Aluminium Framed Router

[lucan07]

A little googling indicated that problem may well be with me using opto isolated Bob to feed opto isolated drivers but this was not conclusive, however a post on Mach3 forum got the same answer from on of the Mod's Tweakie who I class as a reliable source so hopefully new bob without opto isolation will solve my problems with axis stalls.

[Davek0974]

I have the same setup and asked the same question to a lot of suppliers - the answer was that using opto isolators to drive opto isolators was no issue at all and is very common as it protects both ends of the system.

[Clive S]

A little googling indicated that problem may well be with me using opto isolated Bob to feed opto isolated drivers but this was not conclusive, however a post on Mach3 forum got the same answer from on of the Mod's Tweakie who I class as a reliable source so hopefully new bob without opto isolation will solve my problems with axis stalls.

I have not seen Tweakie post but I am pretty sure that using double opto's won't make any difference to an axis refusing to go in one direction or the other. I would check the cables for loose connections.

[lucan07]

I have not seen Tweakie post but I am pretty sure that using double opto's won't make any difference to an axis refusing to go in one direction or the other. I would check the cables for loose connections.

post in question attached with reply had seen this mentioned elsewhere all other cables checked have replaced Bob alone and problem is now solved, in short if not problem on occasions why did tweakie come up with response straight away without opto bob or drivers mentioned, why did non opto bob solve problem?

Re: Router/Mill Design & Build « Reply #12 on: May 02, 2016, 06:30:42 AM » Bit of progress made over the weekend sorry to say weather was nice so my bikes took most of my free time been neglecting them too much lately they need riding and I need the exercise getting old, London Surrey 100 end of July and Box and Neath hills are both killers if you are out of shape and practice. However fixed problem of slipping pulleys before it occured, a bit of testing/tuning first cuts a few slats of 25mm mdf which I have decided to use for first sacrificial bed, had a selection of 2020 off cuts laying around from printer builds etc so using these for clamping t-slots gives me 5mm to skim as needed. Using 6mm Router bit 1st DOC 3mm 2nd 6mm 3rd 12mm MDF using 12000rpm and 1500mm pm feed no problems with cuts. I have used a BOB I was given I think its a cheap chinese import and I appear to be having occasional problems, axis will refuse to operate in one direction, jogging a different axis then frees the original axis to move as required so another BOB on its way, double checking wiring next on to do list, all wiring is CY shielded cable currently all mounted in small pc tower case whilst waiting for cabinet to arrive so may just be everything to close for comfort. VFD is mounted well away from everthing else.

Tweakie.CNC Global Moderator Offline Posts: 5,716 Super Kitty.

Re: Router/Mill Design & Build « Reply #13 on: May 02, 2016, 07:18:20 AM » Nice work sir. Let's hope that changing the BoB cures the axis one way problem (issues such as this can occur when using an opto-isolated BoB feeding into an opto-isolated driver). Tweakie.

[Clive S]

post in question attached with reply had seen this mentioned elsewhere all other cables checked have replaced Bob alone and problem is now solved, in short if not problem on occasions why did tweakie come up with response straight away without opto bob or drivers mentioned, why did non opto bob solve problem?

Well obviously you have found a trusted source but I still don't think that this is the cause of the problem and you will have to ask Tweekie why he came up with the response.
I also notice that you are mirroring all your posts over there so why bother asking questions here?

[lucan07]

Asking questions on different sites is likely to have different people responding, just wondered if anyone else had come across this problem, couple of posts I saw elsewhere that were unconvincing to me, I was as skeptical as you that this would/should cause any problem. The fact that a trusted source came back with identical response lead me to believe there is something in this which I do not understand, therefore ask question where I think advice will be most reliable and well informed. I will ask Tweakie his reasoning behind the response now problem has been resolved and pass on information I am as puzzled a you as to how this can affect operation across two seperate circuits.

[lucan07]

Checked back with Tweakie regarding this and no explanation available response was

"I have not looked into the reasons behind opto - opto problems, perhaps it's timing related, it is just that this issue has been reported on the forum many times in the past. Tweakie."

so no nearer to knowing the problem, unfortunately the Bob I used I was given new and sealed so no real information on it, but out of interest I connected it on the Seig X1 conversion which does not have opto isolated drivers and it worked perfectly. It may just be the Bob is a poor quality cheap import possible others reported are same, more may just have been replaced as faulty, it will remain a mystery for now.

[Clive S]

Checked back with Tweakie regarding this and no explanation available response was

"I have not looked into the reasons behind opto - opto problems, perhaps it's timing related, it is just that this issue has been reported on the forum many times in the past. Tweakie."

Ok So not quite the response you quoted !! really just a comment from him. (I have read many of Tweakie's posts over the years and do respect him but in this case he only made a comment and not a statement) But glad you have it sorted.

I think you will find that a lot of these cheapo bob's don't work well with modern pp on pc's because the pp will only output about 3.5V the older one's output 5V this means that the bob has to convert the 3.5v back to 5V to get the correct logic. This is a known and well documented problem with cheap bobs.

I have said this for the benefit of others reading this post and thinking double opto's won't work.