[daedalus]

Hi,

I have been planning to get a mill to convert to cnc for a while now, but i would like to get the opinion of everyone here first. My main interest is in producing mainly aluminium parts for small robots, as well as the occasional steel part. Originally i had planned to get a sherline 5410a cnc package, and add my own cnc hardware. Being based in UK I would have to pay a high premium for such a package, and for roughly the same price i could get a micromark microlux mill instead (really a rebranded seig x2).

What i would like to know is how the accuracy and construction of the x2 compares to a sherline mill. I understand that i will need to change the screws in the x2, and i assume this will determine the accuracy of the axes, are there any other considerations?

As far as i can tell the x2 has a slightly smaller workspace then a 5400 mill, are there other reasons why an x2 would be a better choice?

Does anyone here have experience with both mills? And if so could you please give me your views on what the relative pros and cons of each are.

I have had a read through previous posts describing these mills, but as this is my first mill, (and the only one i am likely to be able to afford for a long while)
i am keen to get the most suitable tool.

Also does anyone know if the x2 drive electronics are rated up to 240v 50hz?

one last question, is there going to be much difference in tooling costs / availability between these machines? (I am new to this, so need to invest a fair amount in tooling).

Thanks,
Tom

[itsme]

Hi there,

As an alternative to both the X2 and the Sherline, I would suggest the Micro Mill from Sieg (X1). This mill is available in the UK from Arc Euro Trade. It has recently been updated to have an extended table and therefore more x-axis travel. The travel on all axes is now similar to (if not more than) the X2 and the X1 mill is cheaper.

The X1 also seems to be better suited to CNC conversions than the X2. It is easier to do and if you want you can get away with using the standard leadscrews and still have fairly good accuracy. The X1 is capable of cutting steel/aluminium etc.

I don't have any experience with Sherline machinery, but from what I've heard it sounds like both the X1 and the X2 are more solid machines.

If you buy your machine from Arc Euro Trade, it will be suitable for UK wall sockets. The guys there are also very friendly and give good support.

http://www.arceurotrade.co.uk/

Also have a look at the Yahoo group for the X1 Micro Mill - lots of information.

http://groups.yahoo.com/group/hf47158toCNC/

I hope this helps.

Regards
Warren

[pacosoide]

I own both a Sherline and an X2 mill. The Sherline is a more precise, accurate machine out of the box. If you are doing aluminun, plastics, soft metals only, it will do the job.
The X2 is a much more robust machine but, it is not very accurate out of the box and you will need to work hard to fine tune it. Tolerances on the parts are not good and worksmanship is non existant. I took my apart and took some pictures to show some of the pitfalls you can encounter. Take a look at my site at www.hexit.us.
SuperDAD

[daedalus]

itsme: thanks a lot for the link, had missed arceurotrade when doing my research, and was planning to pay shipping from the states, so now i should have a bit more cash for tooling

have you bought a mill from arc before? if so did you get a prepared one? is getting them to prepare the mill a good idea?

pacosoide:

Thanks for the info, have read through your site and i see what you mean about the construction.

I think i will probably get the x1 with a large bed, as its far cheaper then the x2, and i doubt i need the extra power, as most work will be alu.

[itsme]

Hi Tom,

I bought my X1 from Arc Euro Trade. I didn't get the prepared version, as I was planning on stripping the whole machine down to do the CNC conversion. Getting the prepared version will probably save you a few hours of cleaning and setting up and they also do some kind of modification to the drawbar so you don't have to use a hammer to release it, although I'm not clear on the details of this.

I have been very happy with my machine. I don't agree entirely with pacosoide. The final assembly and quality control on the Sieg machines is not the best, but the general quality of the parts and machining on my machine seems very good. I can't really fault it - especially for the price! I am using the standard leadscrews on the x and y axes for now on my CNC conversion and they are working very well and holding fairly good tolerances. I used the 180Ncm stepper motors available from Arc Euro and they perform very well on this mill.

The X2 may be a bit sturdier than the X1, but the X1 is still capable of cutting steel (and cast iron...). I've cut a fair amount of steel and cast iron with my mill and the results have been very good. I am extremely pleased with my X1 (in case you haven't already picked that up yet)!!!

Regards
Warren

[daedalus]

Warren,

Thats great to hear, i was expecting to have to replace the screws with ballscrews, but if you can do without to start with then i should be able to get up and running quicker. I have a set of servos on the way from US which are rated at 320Ncm continuous, so they should be ok with the factory screws.

How have you done your z axis? Do you think i might get away with using the factory screw with that as well?

Its not that i dont plan to move to ballscrews eventually, its just that at the moment any cash i can save to start with will let me get more tooling.

thanks,
Tom

[itsme]

Hi Tom,

The standard leadscrews obviously aren't as good as ballscrews and I doubt they will last forever, but are an excellent start. I have got ballscrews to put onto my mill eventually, but I just can't see the point in doing it now, when the standard screws are still working well. As soon as my standard screws start to deteriorate, I'll change to the ballscrews.

Your 320Ncm servos will be more (...MUCH MORE) than adequate. My 180Ncm stepper motors aren't running at maximum current, so I would guess that I'm getting around 140 to 150Ncm of torque. I am using timing belts with a 1:1 ratio on the x and y axes and getting 1500mm/min rapids. I could even go a bit faster than this, but I don't want to wear the leadscrews out for nothing. I'm looking forward to seeing what speeds I will get with ballscrews. In case you are wondering what the point of using timing belts with a 1:1 ratio is, it was done to eliminate alignment problems between the stepper motor shaft and the leadscrew. It seems like alignment problems can be a killer.

My z-axis is quite different to most CNCed Micro Mills. If you look at the Yahoo group, you'll see that most people there use the standard z-axis leadscrew and they seem to get good results with it. I wanted to use a timing belt for my z-axis and with my planned arrangement, the standard leadscrew was not long enough, so I replaced it with a 12mm trapezoidal screw. The new screw is also much more rigid than the standard screw. Replacing the z-axis screw involves quite a lot of work. You'll need to replace the standard bearing block as well as the 'arm' that holds the leadscrew's nut. If you can find a way to mount your motor to the stock screw, it will probably do to start off with.

It is also worth mentioning that you should put some kind of bearings onto your leadscrews. At a minimum this should be 2 thrust bearings per axis. You can bore the standard bearing block out to take these bearings or make new bearing blocks. I decided to use 2 angular contact ball bearings per axis. They can take the axial and radial force very well. I mounted these into custom made aluminium bearing blocks that replaced the standard bearing blocks. Besrings are a must and you WILL notice a significant difference when compared to the standard steel bushes. Another reason for replacing my z-axis screw was so that the angular contact bearings would be able to fit. This will probably all make more sense once you have the mill in front of you to look at.

Once again, I hope this helps.

Regards
Warren

[MIKE JEFFERS]

Tom
as warren says the x1 is an excellent little machine (more so now with the bigger table) .i cnc'ed mine about a year ago just to see if it could be done and it exceeded
my expectations,i cut mostly ali or plastic and its fine, steel takes a bit more care.
tooling - ARC can supply most every thing you need, try chronos & axminster as well
machine mart sell collets & stuff for these mills ( the x1 they sell is the machine i have ,it lacks the y axis travel of the x1 super )
regards
mike.

[daedalus]

Thanks for all the help everyone!

Have decided to let arc do the setup of the mill, as its my first time and they will probably do a better job of it. Just waiting for my cnc hardware to arrive from the states (1 week eta), then its mill buying time.

One thing to note is that the price difference between x1 super and x2 is about £8 when you are buying ready to use, so it seems to be a trade off between a higher power spindle or a slightly larger table. I have taken a good look at the mechanical drawings of both mills, and the x2 looks quite a lot stiffer, but unfortunately has a rack and pinion z axis drive. If i can figure a good way to mount a leadscrew to this i might go for the x2 instead, but at the moment the x1 looks like an easier conversion.

now im stuck between x1 or x2, will have to do some more research and see if i can find some good examples of x2 cnc retrofits, as for £8 the extra power afforded seems like a good call.

x1 super has 4.5cm more head travel 11cm more longitude travel, 4.5cm more cross
x2 has over twice as powerful spindle drive. Its a shame amc dont have a larger table mod for the x2, as that way there would be a clear winner (or at least an upgrade path should i need to make larger parts later).

[MIKE JEFFERS]

Tom
without looking i think the price difference was about £150 from x1super to x2
mike

[daedalus]

Mike,

sorry, dont quite know how i made that mistake, difference is actually £100 when you take postage etc into account, looks like the x1 wins.

[MIKE JEFFERS]

Tom
A wise choice sir you won't regret it, in reality the x3 is better value than the x2
but for the £280 the x1L is unbeatable. £280 that's like a years sky subs,which
gives more pleasure? :-)
Mike.

[KDN Tool]

Daedalus,
Check my site www.kdntool.com. There you will find examples of how I do the conversion. I have been retrofitting the X1 and X2 for over two years now and have shipped kits worlwide. I can provide ball screws and other components on an ala carte piece part basis as well as sub-assemblies for the Z only or the X&Y.

My two cents on the choice between the two: go with the X2, the added stiffness and machining power are worth the extra $$. The X1 has it's own set of design flaws just as all the Asian machines do. Over the weekend I installed my advanced kit on a X2 and am easily hitting 150 IPM rapids right from the start. This with 270 OZ NEMA 23 steppers and a 48 VDC drivers. I have feedback on my site from a gentleman in Belgium who experienced the same results. The X2 makes for a hell of a conversion if you do it right. Any help I can provide, feel free to ask. I have some first generation conversion components hanging around that may be of use to you. They are for a conversion that retains the factory lead screws.

Regards,
Ken
KDN Tool

[pacosoide]

I agree 100 % with Ken. Buy the X2 as it is a much sturdier machine. Nothing can replace that! If you do a full tune up, you will end up with a much better machine than the X1.
Warren points out very accurately other mods needed to get the machine running smoothly. So, there is a lot of work to do to get them to perform accurately.
For many of us, that is part of the fun!
Jose.

[phantomcow2]

X1! I love my little mill. My teacher told me i could never cut steel with that "baby of a mill", well i came in the next day with a beautifully faced block of steel.
Its geared low, 1/2" end mills are no sweat.
I just got a Y axis extend kit, i cant tell you how much of a difference it is!. Like others siad, order frm Arc Euro trade because the have that Super X1L now with more travel then the x2. Here in the states we have to wait until november to get this .
And making motor mounts and all is really easy, its basic construction

[whelen]

Daedalus, I just had my SIEG X2 mill converted to CNC. I was looking through the bench mill posts and saw yours. I studied the specifications of many of the commercially sold CNC mills before purchasing my CNC conversion of my X2. My major criteria for selection of the machine and conversion to CNC was price value. I concluded that I could never afford any of the commercially available CNC mills. Also my objective was to emulate a $10,000 engraving machine. So I had the added requirement for a high speed spindle. Well I wrote up my requirements and posted them on CNCNet. A CNCNet member answered me and told me about KDN Tool, and Ken Cardolino ([email protected]). This was a breakthrough for me because I know nothing about electronics, and about this time I was getting discouraged. I looked over the KDN Tool web site and was happy to see that that they specialize in the X1, X2, and X3 SIEG mills. They have individual mechanical conversions for any of the axis, or two complete conversion packages at two price points. They also have complete electronics packages at two price points. Lastly they offer two different price points for their stepping motors, each with a range of torques.

I contacted Ken at KDN Tool and had many, many conversations over e-mail. I went with the best mechanical conversion package, and the best electronics package. I chose the imported stepping motors. Well that is only the beginning. I also ordered lubrication grooves machined into the vees and slides, along with the "one shot lubrication system". Opted for optical home and limit switches with solid state relay controll of the switches. I upgraded the premier electronics package to Gecko drivers, and had the DeskCNC card integrated into the electronics package. These upgrades were the result of Ken at KDN Tool answering my questions concerning electronics functionality. It seems that no matter how much reading I did on the forums, I could not get a straight foreward understanding of the electronics functionality. Ken's explanations helped me tremendously in making my decisions.

Then I discovered I needed a high speed spindle at about 10,000 rpm. The stock spindle is at 2,500 rpm. That opened up a whole world of required learning, and introduced me to the new technology of high speed machining. Ken worked with me and incorporated the Little Machine Shop tachometer and speed read out. He then designed for me three belt drive systems. The first zero to 2,500, the second zero to 5,000, and the third zero to 9,600 rpm. The third speed range has a kevlar timing belt. You should know that the Little Machine Shop tachometer package will not work over the range of the three timing belt / pully systems. Ken studied the bearing pre load requirements for this new drive design, and implemented his findings. His design solution for housing the drive belt system is elegent and insures safety. I opted for a Bison ER-32 collet chuck system for tool holding, because of the high speeds. Ken made me the draw bar for the Bison ER-32 collet chuck.

Ken worked with my software manufacturer, Daniel Carr - Designs Computed (www.designscomputed.com), Virtual Sculptor VS3D / VScad3 to insure that there would be no G-code dialect problems between VS3D and DeskCNC.

I also asked Ken to design and build a 4th rotational axis, which he did. Lastly Ken sourced a vacuum table, and vacuum pump for me, and recommended a source for the way and ball screw lubricants.

In conclusion, I have the best price / value solution CNC mill, at only a very small fraction of the commercially sold CNC mills, or commercial engraving machines for engraving, sculpting, and embossing applications. And it is also a robust milling machine that can make the most accurate steel, cast iron, aluminum, brass, or plastic parts.

This has been a real adventure for me and a real pleasure to meet and deal with people like Ken at KDN Tool and Daniel at Designs Computed.

The best of luck to you on your adventure.

Whelen

[whelen]

Daedalus, I made a mistake on the KDN Tool web site url. It should be www.kdntool.com, the e-mail address is [email protected]

Whelen

[daedalus]

Thanks for the info whelen. Most of my cnc hardware has just arrived from the states today, and am going to place my order for the mill at the weekend. At the moment i am planning to use it as manual for a bit whilst i scrounge together the last few parts i need. I will probably have a go at doing my own conversion, and see how that goes first, as i dont really have the budget for a complete kit (X2 + tooling is quite a lot as it is, plus as i am in UK shipping will be quite high). Might get some of the parts from kdn tool, but will have to wait until my balance has recovered.

Out of interest what grade ballscrews are you using? I am planning on picking up some ground thk screws second hand, but am unsure as to the accuracy grade required.

One other thing i am trying to sort out is a rotary table suitable for the X2, which i can drive with a servo, do you use a 4th axis?

[whelen]

Daedalus, I contacted Ken at KDN Tool and asked him about the ball screws that are in my conversion. The following is Kens reply.

"The ball screws are actually a transport grade with .004"/12" lead accuracy. I have these same grade screws on my X3, and have done some really nice work. I have just placed an order with my ball screw supplier so he will be stocking some .001"/12" lead accuracy screws. While not quite ground ball screw specs, there are much more affordable than the ground ones. Brand new ground ball screws would cost as much as my whole X2 advanced kit!!!"

This is why I went with KDN Tool for my CNC conversion, and was able to get the performance of a very expensive commercial engraving and milling machine for a very reasonable price. As you can see Ken at KDN Tool will work with you to meet your customer requirements.

Also when I was researching doing it my self, I found forum threads where people were anealing hardened precision ball screws so that they could machine the ground ball screw ends to fit their machine bearing configuration.

Ken at KDN Tool specializes in the SIEG X1, X2, and X3 milling machine CNC conversion. He has done so many that he knows that thrust bearings are required, as well as radial ball bearings to insure performance. He also reloads the ball nuts with larger ball bearings to ensure "zero" backlash.

Well I wasn't about to get into all of that and everything else involved in a CNC conversion. Although my hat is off to anyone that has converted their machine themselves. I am having enough of a challenge just learing DeskCNC, and the software I purchased to do engraving, sculpting, burnishing, and machine part milling. I am also trying to learn Albrie CAD over and above so that I can design mechanical parts some day if I need to.

You are doing the right thing in first running the machine as is, and in parallel studying the conversion process.

As far as a 4th rotational axis, I did purchase one, and had my KDN Tool electronics upgraded to 4 axis. At first I suggested to Ken that he build me a right angle bracket, mount a stepping motor to the bracket, and mount the assembly to the X axis tee slots. Ken was certainly willing to do this. However, he has a proprietary 4th axis design. After he showed me it I realised it's elegence and again price value. So I went with his design instead of my 90 degree bracket idea. I guess that G-code can be written to turn a stepping motor so many degrees, and with micro stepping, it can get down to arc seconds of rotational indexing. My 90 degree bracket would work but I would be canterleaving the work piece, and putting all of the cutting load on the stepper motor bearings, and the stepping motor would have to "hold" the workpiece from being moved by the forces of the cutter. Ken's design is much better, and you are not spending hundreds of dollars purchasing a dividing head to then drive with the stepping motor. The stepping motor is a dividing head.

Hope this helps. Good luck.

Whelen

[daedalus]

Whelen:

Thanks for the info about the screws you are using. My situation at the moment is quite helpful, as i am just starting a phd, and have access to a well stocked workshop, so hopefully i will be able to get some surplus ballscrews cut to size for this project. Im kinda regretting not buying the ballscrews earlier, as i had found a supplier offering 36" C1 grade precision ground screws for $350, with bearings, but looks like they have sold out now, guess its what you get for being indecisive. Time to stalk ebay looking for ballscrews