[extrapilot]

Hi all

Well, I purchased an SX3 and did the CNC conversion (CNC Fusion kit) a couple weeks ago. Potential problem though- wondered if there are any other SX3 users who can respond-

The Z axis gib seems to me to be installed backwards- or more to the point, machined backwards. The Z is a wedge type, and it seems like the wedge was formed by a 5 year old with an old file scraping away at a standard gib. Thing is, the wedge side is actually facing the Z column Way, and not the head. So, basically, I have a bearing surface that is about as smooth as (a piece of metal filed by a 5 year old). Since the gib is machined at the head for a special adjustment bolt, I cant just invert it- and even if I could, Im not sure that inverting wouldnt just negate the whole wedge concept- since the gib would no longer be parallel (if Im visualizing this correctly).

On the gib, there is an oil hole that feeds a slot on the opposite side of the gib. If anyone recalls, which side is this slot on (the bearing surface, or the tapered face)? And, is the bearing surface the smooth or the machined face?

Regards,
Rob

[Oldmanandhistoy]

I don’t have an sX3 but looking at your picture if the top surface is the side that contacts the dovetail then it looks fine to me. What I think you are describing as “5 year old filing” is a scraped surface (the surface should not be perfectly flat). The picture below is one of my gibs and the surface you are looking at contacts the dovetail.

John

[extrapilot]

Well, I dont think this was scraped even remotely close to what would be expected. For example, laying this rough surface on a flat, we are talking about perhaps .05" peaks and valleys. I dont think the pic really did the situation (in)justice. Anyway- I just cleaned it up a bit and found that now it actually fits in the head properly (i.e. the adjustment screws can actually engage their threads).

Sorry to rant a bit here- overall, the mill is pretty good, but in doing the conversion, and opening things up, I sort of wish I didnt have good vision. Set screws that were stripped and not tight, loose thrust bearings, 'epoxy' paint that literally runs off with the slightest exposure to a solvent, etc etc.

The CNC Fusion kit went in pretty well given the tolerances on the SX3, and the machine holds amazingly good tolerances in operation- but it is a lot of work to get it there

Regards,
Rob

[Oldmanandhistoy]

I think it is just the price we pay for a low cost milling machine. As long as you know that and are willing to put in some hrs they are worth the cost imho.

John

[VWiking]

Do you have the new spindle control board on your SX3 and are you also controlling the speed of the spindle ?
I am about to start a conversion of a new SX3 myself, but don't know how to connect to the control board of the spindle.
I have the control board shown below on my SX3, and was planning to use a cnc4pc C11G BOB with g203v's, but there is no information to be found how to wire it up with the spindle board. The information I can find is only valid for the standard X3 with the speed-pot.

VWiking

[M100]

If I get a spare 5 mins tomorrow I'll pull the gib from my X3, check it on a surface table and post a picture. It's the only gib I haven't removed so far.

Edited to add pics:

OK this is from a new X3 delivered in the UK about 2 or 3 months ago, it hasn't been used in anger nor has it been completely stripped for cleaning.

There was no point in checking the flatness on a surface table. I could feel the valleys and hills with my fingers!

Three sides of the gib are rough ground, one side is more finely ground with a frosted surface complete with numerous surface scratches (more like gouges!)

There is no 'oil hole'

[extrapilot]

Thanks for posting the pic. It looks smooth as glass compared to the disaster I found in mine. I just fixed it up with a couple hours labor, and now it seems to work pretty well. At least, the Z-axis bearing faces are actually touching in more than a few spots!

I have the SX3, so presumably there is a different design on the gib?

Kind regards,
Rob

[daedalus]

vwiking: i have an X3 here, and i am planning to use a C6 - Variable Speed Control Board from cnc4pc to control the spindle via step dir. There is a wiring diagram for the X3 drive pcb, but it should be pretty simple to figure out the connections for the sx3 pcb.

[extrapilot]

The SX3 is a very different beast- it uses a brushless dc motor, which is effectively a 3-phase setup. The drive board uses feedback sensors on each of the 3 phases to close the loop. It is not as simple as just doing PWM as with a brushed DC motor.

Im going to have a closer look at the board though- since it appears that they are using a daughtercard to interface between the speed control panel/LCD and the control/power board. The output of that daughtercard is probably the easiest to probe and emulate, vs building a new drive board. Or, I suppose one could just go with a standard 3phase VFD drive and rip out the legacy internals. Probably not a cheap alternative-

[VWiking]

deadalus: From what I understand the standard X3 has a pot that variates the Volts to the drive-board, but the SX3 has a touch panel where the speed is moved up and down via two arrow buttons. The signal from this touch panel goes enters the speed board through 8 wires (thin cables to the baby addon board down right on the picture). This, I think would suggest a digital signal system rather than a simple Volt signal to the board. Being not an electronics expert I don't dare to put my Multimeter on it being afraid of scorching it all. I'm still confused. At this stage I'm beginning to regret buing a SX3 instead of a X3. Alternatively I have to rip everything out and put in a VFD with a documented 0-!0V port instead.

[extrapilot]

Before I go to some trouble with a DSO to scope out the board, a practical question first-

Is there a real benefit to remote spindle speed control if you dont have an automated tool changer? Yea, I guess in a pseduo-production process it is one less mistake to be made, but assuming you dont need to adjust speeds mid-path, and that it takes 20x longer to change a tool than it does to change spindle speed, is this really all that necessary?

On the 'regret' thing- IMO digital is often easier than analog, because your PC is speaking digital already. That's not to say buffer circuits arent needed, or even a full microcontroller, but often it is a lot more simple to generate a logic level PWM signal from a uC than it is to try to generate a clean DC voltage from 0-10v (at least, if any current is required).

Im missing something on the speed control, let me know. I might build a simple kit just for fun anyway- but I dont know how much interest (or need) there really is-

[daedalus]

extrapilot: your completely right, digital is the easier option if you were designing the drive from scratch, but the benefit of using analog with the drive is you have an easy way to interface, and you can use premade hardware. That said from my experience of the X3 board you would have to be very careful trying to modify it, as some digital parts are floating at dangerous voltages.

[extrapilot]

daedalus-

Im not entirely sure if when you say 'both boards' you mean X3 and SX3. If so, the SX3 does not leverage a pot for speed control, and so far as I know, except perhaps for a hidden trimmer or 2, there are no pots on the board or anywhere else in the command circuit.

Im always concerned with Chinese board designs- they seem to tend to knock-off established stuff and then just patch it until it works for their implementation. But, the daughterboard is simple, and seems to leverage common parts, so it appears that a different interface to the main board would not present any special problems so long as level shifters or buffers were employed. Maybe some extra shielding and grounding would be helpful, as I suspect it is a noisy environment in there...

R

[daedalus]

extrapilot: yeah sorry about that, please ignoer me i was working off some pictures that i assumed were shots of the SX3 column at superX3.com, it turns out its just one of the large variety of x3 variants.

Personally i would go for a completely optoisolated design. I have previously seen logic in chinese pcbs which runs with its ground level at potentially dangerous voltages, and god knows how the board will behave should it ever fail.

[tauntdesigns]

I asked Arturo at cnc4pc about a link for connecting X3 motor control to c11g bob:
http://cnc4pc.com/Tech_Docs/C11G_&_S...0storybook.pdf

I haven't had a chance to check it out yet but, their it is

Jack

[VWiking]

I asked Arturo at cnc4pc about a link for connecting X3 motor control to c11g bob:
http://cnc4pc.com/Tech_Docs/C11G_&_S...0storybook.pdf

I haven't had a chance to check it out yet but, their it is

Jack

I have checked this manual, and it describes the X3, not the SX3. It tells the user to connect the C11G to P1, P2 and K2 on the speed board. My SX3 board has none of the mentioned pins on it.

Another interesting thing - The announced cnc-readied SR-X3 from Sieg seems from the picture presented to have the same board as my new SX3.

http://www.artsoftcontrols.com/forum...3446.0;id=2954

Maybe there is a solution out there to be purchased as Sieg spare parts in near future.

[ppBuilder]

Hi,
I have a X3 and have used it for hundreds of hours, but not for high prec. work. Problem is the Z axis. Have anyone tried to (or considered) to mount
linear ball rails on the column? I'm thinking about doing this but the risk is high
and I'm not sure the setup will be stiff and stable enought...although the friction and tramming problems would surely be cured. Suggestions?

[extrapilot]

I need to do another set of measurements, but my frist run at them indicated that the Z column contributes approx .003" to the X axis deflection at 10lbs cutting force. Presumably, changing the dovetails to rails would not change any other aspect of the coupled system (i.e. the head itself with the bearing for 90deg rotation, or the actual column- which probably suffers from more twist than from linear deflection). I dont know how much force is on a cutter for a typical finish pass on a benchtop machine- so if it is .1lb, then maybe .0005 is possible. If it is 50lbs, then probably .005 is the best this machine can do. I know this is a very open statement, since a finish pass is dependent on so many variables- Im just making an observation that without modifying the column and/or the head, there is going to be significant deflection if more than a few lbs of force is applied at the cutter.

Hope this helps-

R

[S_J_H]

I think I use my x3 at least 3 times a week and have been doing so for 1.5 years or so. Working to .001" is pretty easy with this mill. I don't run endmills over 3/8" diameter very often although I'll pop in a big 3/4" now and then for certain duties.
I'd junk this mill yesterday if I all I could muster was a .005" tolerance.
The x2 is a limp noodle compared to the x3 and guys do very good work on the x2. I have machined some nice 4" diameter/.5" thick stainless flywheels on my now retired cnc x2.
You just need to learn what the machine can handle and stick to it.
Steve

[extrapilot]

Well, it is certainly possible that part of this slop is in the SX3, which has this additional (4th) axis for head rotation. Maybe this exends the head a bit (leverage), maybe it is just a little sloppy, or maybe it is just a bad gib in my machine (Grizzly has been very supportive of this investigation, and is sending new parts in an effort to help- great CS there).

Ill post again once I get the replacement parts in.

btw- I hear from Sieg on this, and apparently they have a different table (improved dovetails) for their CNC model. I dont know if this is just for their internal project, or for any SX3 destined to retrofit to CNC (i.e. Syil and similar larger conversion houses- maybe a special order part). But, they do seem to recognize that this table has some issues near the end of travel.

For the money, I think it is a great machine. I just think people with them who are relatively new to mills should make sure they spend a few days after cleanup measuring and tuning- gibs, preload on the spindle, tramming the table, etc. They are definately not .001 machines out of the crate.

Regards,
R