[Imaginebreaker]

Good morning,

This is my first post. I'm designing a machine tool and I want to know all about linear guides. What kind of linear guides exist? I wish someone could help me.

Thanks.

[Bear5k]

Start here:
LM Guide [ THK || USA ]

And here:
Ball Spline [ THK || USA ]

Lots of reading ahead of you, unless you have specific questions.

[Imaginebreaker]

Thank you very much. I want to achieve a high resolution. Should I use air linear guides?

[jharvey407]

Here is another link for you.

I am using their modular V rails bolted to 8020 extrusions. They are very smooth and precise.

Linear Bearings, Linear Actuators, Linear Guides, Roller Bearings, Linear Motion Solutions

[Imaginebreaker]

Thank you.

[Bear5k]

Thank you very much. I want to achieve a high resolution. Should I use air linear guides?

Pneumatic solutions are low cost and can be very high speed. Variable accuracy is not their strong suit compared to purely mechanical solutions (air acts as a spring which necessarily has variable amplitude).

You may also want to look into a kit. This will take a lot of the design out of your hands so you can focus on assembly. Designing a moderately high precision CNC router can be a challenge, but actually assembling one that lives up to the design is an even bigger challenge, IMHO.

[RICHARD ZASTROW]

Imaginebreaker, You said "machine tool", what are you wanting to build? Mill, lathe, drilling machine or a router? Actually, it depends on what you want to machine, what will the product be?

Dick Z

[Imaginebreaker]

It's a mill. Its purpose is make microcomponents or at least components with one of its dimentions in micrometers.

[Bear5k]

It's a mill. Its purpose is make microcomponents or at least components with one of its dimentions in micrometers.

Sounds like you don't need a big format machine, then. If true, then definitely look into the linear guides, rather a ball spline. At small dimensions, the cost of the rail on eBay isn't too bad. The real trick is getting enough rail so that you have room to have two carriages per rail with enough room for them to move. If you go digging on the THK site I linked, above, you will find information on how to mount the rails, which is the real challenge.

After that, you will want to look into ball screws with sufficient accuracy for your parts. Fortunately, you can get C3 ball screws for not a lot of money on eBay, but the question is whether even that will be sufficiently accurate for what you want to make.

[Imaginebreaker]

This is the first prototype, so I guess I can achieve a good accuracy if I follow your recommendation. Thank you.

[RICHARD ZASTROW]

You want to work in microns? How many microns (.000039")? That's fine grinding and lapping territory. Pretty difficult on a DIY mill.

Dick Z

[Imaginebreaker]

I'd feel satisfied if I can get 100 microns dimentions.

[Bear5k]

I'd feel satisfied if I can get 100 microns dimentions.

Do you want 100 micron features or a total error tolerance of 100 microns for macro features?

[Imaginebreaker]

I want 100 micron features and error tolerances lower than 10 microns.

[Bear5k]

I want 100 micron features and error tolerances lower than 10 microns.

https://tech.thk.com/en/products/pdf/en_a15_017.pdf

You will want laser measurement to mount the screws and to align the rails. This is before thinking about things like runout in a collet or the practicality of using a COTS spindle. You are into some seriously high-end tools and tools to build tools here.

[Bear5k]

One thing I forgot to add to the above: there are several linear scales that can be added to a CNC machine to allow the control system to correct for positioning error. Renishaw makes one of the more popular in the commercial space, and it can get to the micron and sub-micron level of accuracy and precision for measuring linear position. However, from what I understand, installation is non-trivial and the sensors and control software are beyond the basic stuff used by hobbyists.