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Re: AXBB-E encoder problem

PostPosted: Tue Feb 11, 2020 10:59 pm
by Robertspark
Re the circuit I'll come back to you tomorrow (I'm not Liverpool, I may be able to sort you a PCB out as you are local)

Re: AXBB-E encoder problem

PostPosted: Fri Feb 14, 2020 9:21 am
by Robertspark
Been busy, work + life....

Circuit below originally taken from here:

2020-02-14 09_08_07-frequency-divider-circuit.png (816×403).png

You can cascade CD4017's if you want higher division numbers + you can ground other pins (such as pin 7 if you want F/3 or Pin 1 if you want F/5 etc).

For an encoder you will need 2 x CD4017's and two parallel circuits as the A+ and B+ encoder inputs will need to be equally divided.

Z (the index) does not need to be divided as that is triggered only once per revolution.

Re: AXBB-E encoder problem

PostPosted: Sat Feb 15, 2020 11:14 am
by Battwell
on my triac conversion i swapped the spindle motor for an ac servo )1kw 80 frame size fitted ok
encoder resolution was 2500 ppr (10000 counts)
i found i had to divide this by 8 in the drive to get proper rpm readings- up to 3600 rpm.
for the index pulse i couldnt get it to work off encoder so i used the original 1 pulse per rev pickup from the spindle direct.
all works great now.
i used step/direction for my spindle control so i could command as an axis.
homing spindle orientation for atc drive dog alignment drove me nuts. in the end i used a programmable drive with encoder backoff after drive homing. this is perfectly repeatable.
few videos of what i got working on youtube

Re: AXBB-E encoder problem

PostPosted: Sat Feb 15, 2020 11:22 am
by Battwell

Re: AXBB-E encoder problem

PostPosted: Sat Feb 15, 2020 12:33 pm
by drumsticksplinter
@Roberspark: No problem, I totally understand how busy life gets... Thanks so much for that circuit, that will work perfectly! So are you into making PCB's? I can probably do a half decent job with some proto board and jumpers etc, but a proper PCB would be neater ;)

@Battwell: Ahaa, its your machine vids that inspired me to try and achieve rigid tapping on the triac. Mine hasn't got the atc unfortunately, but that makes it easier to retrofit on the plus side. I've got a Denford Cyclone with 8 pos turret that was quite a headache to get working properly! Your machine works very well indeed, very capable now I imagine? I do like the idea of swapping out the DC spindle with an AC servo and drive, but at the minute cashflow is diverted elsewhere within the priorities list. I'll keep my eye out on the market places for a good deal however.... For now I was hoping to still use my original dc servo spindle and replace the drive for a DG4S-16035 maybe. I have used this setup on a Bridgeport for the XYZ servos, while the system was a pain to tune, the resulting setup had quite good response and minimal servo error.


Re: AXBB-E encoder problem

PostPosted: Sun Feb 16, 2020 7:56 am
by Robertspark
My denford orac lathe has a 750w servo installed with a 2:1 ratio belt drive so I could keep the maximum spindle rpm at 2000 as per denfords orac datasheet so the spindle bearings were still running at the original rating.

The 750w spindle was in part chosen as i wanted a motor that had a similar frame size to that which I was replacing. › cataloguePDF
Delta AC Servo Drive & Motor ASDA-A2 Series

PCBs, I use

And normally get them made in china and delivered in around a week via DHL... Shipping costs more than the PCBs

Very easy to use

Re: AXBB-E encoder problem

PostPosted: Sun Feb 16, 2020 9:22 am
by drumsticksplinter
Less than a tenner for 5 PCB's delivered?? that is pretty darn cheap and in around 1 week delivery?!? :)