Cnc4newbie

X-Carve Upgrades
1

I am helping a friend build his CNC. It will be at a larger scale than the X-carve. I have been happy with my CNC4NEWBIE Z-Axis. So we are looking at their larger units. Has anyone used the SBR10 or SBR12 units?

We are placing a 2.2kw water cooled Spindle on the machine and I want to make sure we order the proper unit. There is over $100 difference in price between the two units and the most that I can tell that is actually different is 2mm on the slides. Is it worth the extra $$$ to go to the SBR12?

Thanks

3

I really do not see that much of a difference to justify the $110 price difference.

Granted the More Expensive Unit has 12mm slides as compared to 10mm slides, but both of them are supported so I do not see how the extra 2mm will add a substantial difference to justify the price increase.

The cheaper unit has a 1” wider front plate, 1/4” more travel, and it is .2” thinner.

The biggest differences that I see are on the screws. These are the two offered on these units

TR10 precision lead-screw and ANTI-BACKLASH nut

1204 BALLSCREW AND BALL NUT

I do not know if one or the other of the above set ups will technically be superior to the other and justify the price difference.

As of now we are considering the SBR10 unit to save the extra cash unless someone can provide a convincing argument that the SBR12 unit is the better option.

I am assuming the major price difference has something to do with the screws but I don’t know the advantages/disadvantages between the two. So any help will be much appreciated.

Thanks.

5

This might be a read well spent:

https://www.electromate.com/ball-screw-vs-acme-screw.html

6

They compare 6:5 in dia, so 36:25 in cylinder base (and therefore volume and mass, if same length). However, given that they are supported and the length in Z is short, it’s unlikely you will challenge the SBR10’s rigidity with a 2.2kW spindle. Something else will give in first.

You can bet that this something else will be the bearings inside the linear blocks. The LMxxUU type bearings inside that kind of blocks have their own limitations.

Quick googling says:

  • the LM10UU-OP inside the SBR10UU blocks are rated for 0.35/0.5kN (dynamic/static load)
  • the LM12UU-OP inside the SBR12UU blocks are rated for 0.37/0.55kN (dynamic/static load)

For reference, the smallest Hiwin HG series blocks (for 15mm profile rail) are rated for 11.38/16.97kN (dynamic/static load).

The bottom line is less than 10% increase in performance as allowed by the system’s weakest link might not justify the 33% increase in price. Unless you know you will not push it to the limit and want to pay the premium for least backlash (i.e. the ballscrew) .

1 Like
7

Thanks.