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9x20 Lathe CNC conversion

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Dirty Engineer

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Do you have any further info on what you did for a spindle pickup? Did you used a single tang mounted inside the headstock or a wheel mounted on the exterior at the rear?

Also, I noticed you did away with the floating bearing mount on the z axis and now just have the motor mount and coupler supporting the screw. You found it wasn't needed? Will this change when you mount a ballscrew? Do you plan on covering the ballscrew at all with guarding?

I have heard the turn version of Mach3 is far from polished. It's unfortunate there isn't the support for it. I have been leaning toward going with a Dynomotion KFLOP/KSTEP setup for my builds.

Thanks again for the great documentation of your build and for answering my questions. There are not many recent 9x20 documented builds out there.
 

jumps4

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the bearing at the coupling end was causing a problem in the cutter pattern because of the leadscrew being poor quality ( warped ). removing the front bearing stopped the screw from moving the apron up and down with screw deflection and made no difference in backlash because the endbearing is a thrust bearing. I will probably install the ballscrew the same way it adds a bit of flex without backlash and makes screw alignment very easy.
i am on the email list for dynomotion forum posts on the kflop/kstep on site and decided to not use one because of all the hand coding and problems i have read in posts for the initial setup. it looks to be a great product but requires a lot of coding knowledge. so i went with the uc100 on my mill but do not use a uc100 on the lathe yet it has a problem with spindle sync at this time and will not thread. i have been beta testing for them almost daily by email from hungary but there are still problems to work out. a lathe will work fine with just parallel and dont really need more than 50ipm for anything i can think of.
as far as the spindle pickup i use a infared sensor and reflective tape it is sending a perfect square wave. i purchased a slotted wheel sensor and buffer prior to using the oscilliscope but now i know i dont have to install it. the problem i was having was with the uc100 so i now run parallel port it is real time sync.
there is a cover above the screw that keeps all the swarf off the leadscrew it moves along with the apron retracting in and out of the belt cover. its hard to notice
steve
 

redman

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sure that would be an option instead of the gender changer. the option came up when using a uc100 or not with the same parallel cable. i have had good luck with everything i have purchased off of ebay as far as working but you have to be careful about the power supplies not being big enough (amps) or too low of a voltage. you really have to read the add and not just go for the cheapest. the seperate drivers and power supplies work better than the tb6560 boards with everything built into one, i have 2 tb6560 boards running, one on a sherline mill and one on a sherline lathe and they are good for that. anything bigger and they go poof too often. i have never owned geoko drives so i know no comparison. but what i do know is these guys are really competitive on ebay and to make the kits sound better they will fudge a bit on the specs. they may say the motor will be 880 oz/in but the power supply you get will never get that kind of power out of the motor because it is too small. or the motor is high power high speed but that requires twice the amperage your controller is rated at so you never get to wire it to get those results.thats the problem i'm having threading on my lathe. the motor drops in power rapidly as the rpms go up, so to move fast to thread i need a faster lead screw pitch and a bigger motor to get those speed or drop the spindle rpm really slow resulting in a poor finish on the thread. the ideal in cold roll i have found is to thread at about 600 rpm but that requires over 30upm feed to do 20tpi (not exact math) i start to falter above 20ipm right now so i have to drop the spindle rpms conciderably on course threads. if i wasnt threading the lathe works really well.
steve
I forgot to mention I am mostly referring to your mill with 3 axes.

OK. I was just wondering if the power supply sold at keling like 60v - 20 amp would handle the loads a little better. Most of the time you are just running 1 or 2 axes so having that much reserve power might be benificial rather than having 3 separately wired supplies.

(still referring to your 3 axis mill) Another option may be wiring 3 of the ebay power supplies in parallel. I would think that running 1 or 2 axes on one 18 amp circuit would be better than running 1 or 2 axes on 1 each - 6 amp each supplies. Of course if you run all 3 axes at the same time you would be getting the same amount of power to each axis as having them wired separate but you would have the advantage of 3 power supplies running only 1 or 2 axes when not.

I don't know if any of the above makes much sense to you or if you have already done it or considered it?

Edit: I just realized that your z axis is a much larger motor with it's own power supply built together with the driver. I guess we would just be talking about 2 supplies. One for your x and one for your y. I guess the same question applies for 2.
 

jumps4

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the motors and power supplies were a package deal and they work great the way they are
a big power supply costs more than 3 smaller ones (i have 4 axis on the mill ) and allows me to shut one off when not using the 4th axis.
and z is bigger for the 4200 motor
steve
 

Analias

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Steve, with tax return in hand, I am spec-ing out what parts I need for my HF 9x20 conversion. I like the way you have gone with your conversion and would like to duplicate much of it. There are some changes: motor mounts, ball screws, etc., but I would like to use your design as a base line for my effort.

Would you be willing to put together a short list of dimensions, materials, approaches that you used?

* What size lead screws did you use (Z & X)
* What thickness of stock for the motor mounts
* What size and grade screws, nuts, bolts
* Size and source for the bearings
* Dimensions of the X motor assembly and how it effected your X travel distance
* Sizes of your motors
* Size and source of your power supply
* Where did you get that case? Did you make it yourself with sheet metal (I like it)
* Any drawings you might have
* How you determined mounting height for the Z screw (I figured I would make the end mounts vertically adjustable)

I have some Keling NEMA 34 460 oz/in steppers that I was going to use. A NEMA 34 motor seems a bit large (physically) for the X drive. Did you find any problems with that?

I'm interested in the sheet metal brake you have. Could you post a picture? I would like to get one myself, but have no idea where to start. My last use of a brake was 60" brake in middle school shop class - doubt I would find one like that cheap. A 36" would be nice though.

-Freeman
 

jumps4

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hi freeman
thats a lot of questions lol
what i'm using for motors now are nema 34 880 oz/in
i have the parts now to change the z axis to 1605 ballscrew and a nema34 1600 motor, I want more speed for threading at higher spindle rpms
there was plenty of room for the nema 34 motors (and the 1600 will fit )and once the lower half of the apron was removed mounting the ballnut is easy with plenty of room. the best these 880 motors would do on the 10tpi screw is 30ipm and that is even less in mach3 while running in spindle sync more, as low as 20 so to thread a course thread i had to run the spindle under 150rpm. thats not a problem at 16tpi but at 8tpi the motor would have to run at less that 100rpm and mach3 spindle tach wont work under 100 rpm. so you can see my need for speed. the x axis motor mount is a single block milled out to fit and there is a ridgid coupling turning the original screw from the back. it has worked very well with the 880 motor and no changes are needed there. the only thing is the alignment of the motor, screw and nut have to be exact or there will be binding and premature wear of the nut. i made a tool to align everything then install the motor with screw attached.
if you dont plan on threading smaller motors will work but i mainly wanted the cnc lathe for threading without changing gears. I would not build one with smaller motors and be happy with it.
I made the enclosure and tried to match its shape to the original covers, the 30in box brake shear came from harbor freight and it is 400 if you dont get a discount or coupon. it is a really nice tool that works great for 20 gauge.
I didnt draw anything i just cutout the parts and fit them together. i measured the existing bolt holes in the fron of the bed and used them to locate my cnc parts. the only alteration to the lathe was threaded holes in the back of the cross slide to mount the motor on the back for x. the lathe could be returned to original in about a half hours time.
I think there is a parts list in the beginning of the thread for the motors and electronics, it is really basic nothing fancy just 2 axis. i control coolant and spindle manually.
steve
 

Analias

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Thanks Steve for responding.

The only real surprise was the size of the motors. I've never seen numbers for response time mentioned in motor specs. Do stronger motors equate to faster motors, or does it have to do the with overall inductance in the motor itself? Do you need 1600s on both axis or just the Z axis to address the threading issue? I wouldn't expect to need much more than I have for the X axis.

Is the brake this one from HF?

http://www.harborfreight.com/30-inch-shear-press-brake-and-slip-roll-5907.html
 

jumps4

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your motor would work with x fine with a ballscrew but not with a 20 tpi screw
the x axis really does not need the power that much but when you are contouring the axis's move in conjunction with each other. so a really slow x and with a 20 pitch screw has to turn twice as many rpm to match the same amount of z movement. when contouring the slowest axis determines the fastest movements available and everything slows down to its speed. the slower a stepper motor turns is when its at it's highest power. thats why they give you a ratings for motors at holding torgue. the faster it pulses by microstepping or higher speed the less power it has. if you think about a fine pitch screw compared to a course pitched screw the fine pitch is easier to turn but because it causes a stepper to turn faster you are loosing power at a faster rate than the torgue you would gain in a finer pitch. so a high pitch screw with a stepper gives more power. by making it a ballscrew you remove most of the friction a course thread would have and then most of the torque is now available for movement not overcoming friction caused by the higher pitch. it took me forever to understand all this it all seems backwards but stepper motors are totaly different in function they look to be rotating smoothly but really they are jumping a step at a time to the next location with a pause in between each jump. the electric stored in the winding takes time to drop before the next pulse comes, if it gets there before the last pulse has dropped to nothing they work against each other. also it takes a certain amount of time for the coil to charge so to make that faster the voltage to the controller is raised to force the coil to charge faster. steppers run at up to 10 times their rated voltage because of this time needed. the motors coil never reaches that 48 volts your power supply may be putting out before discharging. the extra voltage makes it reach its rated voltage faster making the motor more powerful at higher speeds. electric is not instant it takes time to move and the pulse is so short at higher rpm the voltage got high enough to produce any power.
thats probably way more than you wanted to know. but its why you want the biggest strongest motor that will fit you can afford if you dont want to compromise somewhere else like not getting to microstep and running rough and loud.
yes that is the brake it works really well, it has a poor finish rough castings but what counts works perfect. northern tool asks about 600/700 for it i think and the same one from wholesale tool is about the same, they are identical.
you can put small motors on a cnc but to really get one to be a machine to produce, you need power. a friend has one that is so underpowered it will only make .005 passes at best in aluminum it takes all day to make a part. granted it gets it done it's not worth spending the money to accomplish that little amout of production unless its to just play with it like a toy. i have sherline cnc and they were great for learning, cost about 3500 new and my zx45 mill cost less than 5000 to build 4 axis, will snap a 1/2 4 flute mill like nothing if you make a wrong move. it does not care if its in steel or aluminum it just keeps cutting.
steve
 

Analias

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Thanks Steve, this was exactly the level of detail I wanted. I think I understand what you are getting at.

So, I should be fine with the Keling 460 oz/in motors for both Z and X as long as I use ball screws. I'm planning on a 1605 ballscrew for the Z and I have a smaller diameter ballscrew for the X. I'm using Gecko 203V with a 72v 20A power supply.

What thickness stock are you using for your motor mounts? It looks like 5/8".

I saw your comments on Mach 3 Turn and Mach 4. I'm now a bit nervous about the conversion until Mach4 comes out. Maybe purchasing a fully functional manual lathe would be a better option at the moment. What is your opinion?
 

jumps4

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the z motor mount and thrust bearing mounts are the same distance out from the bed so 1/2 will work, i just used scrap i had and it is probably close to 5/8. the thrust bearing thick section is 1" and there are 2 thrust bearings in there. center bore is a loose fit to allow the shaft to self center, nothing precision it just maintains backlash and the screw is actually floating with no endplay. that keeps the motion of the screw turning from affecting the finish. the screw i used was not very straight and a ridgid mount showed it up in the finish when everything was too tight. so thats why the front bearing at the motor end was removed and the thrust end left to float. i have no backlash and it worked really well for being so unorthodox.
as far as mach3 i start with i'm a novice at lathe cnc and I would not use my comments as advice i'm hoping someone straightens me out and puts me on the right track lol
if i had to do a big run of parts i'd figure out how to do it and tweek everything until i got what i needed it to be but there are other factors involved like cutter deflection so it will always take some fine adjustments. the mill is live tooling and a lot more predictable than a lathe operation just because you dial in a .010 pass does not mean your going to get a .010 pass exactly on any of my lathes there is always little differences. these are things i have to learn yet.
steve
 

Analias

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Steve, what QCTP do you have and how is it mounted? It looks like you removed the compound slide.

My AXA QCTP is about 3 or 4 mm to high when mounted on the compound slide. I was thinking of disassembling the slide and mill down the boss. The tool post bolt is pined and I'm not sure how to remove it. I'm also worried that I may need to take down more than the boss on the slide to drop whole QCTP down low enough. I may have to remove material from the whole slide itself when I remove the boss to get it low enough. Have you run into any of these problems with your 9x20?
 

jumps4

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I have to look at my compound i believe it had a different bolt than yours. and the "axa" kit from little machine shop had an adapter bolt that screwed over the original. the original bolt was smaller on mine i'm sure.
the largest tool i could use was a 3/8" with the compound.
when i went cnc the compound was not needed and i now have the post lowered and use 1/2" tooling.
steve
 

donthack

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So much leaning my head is exploding. My little logan does not have that much toolling. I just might be able to justify the conversion in my budget. Thanks for the knowlage and the money saved!
 

jumps4

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Today I started converting my 9x20 cnc lathe to ballscrews, I originally used the acme lead screws and they worked well but there was room for improvement.
I needed to regrind the v grove in the saddle and lap it back in, the wear was bad and the saddle would rock when changing directions. that all came out very well and I made new brass gibbs so I decided to put the ball screws in now that the machine is tight.
I probably will try hand scaping the saddle to reduce wear and hold lube better. ( I know nothing about how to do it but anything is better than it was new, just flat on flat.
I didn't take a lot of pics but if you go back to the start of this thread you can see how I did it the first time.
here is where I'm at now on the x axis, relocating the screw , motor and thrust bearing.
thanks for looking
steve

DSCF1100.JPG DSCF1101.JPG DSCF1102.JPG DSCF1103.JPG
 

jumps4

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I installed a 1204 ( 12 mm 4 pitch ) on the X axis and today I made the mounts and installed a 1605 ( 16mm 5 pitch ) on the Z axis.
I still have some shields to make but I filmed it, doing a warm up cycle at 75ipm.
after regrinding the saddle and the new brass gibbs I now have zero backlash.
tomorrow after I make the covers I'll cut something besides air.
thanks for viewing
steve

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

DSCF1104.JPG DSCF1105.JPG DSCF1106.JPG DSCF1107.JPG
 

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That's awesome Steve! Now, I want one.:thinking: I'm envisioning making fancy knobs and such with ease. That's where CNC really shines- making parts that have non linear shapes.
:))

Marcel
 

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today I got to run my first test on the new setup and it was something I had never done before even on a manual lathe. cut an inside thread.
he had a barrel from a gun and wanted to cut a tread on the inside of a tube to fit the end of the barrel to deflect the muzzle flash. I'm not a gun guy so I don't know the terminology. we measured the thread inside and outside diameter and pitch it was 1.125 od and 24tpi. I had to make a tool holder for an inside thread to hold a carbide insert then I ground the insert to a full 60 degree point to remove the radius. the thread length was .5 so I entered in all the information and did an air pass to make sure everything seemed to be moving in the right direction and it was fine. I inked up the inside of the bore and came in to touch off and set the diameter in the dro. I hit cycle start and let it complete 1 pass at 200 rpm to check the thread pitch with a gauge and it was correct. at this point I'm backed away from the part about 3" to get my hands in there. I hit rewind to start the program and with out repositioning the axis I hit cycle start. the tool moved into the correct position and cut the entire thread in the previous track I backed out to test the barrel and it screwed in about half way and was getting snug , at this time the tool is a foot away from the end of the tube to test the barrel. I just hit cycle start again and it picked the thread up again perfectly then without changing the setting I just let it chase the thread. the barrel screwed on perfectly smooth and snug. we just stared at each other in amazement I could not have been happier.
he videoed it and was going to send it to me because he used his phone. yahoo mail would not let him send it because it is too big so I'll make a video a second time to show it working.
what a great first test this was
steve
 

jumps4

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I finished installing the covers over the ballscrews today
this is also a pic of the first inside thread I have ever cut on any lathe, the cnc did it perfect.
steve

DSCF1124.JPG DSCF1117.JPG DSCF1116.JPG
 

jumps4

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just an update
I installed home switches under the x axis ballscrew cover and a movable z axis stop so I can start building my tool table in mach3. with the switches installed now the machine is zeroed when I turn it on and each tool is zeroed to it's own offsets by selecting the tool number.
I wrote a g-code to make jt33 to 5/8 adapters for my tail stock turret and made 4, they came out really well.
steve

DSCF1167.JPG DSCF1168.JPG DSCF1169.JPG DSCF1170.JPG DSCF1175.JPG DSCF1176.JPG DSCF1178.JPG
 

jumps4

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There isn't much to tell,
I machined a couple backing plates and have added a 5c collet chuck and a 5" 4-jaw scroll chuck for working with square stock.
I purchased new headstock bearing but I haven't installed them yet. maybe I can do a how-to on the bearing replacement in the near future.
steve
 

Dirty Engineer

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I purchased new headstock bearing but I haven't installed them yet. maybe I can do a how-to on the bearing replacement in the near future.
steve
I would find that very helpful! Glad to hear the lathe is running well. Thanks for the update.
 

Punisher 67

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Beautiful Job on the conversion Steve.

I have two Taig micro lathes that I converted myself also and they are indispensable when making repetitive parts
. I just joined to get some insite
on a larger machine lathe and mill as we have the Craftex line available at busybee here in Canada but I am now leaning heavily on a tripe across the border to buy a Grizzly instead .

Sorry not hijacking Steve's thread just showing the versatility of a CNC lathe and adding to Steve's excellent conversion

My smallfry CNC lathe in action. https://www.youtube.com/watch?v=YTaiG_cs178&list=UU4TXqxzgEPUt-SoF9ztUXfw
 
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jumps4

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Thank you for the compliment punisher
I can't get your link to work in Youtube?
what cad/cam software are you using and if you are using mach3 what version are you using?
mach3turn is so buggy, I get it to do what I need to do but it's no where as easy as mill. mach4 was written because mach3 turn cannot be fixed according to Art Fenerty the original author.
I am so far not convinced mach4 is working any better yet. I read their site daily on yahoo and very little is said about turn.
steve
 

Dirty Engineer

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Thank you for the compliment punisher
mach3turn is so buggy, I get it to do what I need to do but it's no where as easy as mill. mach4 was written because mach3 turn cannot be fixed according to Art Fenerty the original author.
I am so far not convinced mach4 is working any better yet. I read their site daily on yahoo and very little is said about turn.
steve

Have you thought or investigated using LinuxCNC (formerly EMC2) for a turning software?
 

Punisher 67

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Hello Steve

I write my G-code the old fashion way out of my head with manual measurements and
use the wizards in Mach3 for more complex arcs and circles . As far as the Mach3 version it
is the most latest one , I do not use machturn i just use mach3 the version for milling on my lathe .
I am also waiting for Mach4 to be completed .

The link works at this end but try this one instead

http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB0QtwIwAA&url=http://www.youtube.com/watch?v=YTaiG_cs178&ei=D9AbVOb_KMXooASL3IKwDQ&usg=AFQjCNHcFoKLPsas8bAnxTPXYDZMkBeK-A&bvm=bv.75775273,d.cGU
 

jumps4

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punisher
the little Taig lathe runs nice, I have a sherline I converted from Denford to Mach3 I haven't turned on in years. nice video

dirty engineer
years ago I did look into EMC2 and I still have umbutu installed on one of my pc's. at that time I was just starting out with machining let alone mach3 and cnc so adding another learning curve with a different operating system and software would have just added to the massive pile of mistakes
I was already making....:nuts:
If I really needed my cnc lathe I'd probably find other options, but I got far more enjoyment out of converting my lathe than I have using it. I'm lucky if my 9x20 cnc gets used once a month because I only do my own hobby work.
Our conversation did get me interested in improving it's performance again and yesterday I was on the internet all day looking at options. At this time I cant see converting from parallel to usb because there is really no controller in a hobby price range that does closed loop threading and a $500 smooth stepper for a machine I use once a month is money well spent else were .
My lathe works really well and is reliable and accurate so I guess if I'd quit trying to compare it's use to the ease of use I find in my zx45 mill and mach3 mill I'd really be quite satisfied. I use my zx45 cnc almost daily and haven't even turned on my manual mill in years where as my manual lathe is used more and the cnc lathe only comes on for special needs or multiple parts.
At this point in time the lathe is perfect for my needs I just need more practice to improve my knowledge and skills using it.
Steve
 

mrich0908

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Hi Steve ,
Mark from youtube.
I knew Ive seen this thread before. I was following while you were building it in twenty twelve. When ever you get a free second can you take some close up pictures of the mill with the ball screws.
I have the Z axis figures out im unsure what I would like to do with the X . You did a great job manipulating allot more travel out of the X axis.
Im in the process of taking everything from my G0704 (that I will be selling with mounts and ballscrews) and putting half of it on my 6x26 and the other half on my 9x20 plus new goodies for both. Maybe Ill do a build thread . Never have before.
 
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