Fehlmann Picomax 50 CNC conversion/refurb

[Agathon]

Thanks for the welcome(s). I've already done a great deal of the groundwork to get this thing up and running, so it shouldn't be too difficult to get it actually doing some work.

I spent this afternoon looking at the ways and ball-screws of the X-Y table and after a little adjustment it's working much better. This thing is, like most Swiss stuff, beautifully made and really nice quality components have been used including dual-ball-nut screws allowing the micro-adjustment of the pre-load. I'm going to stick to the 2000mm/min rapid as this is reliable.

I'm running from the parallel port of a 10 year old Dell PC - two parallel ports actually (in anticipation of the many inputs required for the extra limit switches). I really like your suggestion of using LinuxCNC. I've only been using Mach3 up to now as I have a friend who's been building small CNC machines for the last 15 years and is very knowledgeable about Mach3. However, I've always used a Mac and am not overly keen on the MS operating systems so switching to another Unix based OS appeals to me.

Would I be better off using a motion controller rather than the parallel ports?

[Clive S]

Using a motion controller is night and day difference. I don't want to get into the Mach3 V Lcnc I use both. But If you say do a feed hold in Mach3 and it is in a cycle it won't stop until the cycle is finished with Lcnc it will stop immediately.

I you decide on the Lcnc route with steppers you would need a Mesa 5i25 or 6i25 (pci or picx) and a 7i76 bob that would give you at least 34 input and output, 5 axis 2 encoders. spindle control, 24V inputs differential signaling etc.

edit: You could also just use a 7i76e if you want an ethernet version without the 5i25 etc

Lcnc is a steep learning curve but it is a rock solid system. It will do what ever you want.

I think you said you had 4mm screw if so I don't think you can go much faster rapids with a nema34 I think the max motor speed would be 500-800 rpm.

[Agathon]

Using a motion controller is night and day difference. I don't want to get into the Mach3 V Lcnc I use both. But If you say do a feed hold in Mach3 and it is in a cycle it won't stop until the cycle is finished with Lcnc it will stop immediately.

I you decide on the Lcnc route with steppers you would need a Mesa 5i25 or 6i25 (pci or picx) and a 7i76 bob that would give you at least 34 input and output, 5 axis 2 encoders. spindle control, 24V inputs differential signaling etc.

Lcnc is a steep learning curve but it is a rock solid system. It will do what ever you want.

I think you said you had 4mm screw if so I don't think you can go much faster rapids with a nema34 I think the max motor speed would be 500-800 rpm.

Thanks once more Clive. Many things to look into and think about. I'm happy with the 2000mm/min rapids, I'm still somewhat incredulous that those old Superior steppers could run any faster.

Sorry about the cock-up with the video editing btw. Don't know how I managed to get two copies in one video.

[Agathon]

Here's the latest on the Fehlmann table. Sorry that it's a bit long - will try and be brief in future.



Making good progress on other stuff and will post more soon - watch this space!

[Clive S]

Coming along nicely I enjoyed the vid. Re the Nema34 they might run better with a higher voltage that 70v I think you can get 230v drives for them.

[Agathon]

Coming along nicely I enjoyed the vid. Re the Nema34 they might run better with a higher voltage that 70v I think you can get 230v drives for them.

Hi Clive, just come in from the workshop after more fun. More vids tomorrow...

Do you think it sounds like they're missing steps or is it a step-generation/processing issue? Difficult to answer without test I suppose. The quill has always made the same noise from time to time. I've was driving it with one of those crappy HY-DIV268 things and when running a repeating cycle of ten up an down movements it always returned to the same place with better than 0.01mm variation - which I was very impressed with.

I think after going to the effort of buying the highly recommended AM882 drivers, in the short term at least, I'd rather replace the motors - they only cost £27 for the pair including delivery so I can afford to replace them!

In the longer term I still favour going all-out for servos. Those Teknic Clearpath things look very impressive. If confidence in Sterling would just improve a little I'd be tempted to order.

[Agathon]

Motor operation and control issues: