Mystery Project...

Cruz'n right along...

Here's the bottom holes of the taper block which are lining up quite precisely with the bolt holes and registration pin hole. Haven't made the pins yet (we'll get there) but, I used a drill bit for a test and it was dead on (wheew!).

Threaded Holes.JPG

The bolt at the top is a tang keeper. MT has a tendency to spin so the bolt can optionally be screwed in lightly up to the tang to keep it from spinning.

Tang Keeper.JPG

And of course, MT's tend to get stuck so there's a threaded hole in the back to push out a stuck taper piece.

Knock Out Hole.JPG

Here it's just sitting in position to give some perspective. The disk accommodates 6 attachment pieces. Perhaps the pictures are clear enough to see a rounding bit was used to break the corners of the block. Quite necessary to do that or this thing would be a knuckle widow maker.

Positioned.JPG

Now it's time for heat treating which I might start tonight -possibly tomorrow. After that, we'll black-oxide it then clean-up the taper and holes after treating.

Ray

Knock Out Hole.JPG Positioned.JPG Tang Keeper.JPG Threaded Holes.JPG
 
Heat treating went very well -amazing what happens when you follow the instructions exactly... I was working during some intense rain and windstorms in the area and keeping my fingers crossed we didn't lose power. -Got lucky today.

I made a change of plans on the final Rockwell by testing some old MT tapers. Of course, I went through a mental exercise wondering if the taper block should be harder or softer and since I couldn't make-up my mind or find info about it, decided to make it the same as the tools which were about 45 on average.

Also, I used argon gas this time around and no foil wrapper. I rigged a steel tube in the heat oven, calculated the amount of cubic space and squirted gas in long enough (with a little extra for good measure) to theoretically displace the same volume. During the process, I gave it a 5 second shot about every 15-20 minutes. This seems to have worked very well. The part is 4140 which calls for a 1575 degree soak until the part is thoroughly heated (which is roughly 30 minutes for a part this size) followed by an oil quench. When the door was opened, there was no scale or decarburizing on the surface at all -just a glowing red/orange object with no flakes peeling off. I used 2 gallons of trans fluid in a steel bucket with a piece of bent-up expanded steel in the bottom. Much to my surprise, it brought the oil temp up to 350 degrees. It was constantly agitated. The part air cooled to 150 and tempered at 700 for 2 hours followed by a fast water quench. After the oil quench, the part turned black but that's just oil burn-off that came off easily with a few moments of sandblasting when it was all done.

The Rockwell near the edges and next to holes was 47 and the thick cross sections were 44. It hit an average of 45 almost on the nose.

The part dimensions were measured very precisely before and after treating. No change whatsoever. The finish reamer was used to clean-up the taper. No metal came off, just the black coating from the oil. All the MT centers and drill chucks etc fit like a glove -just like a store-bought unit... Happy camper tonight!

Tomorrow: A little more sandblasing and then black oxide.

HeatTreatedMTBlock.JPG

HeatTreatedMTBlock.JPG
 
Today I made three more taper blocks; one is for 5C taper and two more MT3. To see pictures, just look at the last post 3 times.

I also normalized the pieces of 1x6x8" 1018 plate that will be used for the base. Can't open the oven door to take pics -they need their privacy until they've cooled down to below 300F.


Ray
 
Today, the three blocks were heat treated and it was no picnic quenching all of them. On the first one from a few days ago, the quench left the oil at 350 degrees so this time around, I put the bucket inside a large flowerpot filled with ice water. This time, I was able to keep the final oil temp at 170. It took 3 large bags of ice; one for each quench.

Also, here's a pic immediately after the final tempering -and this is what it looked like after the quench. I used a little more argon (and more frequently) when treating today and it came-out a cobalt blue color. If you look closely, there's no sign of scale or decarburization. The exact same recipe was followed and the Rockwell results on these were dead-on compared to the first one. 45 +/- 2 RC.

All that's left now is a light finish pass in the surface grinder followed-up by grinding the bases to proper size.

Soon we'll start working on the base/pedestal portion.

Ray

Cobalt Blue.JPG

Cobalt Blue.JPG
 
Ray, thank you for a very interesting thread. I appreciate the knowledge you are sharing with us.

Tom
 
Here's just a tiny bit of eye-candy... I only had time to do some finish surface grinding today. Here's the bottom of the taper block and man, this piece of treated 4140 is both hard and tough! It's been giving the surface grinder a run for it's money and I've tried several wheels. Any downfeed more than a thou and you can hear the (1HP) motor slowing down. On this one, I didn't mill the step as closely to spec as the others and I had to take 10 thou off to allow the centerline of the taper hole to be at 1.125". Took a long time to take that 10 thou off. The walk-over was limited to much less than 1/8". -Won't be making that mistake again.

Anyhow, it looks really nice to see in person and it's a real pleasure to hold something you made that is unbelievably hard and tough...

BTW: The chafed areas around the bolt holes are from the sandblaster held at very close range to clean-up the threads. For the most part, normal sandblasting doesn't phase this piece of metal.

Ray

Hard and Tough.JPG

Hard and Tough.JPG
 
OK, decided to make one more taper block. This one will be a 5C collet holder.

Once the metal block is square (which I should give a description of how I do it -I'm sure there are many ways) it is placed in the lathe. The piece needs to mount in at an offset because I make a ledge on the bottom with about 1/4" overhang. The center height of all holes must be 1.125" from the base as that's what I've chosen and it will also allow taper blocks up to MT4 with plenty of meat on the sides to drill the hole and not interfere with the bolts. I designed this in Alibre CAD so there is no thinking/measuring on the fly.

The part has to be flat in the lathe for the starting hole to be straight. A travel indicator is used and by running the carriage back-forth and by checking all 4 sides, adjustments are made until the part is "perfectly" flat. In all reality, I quit making adjustments when the indicator shows under a thou from front to back. No doubt, the hole won't be perfect no matter how hard I try.

This alignment is done while checking to see the offset center is still perfect with the tailstock. The center mark was pre-struck on the bench.
Squaring-Up.JPGFind Center.JPG
I'm making this one today (took a vacation day to pick-up the new tool grinder) so I'll take more pics of drilling the hole etc later on.

Oh, here's a sneak preview of the metal for the base...
Metal for Base.JPG

Ray

Find Center.JPG Metal for Base.JPG Squaring-Up.JPG
 
As promised, here's a few more shots.

First the hole was bored. I want a very tight fit -and I got what I wanted and managed to get the collet a little bit stuck. The part was warm and I bored it to 1.25" -knowing well that it's going to shrink about 0.0015" when it cools down. My plan for this one is to make a 1.25" power reaming bit. [BTW: I picked up the tool cutter from the terminal today. It's going to be a few days before I get to it.] Anyhow, I went inside for a cup of coffee and when I got back the collet was pretty stuck in the hole. A few moments of heating the outside got it unstuck.

For reference, I found this collet chart on google images.

See that kitchen magnet on the ways? That was my depth stop indicator when power boring the hole.

BTW: That boring bar is home made. Works just peachy.

Boring hole.JPGColletDimensionsMedium.jpgIn the truck.JPG

Next, the compound was set to 10[SUP]o[/SUP] and the 5C taper was cut in. That took all of 2 minutes. Mondo got smart and heated the block a little for another quick test fit. Looks good. Mondo was real smart and didn't get coffee before removing the collet.

Basic Shape.JPGSeated test fit.JPG

And finally, I wanted to get an idea of the concentricity of the hole. That's pretty important here. The inside calipers along with inside telescoping gauges (not shown) showed the diameter to be very consistent. -That's not too important now because it will be reamed. The important part is knowing if the hole is straight. Using the long (chopstick-like) calipers, I could pinch from the inside of the hole to the outside of the side and it showed no gross error from front to back. There are other ways to do this (based on the same theme) and I'll do a more precise job once it's reamed.

Chopsticks.JPG

That's it for today...


Ray

Basic Shape.JPG Boring hole.JPG Chopsticks.JPG ColletDimensionsMedium.jpg Seated test fit.JPG In the truck.JPG
 
Moving very slow today but got my morning chores done and also cleared the area for the new roof. Work starts on that Thursday.

Anyhow... Here's the start of the drawbar for the collet closer. Easy enough. 24TPI and something like 1.055" diameter according to my measurements. Just using a piece of 1045 for the threaded end and a scrap laying around for the drawbar. I'll heat treat it next time the oven is hot. BTW: That's a fast & hot carbide cut on the shoulder. About 900 RPM, 25 thou DoC with probably 0.007 IPR. Just guessing at the IPR as I usually don't mess with it all that much.

Endcloseup.JPGThreaded End.JPG

Here's the drawbar. The shoulder on the threaded end fits precisely into the 5C hole. That will keep it aligned when it's tightened. The collet is not screwed on all the way for demonstration purposes. The back end of collet seats against the shoulder to help keep things square.

Drawbar.JPG

Here's a quick preview of the setup. I'll be making a new base but now, it's just sitting up there to see what it looks like.

RoughLayout.JPG

And here's yours truly commemorating what is probably my three hundredth shaft with a threaded end. -Pretty sure I can do them in my sleep now.

Me.JPG

OK, maybe when it cools off later today, I'll do some more on it.

Ray

Drawbar.JPG Endcloseup.JPG Me.JPG RoughLayout.JPG Threaded End.JPG
 
Back
Top