Retention Knob Hardness?

A

AJ H

Hot Rolled

Joined

Feb 5, 2019

• Jul 8, 2020

• #1

We have a HBM that I decided needs a 90 degree head on it. The problem is it's a CT45, after months of looking for one I settled on a BT45 unit. There is no ATC so no issue with the flange. It did however pose a problem precuring a pull stud for it. I did some research on materials used for them and decided to use 8620. I combined the features needed for the stud end into the machine with the features needed to thread into the BT unit and whipped some up on the turning center. I know they get hardened but I can't find where anyone says to what.

Thanks

 

fmari --MariTool-

Titanium

Joined

Nov 15, 2005

Location

Illinois

• Jul 8, 2020

• #2

case harden .03-.05 deep. 52-56rc. table blast. You dont want it too hard.
If it is coolant thru plug the hole with a screw and nut on the other side.
Make all corners with nice size fillets so knob is nice and strong with no stress risers.

 

A

AJ H

Hot Rolled

Joined

Feb 5, 2019

• Jul 8, 2020

• #3

Thank You Sir!

 

Cole2534

Diamond

Joined

Sep 10, 2010

Location

Oklahoma City, OK

• Jul 8, 2020

• #4

fmari --MariTool- said:

case harden .03-.05 deep. 52-56rc. table blast. You dont want it too hard.
If it is coolant thru plug the hole with a screw and nut on the other side.
Make all corners with nice size fillets so knob is nice and strong with no stress risers.

Click to expand...

Is this to help keep the core more malleable?

 

G

Garwood

Diamond

Joined

Oct 10, 2009

Location

Oregon

• Jul 8, 2020

• #5

I have a shitload of BT45 pullstuds. Even a nice Jarvis BT45 90 degree head.

Post up a picture of what your stud looks like.

 

D

Dan from Oakland

Titanium

Joined

Sep 15, 2005

Location

Oakland, CA

• Jul 8, 2020

• #6

Yes the screw and nut blocks the carburizing gas and prevents carbon from migrating into the inside surfaces.

A screw in a threaded hole will also keep the threads in the part from being hard all the way through.

 

litlerob1

Diamond

Joined

Nov 4, 2013

Location

Utah, USA

• Jul 8, 2020

• #7

I've seen more Thread topics on pull studs in the last year than ever before. Is there a pull stud depreciation epidemic going on that I don't know about?

R

 

G

Garwood

Diamond

Joined

Oct 10, 2009

Location

Oregon

• Jul 9, 2020

• #8

litlerob1 said:

I've seen more Thread topics on pull studs in the last year than ever before. Is there a pull stud depreciation epidemic going on that I don't know about?

R

Click to expand...

You might be on to something. BT50 90 degree studs are just about unobtanium.

 

A

AJ H

Hot Rolled

Joined

Feb 5, 2019

• Jul 9, 2020

• #9

Garwood said:

I have a shitload of BT45 pullstuds. Even a nice Jarvis BT45 90 degree head.

Post up a picture of what your stud looks like.

Click to expand...

I tried attaching the .STEP file with no luck. Anyway the ones I made are off to heat treat, they should work fine. If not I'll reach out, thanks for the offer anyways.