Very fine thread M10 grub screws

**Voicecoil** · 19-02-2019

I was thinking of these for a situation where you're clamping down on the axis of the adjuster (e.g. like the Z-axis alignment on @routercnc's machine, obviously clamping down a number of M8's working on a little M4 adjuster might shift it.

**mekanik** · 20-02-2019

https://www.spaldingfasteners.co.uk/thread-data/
There's an M10 superfine in that list
Regards
Mike

**Snapper** · 21-02-2019

You can’t beat a Thor hammer for getting things square.

**John McNamara** · 22-02-2019

Hi

If you are going to set a machine up using jack screws the frame members will end up only touching at a few points, while this may achieve good frame geometry and depending on the fasteners and jack screws used if they are big enough, sufficient static load strength of the frame.

However machines with rotating components and moving frame elements will also impose dynamic loads and vibration, vibration in particular has to be damped out by the mass of the machine and maybe vibration damping elements.

Any fixed joint gaps left after jacking machine members into alignment need to be filled. Metal filled epoxy is used my many modern machine builders to do this.

Eberhard Bambergs excellent paper on Precision machine design, and in particular vibration is well worth reading. Link Below.

http://www.mech.utah.edu/~bamberg/re...e%20Design.pdf

Regards
John

**Voicecoil** · 22-02-2019

Thanks for the link to that very interesting paper John, it confirms many design principles I would love to implement - oh that someone would gift me full copies of ANSYS and Solidworks... and food & rent for 6 months whilst I learned to use them to their full advantage

The idea of filling adjustment gaps had crossed my mind - more from the rigidity aspect than damping (I will be doing the damping elsewhere), but it raised the question as to what do you do if something moves?? Lots of pretty rigid machines (much more rigid that the likes of most forum members would ever make) have tramming adjustments, and I've learned over the years to always check (and if necessary adjust) machine alignment regularly if you want good cuts. With the sort of machines we're making having a lot (probably too many) bolted joints there's a lot of scope for things to drift when pushed hard.

**John McNamara** · 23-02-2019

Machines that have to be "Trammed" can have built in sliding or rotating adjustment, they have finely finished surfaces held together by clamping screws. They only work in one plane there is no gap after they have been tightly clamped together. A Bridgeport milling machine head is set up this way.
Most lathes have a tail stock that can be adjusted in the same way. again no gaps after tightening.

Here is another interesting link:
https://www.google.com/search?q=mogl...w=1155&bih=579

Moglice is a mix of metal powders in epoxy, it is rather expensive.

Or make your own by mixing iron powder and 24 hour Araldite. Add the powder to the epoxy and stir adding more until you get a stiff paste. Fine for grouting fixed joints.

Regards
John