Sourcing Inox M8 Smooth Rod - Again

Hello Everyone,

I'm still trying to get a hold of M8 smooth rod of the inox(aka stainless) variety.

I'm making a few printers for others, and selling them at cost. We are trying to find good prices for things. The only thing I have not be able to source is this smooth rod. I've used M8 drill rod on a few machines, and it is okay. It is accurate and the linear bearings run well on it, but it can rust if not oil in less than ideal environments.

So far everyone I talk to can get me very high quality US made A2 inox(equivalent to SAE 304) ground and polished rod, but at around $65 Cdn. per metre.

Should I just give up on North American suppliers and order a big pile of the cheap stuff from China?

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Yvan

Singularity Machine

ah a fellow canadian. i feel your pain.

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[mike-mack.blogspot.com]

Idea:
Hard chrome plate the drill rod.
Ask a plater what they recommend.
I don't know how well it would hold up.

Walk into a mold or tool and die shop, and ask them if you can look at their steel supply catalogs.
I've worked with CAN molders, they can get every thing.

A2

dissidence, LOL! The fun never stops up here, have you ever tried to patch an old Hypalon inflatable? Don't look for tuolene...

A2, both good suggestions. The chrome would hold up longer than the bare drill rod. It would flake off once worn through, but it is more wear resistant than the steel underneath.

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Yvan

Singularity Machine

i have wondered if chrome would be better for pla bushings though, do you know anyone who has tried that.?

the sad part is that we are supposed to be a metric based country.

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[mike-mack.blogspot.com]

no i have not tried to patch one of those boats. but i would imagine its not much different than a bike patch.

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[mike-mack.blogspot.com]

Did anyone find a supplier etc

I've been contacting my local suppliers in Melbourne Australia, and the best M8 bar I can source is H9 quality (0.036mm tolerance instead of H6 which is 0.006 mm tolerance as specified in the wiki)

I've noticed that some suppliers (on eBay) don't specify what precision the bars are. Some people quote that its 304 grade, but as far as I can tell, this is a measure of the quality of the steel not the precision of the manufacture.


I wonder how may people actually have H6 precision / tolerance rod in their machines, as its seems very hard to source.

I strongly suspect that my MendelMax it doesn't have H6 precision rods and still works OK.

Can anyone else share their experiences on this ?

Thanks

Roger

Quote
Yvan
I'm still trying to get a hold of M8 smooth rod of the inox(aka stainless) variety.

Sorry to nitpick, but M8 is by definition threaded. If you're looking for smooth rod, then it's 8mm dia., not M8.

Good luck!

Another Canadian, and punctilious at that

dissidance, yes I believe chrome with PLA would be a good combo. I'm fussing with nylon bushings right now(my linear bearings are in Singapor at the moment!). I would think that nylon would be slippery and tougher than PLA, does anyone know more about one versus the other? I have not used PLA.

BTW, patching a Hypalon boat is like patching an inner tube but much fussier and a lot more critical!

Roger, all the 304(which as you probably know is just type of alloy steel and has nothing to do with precision) rod I have encountered is not as accurate as the H6 designation you mention. The drill rod I have been using is much more accurate, and has a smoother finish to it.

From what I can see, there is too much play or slack in the bearings and the designs of the machines to see any difference with higher accuracy rods. Other issues cause more play than the rods themselves.

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Yvan

Singularity Machine

NormandC, thanks for pointing out M8 vs 8 mm, I was trying to sort that out on the phone with a supplier the other day, and it helps to know what the proper terms are. At least then you can talk to others, even if they sometimes use innacurate terms exclusively in a specific industry. Don't get me going on French terms for woodworking machines! Un planeur ça vole dans l'air!

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Yvan

Singularity Machine

Guys,

Sorry I meant 8mm smooth rod as well

I'll probably get some normal H9 stainless rod from a local supplier and see how bad it is. The price I was quoted was only $6 (AUD) per linear metre, so its not going to break the bank getting a bit to test !

Cheers

Roger

Haha! Over at my last job I once had the great idea to use the correct French terms for regular hardware in my shop drawings. The shop guys (all French-speaking) kept asking me what a "vis de pression à six pans creux" was. (it's an Allen set screw! Sometimes French takes a lot more words to describe something)

I would be very careful electro plating precision rods. There is a thickness to the plating and it's quite hard to get it absolutely uniform. The risk is that you would turn your precision ground rod into something no better than the lower grade part. Vapor deposition plating is another approach, but good luck finding that. If you can find it, it's not cheap. It also has uniformity issues, but it's thinner. The net result is less distortion to the part.

Edited 1 time(s). Last edit at 10/30/2013 09:35PM by uncle_bob.

FYI Wikipedia has some useful info on metric threads. [en.wikipedia.org]

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Wikipedia
A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (Dmaj in the diagram above) and the pitch P, both expressed in millimetres and separated by the multiplication sign, × (e.g., M8×1.25). If the pitch is the normally used "coarse" pitch listed in ISO 261 or ISO 262, it can be omitted (e.g., M8).

It's a pity us North Americans have stuck with the US/imperial system while the rest of the world embraced metric.

Canada is "supposed" to be metric

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[mike-mack.blogspot.com]

I looked at Fastenal as I think they have many stores in most provinces. They have metric threaded rods (they seem cheap too), but they only have imperial size smooth rods (no stainless).

@ dissidence: yeah, we suposedly switched to SI 30 years ago, I learned the metric system at school then had to learn the stupid imperial system the first job I had. Gotta love those sixty-fourths (and I had them memorized too!)

Edited 1 time(s). Last edit at 10/30/2013 10:01PM by NormandC.

I am having a hell of a time getting m8 rod from fastenel. But they are still handy for a lot of metric stuff overall.

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[mike-mack.blogspot.com]

Hi guys, another Canadian RepRapper here and first post on this awesome community forum

Could I ask why you would want to use stainless? Besides the anti corrosion properties, it's pretty soft to use for long term as a linear guide. We use all grades of stainless for hydraulic piston rod and I can tell you they will wear/polish themselves in time, no matter what bushing material is used (even soft o-rings). Have you seen old school epsons or hewlitt-packer printers with a rusty shafts? Drill rod that has been chromed would look mega lumpy under a microscope. Thats why chrome shafting for hydraulic cylinders are precision ground after the chroming proccess.

I'm probably going to price various diameters and lengths of hardend linear shafting, in the next day or two from my industrial suppliers. Specifically Thompson bar, which is case hardened and ground linear shaft. They used to make it in Hamilton Ontario, so it better be cheap!!! I'll also price chromed shafting which is cheaper, but soft like drill rod. My supplier can get wacky sizes (we use 9mm all the time), so metric should not be an issue. However non metric will be cheaper and i'm open to using it. If there is interest, the price will go down if we order full lengths.

Daniel

uncle bob, good points about the chroming. The 304 rod I've seen is far from precision anything, and usually undersized. The drill rod on the other hand is more accurate and if the chroming added more than one thousanth of an inch or so some of these cheap LM8UUs might be a bit tight. They have slack, but I don't know how much.

Daniel, I'm glad you are posting here, lots of interesting info in your post.

The price range I get for anything smoother and harder wearing than 8 mm 304/A2 is about $40 to $65 Cdn. per metre. That is way more than the drill rod. I haven't seen any of it rust, but others seem to say it can in normal usage.

The drill rod I have is not as smooth as Thompson shaft, chroming it would not take away from the surface finish. If anything, I would very much expect it to improve it!

BTW, I'm seeing a split with the machines I'm building. The smaller less expensive ones can't justify anything more than the less expensive types of smooth rods, but the bigger machines could benifit from something harder wearing if cost effective.

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Yvan

Singularity Machine

Plating > .001 inch will exacerbate surface roughness, and would need to be ground.
Hard chrome plate can be applied to .0002 inch.
You want your surface finish to be very smooth, ref: RMS 4 to ~8 is a mirror.

I personally wouldn't worry about drill rod tarnishing, periodically wipe it down.
Don't touch the metal with your hands.
I would be more concerned about the straightness.

304L SS is soft, electropolishing will put a mirror finish on it, probably not very straight.

Have you considered heat treating the drill rod, you will probably need to OD grind it.
But if comes out straight, without much oxidation, it might work after hand polishing.

Don't run your bearings tight, if using unhardened steel.

So plating less than one thousandth of an inch thick will roughen a surface... but drill rod seems to start off smoother than the inox rod I've seen, so maybe it wouldn't matter much?

8 mm rods in inox or tool steel don't seem to be particularly straight, but I guess that doesn't matter too much given the reality of RepRaps. Warping plastic after printing would be a bigger source of error I suspect! I'll look into heat treating the rod, would this be something machine shops would be able to do inexpensively?

BTW, it seems the drill rod I have is slightly oversized, it doesn't fit into a 608 bearing! It is about 1 thousandth over. The LM8UUs fit fine, but there is no play in some cases.

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Yvan

Singularity Machine

Hi guys. Had a few messages with interest on the linear shafting, so I'm just putting this out there.

Just priced out some 8mm and 12mm true Thompson brand linear shafting. I can offer it for around a dollar per inch, and a few cents more for 12mm. I can cut them to any length. We're in Southern Ontario, Canada.

(Unfortunately our EDM is offline so I won't be able to bore a hole through it.)

Daniel

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Yvan
LOL! The fun never stops up here, have you ever tried to patch an old Hypalon inflatable? Don't look for tuolene...

Being an inventor in Canada is about as much fun as a sharp stick in the eye sometime ... LOL. But HomeDepot Canada has Toluene in case anyone is needing it: Toluene

Daniel, that is a good price for Thompson shaft. I just might need some at some point...

Garry, it looks like toluene is not available at HD in Ontario! I'm going to have to call around, it is still being used in the real world from what I know.

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Yvan

Singularity Machine

Funny we have it in Home Depot here but they don't carry it there. I like it mainly because it is an excellent thinner for Plastidip.