Guide versus Bush (footprint)

[Chunky]

Please see my pics below and help me understand the footprint issue. Thanks

[ger21]

First of all, they'll be a lot closer in size to each other than your picture would indicate. Second, the linear guides are almost always bolted to a steel or aluminum plate, with bolts every 4-6 inches. Third, linear guides carrying loads in any direction other than along down (in your pic) should be used in pairs, which would eliminate the twisting you're worried about. Fourth, the linear guides can carry much higher loads because the balls ride in a ground race, as opposed to riding on a round shaft with an infinately small contact point.

[Chunky]

ger21: First of all, they'll be a lot closer in size to each other than your picture would indicate.

That's precisely what I thought until I read the notations. The guide is rated at a dynamic load of 9.51kN while the bush, the giant to its right, is rated at mere 7.35kN. ??? Presumably they're comparing oranges to oranges.

Second, the linear guides are almost always bolted to a steel or aluminum plate, with bolts every 4-6 inches. Third, linear guides carrying loads in any direction other than along down (in your pic) should be used in pairs,

I considered the "pairs" configuration. But then-- you're no longer examining the initial question. Two contact points compared to one has exponential advantage. But if you're going to claim equality "as is" well....

[ger21]

The little guides WILL carry more weight then the large bush type will. Say the small guide is 1/2" (12mm), that would make the round shaft about 2". You're not going to use 2" shaft, is what I'm saying. For a hobby machine, either type 3/4" or bigger will usually suffice. I have some 15mm guides. I wouldn't use anything smaller. Most people go for 25mm or so. The 25mm ones come in longer lengths, and I suspect that most people just can't believe the 15mm ones can carry the loads they are rated at. Our machine at work has a cantileverd 1000 lb head riding on 25mm guides. It hangs about 4 ft beyond the rails!



They both should be used in pairs for any type of machine tool application.

[Chunky]

Our machine at work has a cantileverd 1000 lb head riding on 25mm guides. It hangs about 4 ft beyond the rails!

That is beyond belief!