[Closed] Quick question o replacement rods  

Re: Quick question o replacement rods

jay,

If the Iglus bushings work well with the stock rods there is really no reason to change them.
Bushings mainly need the right diameter tolerance of the rod, and an accurate geometry to prevent binding.

The MK2S rods are hardened and ground steel rods and are actually quite good!

The igus aluminum shafts are anodised aluminum, which has a hard, silky smooth surface.
Their tolerance is h8, meaning they are between 8,00 and 7,978 mm thick
They are NOT suitable for ball bearings, as their hard coating is much thinner and softer than hardened steel and the aluminum underneath is too soft to support ball bearings.

The hardened misumi rods are again a lot harder, which is really needed due to the extremely small contact area of ball bearing balls.
The tolerance is even tighter at h5, which means they are between 8,00 and 7,994mm.

However - the tight tolerance of the Misumi rods might be a little bit of a waste for use with Igus bushings, considering the fact that bushings have a slightly larger diameter (play) anyway to allow free movement. But if you ever change back to ball bearings, those rods will be perfect.

If you do change the rods please post your experiences. It's an interesting subject and every experience counts.

Re: Quick question o replacement rods

Hey George,

Thank you so much for taking the time for your detailed reply. Really appreciate it.

To be honest, I've ordered the 2.5 upgrade and with the spare bed and pinda sensors left over, I'm considering building a 2nd using aluminum extrusions, it's for this reason that I wonder about new rods and whether to go for close to stock rods with igus as per my mk2s or to go with misumi and subsequently which bearings to use with them.

Your reply has definitely left some food for thought and she'd some light on this so thank you.

Re: Quick question o replacement rods

Hi Jay!

I sold my stock MK2S shortly after it arrived and ordered the MK3, and while waiting couldn't help but look at upgrade options.
The MK2S printed really well but the precision of the Y-axis was not that great. I am really not a fan of the U-bolt mounted bearings.

So I researched the subject and brushed up my mechanical engineering know how back from university times.

My conclusions were:
IGUS: quiet, but possibly introducing more play into the system
Quality linear ball bearings: relatively cheap upgrade for smoother operation and more precision
Precision hardened rods: tighter tolerances should further improve smoothness and precision

If you have to get rods and bearings anyway, the Misumi combination should be a great choice for precision, the Igus pair for noise.

In Europe, I could not find Misumi bearings for a reasonable price, so I opted for precision rods and some medium quality linear ball bearings from cncshop AT, which look and feel very good. Can't wait for the MK3 kit to arrive, then I can compare to the stock parts.

Cheers, George

Re: Quick question o replacement rods

Hey George,

Thanks again for your great insight!

Jealous of the MK3 order, I couldn't quite justify it though. . . yet 😆

That's some interesting info, primarily my priority would be noise due to living in an apartment with a fiancee fit to kill me though precision is a very close second. I'd be interested to know what the noise is like with the quality linear ball bearings on the precision rods? (even if it is just manually moving them on the rods as I guess they are not in service yet?) Also, would you happen to have the part numbers for the rods and bearings?

Re: Quick question o replacement rods

Jay,

@Misumi parts: I don't have any parts numbers, but should be easy to find on their web page,
If you are in the US you are lucky and can order directly from them. In Europe they only sell to businesses.

Regarding noise, I found the biggest factor in noise with the MK2S was the surface on which it was placed.
Sitting on a solid wood floor the noise was ok, but clearly audible, even annoying my wife.
On an IKEA Lack table it was terribly loud, because the thin table top acted as a membrane, amplifying the vibrations.
With a granite slab on the IKEA table (piece of carpet in between) it became pretty quiet, but I'd still consider it an annoyance in an apartment.
That was with stock rods and bearings.

I expect an even quieter operation with the MK3 and upgraded bearings and rods, but for ultra-quiet operation the Igus bushings will be hard to beat.

Cheers!

Cheers!

Re: Quick question o replacement rods

I swapped to Misumi bearings on the stock shafts. Much quieter in the Y axis moves, no change on all others. The rattling/harmonics I used to get in the Y axis moves is gone. Precision, not much changed there, I had a tight machine to begin with. Saying that, I have ordered the Misumi rods as I am planning on creating a second printer as I have enough parts and motors, so good start to the process.

I don't think the MK3 has different rods and bearings. Could be wrong, but I thought they were the same as the MK2S.

RE: Quick question o replacement rods

They are in fact the same. I confirmed this with support a while back as some components (IE Motors rods bearings etc.) Are not listed under the MK2/MK2S spare parts sections. Identical components are only listed under the newest machine with that compatibility. 

Not the way I would do it, but now that I know it isn't a problem!