OK, Y axis.

Fast running out of time now so this axis will have to be a mock up.

On the base of the mill is a standy proud block for the original nut to sit on and this stops anything fitting.

Block just visible under the circular part of the ball nut. At this point it's a quite thick casting, over 25mm.

If that block was reduced in thickness by 6mm it would allow a new nut block, bored to 28mm to be fitted. It would mean that both flats on the nut would have to be reduced to the nut diameter and rely on the two side holes for mounting on the nut block.

Then it just requires the same mounting as the X axis to be fitted to the front of the saddle.

The Z axis is a whole different ballgame.

I have seen all types of fittings, none in my book good enough. The side mounted screws cause the head to tilt to one side, same with the rear mounted. The only central mounted screws I have seen rely on a driven nut which makes the whole machine look top heavy and not thought out.

In the next couple of days I'll post a mock up of the head mounting with ball screw fitted and it looks the bizz.

Remember he who bodges wins

OK Z axis where all the work is.

The problem with this machine is lack of space, the motor takes up all the space on top of the head and getting a screw in is not good.

Head removed from the column and you can see where the rack fits just under the dummy screw.

Some people have moved the motor forward slightly with different pulleys / belts to allow the screw to be fastened at the rear and use a rotating ball nut which adds to the hight of the machine and looks a bit out of place.

Some like the kit from CNC Fusion in the States hang the screw off the side.

Not ideal as it forces the head to bind or tip with unequal forces.

So looking outside the box the problem is the motor is in the way, so, light bulb come on yet ? ?

Spin the motor 90 degrees and we have enough room to get the nut where we want it and hold a firms dance.

Nothing wrong with hanging the motor off the side, the X3 does it and many of these have been CNC'd in the past.

Two holes have to be re-drilled and tapped in the top and an angle bracket needs fitting to the side to support the rear and cover the exposed belt up. This can also double as a switch box later in the conversion.

Only thing to take into account is the weight will be more to the left than before, so ,

So at great personal expense a precision balance plate was machined up from a selected bit of Scrapbinium and the pivot bolt adjusted until the head hung in sideways balance which upon measurement to micron precision it was deemed that the nut needed to be off centre by 15mm.

So,

Belt it on the mill and waz a 28mm hole in it and an 18mm hole thru the bottom to allow the screw to poke thru.

Now if you are not particular you can mount the nut central which will save a bit of work as it breaks into two of the mounting holes and you have to deepen the counterbore and replace two screws with shorter ones.

Now once cleaned up and few holes drilled and tapped we get this.

At this point all the heavy work has been done and it's down to making thrust blocks, motor mounts and the rest of the general conversion work but it proves that the SX2P can have large [ and the cheapest model ] ballscrews fitted and still look like a small CNC machine and not a mackle up.

Edited By John Stevenson on 27/07/2016 21:54:12

Putting the screw 15mm off centre puts the head back into balance.

Does it make a difference if it's left central ?

TBH I have no idea, probably not but hey it's Wednesday and I'm in full metal jacket anally retentive mode, after Thursday everything normally goes down the crapper.

Good heaven’s Jason, don’t even joke about tack welding on the headboard or the Delectable Debs will throw a wobbly.
I have to go through a 21 point MOT to even be allowed upstairs.