Kossel rails vs wheels

Hi,

Finally I've decided I want to tackle building a printer from scratch and have settled on the Mini Kossel design.
There seem to be two approaches for the linear motion, steel rails or wheels/rollers and I'm trying to decide what to go for.

Does anyone have insights into the advantages/disadvantages of each approach?
Price is something I can look up, but how about accuracy, durability, maintainability, noise during operation etc.


Any input will be appreciated by this n00b

I'm glad someone asked this as I was going to myself

Here's what I can tell so far. There are three common variants.

1) Use smooth rods either side of a makerbeam/open beam/standard t slot/square box section and the smooth rods do all the motion control.
2) Use smooth rods only (possible downside is frame rigidity)
3) use a beam only (upside is that it's a lot cheaper, downside is that it can be a bit louder)

Personally I'm going for option 3 with my delta build. There seemed little to no benefit in using both a beam and smooth rods together, other than sound. I'm going to be using pretty standard, cheap 20/20 t slot for mine, which should provide ample frame strength, and good motion. You also then have the added benefit that should you need to, you can add extra horizontal braces to the outside of the frame structure, at a tiny cost for a simple strip of metal and a couple of screws.

Also if you go for option 2 or 3, you can actually print the parts to fit a t slot and the smooth rods, so if you ever change your mind you can upgrade the machine without needing a whole new set of parts.

Take a look at the Cherry Pi thread for a good example of option 3 in use.

Thanks for the input, your Cherry Pi looks like a really nice build!

I was indeed thinking about option 3 and have also found a similar discussion regarding Graber wheels vs MGN12 rails on the google group here:
[groups.google.com]


Seems like both perform very similar, noise on the rails may be slightly more but most of the noise reduction can be gained by isolating the machine from the table and motors from the frame.

It's not my build - it's someone elses. I'm just using it as a basis on planning my own build as I loved the idea of using the rails as both support, and for movement, and probably even for getting 5v of power to the top of the frame for things like LED lighting

With regards to noise reduction, a lot of the noise is likely due to the 'channels' along the rail. You could actually use some sort of material, or maybe something as simple as tissue paper in those holes to dampen the sound if it really did become a problem.

Hi Guys

I did just that with regard to running wires up the T slot. All my electronics are in the Cherry Pi base but I needed z endstop micros witches at the top and I wanted lights. IKEA do some superb led strip lights for £11.00 for a set of three 250 mm long. I have them wired to a pin on my Rumba that lights them when the steppers are live. They work great. I ran the wires top to bottom in the hole in the centre of the extrusion and ran them around the top in the T slot. I got some cf effect self adhesive tape to cover the slot. At first glance you can't see any wires on the machine. Unlike my Huxley which is a birds next!

Good luck with your builds. Merry Christmas.

Andy