Real 1144 "Stressproof"

[jgedde]

Add one more naming varietal: Cold Drawn Stressproof 1144. I've yet to do anything serious with my stick, but its going to get a try for a cylinder liner & a crankshaft. The C/S is not as complex as yours.

With OLM you get a manufacturer spec sheet for everything purchased so at least some confidence what's in the box corresponds to a specific alloy/standard.

https://www.onlinemetals.com/merchant.cfm?id=286&step=2&top_cat=197

Yes, true. Cold drawn is the same as cold formed but has a different name.

The 1144 in the list are all different. Not just different names. The materials are not equivalent...

-J

 

[10K Pete]

Be careful here!! "cold drawn", "cold formed" and "cold worked" are all different things.

Please note that La Salle cold works the steel to achieve those physical properties. They bend it back and forth through rollers to alter the properties. Think of it as a mixture of work hardening, toughening, etc. It's not just work hardening.

Cold drawing is pulling the metal through dies to compact it and reduce the size. This is cold working also but without the bending back and forth.

Cold forming can be anything but is usually used to describe bending to shape during fabrication to achieve a shape.

The devil is in the details.... Always!!

Pete

 

[django]

Any "Cold" working will introduce internal stresses and therefor need stress relieving/annealing. Have you actually asked your supplier if the material they are selling you has been stress relieved/annealed? We used to use "Pit cooled" black bar for rollers and shaft work and it is very stable.

 

[jgedde]

Hey Guys!

I did it!!!! No significant warpage! The new material obtained locally (which was certified A311 Class B) worked like a champ!

The crank is finished except for facing of the ends to length to get rid of the centers and to cut a keyway.

Good day here!

I use spray glue to put a paper drawing (1:1) scale on the part as an aid to use for roughing and as a sanity check against carriage movement measurements. Way simpler than marking out...

The cuttng tool shown in the pic is a .125 parting blade with a slight dish cut in the face of the cutting edge. The dish more or less eliminated chatter.

John

 

[Wizard69]

Thanks Brian,



I'm still not 100% sure it's the McMaster material. There is a decent chance it's me or my technique. I don't feel comfortable complaining until I know for sure.



I'm virtually certain it's not a grinding problem since the first crankshaft was fully turned, not ground. I only went to the grinder because chatter was an issue. At that, I was only taking a few thou at a time.



Oddly enough, and this may be another clue: a few times I took a break. When I came back and ground another few thou, I noticed the sparks occurring irregularly (sparking out once per revolution). No changes except for time. This, of course, would clean up after a pass, but it makes me wonder....



John

Your use of jack screws bothers me significantly, especially after saying above you give the nut a quarter turn after the jack is snug. While screw pitch dependent that will distort your crank. The more jacks you put into place the greater the distortion.

Your material may be bad but i suspect your machining methods are a bigger factor. Basically you will bow the crank with the jacks. How much would be very interesting to figure out but you need to start with the lead of the jack screw.

To look at this another way if you are using machinist jacks in a setup and turn the jack screw a quarter turn how much does the jack lift the work piece? It depends upon the lead in the jack screw of course but it is very predictable.

 

[jgedde]

Your use of jack screws bothers me significantly, especially after saying above you give the nut a quarter turn after the jack is snug. While screw pitch dependent that will distort your crank. The more jacks you put into place the greater the distortion.

Your material may be bad but i suspect your machining methods are a bigger factor. Basically you will bow the crank with the jacks. How much would be very interesting to figure out but you need to start with the lead of the jack screw.

To look at this another way if you are using machinist jacks in a setup and turn the jack screw a quarter turn how much does the jack lift the work piece? It depends upon the lead in the jack screw of course but it is very predictable.

Thanks Wizard,

Remember the jacks are held in place by the side plates. I finger tip tightened them, then grabbed the screw heads with needle nose pliers 1/4 turn more. Then locked down the nut which loosened them somewhat. They were a snug fit between the throws but could still be pulled out by hand. Then I clamped the side plates which keeps the jacks in place.

Since my original post, I've since been successful making a crankshaft which is now installed in the engine along with the cylinders and connecting rods. I used the method described above. Rotates nicely with no binding.

Finally beat the problems. When I used real 1144 Class B, the first crank I made came out perfectly! Problem was with the original material I bought.

Cheers!
John