My new 6040 improvement plan.

[PaisleyPCdoctor]

I think for now, I've went as far as I want to improve the wiring- mainly shielding, replacing cables and repositioning components.

My next area that I'm going to look at is the flexing of the unsupported x-axis 20mm linear bearing shafts. They can be flexed, tilting the spindle back and forth on the y axis direction. With decent pressure on top and bottom of spindle, I can deflect it by as much as 1.5mm (estimate) either way.

I knew about this design weakness BEFORE I purchased the mill, knowing that I may need to address it. No big deal- I'm having fun!

I have some ideas to mitigate the effect and later to help cure it.

[PaisleyPCdoctor]

The first and easiest (and free) change is to the Z-axis assembly.
On this model, a 35mm spacer block has been added on top of the top bearing, increasing the Z axis length/travel by 35mm.

The way it's been built, I can very easily remove it and instead, mount it under the bottom bearing. The entire Z axis will be moved 35mm closer to the bed, but I can recover exactly that much by raising my spindle in the mount. I couldn't do that before as my tools wouldn't reach.

This will shorten the length of the "see-saw" motion, so in effect, the spindle tool will not move as far.

I'll measure deflection properly both before and after the modification.
Here a picture of the spindle and the 35mm spacer block.

[m_c]

If you're going to do what I think you are, it won't have any effect on the X-axis deflection. The pivot point (the rails), and the spindle/tool, will still be in the exact same positions relative to each other.

It will make a difference to the Z deflection, however I'm not convinced it will be that great. The Z-axis, although using unsupported rails, is quite a compact and stiff assembly. Although changing things around will reduce the pivot distance between tool and Z-rails, I wouldn't expect it to flex that much anyway. Certainly not much in relation to the flex of the X-axis.

[PaisleyPCdoctor]

Thanks for the reply.

You are of course right, the pivot point and tool tip will be exactly the same distance so deflection will remain unchanged. However...

The mod will allow me to move the spindle (and tool tip) 35mm CLOSER to the pivot point (by raising the spindle motor 35mm in its mounts.

I'll work out the deflection angle and I'll be able to exactly predict (using distance to pivot point and angle) the deflection distance before and after.

I couldn't raise spindle any further without the mod because of tool reach.

[PaisleyPCdoctor]

Although... on thinking about it, I'm really just lowering the spindle one way just to return it to the same position another way.

My head hurts. Lol.

I'll need to do some more thinking. Good catch! Appreciated!

[Doddy]

My next area that I'm going to look at is the flexing of the unsupported x-axis 20mm linear bearing shafts.

Give us a pic.

[PaisleyPCdoctor]

Here are pictures of the y axis assembly. Excessive flex in x axis direction.

[PaisleyPCdoctor]

Okay- some interesting results with dial gauge.

In middle of x axis (must be worst deflection zone), I can deflect the machine up or down a staggering 1.3mm! (worried).

I then thought- to prove the theory- deflection must be better or even minimal at either end of X-axis...

Its better, but still 1mm. So looks like its actually entire gantry flexing. Opens new possibilities.

Looking at Y-axis bearings, I previously closed the allen key sdjuster until it stopped, no further. I gave all 4 side screws a wee tweak tighter and deflection has been reduced to 0.4mm at ends and 1.1mm middle of Y axis.

I think theres another adjuster on top of bearing. I'll need to dismantle bed to get to it.

SIGH!

[magicniner]

Go on mate, explain to me just how good they are, and how you'll fix yours :D

Still incomprehensible to you? :D

[PaisleyPCdoctor]

Still incomprehensible to you? :D

Thanks for that constructive advice, I'll try that!

Now where's that middle finger emoji gone?