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Steamymoomilk

Stainless Steel Spikes (electrodes) (lemmy.ca)

submitted 5 months ago by [email protected] to c/machinist

9 comments fedilink hide all child comments

Hey folks, pardon the rookie question. We need to build a few hundred of these per year, so I thought I'd tool up, and wanted to figure out how to do this "cheaply".

Parameters. Stainless steel rods, with one end sharpened to a point, and the other end deburred. Typically 30cm long with no real tolerance issues, and no real parameters on the point other than "if you hit it with a hammer, you should be able to drive them into the earth." Typically made of 3/8" or 1/2" stainless.

My main problem is: stainless is fucking hard and destroys my bench grinder when grinding tips onto it. Is there a better grinder I could be using? Or perhaps I should be cutting these on a small lathe?

Also, when I buy stainless stock, I usually have the metal wholesaler cut them to length for us, but they charge quite a bit. The stainless destroys my bandsaw blades, so perhaps there is a better option? Is there a mitre saw blade that is rated for stainless? Or should I also be using a parting tool on a lathe here?

Thoughts are appreciated. Such a simple thing, but stainless so...

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[–] [email protected] 6 points 5 months ago (1 children)

Ahh, okay. 304 is austentitic and doesn't heat treat really but it does work harden like a mf. With those requirements it is a fine choice. So I'm guessing that work hardening has been your processing problems.

[–] [email protected] 5 points 5 months ago (2 children)

That makes sense. I just looked up cold cut saws and stainless blades on Amazon. Looks like I can experiment for about $500, which is great! Something like this blade: https://www.amazon.ca/Evolution-Power-Tools-14BLADEST-66-Tooth/dp/B004Q0994I/ref=pd_aw_fbt_img_m_sccl_1/134-0371646-0898112 in the matching cold cut saw.

Thinking aloud to myself: I wonder if I can put a pyramidal or tetragonal point on them, instead of a conical point, just using the 45° miter option. That would save me from having to use the grinder, and avoid the work hardening...

Thanks for your feedback. Simple things sometimes are not simple when you aren't already skilled in the trade :)

[–] [email protected] 4 points 5 months ago* (last edited 5 months ago) (2 children)

you might even try a single bevel 'point.' Just cut the end at an angle on one side - the point won't be centered, but it doesn't seem like you'd care if there's a little bit of drift as you pound these spikes in. Might want to go steeper than 45, but you go through and do a bunch of 30 degree cuts every 60 cm, then come back with 90s to length, and you might save a lot of work.

eta: you might also look at rebar cutters for just cutting to length. Basically hydraulic shears, maybe a little more expensive than the cold saw, but quieter.

[–] [email protected] 3 points 5 months ago

Shear cutting can work, but you run into the work hardening problem again where the round stock will squish on the sheared end and be very hard to machine a point onto.

[–] [email protected] 3 points 5 months ago

This is definitely worth testing. I worry that, in hard ground, it might bend the electrodes into a J shape if pounded in with a non-centred point. One they're bent too badly, we put them in the scrap bin as they become hard to pound and pull. But perhaps that worry is unfounded in practice and I can do some A/B testing on the points.

[–] [email protected] 2 points 5 months ago

You're very welcome, glad to help! I've not had to work with stainless too much in my job, but I did take some decent material science courses on my way to becoming a mechanical engineer- and quickly applied them to actual machining.

The pyramidal point may work, but rotary saw blades may want to deflect and start rubbing when going diagonal across a round cross section, especially one so small. It ends up being a pretty small bit to cut. It's worth trying though, as it'd really reduce the amount of labor and tooling you'd have to put into this.