Here is a simple linear slide design using bearings.

Paul, That's pretty neat.
I see some potentional problem areas, but they might not even be a problem once the thing is made.

1. As shown, there is nothing keeping the bearing assembly from falling off the rod. (To the right, in your picture.) I guess that you are relying on an opposing bearing on the opposite side of the table to counteract this. The only issue might be that it might be difficult to assembly your gantry.

2. The 1/4" bolts holding your round linear ways are right on top of the honeycomb. This might make the honeycomb hard to change out.

Overall, it looks pretty good though, and I'm interested in seeing on how it works out.
Trent

Good points, the other side of the gantry will keep the sides from falling off, and the honeycomb does not have to fit so close to the site.

I took the liberty of changing your design in the new dxf (It's easier to explain this way). I hav machined a shaft with a flat like you showed with disasterous results. THe shaft after machining was warped alot and was useless. I since then have come up with the design that you have exept using cold rolled steel bar. WOrks great so far.
Any way see the attached file

I have thought about doing that, but never consider that cutting a flat spot could "unstressed" the rod and warp it. I think I'm with you and I'll go with the flat bar, BTW how is the wear factor? How did you build in adjustment for play?

I haven't sat down and calculated that but with the bearings I think that if under constant use (1 1/2 years at about 8hrs a day) could be expected. As for adjustabliity on the bearings I have designed the bearing shafts around an eccentric shaft. There are many styles and sizes available at most power transmission suppliers. I have used this design many times in my industrial designs with great success.

I've thought of something very similiar, only using round stock attached on top and bottom of the square tubing, and maybe using pulleys as wheels.I think you could then eliminate one bearing, because the round stock is self guiding.
To reduce the amount of play between the roller and rail, use an excentric bolt.
I have a radial arm saw with this same setup, and there's no slop.

I think your idea is great but if your going this route you may as well use a v roll design instead of pulleys. The radial arm saw does not need to be "as acurate" or as friction free as possible. But you've made me rethink my next machine!

I agree that the saw is not that acurate and it does use vee rollers, I've priced them and seem some what costly.
The use of pulleys was something that came to me this morning. They are available in the required sizes for what ever size rod you may choose.I'm going to the hardware store today and do some more research.
I do believe the pulleys would need to be polished to remove any roughness, before using.

Just watch out the pulleys are usually low quality and low acuracy. Do you have access to a lathe you could make your own v rolls for fairly cheap.

I do, but thats not a road I want to go down. My own lathe is a small craftsman 109, with a four jaw chuck, no fun to setup. A friend has several pieces of equipement he's offered the use of, may have to take him up on that, but I'm still looking for off the shelf materials for my second machine.

I'm curious as to what this looks like.

However I don't have AutoCAD at work. Can you guys post a simple picture?

Thanks

ok, took some time, but here it my take on it

need to read up on photo attach, i guess

here is a file for you

ok, that's kinda small
I would like some help with the PROPER method to send a screen capture

Instead of saving it as a .bmp file, save it as a .jpg with a max size of 700 pixels wide. The upload it again to the forum.


or you can email me the full size image and I'll format it and upload it here.

Try this one

This one is of the changes I spoke of earlier

Is the outside bearing free floating in a pocket with set screws used to tension it.

In my design I used a slot or pocket. But maybe for ease and simplicity on could use a shoulder bolt and thread the bearing shaft. I'll work on this idea and post it later.

I have it all re-designed with the flat bar, in fact I got the whole machine done, I'm post some pics tonight. I'm going to re-model it in Alibre and see how well I can do with it. This design is a light weight application, this is for my laser machine. The whole machine is belt driven now instead of servo.