Stainless Steel Hydraulic Fitting
Posted: Sat 27 Apr , 2013 7:04 am
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.
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.