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I use the smartphone as a camera, protractor, guitar tuner, FM radio, stellar map, ball bearing catalog, H-M forum reader when in bathroom… then I generally use this one to call and receive:
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Slip Roller
- Thread starter Ray C
- Start date
I use the smartphone as a camera, protractor, guitar tuner, FM radio, stellar map, ball bearing catalog, H-M forum reader when in bathroom… then I generally use this one to call and receive:
- Joined
- Nov 16, 2012
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A beautiful, cool day today -perfect for some shop work and heat treating...
Both ends of all rods were drilled 1.1" deep and tapped with a 5/16-18 thread. Slots were cut across the centers for a drive mechanism -which I haven't decided-upon yet. We'll start with a simple handle on one roller and if that's not enough traction, I'll add some gears to drive the bottom two.
Next up is some heat treating. I've been using argon flooding to displace oxygen in addition to a few small pieces of cardboard to burn off. The argon is proving to be very effective because, the cardboard didn't seem to combust during the 1570F heat treat; rather, as soon as the door is opened when it's time to remove the pieces, oxygen hits the cardboard and it immediately bursts into flames. BTW, that's stainless steel safety wire pre-strung on the shafts for handling purposes. If you do something like this, do not use normal bailing wire (unless you want to pick a 1570 F hot object off the floor). Wire hangers are used because handling the shafts with tongs will damage the fragile hot surface.
I've been experimenting with some quenching solutions and this quench went very well. Absolutely no boiling took place and hardly any fine bubbles at all... -just the sound of screaming metal. -It makes a screeching, screaming sound a few moments after it's dunked in. That sound, by the way, is from the rapidly contracting outer skin crushing down on the center which is so hot, it's technically a solution. It's this rapid compression that locks the molecular structure in place giving it hardness. Somewhere along the line, I read about the pressures taking place at that time -and the numbers (which I don't recall) were astronomical.
Very little decarburization which means the argon flood is doing it's job.
The pieces were tempered for an hour at 600F to bring them to about Rockwell C 50.
As soon as they cool down, I'll measure them, roll them on the granite and see how much distortion took place. The bearing shoulders are oversized now and I'll use ceramic inserts to bring them to size.
Ray
Both ends of all rods were drilled 1.1" deep and tapped with a 5/16-18 thread. Slots were cut across the centers for a drive mechanism -which I haven't decided-upon yet. We'll start with a simple handle on one roller and if that's not enough traction, I'll add some gears to drive the bottom two.
Next up is some heat treating. I've been using argon flooding to displace oxygen in addition to a few small pieces of cardboard to burn off. The argon is proving to be very effective because, the cardboard didn't seem to combust during the 1570F heat treat; rather, as soon as the door is opened when it's time to remove the pieces, oxygen hits the cardboard and it immediately bursts into flames. BTW, that's stainless steel safety wire pre-strung on the shafts for handling purposes. If you do something like this, do not use normal bailing wire (unless you want to pick a 1570 F hot object off the floor). Wire hangers are used because handling the shafts with tongs will damage the fragile hot surface.
I've been experimenting with some quenching solutions and this quench went very well. Absolutely no boiling took place and hardly any fine bubbles at all... -just the sound of screaming metal. -It makes a screeching, screaming sound a few moments after it's dunked in. That sound, by the way, is from the rapidly contracting outer skin crushing down on the center which is so hot, it's technically a solution. It's this rapid compression that locks the molecular structure in place giving it hardness. Somewhere along the line, I read about the pressures taking place at that time -and the numbers (which I don't recall) were astronomical.
Very little decarburization which means the argon flood is doing it's job.
The pieces were tempered for an hour at 600F to bring them to about Rockwell C 50.
As soon as they cool down, I'll measure them, roll them on the granite and see how much distortion took place. The bearing shoulders are oversized now and I'll use ceramic inserts to bring them to size.
Ray
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- Dec 17, 2012
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Now that would be an interesting video… overall for the audio!
) Very interesting.
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- Nov 16, 2012
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Well, the shafts are done with no immolation of self or property... I wanted to take pictures or videos but seriously, cutting with ceramic is nothing to play games with and it's just too distracting. I was quite busy making sure nothing was going up in flames. I cover the ways with stainless foil, wear a welding jacket and of course full face protection. I clip a piece of thin plywood over the handwheel and carriage lever -and still, I got one nice little burn (but not too bad). The chips coming off are white-hot and make melted spots in the stainless foil.
It's worth it though, have a look.
BTW, whenever I heat treat a part that cannot itself be tested, I toss in a reference/control piece of the same material. The piece used today was the same diameter as the bearing shoulder on the shaft and about 1" long. It tested-out at RC 53 and I'm guessing the larger pieces (probably) came out between 49-51.
Note that the KoolMist is not pointed at the part. You should not use coolant with ceramic bits. The tips turn orange hot and a drop of water would probably blow them up.
... They ring like a bell for 30 seconds. My son's girlfriend is kinda "artsy/musical" and I swear, she was driving me nuts tapping on them for 30 minutes...
Ray
It's worth it though, have a look.
BTW, whenever I heat treat a part that cannot itself be tested, I toss in a reference/control piece of the same material. The piece used today was the same diameter as the bearing shoulder on the shaft and about 1" long. It tested-out at RC 53 and I'm guessing the larger pieces (probably) came out between 49-51.
Note that the KoolMist is not pointed at the part. You should not use coolant with ceramic bits. The tips turn orange hot and a drop of water would probably blow them up.
... They ring like a bell for 30 seconds. My son's girlfriend is kinda "artsy/musical" and I swear, she was driving me nuts tapping on them for 30 minutes...
Ray
- Joined
- Mar 17, 2013
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- 87
Wow those shafts look as though they were ground !! Very nice looking ray.
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- Jun 17, 2012
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Ray, How much material did you leave on the ODs prior to hardening for further turning after they were hardened?
I was watching the guys this week operate the OD grinding machines at the shop I'm subbing for and was asking a few questions. It was very informative. I had really had no prior exposure to OD grinding machines prior to meeting up with these guys. I've been around a few centerless grinding machines but never the centered type. In most respects they're like a super accurate lathe with a a huge toolpost grinder attached and lots of flood coolant.
Marcel
I was watching the guys this week operate the OD grinding machines at the shop I'm subbing for and was asking a few questions. It was very informative. I had really had no prior exposure to OD grinding machines prior to meeting up with these guys. I've been around a few centerless grinding machines but never the centered type. In most respects they're like a super accurate lathe with a a huge toolpost grinder attached and lots of flood coolant.
Marcel
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- Nov 16, 2012
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25 extra and I almost cut it too thin. I didn't normalize this metal before working on it and one piece bowed a good bit and to get it straight I had to under-shoot my target diameter by 5 thou. The other two didn't bow as much and cleaned-up easily. I'll used the skinny one on the top since the bottom two might end-up as drive rollers and I want them spinning at the same SFM.
Ray
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- Nov 16, 2012
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Thanks... I have a nice OD toolpost grinder but, these came out OK and the application doesn't need that level of precision... Somewhere here, I showed some shafts that were turned with the grinder. That's really good when a shaft has to be dead-on from end to end.
FWIW, I've only used the ceramic a handful of times and the finish usually looks pretty snappy -but no different really than medium hardness metal cut with carbide. LOL: In all honesty, it doesn't look much different than any one of the several hundred boat shafts I've turned except it glimmers with that nice rainbow color more than stainless does.
Ray