Anybody do a Sieg SC4 lath CNC conversion?

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jmecruz

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I have the LMS Sieg sc4 8.5x16 Lathe.. I love it! dam good accurate machine. anybody know of CNC plans?

Also I have a LMS Sieg x2 mill with DRO. Can I put motors on it and make it NC? How would one go about doing this. I have seen Bridgeport's with motors and dro that I was told are not cnc but numeric controlled. You can input some commands and write a small program to make a part right into the dro.
 
If that is the one LMS calls the HI torque mini mill then I have lead two classes that converted 22 of them. On the first batch we used the kit from CNC fusion, on the second batch a friend made up the conversions, but he is not willing to do that again so I would go with the CNC fusion kits. They make a fine small mill.

The term NC is a very old term, before computers were common and hardwire controllers were the norm. No one today could build an NC machine in any reasonable way.

There is no reason you could not put motors on the X2. I believe that is the machine Weston Bye did a conversion on in recent issues of DIGITAL MACHINIST magazine. Its a nice small machine.

Once you have CNC the DRO is kind of superfluous but it wont hurt anything.
 
I second Ron's view on the Fusion cnc kit.
(be sure to check out the useful links page too)
I have used the kit for the SX3, I found it very good although I was not happy with the ballscrews. I ended up replacing them due to backlash. The ones I used were available very cheap off Ebay and are still performing well 3years later with heavy use.

And as Tin said,
http://www.hossmachine.info/
This guy is out of control with the mods he has done to his X2 mill. one very resourceful and helpful guy.

It is not hard to do a lathe for someone that is handy with machining/fabricating and also has basic-intermediate electrical skills.
I have completed several machines.

Be warned it becomes addictive for some of us the point where you may decide that "I might just do this, I might just do that" in order to make the machine work better or to make the job that little bit easier. Sometimes to the point where the machine spends more time in pieces than together.

Here is a little bit of encouragement,
[ame]http://www.youtube.com/watch?v=7c42c_6o4XU[/ame]

Good luck and please keep us posted.

Baz.
 
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Guess I can not read well- the topic said lathe and I replied with mill. Ok, I'll go back to sleep.
 
Guess I can not read well- the topic said lathe and I replied with mill. Ok, I'll go back to sleep.


Ohhh come on Ron,

We all value you'r input and ideas, over 500 posts, I reckon lots of people out there has found them helpful, Including myself.

There was also a question in regards to fitting motors on the mill.
You were on the money mate.
 
Ok, thanks guys. I am just getting back to normal- I have had both knees replaced since May 20- two weeks apart. I am now back to walking, climbing stairs, into the shop, and today Ill work on getting my boat in the water. If the doc ever says you need new knees do it- its a piece of cake. Little pain and easy recovery. And if you are really nuts look up knee replacement on you tube- they actually use something that looks like a stainless steel sawzall and saw off the end of your leg. It is wild.

So, Im back, I will read carefully and post when I see an opening.
 
I've been noodling around the idea of adding CNC to my Harbor Freight mini-lathe. Some time ago, I converted it to a 14" bed and have made some other mods including replacing the gibs with tapered gibs.

My main motivation for doing this project seems to be just because it would be fun. Once finished, I would also want to be able to use the lathe in manual mode as well.

I have a couple of 1605 ball screws with ball nuts that I could use. I'm also considering, instead, using 1/2" x 10 TPI acme screws with anti-backlash nuts. Anybody have any experience with them? Delrin or brass? Spring loaded or manually adjustable? Squeeze adjustable or spread adjustable? On the other hand, since I already have the ball screws, maybe I should just use them.

I think I would prefer to have the main ball screw on the front of the lathe, basically replacing the existing lead screw. I'm leaning toward putting the motor on the left side where the change gears normally go. For the cross slide, I'm leaning toward a rear mounted motor. Seems cleaner and more out of the way.

Chuck
 
I've been noodling around the idea of adding CNC to my Harbor Freight mini-lathe. Some time ago, I converted it to a 14" bed and have made some other mods including replacing the gibs with tapered gibs.

I have a couple of 1605 ball screws with ball nuts that I could use. I'm also considering, instead, using 1/2" x 10 TPI acme screws with anti-backlash nuts. Anybody have any experience with them? Delrin or brass? Spring loaded or manually adjustable? Squeeze adjustable or spread adjustable? On the other hand, since I already have the ball screws, maybe I should just use them.


Chuck


Hi Chuck,
There may be a problem which can be overcome simply.

When the stepper/servo motor is powered it is holding the ball screw from turning.

Obviously to use the machine in manual mode the stepper/servo will not be powered and therefore not holding the screw from rotating.

The issue you may find is that the ball screw has very little resistance in order to move and once a cut is set the axis may slowly wander. This can be overcome simply by locking the axis on each cut or over tightening the gib to create extra drag (not recommended)

On all of my cnc machines if I remove the stepper motor I can move the axis in or out by pushing or pulling against it watching the ball screw rotate.

I have played with the acme screws with brass anti backlash squeeze nuts,
They are great, the only down side is I have found that they require regular adjustment to keep the backlash away and also over time if used in the same area tend to wear the screw slightly which can create tight spots.

I would be inclined to run a ball screw on the Z axis and acme on the X.

Cnc is great, I have found sometimes for the quick one off part it is a hassle though.
 
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Here you go Chuck,
Here is my very first cnc conversion. Full spindle control via Mach3 and also threading capable. Still under testing in this picture and not quite finished.

Turned out to be a very good little machine, huge learning curve for me, unfortunately is now redundant in the corner of my workshop, taken over by an Emco 120P cnc lathe.

Z axis stepper mounted where the change gears originally were. X axis is a ballscrew, NSK 8mm x 1mm pitch very conveniently located in the same position of the original acme screw.

jmecruz,
My apologies for hacking you'r thread, I hope this picture can give you some ides's.

 
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I did a conversion of a Harbor Freight 8x14 lathe. See http://plsntcov.8m.com/CNClathe/CNClathe1.html
I used a ballscrew on the Z but left the X as it came. I think this is Ok because I will always program cuts with X moving in toward the center.

The real need is for a tool turret. There is little you can make with a lathe without changing tools.

I did write a set of wizards for turn, the NFSturn that I think are pretty useful- of course I would think so, since I wrote them.
 
I think I would prefer to have the main ball screw on the front of the lathe, basically replacing the existing lead screw. I'm leaning toward putting the motor on the left side where the change gears normally go. For the cross slide, I'm leaning toward a rear mounted motor. Seems cleaner and more out of the way.
I fixed up an old Denford ORAC (based on the Emco Compact 8 and it's configured exactly like that. It has timing belts between the stepper motors & ballscrews which makes mounting easier. It works well that way and should do nicely on your mini-lathe as well.

A tool turret would be great but is a big project in itself. A decent QCTP system really shines on a hobby CNC lathe as you can easily set up a tool table in Mach (or LinuxCNC) so that all your tool offsets are permanently stored & instantly called up from code or a mouse click. An accurate homing setup on at least the X-axis is invaluable for setting up & using the tool table.

I look forward to your build; you always come up with unique stuff!Thm:
 
The real need is for a tool turret. There is little you can make with a lathe without changing tools.

One of the members here did do an excellent build log for a tool turret.
a heap of usability and convenience.

That said a pallet type tool holder is easy and a good quality Quick change system will work as well. I worked in a pro shop for about a year a lot of that time was operating a cnc lathe no auto tool change but a Dorian quick change holders and a cycle built in to manually drill a couple of holes with the tail stack and polish by hand when done. IIRC one of the parts had a +- .001 tolerance tight but doable

So if a cnc lathe with a QC tool holder will work in a pro shop it will work for home. The lathe did have a cnc spindle control.
Tin
 
jmecruz, didn't mean to hijack your thread. Hope this is all useful information for you. I'll start another thread for my build when it gets underway.

rcfreak, thanks for reminding me that ball screws offer little if any resistance to unwanted movements during manual machining. I've already run into that problem on my CNC mill when I've used it in manual mode. Looks like I'll have to add carriage locks to the lathe for that eventuality.

Chuck
 
I put a ballscrew on the x, and am now putting one on the z.
A ballscrew is very, very much better than an acme screw.

I used an unusual overconstrained solution, with the screw in tension. This makes it much more stiff, which is the ultimate goal.
1. Supporting both ends, makes the free length 1/2. This doubles the rgidity.
1.1. A tensioned screw has double the rigidity of a std screw, according to standard lit from screw manufacturers.
2. I also went from a 16 mm screw to a 19.05 (3/4"), approximately doubling the rigidity.
In total its 14x stiffer, and 6x more accurate (=6x less stiction).

There is no issue with freewheeling the screws.
I simply disable the drive, which leaves an ideal slight drag on it.
If I want to lock an axis, I just enable the drive again.
I just put 2 small electric switches leading to the drive.

My step sizes are about 0.1 and 0.2 microns, on z and x respectively.
30.000 servo counts on z, at 1:3, with 15 mm wide HTD 5 mm profile belts.
Actual mechanical resolution is better than 1 micron, according to DTIs.

I am now changing the z axis to a 32 mm ground class 0 ballscrew with nut.

And to AC brushless servos, as the geckos have all sorts of problems (after 8 years).
(Common 5V vs common ground mixup, horrible start-up current surge ie no soft-start, cannot be freewheeld as they dont have back-emf protection, single ended vs differential wiring, hissing ie noisy vs silent. New drives are just that, new).

I am fitting the z screw it behind the lathe, where it belongs, out of view/bother/swarf.
I have also kept the original manual operations, although the electronic cnc infinitely adjustable powerfeeds are betterr.
Haas also fits the screws behind the lathe.

My lathe is a 12x24" light industria model, fwiw.
 

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