Wow this linear gear is expensive - Advice Please?

[psiron]

Hi everyone,

Im looking to design an affordable 2500mm linear system. I have looked at the profile rail which is way too expensive for me. This has brought me to a point where I need to find a reasonably affordable way to spanning this distance. I have narrowed a few options down here:

1. Precision Round Bar (approx 2500mm)

I can source some hardned or stainless steel preicision round which I was considering drilling and tapping to the frame, Im not sure however just how easy this is to drill and tap? I would then use open ended pillow blocks.

2. Aluminium Angle & DIY Trucks

Using the buildyourcnc.com method I was thinking of making a DIY rail. My problems with this is securing the angle to the frame as I do not have the facility to tack or weld this in place. If I was using MDF I see that a notch can be cut out for the angle to sit in, maybe I could install a strip of HDPE to the rails first and then notch that?


I know my ideas may suck but I am learning based on what I have been looking at. If anyone has any suggestions I would really appreciate any advice available.

Thanks all in advance,

JJ

[ger21]

I'd stay away from #2 for something that long. Imo, it's just not rigid enough. I'd recommend V groove wheels. http://www.vxb.com/page/bearings/CTGY/V-Groove-Bearings
You can run them on steel angle. If you look through the Mechmate forum, you'll see how they grind a 45° on the angle with a home made jig. www.mechmate.com

[Kipper]

Why not blend a few different ideas together....rods spacers flat bar ball races=linear bearings.

The bearings themselves are made from 3 bearings.....a large ID (15mm) and two flanged with a 15mm OD......The larger has 6mm balls in it....now the inner is a U groove running on 6mm round rod with spacers between flat bar.....You can blow the carriage along with a puff of breath.

[ahren]

You can also go with 1/4" cold rolled steel flat bar bolted to alumiunm extrusion, along with a solution like our linear carriages -- this is a fairly cost effective and quite accurate method for getting linear motion. It takes advantage of the inherent tight tolerances of cold rolled steel directly from the mill.

Best regards,

Ahren
www.cncrouterparts.com

[psiron]

Thanks everyone for the replies, much appreciated.