Best CNC accuracy and repeatability?

[DeepWoods]

Just curious to what the best accuracy and repeatability everyone is getting from their CNC mill? A good comparison of all brands(taig, sieg, etc..), model, and setup is what I'm shooting for. I've seen some figures for the Model Master CNC 1000 and Revo540 that are impressive but can't understand if/why it's not possible with some of the common mini mills?

Thanks,
Rob

[jalessi]

Rob,

As far as accuracy is concerned a bench top CNC machine with iron ways and gib strip is never going to compete with one built on linear rail components especially if they are both constructed with the same rigidity.

The Revo, Modelmaster and Mini-Tech are linear rail equipped, the Taig, Sieg, etc.. have iron way's.

There is of course a price differential on the small bench top style machines.

On larger industrial sized machines linear ways have taken over because it is much more labor intensive to hand scrape.

A linear rail is so much more accurate and has hardly any friction to boot.

Hope this helps,

Jeff...

[Harryman]

The accuracy and repeatability of a machine is determined by the sum of all its components, and the sum of all the errors introduced by each component, so besides the ways, other critical areas are the lead screws, the number of steps per revolution your motors/software and electronics can support and the overall rigidity of the machine.

Mintech, ModelMaster and Revos are more accurate because they all use ball screws, linear ways and microstepping systems, they are less common because they are more expensive.

It's certainly possible to get the less expensive benchtop mills out there to a level of accuracy perfectly acceptable for most milling jobs, but you need precision components to build a precision machine.

[rashid11]

Assuming top components are used, there's no practical limit to just how accurate and repeatable you can get.

It means precision-ground ballscrews (0 backlash and extremely consistent pitch), servos (no lost steps), linear rails (no slack/play).

And of course it assumes the obvious things are also taken care of - spindle, tools, X-y-Z at precisely 90 degrees, the setup is rigid nuff for that you're doing etc

[KTP]

In my homemade fixed gantry mill I am getting backlash of less than 0.00025" and similar repeatability. Also rapids of 2000 IPM. I guess it depends what type of components you use. I started with NSK robot modules with precision ground ballscrews and linear rails/carriages. Everything purchased off ebay for under $2000, but if I bought from the manufacturer...maybe $25,000.00?

If you can't find satisfaction in the commercial benchtop mill specs, you might look into building something similar. It is quite easy.

Link to my build on cnczone is here:

Fixed gantry router

[18ajdcnc]

Hello anyone. I have been using CNC MICRON MADE BY MODEL MASTER for over year which is given me headache all time . By the warranty time is ran out then you out of luck because they use cheap components for their machine,they claim their products are best but I don't buy that .They didn't used ball lead crews as they said, they installed 29.99$ stepper motors,4Th axis is "suck" (it is never alignment).Their price tag is 12G.....All I can say "GOOD LUCK" to whom want to buy their machines.Good Adviser.