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mcphill
03-30-2011, 10:08 PM
OK, I have had this issue since I got my machine. I have told Phil about it, but I have NOT provided any video of it until today. I have heard SWATH say he has what sounds like the same issue. Again, Phil has NOT had time/info to see this video yet to respond.

So, I took this video today (I can't f'ing believe this is from my mobile phone!):

YouTube - Mikinimech 1610L "Jumping" manual mode

As you can see, there are "issues" at the x10 setting. It's a bit comical as the phone was slipping down every time the machine "jumped", so there is no actual video of a jump. If needed, I will take another video with the phone isolated from the machine so that you actually can see the jumping.

The biggest issue I have with this is that the DRO gets totally mucked up with lost steps. With a single "jump", it is impossible to return to a known position.

I believe the issue is either in the actual x"##" switch on the manual pendant, or in the connection of the pendant to the machine.

Do any other current owners see/experience this issue?

SWATH
03-31-2011, 12:58 PM
Yup that looks pretty much exactly like mine. I just quit using x10 all together and only use x1 and x100. I didn't really feel the need for x10 anyway, I wish it had an x1000 though. What Phil said about it made sense but it's strange it just happens on x10, I would have expected it to happen on all settings.

mcphill
03-31-2011, 02:14 PM
IMO, the only way to "properly" ignore it is never use it. If I ever use it, I WILL mess up and switch it to x10 at some point. Then after a single glitch, I will have lost the proper DRO position. That means it is 100% non-funtional in my book.

I won't drive a car that every now and again has brakes that don't work. I can't use a fine movement feature that sometimes is doesn't work...

What Phil said would make sense (although would not be an acceptable answer, IMO) ONLY if it did it on x100 too. The machine moves further with one click at x100 that at x10 (should be 10 times as far, in fact!). If the stutter were due to accel/decel, it would have to be worse at x100 than it is at x10. It ONLY happens at x10, there is a hardware or software flaw somewhere....

MIKINI MECH
03-31-2011, 06:22 PM
Direct response. Additional comments in second post.

QUOTE : I won't drive a car that every now and again has brakes that don't work. I can't use a fine movement feature that sometimes is doesn't work...

Comment : See notes in regards applications for each multiplier. X10 is not for fine positioning (X1 is).


QUOTE: What Phil said would make sense (although would not be an acceptable answer, IMO) ONLY if it did it on x100 too. The machine moves further with one click at x100 that at x10 (should be 10 times as far, in fact!). If the stutter were due to accel/decel, it would have to be worse at x100 than it is at x10. It ONLY happens at x10, there is a hardware or software flaw somewhere....[/QUOTE]

COMMENT : - This is making an erroneous assumption that the acceleration profile in X10 and X100 is the same. You'll find that the positional accuracy of X10 is much more deterministic due to higher accelerations, commanding both momentum and precision at the same time. This an advantage, but needs to be used with some degree of respect for the physics involved.

"Mcphil - please review the email sent to you that provides much greater detail and requests clarification. We're also more than happy to inspect your hardware as offered. We can also offer to disable X10 in your particular pendant if we find it working to spec, but not desirable for your particular needs.


Regards,

- Mikini Mechatronics, LLC
- 831.254.2012
- Support@mikinimech.com (Attn Phil)

MIKINI MECH
03-31-2011, 06:43 PM
In specific response to review of the video :

"Zooming fast" on an MPG input is not something that would be recommended in any mode (On any machine). Generally you have to work at it to move a hand wheel this fast. Axial reversal, stopping loads, and pulse generator wear are all concerns.

Starting and stopping an axis in X100 mode as fast as you do at around 2:20 is not something we would recommend. Remember the intention here is not to bang the machine around.

Reversing the axis at 2:15 is about as fast as we would consider at all reasonable. I'd generally slow down a little more here as well.

Remember you are positioning a machine capable of 1000 lbf dynamic loads to tenths of a thousand of an inch precision in real time.

Mcphil : This all said, as detailed in our email reply, depending on the metrics involved (see email to clarify) this might be occurring at a lower (higher?) level than it is designed to. We'd be more than happy to inspect and repair or replace your pendant as needed at no charge.

To describe what is occurring and why :

At about 1:30 in the video, at a very slow rate of input, in what appear to be something like 1/8th to ΒΌ turn increments the axis is exhibiting high dynamic loads. This is somewhat inherent as explained below. Additionally, this is an attempt at a fine positioning move that should really be done in X1. "bumping" the pendant in X10 or X100 mode is not something we would recommend, and not something that would be generally done. This generates a demand to very quickly start and stop an axis that is moving, in a very, very precise manner. This is a fairly “harsh” command. There is a “dead man’s switch” by design to prevent this accidently for safety and usability reasons. In manual mode, the machine does not know when the user’s input will cease (or what the final position target is). The Mach 3 acceleration graphs hint at this as well, if you study what they mean. Essentially, at least in some cases, the machine is still ramping up when you stop input, and the machine follows suit in trying to stop abruptly. If the force commanded is too high, loss of position occurs with the step system, or an alarm shuts down the machine with the servo system.

----------

In general, assistance and clarification for manual operation for all :

----------

To sum up general expectations by mode:

1) Use X1 mode for fine positioning. Don’t worry about dynamics at all, don’t try to materially “jog” the axis to another position by “Zooming” the wheel. Turn the wheel slowly on a relative basis, or a step at a time. Watch the DRO, and position the machine to where you want it exactly for setup or machining. In this mode actions should not concern feed rate, but totally concern position. We’ve tuned this to allow this with (high acceleration) to get exact position, but the low momentum has a negligible effect (low dynamic forces, relative)

2) Use X10 mode for transitional moves and machining. Don’t try to setup in X10. Don’t try to fine position in X10 by bumping in fractional turns at a low rate or single steps (Use X1). Make a deliberate move, and turn the wheel at a natural, calm rate. Don’t use this for jogging across to a new position (use X100). In this mode position and feed rate is of concern at the same time. This mode is tuned to a compromise between positional accuracy (high acceleration) and generating maximum forces (high forces can be generated, relative to other modes, in this mode). This also gives you maximum dynamic range for machining, but more access to power (feed rate) and precision at the same time - this requires a bit more care (Back to my other manual transmission analogy - this is a car without a clutch delay valve, again sorta). We could re-tune this, but the machines would become less precise in this mode (or would have to slow down, or both).

3) Use X100 mode for long transitional moves. Don’t use this for position deterministic operations, unless a degree of uncertainty is allowable. Don’t use this for setup or machining to any tolerance (an example of an exception is face milling where you transition across the material but position (X/Y is not critical and Z is set). This mode is tuned to low positional accuracy (low acceleration) and thus maximum forces are moderate (moderate forces can be generated in this mode). Reversal in this mode is also the slowest due to a slightly larger lag between input and action (Enough to matter for reversal of signal, but almost imperceptible in most use) . Lots of feed rate, not as much precision.

Additional Hints:

- Think about what the end result desired is when you are controlling the machine manually and select the proper multiplier before doing so. Don’t bang an axis around by reversing travel within a second of coming to a halt. Stop, count to one or two in your head, then start the other way. Do the same when switching axis of control. Don’t get lazy and decide to use X1 to jog the machine to a new position since you were already in that mode for a fine position move and just “zoom” the wheel. Finish your fine position, stop, think, change modes, reset your mind on the feed rate you want, target, and direction, then continue. This is the same thing as not putting your car in 3rd gear to leave a stop light since you were already in it when you stopped, or trying to drive down the freeway in 1st since you used it on the on-ramp.

- Make actions deliberate and know how the machine will respond before doing so. Use the DRO and feed rate calculator. Target a feed rate and tune your input (hand wheel speed) to this input. When manually machining, Know what your chip load, approximate thrusts, and spindle loads. Use your feed calculator to your advantage by optimizing chip loads. Do all the same calculations as a CNC program optimization for feeds and speeds, and implement using the DRO and feed rate calculator. We provided instrumentation for a reason – use it to your advantage.

- Use care when machining or positioning to high precision and at high feed rates at the same time. This is true for CNC or Manual mode. Typically this occurs X10 mode manually as described above. This is also true in CNC mode when you optimize code and tune things to maximum levels of precision and cycle time in a program and controller. Your safety factors are reduced when this occurs. Make these decisions from informed position, understanding that you might not “get away” with a chipload that was 15% too high or low as you might normally in a less optimized cycle. In other areas, starting and stopping an axis may result in loss of position in this case, where otherwise you might “get away” with it.

- If you find your self thinking about how fast you need to turn the wheel, you're probably in the wrong multiplier (X1 or X10) or in too much of a hurry for manual control (x100 – and you should really be automating the process with a CNC program).

- If you are reading the DRO and not thinking about how much or how fast you are turning the wheel, or reading the feed calculator at the same time, use X1. This defines a fine positioning move.

- Don't expect exact motion by discrete index of the hand wheel. Use the DRO.

As an operator of a machine (or a car, aircraft, heavy equipment, or hand tool for that matter) the goal should be to strive to understand and control the tool as an extension of yourself to achieve exactly what you want to occur. We’re here to help you achieve this both through hardware analysis and proper operational methods. We encourage owners and operators to feel free to get in touch for additional assistance.

Regards,

- Mikini Mechatronics, LLC
- 831.254.2012
- Support@mikinimech.com (Attn Phil)

mcphill
03-31-2011, 06:56 PM
Can we adjust the acceleration on x10? I would MUCH rather it never stutter than to be accurate "except when it stutters" - because at that point I am hosed! I can get accuracy with x1 - why not make x10 "stutter-proof"?

If not, tell me what wire to clip to make x10 inactive. I would use the pendant if I knew I could never activate the x10 mode the way it acts now.

MIKINI MECH
03-31-2011, 07:22 PM
Can we adjust the acceleration on x10? I would MUCH rather it never stutter than to be accurate "except when it stutters" - because at that point I am hosed! I can get accuracy with x1 - why not make x10 "stutter-proof"?

- This is a firmware change and not user accessible. We would have to revise the lockdown version of the firmware, which we don't feel is in the best interest of our general user base.

- Making it "studder proof" would be limiting the total performance available to the user. If you don't feel comfortable with this setting or access to this level of control, no problem, happy to help you disable it.

- As an aside, the same exact issue surrounds over travel of safety limits and total distance allowed for the safety zone. We feel the stock setting is the best trade of safety and maximum travel range. Again, ditto for maximum travel speeds and acceleration rates.

If not, tell me what wire to clip to make x10 inactive. I would use the pendant if I knew I could never activate the x10 mode the way it acts now.

- We don't recommend or support user modifications of the control system at this level. We're happy to perform it for you as offered. That being said, I'm quite confident it's fully self evident if you take a look inside the pendant.

Please don't take this the wrong way, but it's much like asking GM to tell you how to modify the ECU of your engine - liabilities exist and are significant enough we have to exercise care as the manufacturer. The same is true for issues surrounding spindle index pins, guarding, etc.

Regards,

- Mikini Mechatronics, LLC
- 831.254.2012
- Support@mikinimech.com (Attn Phil)

mcphill
03-31-2011, 08:36 PM
My side business if modifying cars well outside the "manufacturers recommendations", so I can handle snipping a wire... No way for me to change the accel settings for x10?

I have left you a couple voicemails, could you call me back?

Brian L
04-01-2011, 09:29 AM
Not to be argumentative, but I've never read such a bunch of hogwash in my life! You (Mikini) supply the machine with a pendant with a MPG and then say "don't turn the wheel too fast, don't turn it too slow, don't expect it to be accurate". That is essentially stating we (Mikini) screwed up and didn't design/spec the MPG settings correctly, but rather than fix the issue, we'll blame the operator.... yeah, that's it, it's always the operators fault.

I don't have a lot of experience with machines driven by Mach 3 yet, but I have 25+ years running, operating, programming machines in my own machine shop that ranged in size from Shizuoka knee mills, Leadwell, Fadal (40x20) and a whole host of lathes. All of which have table mass on the multiples of a hundred or more in relation to the mass on the Mikini... all had MPG's, all could be dialed at any speed in any rate, X1, X10, X100, reversed, stopped on a dime, and be expected to move to the tenth of a thousandth of what was specified.

Many a time an operator touches an edge, goes to X100 and moves ten clicks to get an inch of movement, and it better be exactly an inch... if not, the whole system is worthless... loose a step for whatever reason and you are screwed and have to re-home the machine and start over.

forrey45
04-01-2011, 05:52 PM
I have to agree with Brian on this one I have been useing CNC's and there pre-curses for over 30 years and have never had any of the problems as described or had to limit the use of a pendent in the described manner. It would have been useless in a production environment.
This is a pity as I have been following this as a retirement machine, not so much the problem itself but the response to the problem.
Forrey.

mcphill
04-01-2011, 07:24 PM
I stated the same to Phil yesterday. He can go in to depth on the choices made for the x10 position, and why those choices were made. There are reasons for it, and to be honest, I lost track and can't explain it (maybe it is clarified in his post above). I guess I have a different philosophy or primary use of the machine compared to Phil.

I design and build high speed automation and assembly equipment in my "day job". I personally would not let a machine go out where I know if a control were able to be used in a certain way, that it would lead to a challenge. Phil states that once the user is accustomed to the pendant, it becomes "second nature", and went in to depth about how the x10 setting is tuned for optimal use in manual machining.

Like I said, I can understand where he is coming from, but it is not in synch with how I want to use my machine. I will send my pendant in to make sure it is not faulty, but from what was discussed, I am inclined to believe that what is represented in the video is "normal function" from the machine, and the stuttering is brought about by "improper use of the controls by the user" - me. I am willing to accept that explaination.

Now that I am more aware of the boundaries and proper methods of use of the x10 setting, I may be able to use it properly and never have an issue, but I can also imagine a scenario where I forget about the limitation or do something "in a hurry" and either crash the machine, or lose my DRO position - that would bum me out. I can avoid that 100% by never using the pendant, and using only MACH3, or by snipping the x10 wire on the pendant. That is likely what I will stick to for now... It may hinder my manual use of the machine, but that is not the reason I bought a CNC mill. It is a nice "+", but if it didn't have the pendant at all, I would still be happy to have this machine.

BPR
04-12-2011, 07:58 PM
Mike, I have my Mikini now, and I have been following this thread with interest. I have tried to duplicate some of the issues talked about, but my pendant doesn't jump at all. I noticed quickly when I first started playing with it, that you have to be deliberate when making inputs and changes. In other words, reversing requires a second or two delay in 10X or 100X mode, otherwise it will continue moving because of the mass. Again, positional changes need to be thoughtful by choosing the appropriate multiplier and not just cranking on the wheel as fast as you can go.

I have no problem with this, as I believe that with machining, you should never develop the habit of rushing anything. Its not wood working, and its not as forgiving. I've seen some horrific accidents before, and whether its just destroying tools or workpieces vs hurting yourself... Slow is better!

In closing, from your video it is clear to me that there is something wrong with you pendant in my opinion. Maybe its something else, but its definitely not just operator error. It seems to do it even when you are moving slowly in 10X.

I'll try and post a video later with some of my observations on my 1610L. Good Luck!