Source for mm smooth rods in USA?

As the title says

I've been lurking here for a while and have decided to start my build. So far I have only found metal sources in inches. Any idea where to get 8 mm smooth rods in the USA? I rather find something locally to avoid expensive shipping costs, VAT (from Europe), etc. Working on a very tight budget here (personal use). My concern is with the fit of linear bearings on imperial sized rods. Any guidance will be appreciated.

mcmaster.com

Edited 1 time(s). Last edit at 04/22/2013 02:46PM by akhlut.

---

- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

VXB.com will sell you chrome plated hardened steel rods in various lengths, buy it the size you want it's a pig to cut.
But use McMaster.com if you just want drillrod

---

___________________________________________________________________________

My blog [3dprinterhell.blogspot.com]

Drill rod is hardened and is also drawn to a precision tolerance. The composition of the alloy is a more important factor than any sort of plating. Typically hardened tool steel is a high carbon alloy with chromium and molybdenum as well as manganese and other elements. The elements give the material tensile strength and allow the various hardening processes to work. Plating processes don't have the tolerance of a quality drawn steel rod. A shinny finish for drill rod is achieved by a light buffing just enough to put a shine on it and clean any dirt, paint, etc that might make it onto the rod in the manufacturing process. The paint comes from marking the rod ends for identification of the hardening process. As it's hardened it's a bit tougher to cut. I use what is called a metal cutting dry saw and finish the ends with a bench sander. You can cut them by hand but it could take a few hacksaw blades and something to firmly hold the material like a vise. The printers I use/ built as well as the couple hundred kits I've supplied work well with drill rod.

The only issue I have with drill rod, is if it isn't hardened, the bearings in the LM8UU's will wear them. But were talking about 100's of hours of printing and then you can just rotate them slightly.
I find drill rod relatively easy to cut and machine, my bandsaw cuts through it in a few seconds, I am using drillrod in my current design, but I'm using bronze bushings on them not LM8UU's.
the VXB rods I have are hardened, the only thing I can cut them with is an abrasive cutoff wheel

---

___________________________________________________________________________

My blog [3dprinterhell.blogspot.com]

Drill rod is not hardened.

Wow. Lots of very informative answers. Thanks guys for the valuable information.!

Go here:

[www.mcmaster.com]

Note that none of these are very hard. They can be hardened - but may want to skip it to save the money.

Make sure to only get the precision ground.

Misumi is what all the automation guy use,


[us.misumi-ec.com]

Example - 8mm shaft @ 400mm length - $9.70

Customize any diameter/length. You can pick surface finish, and a whole slew of options

Edited 1 time(s). Last edit at 04/23/2013 10:40AM by ShadowRam.

ShadowRam Wrote:
-------------------------------------------------------
> Misumi is what all the automation guy use,
>
>
> [us.misumi-ec.com]
> 20000000_20010000.html
>
> Example - 8mm shaft @ 400mm length - $9.70
>
> Customize any diameter/length. You can pick
> surface finish, and a whole slew of options

Cool! Checking it out now. I'm basing my printer on the Mendel 90 design, but inside a heated chamber. Since I have the chamber (donation from my place of work), I need to "resize" the rods from the original dimensions so I can use the whole volume of the box.

If you're building the entire printer inside a heated chamber there are additional issues ,like how the plastic and more importantly the steppers hold up at the elevated temperature.
Ideally you want the steppers outside the heated part.

---

___________________________________________________________________________

My blog [3dprinterhell.blogspot.com]

Polygonhell Wrote:
-------------------------------------------------------
> The only issue I have with drill rod, is if it
> isn't hardened, the bearings in the LM8UU's will
> wear them. But were talking about 100's of hours
> of printing and then you can just rotate them
> slightly.
> I find drill rod relatively easy to cut and
> machine, my bandsaw cuts through it in a few
> seconds, I am using drillrod in my current design,
> but I'm using bronze bushings on them not
> LM8UU's.
> the VXB rods I have are hardened, the only thing I
> can cut them with is an abrasive cutoff wheel

Wouldn't another advantage of the hardened, chromed rods be stiffness? I can't help but notice on my MendelMax that the rods do flex. In fact, I think the stifness of the filament can and does influence the precision of the print due to the torque it imposes on the X-rods. I can move the filament around with my hand and see the print head move. I can also see movement in the bed from the Y-rod flex as well with just fingertip pressure. I'm using 8mm drill rod now but seriously considering switching to larger (10mm),hardened rods.

---

ΜΟΛΩΝ ΛΑΒΕ

Hardness does not affect stiffness. Going from 8mm to 10mm rod will decrease the flexibility of the rod significantly though.

---

Help improve the RepRap wiki! Just click "Edit" in the top-right corner of the page and start typing. Anyone can edit the wiki!

NewPerfection Wrote:
-------------------------------------------------------
> Hardness does not affect stiffness. Going from
> 8mm to 10mm rod will decrease the flexibility of
> the rod significantly though.


Thanks. Did a little reading on material science.. "Stiffness" is the material's ability to resist elastic deformation, while "hardness" is the material's ability to resist plastic deformation. Hardening steel does not make the steel more stiff, however it does increase the yield point and the range of the elastic region.

For the rods in the printers, this isn't much help.

---

ΜΟΛΩΝ ΛΑΒΕ

rsilvers Wrote:
-------------------------------------------------------
> Drill rod is not hardened.

That's not correct. Drill rod is indeed hardened by using a hardening processe. The processes can include air hardening, oil hardening and water hardening. Dril rod is extruded to a precision tolerance using a tool steel alloy which is harder than mild steel. Depending on the app and desired hardening determines which method is employed. Water hardening drill rod (the most basic) is just fine for Reprap builds though in the US it's a bit more difficult to find in metric sizes but it's out there. I've found oil hardening (O-2, which is what I use) to be more available. I use a few hundred pounds of rod a month for printer kits. FWIW my background encompasses more than three decades in an engineering field with experience in material science.

Polygonhell Wrote:
-------------------------------------------------------
> The only issue I have with drill rod, is if it
> isn't hardened,

Drill rod is hardened. Non hardened rod is called round stock. Some mistakenly call unhardened, non alloy tool steel drill rod when it's really round stock.

vegasloki Wrote:
-------------------------------------------------------
> rsilvers Wrote:
> --------------------------------------------------
> -----
> > Drill rod is not hardened.
>
> That's not correct. Drill rod is indeed hardened
> by using a hardening processe. The processes can
> include air hardening, oil hardening and water
> hardening. Dril rod is extruded to a precision
> tolerance using a tool steel alloy which is harder
> than mild steel. Depending on the app and desired
> hardening determines which method is employed.
> Water hardening drill rod (the most basic) is just
> fine for Reprap builds though in the US it's a bit
> more difficult to find in metric sizes but it's
> out there. I've found oil hardening (O-2, which
> is what I use) to be more available. I use a few
> hundred pounds of rod a month for printer kits.
> FWIW my background encompasses more than three
> decades in an engineering field with experience in
> material science.

Drill rod is an alloy that is hardenable by various methods (depending on which one you buy), but it is not hardened when you buy it - it is called drill rod because you can machine it into drill bits and then harden it. Take for example the General Purpose Water-Hardened W1 Tool Steel from McMaster:

[www.mcmaster.com]

It is listed as 241 Brinell. That is about 23 HRC. After you water-harden it, it becomes up to 60 HRC.

Round stock differs in that it is less precise, and also made from a lesser alloy steel. But neither come to you already hardened when you buy them.

I made these bullets out of drill rod, and hardened them myself:

[www.youtube.com]

Edited 3 time(s). Last edit at 04/23/2013 07:27PM by rsilvers.

I buy a few hundred pounds of hardened drill rod a month, it's readily available. To say drill rod isn't delivered hardened is not accurate. Many sell raw material that requires hardening but many others also sell material that is hardened.

Edited 1 time(s). Last edit at 04/23/2013 08:01PM by vegasloki.

Polygonhell Wrote:
-------------------------------------------------------
> If you're building the entire printer inside a
> heated chamber there are additional issues ,like
> how the plastic and more importantly the steppers
> hold up at the elevated temperature.
> Ideally you want the steppers outside the heated
> part.


Mmm... that would be a pain since the case is 1/8" steel plate with the exception of the rear and the front door (plexiglass). If I go with bigger motors (NEMA 23) with more torque than necessary, would the temperature still be an issue with them? Would Peltier coolers help? (radiated heat from the Peltier helping heat the chamber?) I read in some thread here that the temperature only needs to be around 35 Celsius in the chamber to print large ABS objects. I intend to print mostly in ABS and vinyl. The printer will also have a heated bed. I guess I'm going off-topic now

In any case, everyone is giving me great information and raising good questions. Thanks for the superb feedback.

You said: "The processes can include air hardening, oil hardening and water hardening" and "Water hardening drill rod (the most basic) is just fine for Reprap builds."

They may be just fine for certain projects, but they are not hardened. Only material specifically marketed as pre-hardened is hardened, and it is only air-hardened - not oil or water.

---

[www.matter-replicator.com]