First foray into stainless steel

devils4ever

devils4ever

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Hi all,

I've been avoiding machining stainless steel after reading about how some grades are very difficult to work with and will work harden especially when using a (MicroMark 7X16) mini-lathe and (PM25) mill. But, I have a very simple project I need to be in stainless steel and thought this would be the time to try it.

I need to make some washers with these dimensions:
OD: 0.420" (10.67 mm)
ID: 0.257" (6.53 mm)
Thick: 0.035" (0.89 mm)

The original part is 316, but I bought both 316 and 303 stock. My thoughts are I would try 316 first and switch to 303 if I get into trouble.

So, my plan is to turn down the outside to 0.420" from 1/2" stock. Then, drill the 0.257" hole using a No. F drill. I'm not sure about using a spotting drill first since that seems to work harden the material. Then, finally part off the end to the required thickness.

Any thoughts or words of encouragement?
 
Does the application require 316 and it's corrosion resistance? I haven't turned 316, but I know 304 is considerably more difficult to work with than 303. I practically smoked my HSS parting blade on 304. This was on a mini lathe. The 304 work hardens readily. That being said, it seems like your plan will work as long as you keep ahead of the hardening on both the parting and drilling.

303 is nice to machine and knurl.
 
I'm not sure, but that's what the original part was made from.
 
Spot drilling is fine. Just be sure to keep the tool cutting, don't allow it to dwell. Parting will be the challenge, with limited rigidity it can be difficult to keep the feed going. Use plenty of cutting oil and make sure it gets down to where the action is.
 
Is there a reason for using 316 besides that it was originally used for the part? What is the part's function? In my business I used 303 for every product that needed to be stainless, no problems with it and it can be machined nearly as easily as mild steel.
 
It will be much easier to make those washers from sheets rather than rods. I have worked on 304 quite a few times and abnormal work hardening has occurred only once. I believe it has something to do with the material.
 
benmychree said:
Is there a reason for using 316 besides that it was originally used for the part? What is the part's function? In my business I used 303 for every product that needed to be stainless, no problems with it and it can be machined nearly as easily as mild steel.
Click to expand...

The part is used in a stainless steel pump used to circulate unfermented beer (wort) during the brewing process. This little washer spaces the impeller from the housing.

1651594338412.png
 
Keep your parting tool as thin as you can , it wouldn't hurt to tighten up the gibs on the cross slide as much as possible and be sure to lock the saddle . You might leave some extra stock on the ID and OD before you start the parting operation , then finish up ID and OD when you start getting down to the parting diameter . I would face the part and part it off a little thick and then face the other side and finish to thickness . Yes that is a lot more work you will need to make some sort of a pot chuck but it will insure a seal .

Mark .
 
Last edited:
So, is 316 needed for this application?
 
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