Supported linear rail question.

In my design that I'm still working on, I'm thinking of mounting supported linear rails. But, and here comes the question.
If I mount them on the side, so the Pillowblocks is mounted sideways instead of upright, would they have any problem of working in this way without making any slack over time? The reason is, that this kind of linear rail is somewhat cheaper than THK linear guides are.

But if anyone knows if supported linear rails can be mounted on the side instead of the top, please let me know.

i've seen it done a few times and it is what i'm planning for my first build as i'm only building it to make the parts for my second build.

on my second build i want the rail supported in the upright position not just because it makes more sense in respect to were the load is coming from but also because i imagine the area were the rail joins the support getting completly full of sawdust, chippings, coolant spills and all sorts of other rubbish.

While it can be done, dont expect to put the rated load though the bearing.
The bearing is open and the case is ally so will bend if too much load is applied, and when this happens it will go all sloppy.

Bit weird but ive just been looking at that today, From what Ive found (not finnished yet tho) Basicly for the open bearings used on supported rail then depending on the manufacturer the rated load is only if applied vertically from above, side loads reduce it to 70% and upward forces at 50%

So if the pillow block is mounted on its side then its vertical capacity is reduced to 70-75% but the bigger problem is the open face which is reduced to 30-50% capacity. As the open face is now in a direction of travel you effectivly have full rated strength in one direction but only half in the other.

If the rails are mounted as a pair, back to back ( ie top and bottom) then the weak spots are evened out, and at first glance you end up with an approx 75% reduction from the rated load capacity in all directions.

As I said not finished yet but will post some pic's latter to see if I'm on the right track.

heres what I have so far. Any comments....:smile:

if only i understood :(

Hi Dan
Sorry, The red area is the effective load capabilities based on a 70% reduction for the horizontal and 30% for an upward force (reverse radial). the dotted line is the combined valule for two rails and blocks.

Hence the total vertical load is 100 + 30 = 130N ect....

dont forget that the rail is acting as a cantilever as well so there will be increased flex in the rail

Quote:

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Originally Posted by irving2008

dont forget that the rail is acting as a cantilever as well so there will be increased flex in the rail

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Not quite sure what you mean? are you talking about the actual rail support? if so I wouldnt have thought it would deflect much?

Ross

I'm sure it's a nice calculation you have made. But the look of it, is not the setup that I will use. I will for my X axis, only have one rail pr. side and not two.