0.03mm backlash acceptable, yes/no?

[dazp1976]

0.03mm backlash seems to be as low as I can get at final testing. (0.0012")
Machine has AC bearings & DFU nuts with extra shimming installed.
Would you say it sounds about right?

Mach3 Comp nudges the table if it's set above 0.125mm but I hate it's stop/start nature anyway.
Will likely only use it on important circles and arcs.
The rest of the time I'll use the stock to leave to add the 0.03mm on the parts or tweak the drawings if closer accuracy is required.

It is only a benchtop





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[arizonavideo]

If the mill is new then .0012" is fairly good.

Backlash comes from all the components not just the ball nuts. On of the leading caused in a new mill is stick slip and way friction. After the ways break in the table will move easier and you might get under .001"

I have had a few people over the years report large backlash with a system I knew was tight. I ask them to check how hard it is to move the axes by hand and almost every time the ways were set real tight or the gib strip was binding.

I have seen .008" go to .0008"

After the screws and ways break in you might be able to re shim the screws and get under .0005"

Looks like a nice build, lots of screws.

[ninefinger]

That level of backlash is probably more than fine, except if you are running a tiny end mill (i.e. 1/8" or smaller)... then backlash really becomes your enemy as it becomes significant relative to the chip load for the tool.

[Zenji]

Rolled ballscrew are only good for .02mm positioning, if you want better you need to save up for ground screw which is alot more pricey.

[Azalin]

I have the same BF20 cnc'ed mill. Except my ballscrews are single. Backlash is about .05mm. Loosening way gibs didn't help.

BTW, How did you managed to install double ball nuts on X and Y? It looked impossible when I convert mine.

Best

[peteeng]

Hi Dazp - Wallace & Grommet would be chuffed with the cabinet work. Peter

[dazp1976]

Hi Dazp - Wallace & Grommet would be chuffed with the cabinet work. Peter

It's functional. Lol.
Wish I could weld.

[dazp1976]

I have the same BF20 cnc'ed mill. Except my ballscrews are single. Backlash is about .05mm. Loosening way gibs didn't help.
BTW, How did you managed to install double ball nuts on X and Y? It looked impossible when I convert mine.
Best

I already had a dying sieg X2 conversion.
Machined some of mine on there so the DFU would fit

[peteeng]

Hi Dazp - No welding sucks! Planes aren't welded and Mr Eiffel would be proud of you. Peter