Homemade Linear Design, Feedback.

[MrBean]

I've been trying to come up with a design for a cheap linear motion axis design using skate bearings and belt drive. Ground rods are not too expensive and work well if supported. I can get 1800mm belts for ~£10. The pictures only show one side of what could possibly make one axis.

All are welcome to comment and improve on the idea. Hopefully we can come up with a good design between us.

My basic requirements were that it be:

1. adjustable
2. cheap
3. rigid
4. Leave room for rod supports

The basic idea uses bearings mounted on small dovetail slides that can be adjusted and then locked using some kind of bolt and gib arrangement. The dovetails would probably require the use of a mill. The models are not super accurate and don't show all bolts etc...Just wanted to get the idea of the carriage design across.

So jump in and let me know what you think. Good, bad, don't bother, whatever.

Regards Terry.....

[Torsten]

You may like to have a close look at the one pictured here.

Bearings for home made linear

A good design in my humble opinion.
notice the lateral ajustment screw on the right side only.
It allows for a slight adjustment of the bearing pressure this
is really all that is needed the rail represents a fixed distance
and you only need maybe a little oversize mounting hole giving
a few microns for ajustment.
A further improvement of this design may be to get rid of the nuts
used for spacing out the bearings and making some dedicated
spacers that take better advantage of the bearing shoulder surface
and provide a wider support on the other side.
Good Luck.

[chuckknigh]

I like the idea...it looks like it could be mass produced with relative ease.

Reminds me a bit of this arrangement, though.
http://www.linearmotion.com/pb.html

Don't you think there's a similarity?

-- Chuck Knight

[Hobbiest]

It does remind me of that links idea. They both remind me of this one though
http://www.buildyouridea.com/cnc/hblb/hblb.html. If mass produced it could be worth it. Dave at buildyouridea.com told me that his design, or at least his method was not economical enough.

[MrBean]

I guess any skate bearing design that allows for rod supports is going to look pretty much like any other.

I could make one up and see how it goes.

I have a CNC router that cuts well in aluminium.
I also have a manual mill to cut the dovetails. I'd make the two matching dovetail parts as two long sections, then cut pieces off at the required length.

One of the main things from my point of view, is that all the holes required are perpendicular to the part they are in. (no angled holes).

The bearings being on dovetail slides should allow a single carriage to fit more than one rod size.

I don't think I'd want to mass produce them. It's really for my own use, but If anyone else likes the idea they are welcome to use it. Thought I'd share it anyway.

I guess it's no better/worse than any other of this type of design, but it suits my limited machining capability, and should be fairly sturdy.

Regards Terry.....

[ynneb]

This is an adaptation from mvauhan's crazy idea post.

[mocnc]

have you or anyone tried this linear bearing using the u-bolt and angle irons? How would you get the nuts to hold the bearings in place?? Is the u-bolt threaded all the way?? Do they make all the way threaded u-bolts??

[ynneb]

I dont know if anyone has made this b4. I dont know if the nuts would be able to spin on the curve either. It was more of a concept drawing that could evolve with input and experimentation. Possibly packers should be used instead of nuts. Possibly the angle iron peices should be turned the other way so as to reduce the length of the Ubolt.

Who is willing to give it a go and try to make such a system ? I would be interested in your feed back.

[mocnc]

please bare with me.....but what is a packers? Well at least I don't think I know what they are? Where can we find them?

[ynneb]

Not to be confused with an alpaca, a packer is a bit of material that is inserted into a place to hold two other bits of materials apart. In this instance a stack of washers could be used as packers.

[nuplowboy]

You can also find packers in Green Bay, WI....

Instead of nuts, you could cross drill the u-bolt close and use cotter pins or roll pins, and a shim pack to take up any slop.

[MrBean]

Well, based on the feedback so far. It looks like the answer is "don't bother".
Most poeple seem interested in pointing me to other designs. While I agree it looks similar to other designs. It differs in the fact that it uses dovetail slides for adjustment and should fit more than one rod size. Maybe I'll just abandon the idea, at least for now.

Thanks for the responses.

Regards Terry.....