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Author Topic: Conect 121 cnc retrofit  (Read 18243 times)

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Offline Hood

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Re: Conect 121 cnc retrofit
« Reply #20 on: February 10, 2015, 05:59:51 AM »
Case of try and see Russ, sure I had issues on the big lathe with a small disc, increased the dia and problem gone but that was a long time ago as when I went to the SmoothStepper I just used the motors encoder..


Sooty1986
Probably other ones on RS that would do the same job, just I got the part number from a guy years ago and it worked great for me on all the machines I used it on, even used it as limits on some machines.

Cant really recommend any places in the UK for BOBs as I have only ever used PMDX and CNC Building Blocks BOBS, the latter no longer being made.
Nowadays I use CSMIO controllers so no need for BOBs, sadlly their IP-M controller does not do Lathe threading or it would have been an excellent choice. Looks a bit more expensive at first but when you see that it has no need for a BOB, has spindle control and also analogue I/O for feed override etc, then it suddenly looks a lot cheaper.

Hood

Offline mc

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Re: Conect 121 cnc retrofit
« Reply #21 on: February 10, 2015, 07:40:51 AM »
From my archive -
Quote
Z-Axis
Motor
Label details
Astrosym L281
Volts – 3
Deg – 1.8
Amps – 1.7
Ohms – 1.8

15kg cm (1.47Nm) (Nema 34) (google suggests detent torque of 1kg cm)

Ballscrew
12x4

X-Axis
Motor
Label details
Astrosym L163
Volts – 5
Deg – 1.8
Amps – 1.0
Ohms – 5

69Ncm (0.69Nm) Nema23 (wired bi-polar)

Ballscrew
8x2.5mm

However mine was a newer version, and there were a few differences from what Hood had posted about his.

I managed to use the original spindle slot sensor, which was a Sharp 1A05, with the SmoothStepper I used.

Connecting the KB drive will depend more on your BOB. Provided the BOB has an isolated 0-10V output section, then it's fairly straightforward, you just have to make sure you feed the 0-10V with an isolated supply. DC-DC isolated converters are only a few pound, but some BOBs come with them already fitted (I'm sure PMDX does). The main thing to remember is the control voltage on KBIC style drives is at a floating voltage, so if you connect it directly to your electronics supply, something is going to release magic smoke, hence the requirement for things being isolated.
Re: Conect 121 cnc retrofit
« Reply #22 on: February 10, 2015, 03:47:11 PM »
Hmm, thanks for the info on the motor and the kb controller mc.  me thinks I will leave that for now, I can get by for a while without speed control. I can get the box with the pot on it and set the speed with that.  as long as I can get a spindle a lot sensor to work I will be happy.

Don't suppose you have the wiring diagram for the slot sensor you used mc?  There may be a chance the wiring is similar.

Question, does the thrust bearing on the motor ends do anything?  I ought the force would be put on the small split pins on the coupler before getting to the thrust bearing?

 
Always learning, it's never ending!

Offline Hood

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Re: Conect 121 cnc retrofit
« Reply #23 on: February 10, 2015, 04:29:00 PM »
The thrust bearing is to stop backlash, the ballscrew is held captive by the motors bearing one way and the thrust bearing the other. The thrust bearing is held tight against the motors casing by the alu coupler.
As said it is not really the ideal situation as the motors bearing should not really be used in such a way but with the loads being small it is probably fine.

Hood

Offline mc

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Re: Conect 121 cnc retrofit
« Reply #24 on: February 10, 2015, 04:29:38 PM »
I think I found the datasheet via google. I've not got it saved in amongst my 121 lathe stuff, so you'll have to do your own searching. It's usually worth a quick google of anything written on the sensor, as datasheets for most things are online somewhere.

I can't comment on the thrust bearing setup, as IIRC that was one area where mine differed, but I think all the lathes used quite a crude thrust bearing setup.

If it's any help, all the photos of my lathe can be found at https://www.flickr.com/photos/mc_mtb/sets/72157625154378941/
Re: Conect 121 cnc retrofit
« Reply #25 on: February 11, 2015, 08:09:00 AM »
Thanks for the info!  I have ordered the parts from rs to make up a couple of spindle sensors.  Not got much further with the drivers and BOB as the company i was looking at (Zappautomation)  don't have the items i wanted in stock.

Will be using digital steppers on this build as they seem much quieter and smoother.  I think the majority of parts will be coming from CNC4YOU in the uk, at least for the first build.  I want to try diffrent suppliers before i convert my orac later on.

Another question guys.....   When looking at limit switches i have noticed they are rated at 250v ac max.  Do these work just fine with the 5v dc setup?
Always learning, it's never ending!
Conect 121 cnc retrofit
« Reply #26 on: February 11, 2015, 05:31:58 PM »
Yes!


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Re: Conect 121 cnc retrofit
« Reply #27 on: February 12, 2015, 06:21:47 AM »
Thanks!
Always learning, it's never ending!
Re: Conect 121 cnc retrofit
« Reply #28 on: February 14, 2015, 02:22:52 PM »
The parts are here and the wiring is underway!  question, is it safe to have the cnc electronics in the Same case as the pc electronics ?I have a huge pc tower which will take it all.
Always learning, it's never ending!

Offline Hood

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Re: Conect 121 cnc retrofit
« Reply #29 on: February 16, 2015, 03:14:14 AM »
It should be fine as long as you have the wiring properly shielded and grounded.
Hood