Fehlmann Picomax 50 CNC conversion/refurb

[Robin Hewitt]

You are being very vague, is this sprung or a simple crush?

[Agathon]

You are being very vague, is this sprung or a simple crush?

Crush.

[Robin Hewitt]

It was a bit of a bodge springing mine, I added a spacer and 2 Belleville washers. Well 6 spacers and 12 washers to do all the bearings and nuts. But the reward was out of all proportion to the effort.

[Agathon]

It was a bit of a bodge springing mine, I added a spacer and 2 Belleville washers. Well 6 spacers and 12 washers to do all the bearings and nuts. But the reward was out of all proportion to the effort.

So, if I'm interpreting that correctly, you have a double ball-nut set-up like my machine?

I could do something like this although it would mean making a new retaining flange. I have to say that apart from grinding spindles, I'm not a fan of spring-loaded solutions. I'm also not convinced that backlash of 0.01 is much of an issue. My conventional mill has about 0.25 backlash and it's only a problem with heavy climb-milling or slot milling and then it can be overcome by reducing the feed rate and the depth of cut. Mind you the table and slide alone must way 200kg - mass helps, as do well adjusted gibs.

I meant to have asked what the rest of you mill consists of Robin - got any pics?

[Robin Hewitt]

I don't have a recent pic, here's an old one...

[Agathon]

I don't have a recent pic, here's an old one...

Very neat, especially the Z axis. Wouldn't mind seeing some details of this as I'm sure I'm going to have to go down this route eventually.

What sort of backlash have you achieved on the x and y?

[Robin Hewitt]

There's a build log from many years ago, I will try and link it...
http://www.mycncuk.com/threads/651-W...ht=Warco+Major
I fitted zero backlash double nuts, big disappointment, so I sprung them and it was like magic.
The springs mean that I have no backlash up to 1/4 ton but if I ever pass that loading presumably everything will go horribly wrong.
I do get some sideways slop in the quill if I forget to pack it out with thick, icky grease. Open to suggestions.

[Agathon]

Very neat, especially the Z axis. Wouldn't mind seeing some details of this as I'm sure I'm going to have to go down this route eventually.

What sort of backlash have you achieved on the x and y?

I meant to have complimented you on the really super job you've done on the casings for the drives - very professional.