mounting profile rail - Hiwin Manual vs. typical approach

[dsc]

Gents,

thank you for the replies.

Looking at the manual, you can do without having a datum edge for the rails (ie. use the edge of the plate as datum), but the carriages still need a 'lip' and side bolts to secure in place.

Regards,
dsc.

[AdCNC]

This is how i mount my rails..

[dsc]

Few things I still don't get:

1. mounting against an edge assumes the edge is perfect, otherwise things go wonky. Surely there will be errors when machining the edge every single time.

2. with no side plates pressing the rail against the edge, I don't really see the point of the edge. Surely if the rail moves under load, it will move anyway. Sure the edge will spot the movement towards the edge, but the other way is still unsupported

3. the manual suggests simply bolting the rails down (ie. no edges) if there's no side space, but shows the carriages supported and mounted against edges. Again point 1 comes into play.

Regards,
dsc.

[Shinobiwan]

1. mounting against an edge assumes the edge is perfect, otherwise things go wonky. Surely there will be errors when machining the edge every single time.

Its for registration . A machined reference edge to butt up against makes getting your rails level far easier than without.

2. with no side plates pressing the rail against the edge, I don't really see the point of the edge. Surely if the rail moves under load, it will move anyway. Sure the edge will spot the movement towards the edge, but the other way is still unsupported

I'd love to see you bend a hardened steel rail that's fixed every 80mm lol Rails bending is the least of your worries when you constructing your machine out of only aluminium or steel box section. It ain't the weak link.

[AdCNC]

1. It all depends on what machine you use to mill the datum, so I'm fortunate enough to have a VMC at hand. (when i use this method i get a parallelism of 2um)

2. That would be true if you could exert a serious amount of side force to dislodge the rails, but in this instances its highly unlikely to happen.

3. Its tried and tested and works fine; all depends on the application and I think it would be necessary for the large machines that are doing heavy milling or moving heavy loads.

[dsc]

Its for registration . A machined reference edge to butt up against makes getting your rails level far easier than without.

Ah but what if the edges which are use to butt up against are not parallel? It does indeed make assembly quicker, but the assumption is that whatever is used to mill the edges is near perfect.

I'd love to see you bend a hardened steel rail that's fixed every 80mm lol

Not planning to:) I was simply referring to m_c post regarding shock loads and possible movement of the rails if not fixed against an edge. Surely this will not be a problem when milling MDF:)

1. It all depends on what machine you use to mill the datum, so I'm fortunate enough to have a VMC at hand. (when i use this method i get a parallelism of 2um)

Lucky b*stard!;)

The reason for asking is purely to understand where the edge idea comes from, I do like the ease of assembly, when butting the rails against the premachined edges, but worried about parallelism.

Ad, how do you mount the carriages? similar approach against an edge with a side push plate via a block bolt?

Regards,
dsc.

[GTJim]

So if your a DIYer building a router out of box section what method should be used.