My X2 Mill Machine Planning and Build

[j.steensen]

Hey all.

I have had an itch that needs scratching for several years. I need a CNC Mill. Now that i am out of the Army and have a "real" job where I can actually have my own shop at home, I think its time to make my dream a reality. I make 1:1 aircraft cockpits and am a hobbyist gunsmith.

My day job is as a draftsman/CAD Administrator with one of the big defense contractors in the aerospace industry, so I know CAD cold, however since we outsource almost all our designs for fab, I know almost nothing about milling.

I keep seeing good things about the Sieg X2, and its ability to convert it to a good solid CNC mill for a fraction of the price of purpose built CNC mills. I do plan on purchasing mine from Harbor Freight on the next major holiday when they do a 25% off.

For the actual CNC conversion, I am weighing which CNC Fusion kits to use, and am completely unfamiliar with what motor control hardware and motors to purchase.

One of my big issues, is I would like to be able to maintain a manual control of the machine in addition to CNC for times when I just want to do a small part without drawing up a CAD model, CAMing it, programming it to Mach 3, etc.

I also would like to eventually add an 4th axis on it for small projects such as making handguards for carbines, and such.

I guess my big question is, "Where do I start?"

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[doorknob]

There is a lot of info on this site that can help you. But there is so much info that it can be overwhelming.

I bought an X2 with the HF 25% discount earlier this year, but I've been a bit of a slacker and haven't yet converted it. I am strongly considering getting the CNC Fusion conversion kit, however I have some concerns about their Z-axis design, and so I may end up "rolling my own" Z-axis, along the lines described here: The Home Machinist! • View topic - X2 Mini Mill Conversion begins

I bought a belt-drive conversion kit (sold by one of the members on this site) and plan to make that change as the first step: Untitled Page

As for motors and drivers, there are many choices, but one approach that seems to be favored is the 3-axis or 4-axis 381 oz. in. NEMA 23 kit including Gecko G540 and power supply from Keling (towards the bottom of the page): Page Title

As far as retaining manual operation of the mill, the prevailing wisdom seems to be that using a "pendant" or MPG ("manual pulse generator") accessory to command the mill axes is a better solution than trying to actually manually move the axes through handwheels.

[j.steensen]

There is a lot of info on this site that can help you. But there is so much info that it can be overwhelming.

That is exactly my problem!


I bought an X2 with the HF 25% discount earlier this year, but I've been a bit of a slacker and haven't yet converted it. I am strongly considering getting the CNC Fusion conversion kit, however I have some concerns about their Z-axis design, and so I may end up "rolling my own" Z-axis, along the lines described here: The Home Machinist! • View topic - X2 Mini Mill Conversion begins

Interesting! What is wrong with their Z-axis conversion?

I bought a belt-drive conversion kit (sold by one of the members on this site) and plan to make that change as the first step: Untitled Page

This is a pretty high priority on my mod list as well.

As for motors and drivers, there are many choices, but one approach that seems to be favored is the 3-axis or 4-axis 381 oz. in. NEMA 23 kit including Gecko G540 and power supply from Keling (towards the bottom of the page): Page Title

Thanks for the link, I'll check that out.

As far as retaining manual operation of the mill, the prevailing wisdom seems to be that using a "pendant" or MPG ("manual pulse generator") accessory to command the mill axes is a better solution than trying to actually manually move the axes through handwheels.

This shoulded be too hard, just a project box, a few switches, and figuring out how to connect it to the electronic controls.

Thanks for the piointers, Doorknob!

[photomankc]

J,

I'm not real sure about your intended purpose, the gunsmith comment makes me think that you would be wanting to potentially do some milling on harder steels. I will say that steel is definitely not where the X2 shines. I have had two of them now and in my experience steel is frustrating with these machines. Both in terms of controlling the vibration and chatter and in terms of the bite you can take per pass. That said they certainly are not incapable of cutting steel it just is not the machine's forte.

The other area that is frustrating is the very limited useful Y axis envelope. The X isn't too horrible but the Y is really limiting I have found. There have been many this and that items I have worked on where that limit would be bumped into and add a lot of work to get around. If you anticipate a lot of slender or small work then it's not a huge deal. If you see working on items 4" or more in width then it may be more of an issue. Most of the milling vice options are going to limit that Y even more because of over-hang.

As for handwheels. I'd forget about them. If you convert to ball screws then the dial markings are all wrong and the screws will have a tendency to back-drive. That is to allow force on the work piece to translate into motion of the screw. Not a good deal. The feel is all wrong too and the motors start to fight back even if they are not powered if you try to move the table quickly. There is no reason you can't mill a part without creating a program. You simply type the cut coordinates in and the feed-rate and it makes the pass. Move a little and repeat. You just have to keep the +/- thing straight as that's the fastest way to make a big oops that I have found, along with the 0.635 instead of 0.0635 thing, that will really ruin a day. Also having rapidly spinning entanglement dangers or knuckle rappers is not really desirable.

The X2 is decent little machine and I've seen what it can do in aluminum and really it's quite impressive for the size of the machine once it's tuned up. For steel, if I were doing much of that, I would look for something larger. I would advise you to invest in some screw-machine length drills. Z clearance for drills can be a real bear if you are working on stuff other than plates and there is much added fixturing in the vise.

I'm running a BF-20/G0704 size mill and I'll say that if you can at all swing it, then it really is a WORLD apart even as a manual mill. I can do things in steel that would have the X2 just squeal and die on. That said, there is no pre-finished kit for it so that may make it a no-go for you if you are looking for that. There are kits for the X3 machines though and it too will far out-do an X2. Bill Me Later and 6 months no interest can make that easier to do.

Hey, it's easy to spend your money right? If you do go for the X2, some places that can give improvement are the gibs. Look to either make some nice brass ones or spend some time better fitting the existing ones. Also try to find a way to lock the adjustments on the gibs better. Mine vibrate loose CONSTANTLY. Snug gibs are necessary if you want to do good work. A belt drive is a big plus if you do CNC aluminum. The higher spindle speed means you have a fighting chance at the proper SFM in aluminum.

[doorknob]

Interesting! What is wrong with their Z-axis conversion?

The CNC Fusion Z-axis conversion is asymmetric - it hangs the ballscrew off to the side of the column. Some users have reported loss of accuracy due to that design. In the article that I linked to, the author reworked the Z-axis design to center the ballscrew with the column, directly behind the milling head.

[hoss2006]

Yeah the Z design looks strangely familiar.
Free plans here.
Hossmachine_Cnc Conversion
Hoss

[j.steensen]

J,

I'm not real sure about your intended purpose, the gunsmith comment makes me think that you would be wanting to potentially do some milling on harder steels. I will say that steel is definitely not where the X2 shines. I have had two of them now and in my experience steel is frustrating with these machines. Both in terms of controlling the vibration and chatter and in terms of the bite you can take per pass. That said they certainly are not incapable of cutting steel it just is not the machine's forte.

My main materials will be 7075-T6, 6065-T6, Brass, and Plastic. I'm a battle rifle guy, lots of ARs and such. I have no illusions about being able to work a barrel on this thing, but maybe fabricating sight mounts, etc.

The other area that is frustrating is the very limited useful Y axis envelope. The X isn't too horrible but the Y is really limiting I have found. There have been many this and that items I have worked on where that limit would be bumped into and add a lot of work to get around. If you anticipate a lot of slender or small work then it's not a huge deal. If you see working on items 4" or more in width then it may be more of an issue. Most of the milling vice options are going to limit that Y even more because of over-hang.

Makes sense. Most my work should be small sub-4" Y-axis parts.

As for handwheels. I'd forget about them. If you convert to ball screws then the dial markings are all wrong and the screws will have a tendency to back-drive. That is to allow force on the work piece to translate into motion of the screw. Not a good deal. The feel is all wrong too and the motors start to fight back even if they are not powered if you try to move the table quickly. There is no reason you can't mill a part without creating a program. You simply type the cut coordinates in and the feed-rate and it makes the pass. Move a little and repeat. You just have to keep the +/- thing straight as that's the fastest way to make a big oops that I have found, along with the 0.635 instead of 0.0635 thing, that will really ruin a day. Also having rapidly spinning entanglement dangers or knuckle rappers is not really desirable.

Roger. Understood!

The X2 is decent little machine and I've seen what it can do in aluminum and really it's quite impressive for the size of the machine once it's tuned up. For steel, if I were doing much of that, I would look for something larger. I would advise you to invest in some screw-machine length drills. Z clearance for drills can be a real bear if you are working on stuff other than plates and there is much added fixturing in the vise.

Worst case, I have a bear of a drill press. (My only real metal working tool in my shop currently.

I'm running a BF-20/G0704 size mill and I'll say that if you can at all swing it, then it really is a WORLD apart even as a manual mill. I can do things in steel that would have the X2 just squeal and die on. That said, there is no pre-finished kit for it so that may make it a no-go for you if you are looking for that. There are kits for the X3 machines though and it too will far out-do an X2. Bill Me Later and 6 months no interest can make that easier to do.

I would kill to be able to get the X3, but my son passed away at the beginning of the year, and I had just recently gotten out of the Army and still didn't have a job with health insurance so still got a long ways to go on medical bills. It would be about 2 years before I could get the X3, much less get it converted, as much as I would like one.


Hey, it's easy to spend your money right? If you do go for the X2, some places that can give improvement are the gibs. Look to either make some nice brass ones or spend some time better fitting the existing ones. Also try to find a way to lock the adjustments on the gibs better. Mine vibrate loose CONSTANTLY. Snug gibs are necessary if you want to do good work. A belt drive is a big plus if you do CNC aluminum. The higher spindle speed means you have a fighting chance at the proper SFM in aluminum.

The CNC Fusion Z-axis conversion is asymmetric - it hangs the ballscrew off to the side of the column. Some users have reported loss of accuracy due to that design. In the article that I linked to, the author reworked the Z-axis design to center the ballscrew with the column, directly behind the milling head.

Makes perfect sense, Door.

Yeah the Z design looks strangely familiar.
Free plans here.
Hossmachine_Cnc Conversion
Hoss

Hoss, I do believe that site is the mother lode. You really didn't want me to accomplish anything at work today. Thanks for the link!!!!

[hoss2006]

That should keep you busy.
flsteam did give a shout out as to the source of his Z axis design here.
The Home Machinist! • View topic - X2 Mill CNC Conversion update
the nyloc nut is a nice addition if you can cut threads in the mating part
but I don't see any adjustment ability for the belt.
If you don't get it perfect you'll get either binding or backlash, a slot makes life easier.
Hoss

[j.steensen]

What sort of tolerances should i expect to keep out of the X2 stock?

After CNC conversion with ballscrews?

[hoss2006]

What sort of tolerances should i expect to keep out of the X2 stock? +/- .015

After CNC conversion with ballscrews? +/- .005

generally speaking.
Hoss

[j.steensen]

Thanks Hoss!

[hoss2006]

You can get those a little lower, use a DRO and mod the leadscrew nuts to take out some backlash on the stock machine
or use oversize balls in the ballnuts and better bearings and couplers to get the backlash to near zero for the CNCed machine for example.
Hoss

[j.steensen]

Question in a slightly different vein, do I need the $50 addon for milling for Mach 3?

(getting my three phase parts list together. )

[rpovey]

Depends how you intend to work, it lets you use a number of wizards and chain the results together to produce a tool path.
If you're largely just exporting from CAD/CAM you can skip it.
However IMO it's the real value of Mach, more often than not I just want to do a number of simple machining operations, and I don't want to have to deal with CAD/CAM.

[j.steensen]

Makes sense. And as I am crunching these numbers....meh, whats another 50 dollars?

I am contemplating going the CNC NEMA23 Package #2 route from Keling, Inc.

Will this solution allow me to wire in a tach so I can change spindle speed from Mach?

[j.steensen]

And one more, that Im sure has been beaten to death, but I think I need a 6, 8, and 12 inch scales for the DRO?

[rpovey]

I wouldn't personally bother with a DRO on a CNC'd machine.

[j.steensen]

I will be completing this project in three phases - and the CNCing it will be phase two. I will be adding a belt drive, DRO and tach at first, then I will be saving up for the CNC conversion. The DRO will let me use it accurately in manual configuration. I can always sell the DRO later.

[luv2ride]

And one more, that Im sure has been beaten to death, but I think I need a 6, 8, and 12 inch scales for the DRO?

I put 12" Igaging scales on all three axis' on my x2, mine is modified though. I have the x-axis bolted to the table and the z bolted to the column.
The y is bolted in the front and hanging loose in the rear and the set-up has worked great for me so far.
Two 12" and a 6" is probably more ideal.
I don't have pics on this computer but will try to post them later.
It looks a lot like most others have posted though I think.

[RPCElectronics]

I don't want to hijack this thread, but I am having some difficulty with understanding the mechanical aspects of Hoss' Z conversion.

After purchasing the mill, G540, steppers, power supply and other odds and ends, I am really pushing my spending limits on this project. Having said that, I am going to take a whack at doing my own X and Y mounts/conversions WITHOUT ballscrews for now. If I can upgrade them later, I will, but for now I need to stick with what I have. However, for the Z, I considered the Z only kit for CNC Fusion, but all of the problems I am reading about makes me hesitant.

Having said that, after looking at the Hoss version with the drive directly behind the head, that makes more sense to me from a physics standpoint. I understand quite a bit about the mechanics and I have been building stuff like this for years, but the part that I don't understand is how the ballscrew is actually attached to the head, using the Hoss method. I can see that the bottom of the ballscrew seems to "sit" on an aluminum strip bolted to the top of the head, in the rear, but I can't tell if the ballscrew is actually affixed to this in some way. My first guess is it is and its either attached with a ballnut of some kind OR the aluminum strip had been tapped with the same threading of the ball screw and it's screwed down into it, tight against the top of the mill's head. I am thinking is might be fixed, to keep it from spinning, since the ball screw appears to stay stationary. Am I on the right track? Or even close?

Also, I noticed that a belt drive is used for the Z axis. I purchased three of the NMEA 23 motors carried by Geckodrive and I am wondering if they have enough to direct drive the Z axis. If not, will the belt drive ratio help this and is any counterweight (as seen in Hoss' videos) required?

Thanks for ALL of the help!