Schaublin 125-CNC retrofit.

great to see yout progress!
Now that everything is disassembled and clean the fun part of the retrofitt can begin

I hope people do not have too much expection of this going fast. There is still a lot of work in the LinuxCNC retrofit which I need to do. All that wiring work takes ages.

I thin you make good progress.
My first Retrofit took me roughly four years. The second amount 9 months. It always needs more time than one thinks.

It has become my sunday ritual.. Watch the latest RotarySMP video..

Keep them coming!

sam

Mark,

Nice vid, thanks for posting.

[note - forgive me if I'm covering something you already know]

Noted a number of comments in the vid about 'filtering' the VFD to protect the motor, but none of them appeared to identify exactly what you might need/want.

What you're looking for is a load reactor (pic below).  This goes between the VFD and the motor and smooths out the harmonics produced by the VFD as it does its AC to DC to AC magic.  Also reduces motor heating (helps quite a bit if you're operating a "non-VFD-rated" motor with a VFD).

If you have a decent VFD with a load reactor, you should have no issues running that motor.

They are fairly expensive new, but ebay is littered with them if you search for 'line reactor.'  A line reactor is exactly the same thing, but is installed between the VFD and the incoming line voltage where it reduces noise than can be back-fed in to the mains wiring.

Assuming you're at 380VAC-3P and the motor is 3kw (from the vid), you should be able to find a 10a 600V line reactor pretty easily.

Ebay Austria (your location, no?) has 34 hits searching for 'line reactor' (in English), and plenty in the 7A-15A range.  Ebay Germany has around 40.

Looks like Elau, Allen-Bradley, and Siemens are the top brands available.

Pro Tip - these things can be mislabeled as 'transformers'.  They look similar to transformers - big coil of copper thing - to the uninitiated.  So you might find one for scrap value if you've got a local machinery dealer/scrapper.

Something else to consider while you're deciding if you keep the varidrive... how much spindle torque do you need? You can estimate the required torque for anticipated cuts with a decent Feeds & Speeds program, and I bet you won't need as much as you think.

I suspect the massive gear reduction on that lathe was mostly to slow down the surface speed; the increased torque was a nice by-product.  Coated carbide tooling wasn't as universal when it was built, and a large part with HSS tools would need the lower surface speed.

Keeping the vari-drive would simplify things mechanically right now... until something goes wrong or breaks or you have to replace that belt.

Food for thought.

Cheers,
Ralph

 

Wow, you answered all my thoughts about, what are these dL/dT filters, or whatever they are talking about. Thanks a lot Ralph.

Should the load reactor get mounted close to the VFD or close to the motor?

At this stage it is easier to just plop the motor back in and use it, as the Variator is there, whereas making a set of poly-Vee pulleys might be beyond the capacity of the Boley. It will be interesting whether i can come up with a sensible control logic for VFD + CVT + Back gear. If I only do VFD + Back gear, guys like Andy have already written the comp.
Mark

As close to the VFD as you can get.

Diagram taken from my Hitachi manual.