to align everything any time i take it apart and also to locate the bolt holes for mounting.
i did notice the mount is about .005 to tall for the table to clear right now so i will get everything built and installed and remeasure to mill the top down. i'd like the table to ride on the mount for a little extra stability if i can align it all properly.
the more this alignment is off the faster the acme screw and nut will wear so i'm really taking my time here. i think a ballscrew would take misalignment better than an acme screw due to not having internal friction like a thread has.
steve

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jumps4

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i got the x axis mechanical parts done and assembled they work good, the motor in the vid is from the mill i just hooked it up for testing. i havent done any wiring for the lathe yet. if you watch the very end you can see i didnt get the set screw tight and the coupling is pulling off the motor lol[video=youtube;zwBa5CGJ1O4]http://www.youtube.com/watch?v=zwBa5CGJ1O4[/video]
steve
 
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Nice work Steve. Looks like you are not going to run into any trouble at all'

"Billy G"
 

jumps4

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there is one downside to using the original screw it will never move much faster with that fine thread but i'm not doing production
steve
 

7HC

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i got the x axis mechanical parts done and assembled they work good, the motor in the vid is from the mill i just hooked it up for testing. i havent done any wiring for the lathe yet. if you watch the very end you can see i didnt get the set screw tight and the coupling is pulling off the motor lol[video=youtube;zwBa5CGJ1O4]http://www.youtube.com/watch?v=zwBa5CGJ1O4[/video]
steve
That's a nice motor mount you've carved out there! :thumbzup:
 

jumps4

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i still have to make a cover to keep the swarf out and put the original screw cover back on.
steve
 

jumps4

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this morning i have been going through my scrap bin and parts left from other builds to see what i have left for the z axis on the lathe. on the motor end i'll need a plate to mount the motor bracket and leadscrew support bearing to the lathe bed ( not really a bearing just something to stop whip ) . in the middle under the saddle i need a bracket to mount the leadscrew nut to and at the tail end of the lathe i need a thrust bearing mounted in a loose fitting bearing to the shaft. so i layed out the materials i have and what i think i am going to do.
the z axis should not be ridgid as far as in and out or up and down because the nut is tight to the shaft for backlash and any motion in the screw would be transmitted to the tool by raising the saddle up and down in and out so the bearings on the end are a loose fit except for the thrust bearing to maintain backlash. the screw i'm using is from my zx45 mill x axis, it is 1" 10 tpi and should last a long time and the nut is adjustable. it is not really hard so machining it hopefully wont be a problem. as least i wont have to grind it like a ballscrew. the 10 pitch of this screw should give me some pretty good rapid speeds if i have enough torque left in the motor for higher speeds the cutting torgue with the 880 oz/in motor should be pretty good also.
steve

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jumps4

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there are two main measurements i have to be careful to keep as close as possible on each end of the lathe. the height of the center of the screw on both ends below the saddle and the distance out from the bed to the center of the screw. any misalignment here will cause binding. and motion transmitted into the tool as the screw turns.
steve
 
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I am in awe Steve. You have come so far in just 6 days. You da man.

"Billy G" :+1:
 

jumps4

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i'm not as smart or as well organized as it may seem.
this was planned at the same time as the mill so everything was ordered at the same time and when i went to the scrap yard i had both in mind
while looking for materials cheap. I sat here broke for years studying other builds and dreaming all this up waiting for the day i could start already knowing exactly how it should be done in my mind. this 9x20 is a go between and that is why i'm being so cheap my next cnc lathe will be a lot heavier. so keeping in mind the limitations of the 9x20 and its capabilities but not wanting to buy more motors and controllers for a larger lathe i'm over powering these axis's for future use when a big lathe becomes available at a low price. i had to force myself from buying a 12x36 enco the other day for $700.00 because i knew i would stop on the 9x20.
steve
 
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I cleaned the board for you. I have a question however. Would it not be better to swap the leadscrews involved in favor of Ballscrews?

"Billy G"
 

jumps4

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yes it would be a lot better to use ball screws it takes less torque to drive them so i could run them faster.
but this is a go between thats why i'm not doing anything i cant reverse to make it manual again and i'm saving the money for ballscrews for a bigger lathe build maybe something like my new 11x26 it is really ridgid and cheap new $1600.
then when i find a bigger lathe cheap all i have to buy is the ballscrews and bearings. and if i put them on this build they would be too short for a bigger lathe.
I took a break on this today to finish the mills 4th axis
steve
 

jumps4

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I finished the z axis today and test ran it everything is smooth so now i'm ready to start the electronics and clean it all up and assemble.
the electronics on the lathe are really basic just 2 axis. the speed it is moving in the vid doesnt mean anything the motor driving it is from my mill just plugged into the lathe to test the movement. i'll have to tune the lathes motors after they are installed and i hope i can get higher speeds than this.
steve

[video=youtube;IV3937VFoDY]http://www.youtube.com/watch?v=IV3937VFoDY&feature=youtu.be[/video]
 
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jumps4

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I started on the electronics enclosure and mounting everything today. i used an old pc tower case cover added a vented back and made the rest of the parts to complete the box. the electronics will fit nice in there nothing fancy.
i'll wire everything tomorrow. the third plug is for the tach signal it is a 5v infared pickup i will be mounting inside the belt cover. it is just 3 wires pos 5v, neg and an input signal to the breakout board. i'll post a pic of the pickup when i mount it, it was cheap on ebay... i think it was $3.00 and free shipping. you have to have it if your going to thread with the lathe.
steve

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7HC

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........... the third plug is for the tach signal it is a 5v infared pickup i will be mounting inside the belt cover.................... i'll post a pic of the pickup when i mount it....................... you have to have it if your going to thread with the lathe.
steve
Explanation please! ;)


M
 

jumps4

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Explanation please! ;)


M
there is no gear train anymore so to thread mach3 has to know the exact rpm of the spindle to move the z axis in time with it to produce the desired thread. everything is done by the stepper motors now so to make course threads the z axis better be fast or the spindle speed slow.
here is a video from youtube of a lathe threading with mach3.
steve

[video=youtube;oMsVhZGznbg]http://www.youtube.com/watch?v=oMsVhZGznbg[/video]
 

7HC

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there is no gear train anymore so to thread mach3 has to know the exact rpm of the spindle to move the z axis in time with it to produce the desired thread. everything is done by the stepper motors now so to make course threads the z axis better be fast or the spindle speed slow.
here is a video from youtube of a lathe threading with mach3.
steve
Got it!

Thanks Steve
 

jumps4

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I wired the box today and spent all afternoon trying to figure out why i could not get much speed out of the motors. the opticouplers in the breakout board they sent with the controlers is so slow it will not run on any setting faster than 25000hz so my uc100 controler that does 100000hz is useless with this breakout board. so i'm going to order a hard wired breakout board i dont need optoisolation with the uc100. so the motors are running just not fast enough to cut a course thread unless i install a dc motor drive i have for a slower spindle.
steve

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Tony Wells

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It's more than a mere tachometer, actually. If you could cut the thread in a single pass, then sure, knowing the spindle speed would be enough to establish a correct feedrate to produce a given thread pitch. But since you won't be doing a thread in a single pass, the tool must be timed and synchronized with the spindle throughout the entire threading operation. So after each pass, the control must know where in rotation the spindle is, not just how fast it's running. That requires an encoder for positional output. Of course, the signal from an encoder can drive a simple counter to give a speed readout.

It's the electronic version of the thread dial and knowing when to drop the halfnut lever.
 

jumps4

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tony
mach3 by its self works with a single pulse your right about knowing location but an encoder would also have to be single pulse to work with mach3. there are addon softwares/controlers that use multipulse for mach3 though. this uc100 is supposed to use multipulse but i havent read up on it yet. the problem for mach3 and multi pulse comes back to processer speeds and the 25000hz setting of mach3 the tach would use too much processor time leaving nothing to move the axis fast enough. once i get another breakout board with no lag the i can run my speed up to 100000 hz and use multipulse by adding more reflective tapes. as it is right now i can only get 50ipm and my minimum spindle speed on the 9x20 is 120 rpm that probably to fast for 50ipm.
steve
 

jumps4

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I didnt do much today but clean some parts and install the headstock then i trammed it. for those who dont know there are set screw holes in the back of the headstock on the 9x20 for tramming you have to get your own screws but it makes it pretty easy. i included a pic of their location and a video of the tram and runout 18" out from the headstock it's jumpy but you can see i have about .0005 runout at the collet chuck, and .0025 18" out from the headstock. centering the runout on the bar the tram is 0005. or less.
steve

[video=youtube;D9xz1tn8jHk]http://www.youtube.com/watch?v=D9xz1tn8jHk&feature=youtu.be[/video]

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