Advice on Mammoth CNC Router Build - Steel Framed - 2440mm x 1220mm cutting area!

**Boyan Silyavski** · 06-01-2014

On your last picture it seems you were thinking mainly of cutting aluminum

. If you continue with this design, take care that the rails on the gantry should be maximum low, near towards the table and as round rails don't like that position nor milling aluminum something has to change there, for starters -square rails.

**Wejjmeister** · 07-01-2014

Originally Posted by silyavski

On your last picture it seems you were thinking mainly of cutting aluminum

. If you continue with this design, take care that the rails on the gantry should be maximum low, near towards the table and as round rails don't like that position nor milling aluminum something has to change there, for starters -square rails.

Would it be better to place the rails (HiWins) on the underside of the gantry then? I can incorporate this into my changes too if so? The issue then will be travel...hmm!!

**Lee Roberts** · 07-01-2014

Originally Posted by Wejjmeister

Would it be better to place the rails (HiWins) on the underside of the gantry then? I can incorporate this into my changes too if so? The issue then will be travel...hmm!!

Hi Wejjmeister,

The ideal rail arrangement for these types of rail (supported round) is like what you see in the first pic below on the Y Axis (machine bed), so what your looking for is the base/bottom face of each rail to be facing each other. This dose make it harder when you come to true the rails to each other and get them on the same plane's but it is feasible.

This is true for any axis you use this type of rail for, so if you look at pic two below i'm selected in green the faces I think you should use to mount your rails. If you mount them on those faces, the other nock on effect is that you are also bringing the gantry closer to the bed.

.Me

**Jonathan** · 07-01-2014

Originally Posted by Lee Roberts

The ideal rail arrangement for these types of rail (supported round) is like what you see in the first pic below on the Y Axis (machine bed), so what your looking for is the base/bottom face of each rail to be facing each other.

Except, as specified in post #8, he's not using supported round rails. Most Hiwin (or similar) type rails have equal load ratings in both directions, so just mount them in the way you think is easiest. How they are orientated in the current drawing is not a bad idea as you can use epoxy to level all the surfaces, but there are some disadvantages.

**Lee Roberts** · 07-01-2014

Originally Posted by Jonathan

Except, as specified in post #8, he's not using supported round rails. Most Hiwin (or similar) type rails have equal load ratings in both directions, so just mount them in the way you think is easiest. How they are orientated in the current drawing is not a bad idea as you can use epoxy to level all the surfaces, but there are some disadvantages.

Bugger missed that post, o well its their for everyone else then lol, thanks Jonathan.

So, are you going to go as far as epoxy Wejj or just shim the rails when the time comes?

.Me