Retrofitting a Shizuoka AN-S 3 axis knee mill

02 May 2021 22:13 #207686 by Muzzer
I have a Shizuoka AN-SB, which is almost identical to an AN-S. The main difference is that it has 2 fixed spindle ratios (direct and something like 9:1 geared reduction) ie no varispeed pulley system. It came with a motor that is designed to operate over a wide speed range under VFD control. It also has a fixed head (no tilt or ram) and the X ballscrew is stationary, rather than move with the table. Apart from that it's identical.

My machine originally had a Micon controller with a step/dir "positioner" board that generated +/-10V signals for the Parker DC servo drives. The motors are 160V DC brushed SEM motors. They have a 1000PPR Heidenhain clone encoder and a tacho. Rather than butcher the machine to fit modern AC servos, I fitted the DG4S16045 drives from CNCdrive
These just connect up to the motors and work fine. Being digital, they only need the encoder - the tacho doesn't generate any info the drive can't derive from the encoder signal.

I have to admit I wimped out and fitted a Centroid Acorn system on this machine, as I realised I wasn't up to the full trial by LinuxCNC at that stage. So although I can suggest hardware to run your motors, I don't have anything like INI and HAL files, before you ask!

It was a while ago but if you'd like to see some pics of the machine and its journey to full functionality, I kept a blog which has been useful for my own reference. The process started here and has since morphed into an "anything I do in the workshop" event. And over the last year, perhaps my sanity has suffered but I make no excuses.
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17 Sep 2021 11:04 #220877 by FortheShiz
How did those drives perfrom? I am looking to retrofit a Shizuoka AN-S and those were the drIves I have been looking into. My only real concern was them not being able to reach the peak amperage the servos can. From my understanding that only really affects acceleration but I would love to hear more from someone who actually used those drives on this machine about the performance they managed to get.

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17 Sep 2021 11:25 - 17 Sep 2021 11:26 #220881 by Muzzer
Does your machine have DC brushed motors (likely SEM or clones)? Most of the US machines seemed to use large steppers, so my machine appeared to be a little unusual. I'm in the UK and my machine system was installed by Matchmaker. The base machines were shipped from Japan for CNC use but came without electronics, hence the various different control systems found on them.

The cncdrives DG4S drives have been absolutely fine. I've never had an issue with them and they fly long with modern HSM toolpaths in a way the original system could never have performed. Reusing the original motors and encoders avoided mechanical modifications and the original components used were top notch (HSK mostly). I did crash a couple of times in the early days and the ballscrews survived, which is perhaps a reason not to have stupid big motors. If you work out what the stall torque would do in terms of linear forces at the table, it's pretty big and dwarves any realistic transient inertial loads.

You can see some machining ops on my YT channel to get an idea what it does, although most are fairly unexciting.

As a power electronics product developer (including motor drives) and having done a teardown myself, I can tell you that the cncdrives (and DMM Tech etc) servo drives are not in the "industrial quality" league where you'd find the likes of Yaskawa etc but they are pretty good value for amateur / hobby users.
Last edit: 17 Sep 2021 11:26 by Muzzer.

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17 Sep 2021 13:07 #220886 by FortheShiz
I will definitely check out the youtube this evening when I get the chance! My machine does have DC servo motors I will attach a picture of one of the motor tags. You don't happen to have any documents on the milling machine do you? My machine came pretty well disassembled as far as electronics go and it would much easier to identify what's what with some guidance. Also out of curiosity do you have any links or idea of the price difference if I wanted to step up to a more industrial driver? I don't I will want to spend the money but is nice to know. Thanks so much for your time it is exciting to find someone with real world experience with a nearly identical machine!

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17 Sep 2021 18:14 - 17 Sep 2021 18:19 #220939 by Muzzer
I've got the full parts list which also shows section views of the head and all the other component parts. The "manual" itself doesn't tell you anything of much use but if you are dismantling / rebuilding your machine, the parts lis is a great help. I pretty much rebuilt the entire machine apart from removing the table and knee due to the sheer weight of the things. Luckily you can remove most of the ballscrews and gibs etc without having to do that.

Look at the bottom of Yeltrow's page (Matt Wortley, geddit?) and you can see a link to his Google Drive where there is a scanned PDF copy of my manual. It's a bit ropey but that's not the scanning at fault so much as the state of the pages themselves after almost 40 years. However, the drawings and parts are legible enough to be useful.

You can see quite a bit of the work I did on my machine at the start of my blog. Although mine's an AN-SB and looks different, the guts are 90% the same as an AN-S.

I've also got a manual for the optional (Fadal) ATC - does your have one of those?

A new Yaskawa Sigma 7 servo drive is about $1500 - 2000 - plus the motor itself! You can buy used examples for a lot less eg from one of the Korean machine breakers at about the same cost as a DMM or Lichuan.
Last edit: 17 Sep 2021 18:19 by Muzzer.

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17 Sep 2021 18:24 #220941 by Muzzer
If you can't access that drive without Matt's permission, PM me for a direct copy - it's 6MB.

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17 Sep 2021 20:50 #220946 by FortheShiz
Thank you so much for the link! Looks like a treasure trove of stuff in yeltrows drive and I didn't have a problem accessing it from there!

I am hoping to get my machine up and running before any major teardown and rebuilding. I just need to see it moving before I can commit to all of that but if there is anything you suggest is smart to look into or work on now I'd love to hear it. This is my first milling machine so I am hoping to ride the wave of DIYers that came before me to get through this one and learn as much as I can.

I do not have an ATC on my machine. I tried to close a deal recently on a Hurco BMC-20 at near scrap price because it would have been nice to have a machine with an ATC but it fell through unfortunately.

Looks like I will just be sticking with the servo drives from cncdrive. Do you like your acorn controls? I have been planning to use Mesa cards and a linux pc with linux cnc but centroid is actually a fairly local company to me and I had looked into their more plug and play style control solutions.

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18 Sep 2021 12:41 - 18 Sep 2021 12:42 #220995 by Muzzer
I would get it up and running first as you say, then you can figure out what needs doing to it. You can't easily assess what you've got until it's actually moving. I changed all the thrust and spindle bearings on mine, as they'd clearly got wet at some point. Luckily they are fairly standard sizes, so you can buy good quality replacements without breaking the bank.

I also looked closely at the backlash on each of the axes. When new, Shizuoka claimed you could achieve 10um or so, so you can be fairly certain that 20-30um would have been very good. In practice, I'd struggle to get close to that. I have to snigger when I hear people boasting about "holding tenths".  You also need to check the gibs which play a part in backlash, although they are actually pretty tricky to set up when there are no hand wheels!

If you aren't very confident with Linux and haven't got a good grasp of LinuxCNC, then a system like Centroid Acorn or UCCNC might be a pragmatic solution for now. The Acorn has been very easy to set up and use, with a very enthusiastic and supportive forum, backed up by the company itself. Total cost for an Acorn board including the probing licence is about $700 - plus the motors, drives etc of course. Now that I've done a couple of milling machine conversions, I have almost managed to implement LinuxCNC on my lathe after several years lurking here and getting my hands dirty with the other machines - the knowledge and support on this forum is critical but you still need to be prepared to do a lot of learning. 
Last edit: 18 Sep 2021 12:42 by Muzzer.
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18 Sep 2021 20:49 #221036 by FortheShiz
I think I am pretty set on trying to go the Linuxcnc route. Do you have any recommendations as far as what Mesa cards I should use? There are so many and I honestly don't know what the differences are. Maybe there is a guide somewhere to identifying which cards best suit my needs? Like what is the difference between a 7I76 and 7I76D or 7I77? Any help is greatly appreciated!

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18 Sep 2021 21:26 #221037 by Muzzer
I'm really not the expert on this subject but a 7i76 does step/dir output whereas a 7i77 does +/-10 (ie analogue) outputs. They both also do spindle control, spindle encoder and a fair bit of configurable IO. You can do a lot with one of these.

The 7i76e connects to the PC by ethernet, whereas the 7i76D (like mine) requires a 5i25 inside the PC, so if I bought one nowadays, I'd go for the -e version. If you want additional IO such as encoders, you'd need further boards. So for my lathe I have a 7i85 to interface linear encoders for position feedback. In my case, the 7i85 connects to the second channel of my 5i25 so I expect you'd need a different board if you were using ethernet.

If you can list how many axes, motors, encoders, switches etc you plan to use, you should be able to get some guidance here from someone who knows what they are talking about, to help identify the best combination.

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