[Roadsidejobshop]

Hello people,

I am working on my third build right now, which is a CNC lathe (which can also be used as a manual lathe if needed). It will be built on a steel frame and the headstock will be made from epoxy granite. The lathe frame will have about 300mm of travel( 12 inches) and the largest work piece it can handle is 160mm (roughly 6.5 inches in diameter). I am currently building it with TR12x3 trapezoidal lead screws, but will upgrade to ballscrews of similar size in the near future. I am making the nuts myself and they will be made from Teflon round stock (I had a big piece left over from before).

The rails are HIWIN HGR15 and carriages are HIWIN HGH15CA (no preload, regular accuracy). The motors running the machine will be NEMA 23, 3NM steppers, stepped down to 1:2, giving about 6NM at the screws.

Thats it for now, I'll update when I have more information

[dbsharp]

how are you getting the rail beds flat? is this going to be machined?

[Roadsidejobshop]

Hey dbsharp - I am going to machine the pieces flat on a mill and then stone them to take any high spots off. According to my mill, they should be flat to 0.06mm and parallel to 0.09mm (2.5 and 3 thou respectively), which is plenty good for me.

Some new pictures of the lathe build also here:

[Roadsidejobshop]

More pics!

[Roadsidejobshop]

A few pictures of progress

[kawazuki]

Not a criticism but why do the plates look like you've raided the scrap bin and welded loads of bits together to make something bigger?

[Roadsidejobshop]

Not a criticism but why do the plates look like you've raided the scrap bin and welded loads of bits together to make something bigger?

Well, it was a case of using what was available, since I currently don't have a steady job and I don't really want to use my wife's money on my machines... I like to think that making the plates for 100 different pieces just gives a bit more personality

[lcvette]

Cool build, guessing your employment isn't/wasn't as a welder? Kidding, I applaud your frugal approach, may be that it makes for a really sweet machine from all the patches etc making the natural frequency harder to hit. Keep it up and the welding will get better as you have those "ah ha" moments. Are you migging it or stick welding it?

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[Roadsidejobshop]

Cool build, guessing your employment isn't/wasn't as a welder? Kidding, I applaud your frugal approach, may be that it makes for a really sweet machine from all the patches etc making the natural frequency harder to hit. Keep it up and the welding will get better as you have those "ah ha" moments. Are you migging it or stick welding it?

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Actually, I studied to be a welder, but did not work in the field really for 3 years - Takes a few weeks to get the rythm going again - some of the welds on that machine base are really "crusty"... Btw - I really like your thread on the machine you ordered from China - please, PLEASE make some videos after you get it working

Also, I made a quick video as an update:

[Azalin]

Cool build, guessing your employment isn't/wasn't as a welder? Kidding, I applaud your frugal approach, may be that it makes for a really sweet machine from all the patches etc making the natural frequency harder to hit. Keep it up and the welding will get better as you have those "ah ha" moments. Are you migging it or stick welding it?

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He is welding better than me

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[asuratman]

Do you want to use atc for this cnc lathe?

[chuckorlando]

Your welds look fine. Nice build Brother.

[Roadsidejobshop]

Thanks man.

I am not planning on using an ATC on this machine (not initially at least).

I am planning on making it a gang-tool lathe (2 turning tools, 1-2 drill tools).

[Eldon_Joh]

i highly recommend you heat that weldment up to minimum 1200 F and then machine it again.

even household fiberglass insulation can hold up to that temperature and you can use a regular heating element from an oven or electric range to get those temperatures.

1200F is the temperature at which thermal stresses start to be removed. at that temperature they won't go away completely but they should be reduced enough not to worry about the metal creeping on its own over the next dozen years. my sources contradict a bit, but you can figure at least 20% of the stress will be removed at that temperature. depends how long you hold it at 1200F too. but enough stress should be relaxed that it won't move on its own later.

but there are still locked in stress. if you remove metal somewhere, its going to move on you. just drilling another hole and tapping it will make it relax.. but i'm talking tenths over a foot or less.

if you heat it above 1200F, you have to be careful that it cools back down to 1200F slowly. as in, very slowly, 100F per hour or so. don't take the insulation off and spray it with water to cool it down until the temperature is below 600F.

[hanermo]

I think it will not distort or creep.

The structure as seen is extremely rigid, as are all lathes, in general.
The central members makes it rigid, imho.
Cannot pretzel, as the central part wont compress or twist.

Looks nice.
I would prefer larger rails.

[Roadsidejobshop]

Eldon, I have chosen not to stress relieve it, because I built it specifically in a way that I would not have to do it. Also, after welding, the frame has weathered for almost 6 months now (time flies man, crazy). I also haven't really milled any real material off of it, just enough to flatten it out. I have not really noticed any major distortion happening and while supported on either end (and me standing on it), I could not see any deflection in the frame (btw, the middle running members are full solid 40x40 bar stock. after i added them, the frame weighs around 40-45kg atleast).

Hanermo - I'm on a very tight budget and have to use what I already have . I would like to use 20-25mm ones too, but we have to make chips with 15mm ones . Besides, about 80% is going to be plastics work, 15% aluminium and about 5% steel. So i think it'll do just fine. I am planning on sticking it on the mill once more to re-mill the ballscrew bearing housings and after that, we are off to the races(hopefully next week).

[Roadsidejobshop]

Sometimes it feels like I'm a masochist - after doing all the machining on the frame a few months ago, I decided to add some bracing and other pieces, so I could have stronger frame and had to re-machine most of the surfaces. But atleast now I can say that I won't have to feel bad about it later. I'll add some pictures tomorrow and maybe even a video.

[Roadsidejobshop]

A quick video and a few pictures aswell!

[epis]

Nice job,
I like your build, how you use all available steel, scrap steel, it reminds me time when I was building my 40 taper spindle, and cnc retrofitting knee mill.
keep building, I suggest go with direct drive servo system. and add / weld as much steel to frame as you can.
is it hard to align linear rails ?

[Roadsidejobshop]

Hey Epis, just noticed your reply. Sorry for the delay... I found that aligning the linear rails was actually pretty easy - but I took care to make sure the frame was prepared before machining and bolted down without twisting the frame.