Blast - smooth rod is scoured Bright Mild Steel... advice

Hello All

I thought I had ordered 8mm BZP smooth rod, but it turns out I ordered 8mm Bright Mild Steel!!! <- this is what the Mendel-m4-assembly-data-sheet.ods file off this wiki page gives as the UK supplier example for the smooth rod. (maybe should be updated?)

Now this stuff seems to have been machined in some way as it has score marks all around it in a spiral pattern. If I run my thumb nail along the surface of the rod I can feel the scouring.

Am I setting myself up for failure if I proceed to use this for my smooth rod? My instinct says bite the bullet, be patient and order some other stuff.

It is currently oiled but I don't want my printer rusting on me after a few months... nor do I want an oily printer lol

Nophead mentioned farnell, but they do not seem to have any 8mm A2 in stock.
They do have SS304 8mm round bar, but their SS306 8mm Rod is out of stock. What is round bar vs rod anyway??

I could also try the Silver steel from RS for about £20 for 3m.

??? damn

Edited 1 time(s). Last edit at 06/08/2010 02:18PM by AgeingHippy.

How deep are the marks? Perhaps you can sand it down? I got some scratches on one of the smooth rods on the y-axis, and the bed jumped a bit every time it passed it. But I sanded it down and turned the biggest mark away from the bearings, and it works fine now.

Is there really a big chance of the metal rusting when the machine is kept indoors in a semi-controlled environment?

Yo nudel

The scour marks are about 0.1 to 0.2mm deep. Well, 0.2 is perhaps an exageration but I can certainly feel them.

As for rusting.... I am in sunny England lol

My feeling is to go for the Stainless 304 or perhaps the silver steel...

That doesn't sound like a lot. Try attaching a bearing to a bolt and run it along the rod. If the scouring is even so it runs effortless and smooth, I don't see why it couldn't work?

I personally don't worry about rust. If the machine rusts terribly in a few years, there will be several new, superior RepRap designs available anyway.

Greetings from warm Norway.

Edited 1 time(s). Last edit at 06/08/2010 03:33PM by Nudel.

You certainly don't want plated rods because the plating will wear off very quickly. After printing 9.5 Mendels the y-rods on my Mendel have slight flats on them.

Mild steel doesn't rust in my work room, but it is very hot due to my PC and two machines printing all day and night and has central heating in the winter.

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[www.hydraraptor.blogspot.com]

I've sucessfully used 1/4" "piano wire" on the y axis. It's not a brightly polished surface but has no actual grooves in it. I believe it is available from most model shops.

If you had an 8mm brass bushing instead of a bearing it would probably slide nicely over the spiral grooves.

Vik :v)

Hey guys

A question for those that have already constructed a mendel.

If I do use this rod and decide to replace it later, is it easy enough to take out the old smooth rod and put in some new stuff?

Cheers

Well, it's easy, but it takes some time. So it's probably not something you would like to do just for fun.

The Z axis is simple, you just have to loosen 4 bolts and pull the the rod up.
The Y axis I don't know personally, but it's similar, although readjusting it might be a bit tricky.
The X axis is the worst, as you have to dismantle the Z leadscrew, and then take out and pretty much rebuild the entire X gantry.

I bought 8mm Smooth rod from reprapworld and also have the helix marks from lamination process.
It really cheap but its also scrap as a linear guide.
After sanding was a little better but dont really work. I dont recomend it.

You could try this if you are in the uk: [www.technobotsonline.com]

I use 8mm silver steel from Cromwells in the UK. You can buy it cheap, and in long lengths. They ship true next day, but probably have a depot near to you if you are in the UK that will likely have some in stock. It's about £5 a metre.

My oldest machine running silver steel has slight grooves where the balls of the LM8UUs have worn into them, the machine has probably done about 1000 hours and has printed 5 Mendel90s and a hell of a lot of other stuff. Still prints absolutely beautifully.

So yes, I recommend the stuff!

[www.cromwell.co.uk]

Edited 1 time(s). Last edit at 06/30/2013 07:15PM by SanjayM.

Easiest way i know to polish steel rods is to chuck them into a hand drill and run a scotch brite pad up and down the rod until it is smooth as silk. Sand paper can be a bit to aggressive.

When buying stainless steel rod the foundary tolerences can be a problem. One batch might be a hair bigger or smaller than another. Its best to buy ground and poished if you can or if you dont mind spending the extra $.

ageinghippy why not try to get stuff local

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

He's been working on these for the last 3 years, must be smooth by now

no he just has very high standards,

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[mike-mack.blogspot.com]