Machining 303SS Square Bar down to size

[slatern44]

I just got a new job in requiring 12mm (.472") square bar 303SS. I found 12mm square stock but its about $1200.00 more that just 1/2" square. So I thought next to just buy 1/2" square and double disk grind it to 12mm and save some money. But they want $6.00 per part x the 200 parts that equals $1200.00 that's same as just buying metric material. So my question is do you think I can skim cut off 0.028 off two side in my mill and make 12mm square material or is the material going to bow or tweak out because it cold drawn SS. Any help would be nice.
Thanks,
Neil

[msomerville]

How long is your piece? Depending on the length of your piece you might see some warpage. What other operations do you have to do to these pieces? The more you have to handle your parts the more expensive they will be to make.

[slatern44]

The parts are 6" long. The first op is to do some mill work so that was why I was thinking this time to also machine them to the correct thickness and same some money. I made two last time with 12mm stock and now they re-ordered 200 and it's a on going part. I guess I will find out Monday when I get the material and give it a try. If not there going to double disk.
Thanks,
Neil

[Geof]

Originally Posted by slatern44 .... So my question is do you think I can skim cut off 0.028 off two side in my mill and make 12mm square material or is the material going to bow or tweak out because it cold drawn SS. Any help would be nice. Thanks, Neil

If you take a cut only off two sides they will distort by many thou is my expectation. You might find taking off a cut like this results in a 1/64" to 1/32" bow; I may be too pessimistic but you will soon show if I am.

[slatern44]

Geof,
What would you do if you had to make 600 of them per year. Buy 12mm stock, double disk 1/2" stock, or skim cut off 2 sides or all 4 sides?
Thanks again,
Neil

[Geof]

Originally Posted by slatern44 Geof, What would you do if you had to make 600 of them per year. Buy 12mm stock, double disk 1/2" stock, or skim cut off 2 sides or all 4 sides? Thanks again, Neil

I would experiment; buy 1/2" stock and machine it myself, have 1/2" stock ground and if these did not work out then go to the 12 mm stock.

I did say I may be too pessimistic .

If the 600 was a guaranteed number I would be tempted to talk to the supplier of the 12mm square stock and give them a song and dance to get a better price if I buy a larger quantity.

[ctate2000]

How straight do they need to be? 6.00 x 12mm square may not be difficult to straighten with a simple set up on the bench. It may be worth a try.

[ImanCarrot]

It might be worthwhile speaking to the customer and see if 1/2" stock would be ok instead of 12mm... I've done this many times and you'll be surprised at how many designers/ customers say "yeah, sure- that was just nominal dimension anyway".

[dicksonhof]

l

[slatern44]

Just as a FYI I finished all of the 200 parts on Tuesday. I had to machine all four sides and take 0.014" off of them. If I only machined two sides the material would bow about 0.020". But by taking 0.014" off of all four it stayed within 0.005" of flat. Good enough for a 7" long part.
I wish I could use 1/2" material but this bar has to go between two other parts that have 12mm grooves machined in them.
Thanks again,
Neil

[Geof]

Originally Posted by slatern44 .... If I only machined two sides the material would bow about 0.020". ....

I got lucky with my 1/64" to 1/32" guesstimate .