Hello
This is a post for those like me that read how difficult it is to machine stainless steel grade 316.
Here is a hydraulic fitting I made for my racing kart. It allows a pressure sensor to be fitted to the brake line. This data is recorded by my Aimsports Mychron 4 data logger.
The adapter has a 1/8 female NPT, 1/8 male BSPP and 1/8 male BSPT ports. A standard adapter with this combination is not available. I originally used an assembly of standard adapters but these had high points that made it almost impossible to bleed the brakes. This adapter is has an offset through hole to allow any air bubbles to rise to a high point from where they will bleed out down the line.
I made this from SS316 because I needed something that wasn't going to rust and that's what I had in my metal stocks.
I was fully expecting to screw up and convert this into a small paper weight but it all went well.
I used hex bar which made the job a lot easier than it would have been with round stock. I was able to accurately index 90 degree rotations with ease.
I started with the operation I thought most likely to fail so if that happened, I wouldn't lose much investment in time. That being the 3.5mm through hole. I had no problems drilling this.
To achieve success I used:
sharp HSS tools,
cutting oil,
slow speed (~60rpm)
high feed ( ~4 thou)
high depth of cut (10-25 thou)
power feed to avoid any dwell.
These techniques avoided tool killing work hardening.
Finish was very good with the right cutting conditions.
I found that a very slow cutting speed (~12rpm) caused the metal to tear away leaving a poor finish.
The swarf is long, stringy, strong and very very sharp. I have the scar to prove it.
CNC Expert
Attachments:
- The hexagonal stock made it easy to index the workpiece as each port was machined. Note that the hole is intentionally off centre in two directions.
- IMG_2540 (600 x 450).jpg (63.28 KiB) Viewed 21438 times
- A general view of the finished adapter.
- IMG_2552a (600 x 465).jpg (24.61 KiB) Viewed 21438 times
- The through hole is intentionally offset to make it easier to bleed the brakes.
- IMG_2550a (600 x 415).jpg (31.4 KiB) Viewed 21438 times
- The hydraulic adapter fitted to the kart brake system.
- IMG_2553 (600 x 450).jpg (52.39 KiB) Viewed 21438 times
Regards
Dazz
Dazz
Site Admin
Looks great!
Lethal stuff that you stupidly think will be ok to move by handThe swarf is long, stringy, strong and very very sharp. I have the scar to prove it
CNC Expert
Hi
I found that if I focused on keeping the temperature down and the tool cutting then SS is OK to machine.
The nice finish and properties of SS316/304 justify the extra effort.
To keep the swarf clear, I grabbed the end with long nose pliers as it came off the tool and pulled it away from the lathe.
I found that if I focused on keeping the temperature down and the tool cutting then SS is OK to machine.
The nice finish and properties of SS316/304 justify the extra effort.
To keep the swarf clear, I grabbed the end with long nose pliers as it came off the tool and pulled it away from the lathe.
Regards
Dazz
Dazz