Chinese XK7130 a complete experience Review!

[mjoconr]

I've just read this thread and must congratulate you on your progress. Linux CNC is a very powerful platform which can be complicated to get going, but I feel that its well worth the time because in the long term you can implement any feature or idea you could ever think off.
Other more comerical controllers are hard to expand or very expensive.

Cheers

[lcvette]

I've just read this thread and must congratulate you on your progress. Linux CNC is a very powerful platform which can be complicated to get going, but I feel that its well worth the time because in the long term you can implement any feature or idea you could ever think off.
Other more comerical controllers are hard to expand or very expensive.

Cheers

Thank you sir and sorry for the late reply.. been busy these last few weeks with work and every state moment posing to get the mill finished. I am happy to say the major hurdles are completed!! She is up and running with full functionality including the ATC as of this afternoon!!! Whoohoo!! Lots of time spent on the spindle and ATC getting the orientation and locking nailed down but she's following through tool change functionality flawless now!!

Have a punch list to get through on everything before I mount vises and try cutting anything because I know once I do I won't stop to finish these items and I want to get them banned out while I'm on a roll! Quick video clips below!


New home and limit switches and first home sequence




First tool change sequence



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[pippin88]

Nice!!!

No way covers on the X axis?

[lcvette]

Nice!!!

No way covers on the X axis?

I have them off right now while I set limit distances.

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[ianagos]

Very cool so far. Can you do rigid tapping as well?

[lcvette]

Very cool so far. Can you do rigid tapping as well?

Yup! Fully capable of rigid tapping! The spindle is run with encoder feedback to linuxcnc and when rigid tapping is called the spindle and z axis are linked. The spindle is actually controlled with the 7i77 similar to a servo using an analog +/-10v control and PID loop. Pretty cool!

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[ianagos]

Surely you’ve went over it previously but how are the max rapids? And how many tools can the arc hold?

[lcvette]

Surely you’ve went over it previously but how are the max rapids? And how many tools can the arc hold?

My machine has 6mm screws, Clint's machine has 10mm screws, so everything is relative..

X and Y 3000rpm servos
Z 2500rpm servo

6mm lead screw machine
X and Y - 708 IPM rapid
Z - 590 IPM rapid

10mm lead screw machine
X and Y - 1181 IPM rapid
Z - 984 IPM rapid

These are theoretical. Mine is a bit violent at Max rapid... It needs some tuning done still but that is alot of mass slinging around and I'm not sure if I'd ever need it going faster than 600ish. So that's where I set max velocity at the moment. I can't imagine what Clint's would be like at almost double that, I don't think this machine is heavy enough to handle the mass of the table and saddle getting thrown around that fast and I can see it would certainly take is toll on parts for wear. Is a fairly beefy saddle and table design compared to say a drill and tap machine which has a much lighter table and saddle to sling around. And it's a much lighter machine than a bigger vmc that has the mass to support moving the bigger table around. So I think having it both ways is going to be a compromise..

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[ianagos]

That’s funny I have 400ipm rapids and a dreadfully slow tool change and I hate it so much even though I came from a manual toolchange and 60ipm max. Once I got into making a lot of parts and I know I can trust the machine I’ll have it at as fast as possible.

You may change your mind as well. With linear way machines I don’t see it causing any harm.

[lcvette]

That’s funny I have 400ipm rapids and a dreadfully slow tool change and I hate it so much even though I came from a manual toolchange and 60ipm max. Once I got into making a lot of parts and I know I can trust the machine I’ll have it at as fast as possible.

You may change your mind as well. With linear way machines I don’t see it causing any harm.

Have a video? What's a slow tool change In your opinion, I'm new to too changes so I'm not sure, I'm guessing mine is slow. It definitely is compared to arm type I've seen on YouTube.. but it's also better than manual to change. Oh also it's a12 tool carousel.. think they also have a 15, and now they have a 24 tool arm type as well available but the price was significantly higher and my machine was too far along by the time it became available so I stayed with the carousel type.

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[ianagos]

Ill look for a video but when I say dreadfully slow it’s faster than yours although I have a 21 tool carousel. But my spindle drive has blown its guts and has no more active breaking so I have to wait for the spindle to slow down I add a g4 p20000 between tool changes.


Here is a video I think that is 25% rapids so 100ipm maybe it’s 50% I don’t remember.

[lcvette]

Ill look for a video but when I say dreadfully slow it’s faster than yours although I have a 21 tool carousel. But my spindle drive has blown its guts and has no more active breaking so I have to wait for the spindle to slow down I add a g4 p20000 between tool changes.


Here is a video I think that is 25% rapids so 100ipm maybe it’s 50% I don’t remember.

That's awesome!!! I love Fadal machines! That's what I was considering before this machine. Do you just need a new breaking resistor? I know those go sometimes. I don't think that's slow but again not much to compare it to and like you said, after a while the novelty will probably wear off and I will see it as a slow component of the process...lol. Having 21 tools must be nice! Hopefully my next machine will be a used vmc with fast arm type ATC, that's the goal to step up over time to better and better equipment. For now this is a major step from my g0704... Hopefully I can bang out my punch list this week and start making some chips!!

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[Turbo442]

Looking great! Glad you are over the hump. I wouldn’t worry much about speeds yet. Just keep concentrating on all of those fiddly things you won’t want to finish later.


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[lcvette]

Looking great! Glad you are over the hump. I wouldn’t worry much about speeds yet. Just keep concentrating on all of those fiddly things you won’t want to finish later.


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Yup... I know myself, if I don't do it now...lol. I never put home switches on my g0704 because I started making chips..lol then it was never a convenient time to talk into it and my work around want that much of a hassle..lol.

This time I'm completing it 100% before putting it into service so I'm completely happy with it!

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[ianagos]

That's awesome!!! I love Fadal machines! That's what I was considering before this machine. Do you just need a new breaking resistor? I know those go sometimes. I don't think that's slow but again not much to compare it to and like you said, after a while the novelty will probably wear off and I will see it as a slow component of the process...lol. Having 21 tools must be nice! Hopefully my next machine will be a used vmc with fast arm type ATC, that's the goal to step up over time to better and better equipment. For now this is a major step from my g0704... Hopefully I can bang out my punch list this week and start making some chips!!

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Yea when I was looking at you were doing and seeing what I needed a Fadal fit perfectly and then I found out how cheap they were so I bought one now I’m looking for a bigger one maybe a 60x30 or 80x30 but I’m building a new shop first.

I’m writing programs right now and 21 tools is not enough I have to constantly change tools out and without a tool presetter or probe it’s a pain.

It’s the actual drive somehow when the breaking resistor is connected the dc bus from the drive is shorted to it constantly when it should only be during the slowing down of the spindle. It actually blew out a igbt and I replaced it but same issue. The constant short is probably what blew that igbt. Nobody seems to know anything about it. I need to order a new spindle drive but at a little over 2k I’m just using it as is.

[lcvette]

Yea when I was looking at you were doing and seeing what I needed a Fadal fit perfectly and then I found out how cheap they were so I bought one now I’m looking for a bigger one maybe a 60x30 or 80x30 but I’m building a new shop first.

I’m writing programs right now and 21 tools is not enough I have to constantly change tools out and without a tool presetter or probe it’s a pain.

It’s the actual drive somehow when the breaking resistor is connected the dc bus from the drive is shorted to it constantly when it should only be during the slowing down of the spindle. It actually blew out a igbt and I replaced it but same issue. The constant short is probably what blew that igbt. Nobody seems to know anything about it. I need to order a new spindle drive but at a little over 2k I’m just using it as is.

Oh wow, $2k is steep, what HP is the motor and drive? What type spindle motor does the Fadal use by the way?

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[ianagos]

Oh wow, $2k is steep, what HP is the motor and drive? What type spindle motor does the Fadal use by the way?

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They use a baldor spindle motor that is 7.5hp (I think) with an encoder. There are different drives but mine has an amc drive. My machine is actually single phase as well.

[skrubol]

It’s the actual drive somehow when the breaking resistor is connected the dc bus from the drive is shorted to it constantly when it should only be during the slowing down of the spindle. It actually blew out a igbt and I replaced it but same issue. The constant short is probably what blew that igbt. Nobody seems to know anything about it. I need to order a new spindle drive but at a little over 2k I’m just using it as is.

I think there are braking controllers out there. Or you could build one, Just needs to measure the bus voltage and when it gets over a certain threshold switch a FET or IGBT on.

[lcvette]

Hey All,


I have been tuning the drives and learning to tune the PID in Linuxcnc, not an easy undertaking since I'm so new to both, but I have managed to get a handle on it with a lot of excellent help and advice from the members of the linuxcnc forums and irc chat.* unfortunately it seems I have exhausted the drives tuning parameters and still can't quite get it all the way perfect without closing the loop to linuxcnc.* and when in position control mode with the loop closed and the settings maxed out the motion becomes a little less smooth then I would like during the correction process of the servo.* it is audible and visible at the jerk points of acceleration and deceleration.* I am told this likely wouldn't be an issue during cam controlled motion as the motion is dictated by the gcode but i have not yet tested this.* Anyhow, I am going to continue to try and find a resolution and also see how the machine runs in open loop with the following error tuned out as much as possible.* it is not huge, at a max cutting speed of 200ipm,* think the following error max gets up to about 0.0011"(0.03mm) between start and stop and settles back to correct by stopping point.* the following error improves with slower speeds.* The graphs below are all tests done at 708ipm (18,000mm/m) rapid for test purposes.* they hopefully appear in the correct order of succesion tuning order so you can see the progress of a raw untuned drive as opposed to one that has been tuned (at least tuned by me with others help, I claim no awards for being good at it).* hope you enjoy!


Thanks Chris

And video link of post tuning motion!







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[ebrewste]

it is audible and visible at the jerk points of acceleration and deceleration

What does it sound like? Clicks at the jerk points? If so, I would guess that is your acceleration feedforward (aff) doing its job. Aff causes a current (force) to be output proportional to acceleration. Since you are running trapezoidal moves, Those acceleration curves have square edges. Its like hitting your ball screws with a little hammer. Since feedforward is not a closed loop thing, it's bandwidth is only limited by your current loop performance. So to calm down those clicks, you either need to back off on your aff and sacrifice following error performance on acceleration portions or change your trajectory so you aren't commanding square acceleration profiles. Or put a low pass on your speed loop output. It will limit performance, while reducing the clicking, but you might find a happy medium. However, it will limit your closed loop bandwidth. The one practical downside of those clicks is that they might show up as ringing in the surface finish because they excite the mechanical structure. Or it might not...

I think you are generally getting quite nice performance. You may even think about backing off your system bandwidth. I had an experience when doing servo tuning for a recognizable VMC manufacturer. -- Don't set your bandwidth too high or you will shake the head / column on higher jerk portions of your trajectory. I had come from a background of always shooting for maximum bandwidth / minimum following error, but with max servo bw, those high jerk sections would get the head / column moving, as the servo jerk was like hitting the mill with a hammer. When we backed off on the system bw, contouring tests would have drastically less ringing shown in the tool paths. It was a mixed bag -- I could clearly measure the increase in servo following error, but that was less objectionable than the ringing left in the cut. That ringing was absolutely not measurable by us and was absolutely invisible to running your fingernail over it, but it was easy to see.