Warco Major CNC build log

[BillTodd]

Did you use a parallel or similar between the bed and the DTI? It helps to smooth out bed irregularities.

My base was shimmed from new. The shims are brass coloured and less than 1 thou" (fitted near the bolts).

BTW Don't get too carried away - the head on these things can be flexed a few thou" with not too much trouble.

Next, tramming it 'cause it ain't square

I chucked up a dti on a 9cm radius and measured to the bed at 4 points of the compass. Plus is a dip, minus is a bulge.

North 0.0"
East -0.004"
South +0.0035"
West -0.0087"

As I measured each point I drew a circle around the DTI tip so I could measure all four points moving the bed rather than the dti...

North 0.0"
East +0.002"
South +0.001"
West +.0025"

Yes, my column is out of square and the bed is a ski jump :nope:

RS do pre-cut shims with a MOQ of 10, so I ordered the 0.05mm (0.002")

Never tried this before, think I need 8 of them and a bed skim :whistling:

[Robin Hewitt]

Did you use a parallel or similar between the bed and the DTI? It helps to smooth out bed irregularities.

I measured it two ways to compensate for the lumpy bed, but seem to have cocked up :nope:

I reckon my -4 mils East measurement was actually a +4 mils, giving a +-6 mil East West tilt. I mean the tilt has to show even either side, doesn't it? :whistling:

6 mils over a 9cm radius translates to nigh on 0.3mm of packing at the column base, it's around 0.1 degrees out. I could see it was a bit bent when facing with larger endmills but didn't think it was that far out.

New plan. I have some 0.47mm brass sheet, I'll put a strip of that down the West side of the column base then shim the East side until it comes true(ish).

Not much of a plan, but hey, it's a plan. Now where did I put my piercing saw? :naughty:

[Robin Hewitt]

BTW Don't get too carried away - the head on these things can be flexed a few thou" with not too much trouble.

How anal is too anal? :naughty:

It is now 0.005 degrees out east/west and 0.002 degrees out north/south. Trying to resist going for better but whaddya do.

Started on attempt #2 at a faster spindle because the bearings are unhappy if I try to run the main spindle up to credible small tool speeds.

The fast spindle is an ER11 chuck fitted to the honking plate and driven using a 1:3 timing belt off the main spindle.

Same axial bearings and Belleville washers that have served me well so far, but less than the 1/4 ton preload this time.

I've been looking at those splendid tool location doo-dads based on an electrical contact between tool and workpiece. As featured on this very site

To that end I have added Tufnol insulators to the shaft housing. No electrical contact between tool and machine body until it hits the workpiece.

[Robin Hewitt]

Spindle housing now bolted together and impossible to assemble :nope:

Have to add a bit of internal clearance so the pulley can get past the belt :whistling:

Measured the resistance top to bottom, slightly worried when I found 8 million Ohms then realised I was in the circuit. Moved fingers and it went away

[BillTodd]

6 mils over a 9cm radius translates to nigh on 0.3mm of packing at the column base, it's around 0.1 degrees out. I could see it was a bit bent when facing with larger endmills but didn't think it was that far out.

Seems a long way out even for a Chinese tool. Have you checked the column and base for paint or rust intrusion? Is it bolted down onto something level and flat?

[Robin Hewitt]

You think I might have done a Hubble? :naughty:

It's a cheap mill bolted down to a cheap stand, I don't think level and flat were ever really part of the equasion.

Don't know about paint and rust either, I've never separated it. I will certainly have a look see before I put the shims in. Engine hoist job, wasn't actually planning to remove any of the bolts beyond loose. Don't want to risk it getting away from me :whistling:

[BillTodd]

You've made a nice job of that Robin :)

Assuming 1Nm on the screw is enough to move the table under all circumstances, that's 1256N force on the nuts, call it 280 lbf because I don't think in Newtons

I pre-loaded my roller nuts to about 400N per roller. There isn't any actual axial load on my lead screw; the pre load stops the roller moving axially within the nut. That seems OK for manual milling with my machine.


It's actually hard to tell exactly what pre-load you've set with a belleville you have to guess using a displacement and trust the manufacturer's table for the spring.

[Robin Hewitt]

It's actually hard to tell exactly what pre-load you've set with a belleville you have to guess using a displacement and trust the manufacturer's table for the spring.

I know, but whaddya do? :whistling:

The extended ball nut housings are now cut, see pic. I plan to rip it all apart tomorrow and try for zero backlash by preloading the nuts

Ran the fast milling collet today at a tentative 4150rpm and looking good. I'm driving it with 44:13 pulleys off the main spindle.

[Robin Hewitt]

ZERO BACKLASH ON X AND Y

Well, none that I can feel anyway :heehee:

First pic, horrible things done to Gary's ballnuts :naughty:

Pic 2, Belleville washers just about to get bolted onto nuts.

Pic 3, My extra speed ER11 collet chuck thingy

[Robin Hewitt]

Added a set of Gary's 240 VAC driven stepper drivers and a splash guard.

Don't know how fast they go yet because my computer can't crank them up past top whack and refresh the screen at the same time.

I suddenly feel a need for belt guards on the steppers.

[ame="http://www.youtube.com/watch?v=bAoUW5bszRA&layer_token=c1adb91cff5d14e3"]YouTube- Noise[/ame]

Would you describe this as "quiet"? :heehee: