[LUCKY13]

TotallyRC, I believe you may be right on this. I picked up a different scope ( one I payed for that has been calibrated lately) that works really good. After redoing my electronics enclosure box so I could get to everything much easier for testing I did a lot of testing to find no other reason for the wall. My encoder signals are just rock solid, and in perfect phase at all times. The step direction signals going to the drives showed good results also. My system is just simply noise free at all times. This may change when I get it mounted up on the mill but for now its as clean on all signals as I could ask.


I did get it to go past the wall with the accel/deccel down to number 1. This allowed it to go the full RPM of the motor which wasnt much more than before really. Still its not a tune that could be used. Running pretty good accel/deccel I can still get a good 220ipm out of the system and I expect to be able to get close to that when mounted on the mill (atleast 180ipm). This is pretty good rapids so I am not going to worry with it as long as the system shows to be working like it is.

The HEDS encoders that are claimed to not work very good show very good signal and this is one thing I expected trouble out of. I have even extended the cable to 8ft now and they still work. I have good isolated power running to them. I don't know if that really helps them or not, but the lines are very clean from noise with this setup. I do plan to try some other equipment I have that will allow me to push more encoder counts just for testing later but I don't expect to find anything. I just want to comfirm for sure that I am not being held back anywhere other than reasons that should be. With these motors having a max of 4200rpm its very possible that it is the limit of the motor as you where talking. This being my first system I didn't realize that a motors RPM limit would react this way and I figured it woudl just top out on RPM and not turn any higher. I guess in a sense thats what they are doing but I didn't expect the drive to loose lock when this happens.


If the Gecko drive step pulse freqency limit is 250khz then 250,000 encoder counts per second should be the upper limits if I am understanding this right. I would like to try a higher count encoder on this system, and a little later I will do so. I guess you can get to fine of a resilution but I would like to try one anyway. Of course right now its pretty high res anyway but I tend to try to get all the performance I can get out of machines no matter what they are. I plan to try a couple of different gearing ratios on my motor belt drives so I will wait until I settle in on a ratio before I go any farther.




Jess

[TOTALLYRC]

Hi Lucky13,

It is nice to see that you are taking a very reasoned approach and not just saying that the drives are no good.
I am happy to see that the HEDS modules that you are using are working for you. All three of mine had to be replaced to get the machine rock solid.

When you said that the motor would top out and you didn't realize that the drive would lose lock, your original post was the first time that I thought it all the way through. It really makes sense because the motor is supposed to run in lock step with the drive at all time and if you get outside of the error window, then it faults.

Out of curiosity, with the 8' cable, were you scoping the signals at the drive where it would be weakest or at the encoder?

Keep up the good work.

Mike

[LUCKY13]

TotallyRC I scoped at both ends. This was one of the reasons I redid my enclosure box was so I could get to any where I needed to test. Now no matter what I wish to test I can get to it without taking anything apart.


I did try to add bypass capacitors to see if there would be any change. To be honest this was when I was still looking for what was causing the wall, but never the less it did not help the encoder signal any. It didn't hurt it any either though.


There was no difference in the signals on the encoders between 6ft & 8ft cables, but I have went to extremes to try and eliminate any possibility of noise getting in. For instance all my signal lines are enclosed in a metal box except for a little bit that runs up and goes to connectors to bring them outside. I may wrap this little section with foil tape just to make sure its all shielded extra good. When I get the camera back I was using I will post pics of the enclosure in my build thread so you can see what I mean. I am also going to try and post pics of the scope with all the signals and tuning.


I am not sure why these encoders are working so good for me. The cables are just what US Digital sales for them and the cable I extended them with is nothing more than the cable out of old KeyBoards that I salvaged and used. I used the same for the step & direction lines and both them & the encoder lines go right off the drive and turn down to go through a grommet to go into the metal box it runs through. The power wires run off the drives out in the open but everything else is away from them. I do have some special lining that is made to block noise I have used also, it was salvaged out of old copier machines where they had the mother boards isolated to keep noise out of them. I installed a line filter on the A/C side right before it goes to the main power supply and it also was a piece I salvaged off a copier. Copiers are very sensitive to noise and when you go service them one of the first test the OEM factories have you do is test for noise on the main line before you are aloud to go any farther with any repairs.

All these little extra steps & parts I used may be helping to keep the noise out of the signal lines. But again I may put the system on the mill and find I have problems that I am not aware of yet. It should not be to much longer and I will get to find out, but for now I feel like I have done all I can do to help it.


I hope I wasn't sounding like I was jsut kicking on the drives with my thread. Its not my intention in anyway. Although I will be the first to admit I am not very good with writing or know how to say things. I only wish to get my system working the best I can and I'm afriad that I just want settle for "OK its working" or " OK this must just be my limits". I want to know why, and how. I feel like the better I understand the system the more chance I will have of knowing whats wrong when something does happen. Just starting out I find its nothing to learn something new almost everyday about CNC or the machine. I don't expect this will slow up anytime real soon either and I will probably chase something that turns out to be wrong many more times before I have success with this machine.



BTW thanks for your imput on the subject. Unless something else turns up (and I don't expect it to) I feel pretty sure that you nailed the reason for the limit I was hitting. I find no other reason either.

I am very glad I found a good scope to help with my build and even though it adds to the cost of building a machine I would suggest anyone building one to pic up atleast a small scope to work with. The scope answered a lot of questions for me & when it comes to tuning motors there is not much difference between tuned and not tuned. In other words you could get the motors running good without a scope, but the tune would not be anywhere close to being right. Not that you cant get by without one but you really can have it way out and still have the motors running faily good. If nothing else tuning with the scope may help the motors & drives last better, and I am sure it will help the machine cut better even if it is on some small level.



Jess

[TOTALLYRC]

Hi Jess,
I was not suggesting that you were going to chuck the drives, it is just that so many people, my self at times, will just say it must be bad hardware and I was giving you kudos that you were taking the time to ask questions and figure it out.

I agree if you can afford one and know how to use it, a scope is a great idea. I have a heathkit scope that has helped out a few times but it seems that I need to send it out for repair as the last time I used it it was acting funky. You may have a different version of the encoder module but what aever the reason it is great to see that you are having succes with your machine build.

Mike

[LUCKY13]

No problem, I just didn't want any one that was reading to take the post as such.



I have a very nice HeathKit scope here that looks like brand new but its got problems also. I don't know why but I always kinda liked this older 70's electronic stuff like this and I am hoping to be able to fix mine when I learn a bit more about this electronics game. The driver transitors seem to be bad but I believe it has some caps giving problems also. Getting these old parts seems to be a bit hard but I was going to start buying up parts and tackle fixing it when I am more capable. Its in so nice a shape I tried to get a local elctronics guru to fix it for me but he stays so busy he didn't want to put his time into this because he knew it could get into more time than it was worth to fix it. I would like to get a good sevice manual for it but its not anything I am in a hurry about so for now I have just packed it up to keep its cover and face in the nice claen shape its in. You open it up and it looks something new from back in its time so I feel like its worth fixing even if it takes me some time.


The scope I am using right now is a Secore SC61 that was used in a repair shop and the calibration was keep up with checkups every year. I have a lot to learn before I can make good use of it but its pretty simple getting these readings for what where working on with the CNC stuff. One reason I bought it is because I knew it was keep up good and the other scope I was using is the exact same thing so I kinda have spare parts incase its needed.


I don't know a whole lot about electronics but I have been putting a lot of time into trying to learn. I have started out with one of these pic kits that you can do many little projects with and it helps to learn the hardware plus the software side of things. The math is whats really hard for me and I am a bit slow at learning things like this anyway. Still it helps keep my mind busy and its not a bad skill to be knowing something about. There is just so much envolved with electronics though I don't expect to get very far with it but I do enjoy it so I keep trying.


If you have any info on the HeathKit scope I would be interested in it. I don't really need the scope now but I hate to see it go to waste. If it turns out to be beyound repair the case will make a nice power supply case but if I was to go down that road I would salvage the parts for anyone needing them. I have found a schematic but not a manual, and most of the info I have found with people trying to repair them say the transformer shorts out in them. I have not tried to test anything for now because I have enough other stuff going on but I got the probes that go to the scope and like I said it looks very nice. Its more of a interest in trying to fix it than a need though so I will let it set for now.



Jess