Chris's Build of Battleship Ohio Engine

[Admiral_dk]

Great progress 

but totally impossible at this scale without access to a resident watchmaker!

And me who thought that You are the Resident WatchMaker 

Per

[crueby]

Great progress 

but totally impossible at this scale without access to a resident watchmaker!

And me who thought that You are the Resident WatchMaker 

Per

I can do clocks. Watches, nope. Thats another order of magnitude smaller. Can change the battery in one!   

[crueby]

This morning I was going to start in on prepping the bars for the crank webs, but first decided that it was time to finally do another of those ten-year-and-one-hour jobs, and finally make a work stop for the mill vise!  Dug out an offcut chunk of anodized aluminum bar the right size, a bit of 1/8" rod, a SHCS, and the bolt/t-nut from the old tall toolholder from the lathe (since replaced with QCTP). Drilled a few holes, drilled/tapped a few more, and came up with this, which has three heights for the stop rod for different size stock and depending how its raised up in the vise. The two larger holes with black threads visible were already in the bar, they are not used for this tool.


So, that long-procrastinated job done, it was put to use taking the blanks for the crank webs (8 of them) to size. So far I have one end of each trimmed square on one end, ready to take them to final length. They will also need to be narrower.

[cnr6400]

 

I think you will find the work stop accessory very handy! Don't know how I got along without mine for so long. It was a similar 10 yr + 1 hr project.

Looking forward to seeing the web-based  crank parts taking shape. 

[crueby]

I think you will find the work stop accessory very handy! Don't know how I got along without mine for so long. It was a similar 10 yr + 1 hr project.

Looking forward to seeing the web-based  crank parts taking shape. 

So the Ohio invented the internet as part of its engine... interesting!   

[ddmckee54]

So the Ohio invented the internet as part of its engine... interesting!   

I was told that Al Gore did that, a feller always learns sumthin new in the ole inter-webb.

[crueby]

The crank webs are all trimmed to length, now startin in on the width, taking a little off each side. The new work stop is 'work'ing out great.

[crueby]

All of the crank webs have been taken to length and width but not thickness.


One thing I was concerned about was the tapers that are at either end of the webs - on some of the steel bar stock there is a tendancy to warp slightly if one side is milled off but not the other. Both tapers are right where the shafts go through, as you can see in this shot from the CAD model. The taper at the main shaft end is smaller than the one at the crank pin end.




I ran a test, tapering one end of an offcut like the real webs will be:

I checked it against a straightedge before and after, and yup, it took a very slight bend away from the area cut back. Not much, but I am concerned that if I bore the holes first and then cut the tapers, which would avoid any interrupted cuts in the boring, the end will get tipped slightly, and then the shaft assembly wont run true. That would be very bad over the length of this shaft.

So, what I am going to do is cut the tapers on the ends, and then take a trueing cut on the outer faces to get them flat again before doing the holes.
 

[Prowler901]

Sounds like a good plan.  What about heat soaking them as well?

Todd

[crueby]

Sounds like a good plan.  What about heat soaking them as well?

Todd

I don't have a  heat treat oven that will go to temps needed for steel. My kitchen oven will go high enough for brass. Not sure how high it needs to be for 303 stainless?

[cnr6400]

From my time in industry, I recall that to anneal 303 stainless you would need to hold it at about 2000 F for 15 min per pound of material, then rapid cool it in water. This is just as extreme as it sounds. You can covert it to bananium very easily by annealing it - all the cold working stress loaded into it during manufacture is unlikely to be fully relieved by annealing. If you want to avoid the big "BOINGs" I'd keep it at room temp and machine your bores and tapers cautiously, as you planned.

[crueby]

From my time in industry, I recall that to anneal 303 stainless you would need to hold it at about 2000 F for 15 min per pound of material, then rapid cool it in water. This is just as extreme as it sounds. You can covert it to bananium very easily by annealing it - all the cold working stress loaded into it during manufacture is unlikely to be fully relieved by annealing. If you want to avoid the big "BOINGs" I'd keep it at room temp and machine your bores and tapers cautiously, as you planned.

Good to know!  So 303 doesn't have  a stress relieving temperature,  just an annealing  one? Its so handy with brass to be able to stress relieve without annealing. Do you know if 303 can go to silver solder temperature  without the  issues?


 

[Prowler901]

Well then, let's not do that. 
 

[Kim]

Wow!  No idea that stainless acted like that!  I've stress-relieved steel (like 1018) using a torch to just get it nice and hot all the way through for a while and let it cool slowly to room temp. That has worked pretty well for me.  For steel at least.  Sounds like it wouldn't work for stainless... good to know! Yikes!

Kim

[cnr6400]

Chris, with the 300 series of stainless I used in industry I found that annealing was the only effective stress relief that was practical and predictable, especially with small size stock. With stock 1 1/2" thick or thicker our heat treater did some lower temp stress relief treatment that worked OK, but the procedure was very involved with many temp-up, hold, temp -down etc. steps and took a while, so it was costly. The small bar and rod stock just has so much cold working stress rolled in that it moves a lot during machining unless it's annealed first with the 2000 deg F / water quench. (your mileage may vary - all steel mills are not alike!) 

In industry I always tried to avoid costly heat treater annealing by designing parts in 300 series stainless to be machined with all over cuts on the outside of the stock first, fairly heavy cuts, let it go to bananium if it wanted to, wait 24 hr, re-establish datums and carry on machining. If the part distorted severely, to become full clovehitchium or squareknottium, it was scrapped. Not many parts warped that bad though. We did need to re-calibrate things sometimes if we got a raw stock shipment of really stable low stress material or really unstable high stress material. We really missed the old 'Goldilocks Stainless Inc' mill though, when they went under. Their stainless was always j-u-s-t right! 

I think silver soldering temp is far enough below anneal temp that you would not see annealing happen. But you can get warpage and distortion silver soldering stainless. In industry TIG is preferred for most stainless work generally, but you have to plan ahead and adjust for distortion doing TIG, too. There is no free lunch! 

Kim - yes heating to red heat and slow cooling in sand or wood ashes is very effective for stress relieving mild steel (low to medium carbon steel). Stainless stress is a whole other ball game! It's a fine material to work in but it takes a while to get to know the game plan.