Hello,
I'm designing a CNC Mill at the moment. It is a 12" x 8" x 12" (XYZ) for Milling Aluminum and Mild steel. I did some reading over here and have come across 2 Linear guide based designs. (Please check the attached pictures)
Design 1: Each Axis has 2 Rails (15mm) and 4 Carriages (2 Per Rail)
Design 2: Each Axis has Just One Bigger Sized rail (45mm) and One Carriage
Now I compared the load ratings or 15mm and 45mm Linear Guides and found them to be WIDE APART. The 45mm guideways seem to be WAY higher in load bearing capacity than the 15mm ones.
However I was wondering if using just One 45mm Rail is a Good Idea?
Will it give better Axis rigidity?
I checked the prices with an AMT Linear Guide supplier and found Two 15mm Rails with 4 Carriages is pretty much priced the same as a Single 45mm Rail with a Single Carriage. So its even economic to use a Single Rail concept. Plus since there is just one rail, we don have to go through the time consuming effort to make sure the rails are mounted Perfectly Parallel too. So Prima Facie the Single Rail concept seems better. But if that is so, Then Why is it soo unpopular? in all the posts I have read here, I have come across just One Design where the single rail concept is used.
Here are the Specs for the AMT Guideways
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15mm Linear Guideway Carriage
Carriage Name : MSA 15 S
Length (mm) : 56.3
Width (mm) : 34
Height (mm) : 28
Basic Load Rating (kN)
Dynamic C : 11.8
Static C0 : 18.9
Static Moment Rating (kN-m)
Mp :0.12
My :0.12
Mr :0.14
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45mm Linear Guideway Carriage
Carriage Name : MSA 45 LS
Length (mm) : 169.5
Width (mm) : 86
Height (mm) : 70
Basic Load Rating (kN)
Dynamic C : 102.4
Static C0 : 157.3
Static Moment Rating (kN-m)
Mp : 3.13
My : 3.13
Mr : 3.43
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If you have used Larger sized rails in your projects, Please post your experiences as it would be very helpful in deciding which of the two methods is better. I hope someone can help me with choosing the better idea of the two.
Thank You!
Joe!
PS: The Attached Pictures do not belong to me Nor are they my Designs. I have attached them ONLY for reference. All Credits goes to the Original Designers.