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Robert LaLonde
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Yesterday I did a little bit of work with 304 stainless. I recently picked up several 12' bars in different sizes from my local metal vendor to just have some onhand. Just about everybody seems to be a little bit afraid of 304-316 stainless. They say to use 303 or 416 for its machinability. Well I have some 303 and some 416 also, but not in sizes suitable for yesterday's project. The 304 is stocked locally primarily because its food grade and its stronger than 303, and more common and cheaper than 308 or 316. As an agricultural community most makers and builders build machines with food grade alloys. Coolers, precoolers, processing lines, etc. My vendor doesn't stock 416, but he let me know he can get the 416 for me if I don't mind waiting for their regular supply trucks. I like 416 because its both stronger and cheaper than 304.
Anyway, I had some bars of 304 on hand because its available. Yesterday I needed to make some parts requireing turning, tapping, drilling, and threading. I was a little bit afraid of it because of other peoples comments about it. My solution or key... Use the horsepower of the machine and cut very aggressively. I drilled a modestly deep hole in one bar on the lathe and then POWER tapped it. Not a large thread. Just 3/8-16. I only had a hand tap so I was a bit nervous, but by over drilling the hole, and backing out about every 4 threads it went right in and came right out. I did use LOTS of tap magic cutting oil. I didn't even use a cheater bar on the chuck key. Just two handed it. I had the lathe on low gear turning about 70IPM for power tapping, but the drilling was with a LOT of pressure at 300 RPM. Lots of oil for both.
I cross drilled the bar for a handle the same way. Well. not on the lathe. On my drill press. Mid range RPM and aggressive heavy pressure on the handle. Two hands on the handle after I locked the drill vise down so I could reverse quickly without rubbing.
Then I turned a stud to go with it. One end was 7/16-14 and the the other was 3/8-16. I thought about single pointing it, but then I said screw this. Its seems to really like hard heavy cutting. I power turned it with a die holder. Both ends.
In conclusion. Hard heavy cutting seems to work better on work hardening stainless. I can see why so many folks with small, light weight, not so rigid machines might sometimes have issues with stainless. They just can't do heavy aggressive machining. I know I struggled with it years ago on my old HF 7x10. This 3HP 14x40 made short work of it.
Maybe I'm nuts, and maybe I just got lucky, but on those hoity toity machining sites I have read a comment or two were they said they just went hog wild on stainless and did ok. I never really believed them before.
(P.S. The cross handle was a piece of 1144 stress proof with some lock nuts on the end. As usual it was a dream to thread.)
P.P.S. I did cheat a bit on diameters going go a little over on inside threads and a little under on outside threads before threading. Just a few thousandths. I'm sure that helped.
Anyway, I had some bars of 304 on hand because its available. Yesterday I needed to make some parts requireing turning, tapping, drilling, and threading. I was a little bit afraid of it because of other peoples comments about it. My solution or key... Use the horsepower of the machine and cut very aggressively. I drilled a modestly deep hole in one bar on the lathe and then POWER tapped it. Not a large thread. Just 3/8-16. I only had a hand tap so I was a bit nervous, but by over drilling the hole, and backing out about every 4 threads it went right in and came right out. I did use LOTS of tap magic cutting oil. I didn't even use a cheater bar on the chuck key. Just two handed it. I had the lathe on low gear turning about 70IPM for power tapping, but the drilling was with a LOT of pressure at 300 RPM. Lots of oil for both.
I cross drilled the bar for a handle the same way. Well. not on the lathe. On my drill press. Mid range RPM and aggressive heavy pressure on the handle. Two hands on the handle after I locked the drill vise down so I could reverse quickly without rubbing.
Then I turned a stud to go with it. One end was 7/16-14 and the the other was 3/8-16. I thought about single pointing it, but then I said screw this. Its seems to really like hard heavy cutting. I power turned it with a die holder. Both ends.
In conclusion. Hard heavy cutting seems to work better on work hardening stainless. I can see why so many folks with small, light weight, not so rigid machines might sometimes have issues with stainless. They just can't do heavy aggressive machining. I know I struggled with it years ago on my old HF 7x10. This 3HP 14x40 made short work of it.
Maybe I'm nuts, and maybe I just got lucky, but on those hoity toity machining sites I have read a comment or two were they said they just went hog wild on stainless and did ok. I never really believed them before.
(P.S. The cross handle was a piece of 1144 stress proof with some lock nuts on the end. As usual it was a dream to thread.)
P.P.S. I did cheat a bit on diameters going go a little over on inside threads and a little under on outside threads before threading. Just a few thousandths. I'm sure that helped.
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