[dlenardu]

How do you choose which size linear rails to use and which bearing blocks to use?

I noticed the guide blocks come in light, medium, and heavy preload. How do you determine which one to use?

[jasminder]

How do you choose which size linear rails to use and which bearing blocks to use?

I noticed the guide blocks come in light, medium, and heavy preload. How do you determine which one to use?

well,
Mostly, people check the load rating using the given model number from the officical site of manufacturer. But you can use anything for a light machine. I mean a 15mm lm guide can mill steel very well if used with proper base of steel or iron casting. You just make sure that you use lm guides and not round rods when making a machine for metal working. Round shafts (bushings) don't have enough load ratings. I have checked that a 15mm lm guide can take a load what a 3in supported road cannot take.

what you want to use it for btw?

jasminder singh

[dlenardu]

Jasminder,

Thanks for the reply. After seeing so many amazing scratch built machines I decided that I am going to build myself a cnc lathe. Overall length on this unit will be between 42"-48". I am hoping to end up with about 20" between chuck and tailstock and hopefully around a 9" swing. I'm still working out all the details but was a little stumped on what size rails/guides to go with.

[jasminder]

Jasminder,

Thanks for the reply. After seeing so many amazing scratch built machines I decided that I am going to build myself a cnc lathe. Overall length on this unit will be between 42"-48". I am hoping to end up with about 20" between chuck and tailstock and hopefully around a 9" swing. I'm still working out all the details but was a little stumped on what size rails/guides to go with.

good,
you can trust me on this part because i just finished a cnc lathe after a lot of trobles got from linear bushing (round shafts). I replaced them with 20mm thk linears and it is running good now. You can also use 20 or 25 mm guides on your lathe. 15mm will also work but 20 will increase the budget. Will you be using steppers on your machine? which controller you consider?
btw here is my build log
http://www.cnczone.com/forums/mini_l...lm_guides.html

have fun with your build. gluck
jasminder singh

[dlenardu]

I am going to use steppers 381 oz-in and a gecko g540 controller