8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel I'm always intrigued by recommendations to use "stainless steel - any grade" in preference to mild steel rods. Is this based on experience and research or just presumption? For the record, pretty well all grades of "steel" (mild, stainless, hardened tool steel, etc) have pretty the same stiffness / deflection characteristics as each other, because the Elastic Modulus / Young's Modulus of all grades of "steel" are pretty much the same. (Assuming we are talking about "small" bending deflections well below the yield strength of the material - and I think we can agree we don't want to see "large" bending deflections on any of our axes!) If it's wear that you are concerned about, then hardness is what matters. Hardness depends upon both the alloy you choose AND its heat treatment / cold working, etc. Many common stainless steel grades are actually quite a bit softer than mild steel - if you really want to minimise wear rates, you are probably looking for a hardened shafting steel - which is not the same thing as common grades of "stainless steel". For corrosion, stainless steel and bright shafting steel will outperform mild steel - but in a typical indoor environment, a light coating of sewing machine oil in conjunction with the constant motion of the bushes / linear bearings will keep even mild steel polished and "rust free". I built my Prusa machine using "unidentified" 8 mm steel rod (definitely not stainless or shafting steel). I first fitted it with standard PLA bushes http://julianh72.blogspot.com/2011/08/assembling-y-is-there-always-something.html - they were a bit stiff at first, but freed up nicely with a bit of machine oil and manually running them up and down the rods 20 or 30 times. I have since upgraded to LM8UU linear bearings on the X and Y axes http://julianh72.blogspot.com/2011/11/smooth-operator.html on the same 8 mm rods, and they are running REALLY smoothly! OK, I have only been running this way for a few months, but I honestly don't see any real NEED for stainless steel or shafting steel rods. I can always upgrade later if I see any problems develop. Comments, anyone? https://reprap.org/forum/read.php?1,113177,113177#msg-113177 Sat, 18 Jul 2026 04:54:09 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,113177,805790#msg-805790 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,805790#msg-805790 Inconel alloy X-750 Siddhagiri Metals and tube]]> siddhagiri General Tue, 16 Jan 2018 04:53:18 -0500 https://reprap.org/forum/read.php?1,113177,768872#msg-768872 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,768872#msg-768872 rajeshsanghvi General Fri, 19 May 2017 05:20:35 -0400 https://reprap.org/forum/read.php?1,113177,760254#msg-760254 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,760254#msg-760254 rakeshborge General Mon, 03 Apr 2017 08:38:32 -0400 https://reprap.org/forum/read.php?1,113177,723280#msg-723280 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,723280#msg-723280 Filling a tube with polyurethane foam, makes for a very stiff and strong tube.
You can even tweak the stiffness by using different grades of urethane.

I stiffened up my race car chassis by filling it up with foam. Added a lot more stiffness and only a little weight.]]> Lykle General Tue, 15 Nov 2016 09:05:31 -0500 https://reprap.org/forum/read.php?1,113177,722963#msg-722963 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,722963#msg-722963 DjDemonD General Mon, 14 Nov 2016 06:08:12 -0500 https://reprap.org/forum/read.php?1,113177,722897#msg-722897 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,722897#msg-722897 nileshjain General Mon, 14 Nov 2016 02:48:13 -0500 https://reprap.org/forum/read.php?1,113177,719854#msg-719854 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,719854#msg-719854 nileshjain General Sat, 05 Nov 2016 08:04:22 -0400 https://reprap.org/forum/read.php?1,113177,565363#msg-565363 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,565363#msg-565363 the differnt rods I was wondering about where silver steel, which I used to love at school, Chromed(dont want chrome coming off), and these other ones listed as optical...I got the optical ones, and assume they are hard enough, if they wear out they are cheap enough, but I wouldnt fancy using anything softer.]]> MechaBits General Thu, 01 Oct 2015 20:17:22 -0400 https://reprap.org/forum/read.php?1,113177,565358#msg-565358 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,565358#msg-565358 3DS-QUAD General Thu, 01 Oct 2015 19:56:06 -0400 https://reprap.org/forum/read.php?1,113177,565144#msg-565144 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,565144#msg-565144
I might be over-concerned, but the printer I'm currently building will have igus plastic bearings on this stuff, and I'm wondering whether I should try to polish the rods before assembly.]]> David J General Thu, 01 Oct 2015 11:04:36 -0400 https://reprap.org/forum/read.php?1,113177,565031#msg-565031 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,565031#msg-565031 manish doshi General Thu, 01 Oct 2015 07:55:18 -0400 https://reprap.org/forum/read.php?1,113177,461442#msg-461442 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,461442#msg-461442
Mcmaster sells several coatings on aluminium linear shaft and lists their compatibility with various linear bearings. The anodized coating is compatible with linear ball bearings.

All the information I have posted is easy to access in the datasheets and descriptions of the various components. There is no need to guess.]]> 691175002 General Tue, 27 Jan 2015 09:56:22 -0500 https://reprap.org/forum/read.php?1,113177,461440#msg-461440 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,461440#msg-461440
Quote
Zavashier
Are you sure Marinus ? Doesn't anodization makes the surface roughy ? That's not wanted to make guides.
It can. But you can also polish or lap it after anodizing it. The image that you posted is a very oversimplification of one possible process. Later thickness, chemicals, types of oxides, dying, etc all play a part.]]> cdru General Tue, 27 Jan 2015 09:45:41 -0500 https://reprap.org/forum/read.php?1,113177,461268#msg-461268 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,461268#msg-461268
]]> Zavashier General Tue, 27 Jan 2015 04:40:08 -0500 https://reprap.org/forum/read.php?1,113177,461151#msg-461151 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,461151#msg-461151
Hard anodized aluminium alloy can be harder than stainless steel.]]> Ohmarinus General Mon, 26 Jan 2015 19:11:27 -0500 https://reprap.org/forum/read.php?1,113177,461124#msg-461124 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,461124#msg-461124 Zavashier General Mon, 26 Jan 2015 17:33:43 -0500 https://reprap.org/forum/read.php?1,113177,460930#msg-460930 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,460930#msg-460930
Quote
Zavashier
Ball bearings and aluminium goes wrong because the balls digs into aluminium.

Not true. The rods I was referring to have a surface hardness of C70 and most bearings are C55-65. Hardened aluminum also doesn't flex enough to really ne a factor over the 300-400mm we're dealing with. The only drawback I can think of is that they're really really expensive. Hardened steel is the way to go.

Also on the question of stainless vs regular steel- stainless is much softer and much more expensive. The only real benefit is corrosion resistance, and since it's fairly easy to keep the rods coated in an oil/lube film they really won't corrode a lot. I personally don't feel that the benefits of stainless outweigh the price.]]> SamS General Mon, 26 Jan 2015 11:34:17 -0500 https://reprap.org/forum/read.php?1,113177,460746#msg-460746 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,460746#msg-460746 there's some high precision aluminium or carbon guides, too. Most of them are better than chinese grade chromed rods. Fist, you cannot talk about guides, without talking about bearings. Ball bearings and aluminium goes wrong because the balls digs into aluminium. With self lubricating brass or plastic bushings, aluminium can work at last as good and last longer. What realy matters is the diameter and the admissible load matching your needs. If your carriage is light, aluminium can stay in better shape under the load, because it's lighter. For example, a long chromed rod will flex a bit under it's own weight while an aluminium rod won't. Some are lighter, some stands better vibrations, some are cheaper, each one have its pros and cons. As far they're machined with the same precision, no matter you use aluminium, carbon or chromed steel rods, you just want to calculate the best fit possible for your design.

There's no basic awnser to this question. The good rod/bushing type depends of many factors and needs to be estimated and calculated on each project. For my Reprap purpose, I choosed low-friction plastic bushings on my existing chromed style rods, but I calculated there's no need of chromed rods on Prusa i3 Z and X axis, and if you have a lightweight Y carriage, you can also deal with light rods on Y axis too. Attention, this is calculations for my printer. Your machine may have a different configuration, with or without a bowden system, light or heavy motors, and so on. On word : calculate. ;)]]> Zavashier General Mon, 26 Jan 2015 05:00:42 -0500 https://reprap.org/forum/read.php?1,113177,460650#msg-460650 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,460650#msg-460650 www.vxb.com] they are very high quality at a low cost. I wonder sometimes how they can have such low cost with the quality they have. I have been buying various bearings from them for many years. And no, I don't get paid to tell you this :-)]]> tmorris9 General Sun, 25 Jan 2015 20:52:30 -0500 https://reprap.org/forum/read.php?1,113177,460499#msg-460499 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,460499#msg-460499 Ohmarinus General Sun, 25 Jan 2015 12:55:14 -0500 https://reprap.org/forum/read.php?1,113177,460485#msg-460485 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,460485#msg-460485
What would the drawbacks be? We don't have to worry about them being brittle really and as a plus aluminum is super light..]]> SamS General Sun, 25 Jan 2015 11:57:51 -0500 https://reprap.org/forum/read.php?1,113177,460459#msg-460459 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,460459#msg-460459 Ohmarinus General Sun, 25 Jan 2015 10:23:50 -0500 https://reprap.org/forum/read.php?1,113177,460283#msg-460283 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,460283#msg-460283
Quote
Skypuppet
So after shopping McMaster Carr again (no this is not an advertisement), I found some reasonably priced "type 17-4 ph stainless" precicion ground rod. Not cheap, but not horribly expensive either. I'm not trying to make margins on my machines either, so a few extra bucks is money well spent.

Note that if you want to do this properly (aka as the datasheets recommend) you are not looking for precision ground 8mm stock. The bearings are designed for an h6 shaft which is 4 microns under 8mm in diameter and has specific surface roughness requirements.
[www.tribology-abc.com]
You will note the mcmaster linear shaft ( [www.mcmaster.com] ) is h6(-0.009mm to +0.000mm). If you buy regular 8mm stock it generally has far wider tolerances and may not meet the surface roughness specifications.

Pretty much anything will work okay but if you are going to go through the trouble of trying to pick the best shaft you might as well use the one called out in the datasheet and engineered for exactly this application.]]> 691175002 General Sat, 24 Jan 2015 22:52:17 -0500 https://reprap.org/forum/read.php?1,113177,460279#msg-460279 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,460279#msg-460279
Can anybody share item munbers SKUs from the website where the hard Stainless Steel can be purchased? It would help a lot to ensure to get the by experience veryfied SS.

Thanks.

Ed]]> pedrosk General Sat, 24 Jan 2015 22:07:42 -0500 https://reprap.org/forum/read.php?1,113177,113982#msg-113982 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,113982#msg-113982 NelsonRap General Sun, 15 Jan 2012 03:35:00 -0500 https://reprap.org/forum/read.php?1,113177,113979#msg-113979 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,113979#msg-113979
While the 5/16 rods are ideally only .0027" smaller, mine actually measure closer to .005" smaller, which is definitely enough to cause a rattle in the bearing circuits. I'm sure they'd be spitting out little BB's before too long.

I will say that the E52100 is definitely a very hard material tho. By no means is this run of the mill "mild steel". It is bearing quality alloy steel. High carbon stuff. That wont make it any more usable with LM8UU's (in 5/16"). And they don't stock it in 8mm so...

I plan to put that rod to use on other things. It could be used with bushings, but I'm not real interested in that either, Not for my redesigned/Larger prusa based machine.

My current machine is a prusa from lulzbot. It's a nice little machine, but I felt it necessary to convert it to LM8UU's. It made a HUGE difference on that machine which has 8mm stainless.

So after shopping McMaster Carr again (no this is not an advertisement), I found some reasonably priced "type 17-4 ph stainless" precicion ground rod. Not cheap, but not horribly expensive either. I'm not trying to make margins on my machines either, so a few extra bucks is money well spent.

On a side note, I'm not saying whether you need to have stainless, or such and such hardness or whatever. I'm just sharing my personal experiences. I'm mainly trying to fill in the blanks when I state where I'm buying and exactly what meterial I am selecting so that others might benefit from my experience.

I hope it helps somebody:)]]> Skypuppet General Sun, 15 Jan 2012 03:09:03 -0500 https://reprap.org/forum/read.php?1,113177,113967#msg-113967 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,113967#msg-113967 -------------------------------------------------------

> Earlier today, I placed an order with McMaster
> Carr for some of the materials. I wound up
> ordering E52100 alloy 5/16" rod even though I'm
> using LM8UU's (8mm). The diameter is only .0027"
> smaller than 8mm which is still a HUGE improvement
> over the PLA printable bearings.

LM8UU's won't ride properly on 5/16" rod. I've tried. The ball bearings don't seem to engage well. It'll work, but considering that 8mm rod on McMaster is only marginally more expensive...]]> NewPerfection General Sat, 14 Jan 2012 22:50:56 -0500 https://reprap.org/forum/read.php?1,113177,113911#msg-113911 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,113911#msg-113911 NelsonRap General Sat, 14 Jan 2012 14:38:06 -0500 https://reprap.org/forum/read.php?1,113177,113900#msg-113900 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,113900#msg-113900 -------------------------------------------------------
> I'm always intrigued by recommendations to use
> "stainless steel - any grade" in preference to
> mild steel rods. Is this based on experience and
> research or just presumption?

Just today I visited the local hardware store and looked at the steel rods. The stainless ones were straight and smooth. The ordinary steel rods looked like they were made by the village blacksmith. So specifying stainless steel does seem like a sort of a guarantee of getting straight and smooth rods...]]> ttsalo General Sat, 14 Jan 2012 13:15:54 -0500 https://reprap.org/forum/read.php?1,113177,113595#msg-113595 Re: 8 mm Rods: Shafting Steel vs. Stainless Steel vs. Mild Steel https://reprap.org/forum/read.php?1,113177,113595#msg-113595
Atlas Steels provide an excellent "Technical Handbook of Bar Products" at: [www.atlassteels.com.au]

It goes into a great amount of detail on chemical composition, strength, toughness, ductility, hardness, machineablity, etc - there should be MORE than enough information for anybody!

(I'm not sure that all this information will actually help anyone come up with the definitive answer as to what is the "best" product to use. Having perused the document, I have to say I am much better informed, but none the wiser! :) )

For what it's worth, my 8 mm mild steel rods with PLA bushings (now replaced by LM8UU linear bearings) are holding up just fine so far!]]> julianh72 General Thu, 12 Jan 2012 19:33:21 -0500