Poorly N sick Fadal 15 VMC Will live again!

[JAZZCNC]

A quick walk around today showing current state.

[Jonathan]

Sounds like you've decided already - your new years resolution is going to be learning to use LinuxCNC.

In theory the position control loop for your analogue drive could be put on a cheap microcontroller that accepts a step/dir input and effectively converts it to analogue. I wouldn't be surprised if someone's made a widget to do that. I don't think it would make anything easier though, as although you'd save needing to use the mesa cards (as may get away with just parallel ports), it just makes the tuning problem more difficult as you loose the nice interface that LinuxCNC provides (halscope).

[JAZZCNC]

Sounds like you've decided already - your new years resolution is going to be learning to use LinuxCNC.

Not 100% decided and still chewing on it but yes it's looking very much like LinuxCNC is the front runner. ( Thou John S will be turning in his grave calling me all the bastards under the sun ...Lol)

[m_c]

A KFlop witih a Kanalog can be made to work with resolvers, but it can be hit or miss, as it depends on how the resolvers respond, and how well they can be tuned. TomK certainly doesn't recommend it, but I am aware of at least one person who has done it, as they had nothing to lose from trying.

However as Jonathan has mentioned, I do think I have come across an interface board for resolvers, but I can't remember any details.


I think personally, I'd strip the 4th axis down to see if you can fit a replacement motor without having to modify the rotab itself, that way if you do sell it, you can put it back to how it was.

[m.marino]

A yes learning curves. Wonderful thing and Yes, John S would be cussing you out Jazz. Jonathan, you volunteering to aid in the mission of the Linux CNC side of things? These days for me CNC is mostly design as current location doesn't allow me to run my gantry router due to the locals have very very sticky fingers and crow bars. Though the learning curve is still fun as working with scanning as part of work and with both OpenScan and FabScan Pi (I hate software programming).

Looks like a very in depth project Jazz. Of my two cents I would try to keep the 4th axis if possible.

[JAZZCNC]

A KFlop witih a Kanalog can be made to work with resolvers, but it can be hit or miss, as it depends on how the resolvers respond, and how well they can be tuned. TomK certainly doesn't recommend it, but I am aware of at least one person who has done it, as they had nothing to lose from trying..

I couldn't see anything on the website that mentioned resolvers but didn't ask either, just took it that didn't accept them.

I think personally, I'd strip the 4th axis down to see if you can fit a replacement motor without having to modify the rotab itself, that way if you do sell it, you can put it back to how it was.

Yes but it's not so easy with the way it's built. The cover is designed for round type motor with no room for Encoder and Motor wire connecters modern square type motors tend to have fitted.
Also Iike the DC motors that are fitted I suspect the shaft size will be smaller than AC servo shafts so the coupler will need to be machined etc.

That said I will be taking it apart to have a look.

[JAZZCNC]

Lee if your reading this I can't upload Pics anymore is there a limit.? I have tried deleting some pics from old posts.?

[Jonathan]

A KFlop witih a Kanalog can be made to work with resolvers, but it can be hit or miss, as it depends on how the resolvers respond, and how well they can be tuned.

Most resolvers take the same excitation frequency (10kHz), but they often have different transformation ratios. If you don't have a scope to check, or know what voltage levels are required then it would end up being hit and miss.

Jonathan, you volunteering to aid in the mission of the Linux CNC side of things?

I'll keep an eye on this thread for any questions.

However as Jonathan has mentioned, I do think I have come across an interface board for resolvers, but I can't remember any details.

That not quite what I was thinking, but is probably a better idea. I once programmed a micro-controller to convert a digital encoder (BiSS) into analogue signals to match with a motor drive that wouldn't accept much else. Going the other way round is actually easier.

Dean, would it solve problems if you had a little board that took resolver signals and converted them to e.g. quadrature?

[m_c]

The resolver information for Dynomotion can be found at https://dynomotion.com/Help/Resolver/Resolver.htm
That example uses their old obsolete KMotion board, but the same can still be done using a KFlop + Kanalog.
If you did want to give it a try, I do have a spare KFlop + Kanalog board you could borrow.

I did do a quick bit googling, and this is the only active product I've found so far - http://addi-data.com/products/resolv...tal-converter/

RS do have an entire section of Resolver to Digital chips, but even the bare chips have some interesting price tags, so I'd imagine that converter will be at least a couple hundred euros, if not a lot more!

[JAZZCNC]

Dean, would it solve problems if you had a little board that took resolver signals and converted them to e.g. quadrature?

If I was doing this just for my self to keep then yes I'd probably take a route something along those lines or whatever got the job done. However, this has to be done with selling the machine in mind. So I wouldn't want any bespoke boards etc which would cause a buyer hassles in the future, because the hassles will just rebound back to me.

Saving money isn't a priority but with that said I do need to keep an eye on the budget because it can easily run away. This why industrial controllers are off the table because the machine while still very capable is still 25yrs old with a much reduced resale value and it's highly unlikely to ever see use in an industrial setting again so we cannot command the prices asked in Industry. Any new owner is most probably going to be a serious Hobby or small business user and they won't pay industry prices.

The main priority is ending up with a Reliable machine that uses off the shelf modern components, along with a controller that works and has a decent support network that Hobby or small business person can access freely if required.
Linux CNC/Mesa are proven with massive following and support so I've no concern in this department. Likewise so Is Kflop and Centroid and again wouldn't hesitate to use either of these.
However, LinuxCNC/Mesa are favorites because of the budget and the fact the others offer nothing more but cost more. All of them are new to me at this level with Servo's etc so whichever there is a learning curve to deal with. But I like the challenge.!!