Which stainless steel to order?

[Black Forest]

I am getting ready to make the table for my belt grinder. It utilizes rods as part of the positioning mechanism. They need to slide so I thought SS would be best because of rust. Which type would be the best against rust and also best for machining. I need to mill 8mm groves lengthwise with ball end mill..

[Peter N]

Don't use stainless - it may not rust but there is always a chance of galling and picking up if you use it as a slide.
I would suggest buying some linear shafting instead and use that - it's designed for guideways. It's hard (more like case hardened) but easily machinable with carbide

[old mart]

You could avoid any danger of galling if the stainless is bought ready ground and used with matching size readily available thinwall split bushes which have a PTFE bearing surface. They are used dry and as long as the grooves are deburred they will not be affected. The design could incorporate easy bush replacement. I would use a carbide ball end mill for the grooves.

[plunger]

Black forest .what are you using for the platten.?

[Michael Edwards]

As long as you don't need to weld it, I would go with 303. It's stainless enough, not going to gall, easy to machine and readily available.

[chipmaker4130]

300 series SS does not wear well. If you expect a lot of movement I'd go with 17-4

[MrWhoopee]

For the ultimate, go with Thomson 440c stainless linear motion shaft.

https://www.grainger.com/category/power-transmission/linear-motion/precision-linear-shafts/linear-motion-shafts?attrs=Material%7C440C+Stainless+Steel&filters=attrs

[sid pileski]

BF- Knowing and understanding the design and application, I would use a 303 material.
It should be fine for what you are doing.

Sid

[Willy]

300 series SS does not wear well. If you expect a lot of movement I'd go with 17-4

Another vote for 17-4, very good wear resistance, galling and corrosion resistance is better than all of the other commonly available hardenable stainless steels.
It also welds very well if that is a consideration.

[Peter N]

Is the environment that corrosive that it needs stainless? Just wondering

[boslab]

I think climate wise moist air and unheated shops = rust, it’s a problem where I am, sometimes it’s a thick wet fog for weeks at a time, condensate on any steel.
annoying and I find it depressing to the extreme.
I don’t think it matters what stainless, it’s not moving that often 303 as mentioned machines well my platten is topped with ceramic at the moment, basically a porcelain tile stuck on with silicone mastic!
mark

[Peter N]

I think climate wise moist air and unheated shops = rust, it’s a problem where I am, sometimes it’s a thick wet fog for weeks at a time, condensate on any steel.
annoying and I find it depressing to the extreme.
I don’t think it matters what stainless, it’s not moving that often 303 as mentioned machines well my platten is topped with ceramic at the moment, basically a porcelain tile stuck on with silicone mastic!
mark

Like you, I'm in the UK - in Suffolk about 15 miles from the North Sea coast - so we probably have similar-ish climates.
But I've never had a problem with rusting on any of my equipment - perhaps they just have more oil leaks that prevent any oxidation 😀.
But as a mechanical design engineer (high-speed rotating equipment and robotics) the thought of using a bar of ordinary stainless for a reciprocating guide shaft does horrify me quite a bit, particularly when a piece of hardened linear shafting is close enough in price to replace it with.
Of course there is always the option of hardened & ground stainless linear shafting - maybe the best of both worlds?

https://www.automotioncomponents.co.uk/en/catalog/linear-components/linear-bearings-shafts/linear-shaft-bars/hard-stainless-linear-shafts/l1772.16/l1772.16-0250/g+m+c+s+a+nr

[Paul Alciatore]

Aluminum?

[Black Forest]

I do have a problem with rust in my shop. Maybe I will buy some hydraulic rod in the dimensions I need. The problem with that is milling the grove with a ball endmill. I need to mill six groves in 3 bars. Two each. I am not sure how well even a carbide ball nose endmill will handle the chrome and induction hardened outer layer of the rod.

[Black Forest]

Also I don't know where to buy that fancy rod here in Germany. It isn't about the cost it is about not rusting and machine-ability. I only need about 500mm of 30 and 25 mm rod.