From: none@none.com99   
      
   On 1/17/2026 10:39 AM, Joe Gwinn wrote:   
   > On Fri, 16 Jan 2026 17:28:29 -0700, Bob La Londe    
   > wrote:   
   >   
   >> I've machined 7075 before using speed and feed calculations on one of   
   >> the CNC mills, and it machined just great.   
   >>   
   >> The other day I machined some 7075 manually on the lathe to make some   
   >> mold inserts (for quick ship it was actually cheaper than other options   
   >> in the size I needed).   
   >>   
   >> Dang its tough stuff.  I had to look it up again.  Its stronger than   
   >> some steel alloys, and it machines like it.   
   >   
   > It also rings like hardened steel, and so is what movie prop sword   
   > blades are made of.   
   >   
   > Joe   
      
   I offer one mold with either stainless inserts or at a lesser price   
   aluminum inserts.  Usually 6061-t6 aluminum.  Its less about material   
   cost than machining difficulty.  I was out of the right size 6061, so I   
   priced small quantities from different vendors for quick shipment. The   
   7075 (probably old stock) was the cheapest for a six foot stick.  I may   
   order some more before they run out of the old stock.   
      
   After working with it, and determining its general toughness I may   
   consider pricing it in multi rod quantities and discontinue stainless as   
   an option.  Its not as tough as 304, but its tougher than any mold steel   
   I have worked with.   
      
   I was not aware of a brittleness property, but that may be a function of   
   treatment.  It is used for multiple firearms actions including for home   
   builders in the rather brutal 1911 series.  Of course it was the magic   
   answer to toughness and corrosion resistance for the M16A1 in Vietnam   
   over previous alloys.   
      
   --   
   Bob La Londe   
   CNC Molds N Stuff   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)