Mystery Project...

Here's a little more eye candy. This is the underside of the plate.

Today's a rest day. Gotta pay some attention to the dogs and then I'll do some heat treating and shop cleaning. I spent a good day on that thing yesterday and getting punch drunk from it. (CNC would fix that).

Can't tell you enough how valuable the power down-feed and auto-stop feature on the mill was for this. It did all the drilling and countersinking. Didn't even wear-out any of the bits much less break one. The metal is soft as butter though. 1045 that been fully normalized (spheroidized state). The only thing I had to do by hand was finish the inner circle of holes -lest I drilled into the rotary table. The rotary table is 6" diameter. Sometimes I wish I had a bigger table but this one is so easy to heave around etc... Anyhow, for the inner circle of holes, I set the auto-depth to 85% depth and finished them off on the drill press.

BTW: I got an unusual PM from someone about this and some of my other demonstration projects so let me explain... I'm well aware that nothing I'm showing is rocket science and I try to give decent verbal descriptions and show pictures to help some of the folks that are learning this for the 1st time. Some people learn with pictures some folks need written words etc.. I wish I could show you the turbine engine I'm working on but, it's self-designed with some "interesting features" that I feel are marketable -so, the interesting shop photos are not put in the public domain.

Ray

Finished raw plate.JPGClose up.JPG

Close up.JPG Finished raw plate.JPG
 
I'll refrain from comment about that PM aside from this comment. :)

Personally I love threads like this. I'm watching this to see the project unfold, and if there's any useful methods or tricks along the way that's even better, but certainly not why I follow it. This stuff is like crack to me (or how I imagine crack would be lol). Even if I knew better ways to do every step, I'd still follow it just to see how it turned out.

:nicethread:
 
I love threads like this- thanks Ray! It is a lot of trouble to take pics while working- and even more to organize the info, descriptions, put it all together and post it all.

Not only to I love reading these posts, but appreciate the effort putting them together.

That said, I love that plate already, and it isn't even done yet!
If you have time, in this or another thread, I am interested in how your auto downfeed operates, and auto stop. I am wondering if I can retro fit my mill or drill press someday. :)


Bernie
 
OK... It survived reentry and NASA has no reports of known falling debris. -The scientists are trying to decipher the braille-like code. It's definitely from a different world... It happened to land in a tank of semi-synthetic cooling water in my driveway and made a loud screaming and creaking noise for the better part of 20 seconds and left the water at 155 degrees F. It was a very eerie sound -almost scarey like the sound of tremendous pressure being placed on the outside of metal and the inside was screaming, looking for a place to go -but was trapped. And 20 gallons of water went from 60 to 155 in 30 seconds... You do the math -that's a lot of BTUs in a short time. With energy release like that, certainly a fundamental transformation of crystalline structure took place before my eyes. Before the men in black and dark sunglasses arrived, I happen to do a Rockwell test which indicated 32RC. As those guys with dark glasses left, they took a flash picture of me -and suddenly, my memory of the preceding few hours is sketchy...

Reentry Item.JPG

Ray

Reentry Item.JPG
 
.
... Anyhow, the main plate is all done. Tomorrow I'll heat treat and carburize it hopefully to RC 40. That should be plenty as it's mainly for scratch resistance and to protect the indexing holes as they will used by the operator every time the turret position is changed.

Ray

Ray,
After fussing with lining everything up to tenths aren't you putting all that precision at risk by heat treating. 1045 should get to RC 40 without any particular problem except that the whole thing could warp more than a few ten thousandths. Then once hard isn't it a grinding process to recover? Just wondering.
Paul
 
Hi Paul,

Excellent question! A: Yes and no...

The piece was very well normalized before machining. It was literally like butter all the way through with no internal stresses. When drilling the holes, there were no hard spots and it felt only slightly tougher than 60-series aluminum. When you machine non-normalized metals (which have a lot of internal stresses) the final heat treating process will warp it considerably and screw-up all the machining. Matter of fact, one of the reasons I got into this, is that non-normalized parts were changing shape unpredictably as I was machining them. -Because the internal stresses were being released by removing parts of the outer layers. I can tell you a very easy test to show it in action. Normalized metal does not behave that way and this is precisely why metal is normalized.

I have noticed in previous experiments that tiny features are obliterated. A light scratch on pre-treated materials almost vanishes after treating. This is actually nice and it hides all the little burrs and fine machining marks. The overall dimensions don't change in any measurable way; that is, it neither contracts or expands (once you get the scale off that is). It's still perfectly flat. Yes, a few ten-thous here and there will change but it's not significant. For this piece, final grinding and re-reaming etc is not needed but if it were critical, yes, everything would need to be re-done. For this thing, I'm going to sand blast it (which will have a greater impact on dimensionality than the HT process) and follow up with black oxide.

BTW: It's not until you get many hundred degrees past the austentizing temperature that metal will actually start to droop macroscopically under it's own weight.

I guess I forgot to mention; the part has already been tempered. As soon as it hit 150 in the tank, it was pulled and put back in the oven at 950F for 90 minutes -then re-quenced. That last step brought the RC down to the desired level. I have no idea what the RC was immediately after the HT quench -probably off the charts. Metal in that condition is highly unstable, cannot be used for anything and could literally shatter if dropped, and is considered dangerous.

I started out with the highest precision I could muster-up on manual equipment only because error stacks up. A bad part at the start will only get worse as operations are done.

Finally, just before I treated it, I tapped it with my finger and a drill bit. It just went thud, thud, thud. Now, sitting on the bench in the same spot, it rings just by flicking it with your finger tip and it sounds like a bell when tapped with a drill bit. -Cool. It will pick-up a couple more actual Rockwell points by sitting over night and will show 1-2 more points once all the scale is removed (which is really a limitation due to rebound RC calculations). It will probably end-up at 35 which is what I was shooting for.

Ray

PS: Sorry for the long winded answer -guess I did it again...


Ray,
After fussing with lining everything up to tenths aren't you putting all that precision at risk by heat treating. 1045 should get to RC 40 without any particular problem except that the whole thing could warp more than a few ten thousandths. Then once hard isn't it a grinding process to recover? Just wondering.
Paul
 
Just a follow-up thought about dimensionality changes... When the part was freshly machined you could see rainbow colors reflecting off it. This is because the uneven surface features were on the order of microns -which is the same wavelength as light. The varying sized surface features reflected different wavelengths (i.e. different colors) in different directions; thus, you only see the pattern of colors that aren't getting reflected away from your eye. After heat treating, those surface features are obliterated and you no longer see the rainbow colors... -meaning the external changes due to treating are on the order of microns (1x10[SUP]-6[/SUP]). Macroscopic changes such as large dimensionality changes happen mostly for metal that's not been normalized or, for metal shapes with combined large and small features such as a thick piece of metal with a deep groove milled into it. The thin area in the groove will bend. Actually, it's a mistake to let this happen because, a part should only be heat treated to the extent of the thinnest cross-section... Anyhow.... Monolithic pieces don't change much at all -if any at all.

Ray
 
Awesome write up Ray!! How are you measuring the hardness? I have seen the machines at a shop I worked at while I was in school. But it was a super duper thing in the QC room.

Thanks,
Chris
 
I have a Brinell impact tester and a simple rebound tester. The rebound tester is a clear tube about 14" tall with measured numbers on the side from bottom to top. It drops a chrome steel ball and you read how high the ball bounces then, look-up on a chart and compare the piece thickness and bounce height and it converts to RC. This believe it or not, is surprisingly accurate. I've established a fixed impact method for the Brinell tester (which is basically what a Rockwell test unit does for you). RC and HB (Brinell) are very similar but use different impactor geometry. Anyhow, for clean materials, the two methods show within a point or so.

I did a good deal of reading about the history of the common methods (Leeb, Rockwell, Brinell, and Vickers). Leeb is an electronic version of the bouncing ball method. It's the most commonly used portable hardness test these days. The others are just variations of the same theme (although the inventors strained mightily to differentiate themselves).

I started to get analysis paralysis about which method to use. Conclusion: They're all decent and each plays in the other's backyard. They're all good. Rockwell has name appeal and familiarity hence, all methods do their thing well and most people use tables to convert the number to the familiar Rockwell.

Could say more about this but, decided to do some improvements on the heat treating box today....

Ray



Awesome write up Ray!! How are you measuring the hardness? I have seen the machines at a shop I worked at while I was in school. But it was a super duper thing in the QC room.

Thanks,
Chris
 
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