This is such an awesome project!!! Thank you Tom for showing us how to make this. 👍 I’m just a machining hobbyist with a small manual mill and lathe but definitely want to give this a shot.
I have enjoyed your treatise on the Kingsbury Michelle bearing. As I was watching this I was trying to envision wear this type of bearing would be used in industry. I was speaking with my brother, who has a background as a mold builder but has been in the commercial water well service business for the last 18 years. It came up in conversation that a kingsbury bearing is used as the bottom bearing on some types of turbine pumps. You do provide very useful information.
I needed a place to send a comment. This is as good as any. I am building a thing for my wife. It is a coffee roaster kit. As I was going along I had a thought. I thought, "What would Tom do? Tom would spot drill and put Bozo Marks." You just saved my a...posterior...Thanks. Oddly, I am not a Machinist or a Tool Maker. I watch these to relax and get out of what I do for a living.
Nice High voltage warning sign :D There are also fun ones like: Electricity: Getting up with tension, going resistingly to work, swimming against the current all day long, going home charged, touching the receptable and being slapped.
That hard-milling is giving me flashbacks to when I hard-milled some sprockets on my cnc-converted Harbor Freight mini mill... it somehow did it without issue, but boy was it loud. Hid behind a blast shield for that one.
Hi Tom. Nice project. I think there is a place for improvement: I believe the polished faces should have a knife edge rather than a chamfer. The chamfer allows dust to get pulled in, a knife edge will go a long way toward preventing dust contamination. I think commercial air bearings are designed this way.
I'm led to believe that even machine tool slides benefit from 90 deg sharp corners when they're close fitting, particularly if there's grinding grit about.
I wondered about this too, my thought was maybe the air molecules need a chamfer to be drawn in and float the part? you added doubt that thought though
Nice job Tom. Clever clamping solutions for both ops on the mill, just goes to show you don't need to be gripping on much if your contact areas are good. Cheers, Jon
When removing the carrier on the milled parts, instead of using a facing strategy ( that moves straight across the part) consider using one that moves inward from the outside perimeter ( I'm used to these being called adaptive, but it just depends on the software you are using). That way the unnecessary strips of material on the perimeter are milled away before the end mill reaches the stock that remains. This minimizes the chance of the remaining stock becoming thin and chattering and catching on the end mill. I hope that makes sense.
i get what you're saying, but just a facing operation is easier to setup .. less clicking and making sure everything is perfect :) you can even do it conversationaly right on the machine
I'm almost done making this project. I'm to the lapping/polishing stage. Parts are flat but not very shiny. I've read other places that cast iron laps don't really do a good job getting to a mirror finish. (I copied that project too.) Do I have to use a copper plate or do you have some other secret for getting the mirror finish? It's been a great project. Thanks greg
I'd definitely like to see more retro tool builder logo merch. There have been people here and there making it, but nobody ever really got more than a couple logos.
Thanks for another video Tom. The knowledge you share with us all is truly priceless. Could you please tell me where you acquire your glasses? I can't wear contacts anymore and I'm searching for exactly what you wear... Kinda retro machinist look! Maybe a little green tint to complete the image! THANKS in advance.
Tom, when you milled the counterbore in the hardened part (made my teeth hurt by the way) it appeared the endmill diameter was larger than the radius of the c'bore, this would leave a small convex pip at the bottom (not flat) due to the cutter's end clearance angle. Wouldn't this make the puck want to ride off to one side when resting on the radius end set screws?
Thanks for sharing. Question, When you are grinding with the wheel, how do you accommodate the shrinking of the grinding wheel diameter in relation to the depth of grind? Hope that makes sense Thanks 👍
The grinding wheel diameter only breaks down at the leading edge of the interface between the wheel and the part. As you feed from front to back the front edge breaks down revealing new grinding media, the original diameter of the wheel follows across the newely ground surface. The wheel is occasionally dressed for a true cutting surface and to remove any embedded particulate, at that point the wheel is fed down the appropriate amount.
Hi Tom, what's the purpose behind tappy tapping the parts in a vise AFTER it's been tightened? I understand its to seat the part against the base but why not do it just before you fully tighten the vise?
@@RambozoClownOK, thanks. I'm surprised there's no danger of the part being pulled up or pushed around out of the vise if Tom is able to tap it down with what look like relatively delicate blows.
Every time it slows to a stop there is contact, and it's not in a clean room environment, so there's two reasons for hardening. Third reason is that you cannot readily achieve nanometer flatness with soft materials, if fact they do not respond that well to lapping. The bigger the hardness differential between workpiece and lap, the better.
Yes, but there is a second constraint. The axial bearing must be normal ("vertical") to the plane of the face. So just having a 3 point contact is not enough, you have to be able to either adjust the spheres to bring the axis into plumb, or machine it perfectly from the start.
Hello Tom; You can determine the floating gap quite accurately. Just measure the capacitance with your multimeter. You know the surface area of the capacitor and you know the measured capacitance. There are a lot of online capacitance calculators like this one: hyperphysics.phy-astr.gsu.edu/hbase/electric/pplate.html You will have to work backwards iteratively but it will give you the gap. Great work, always impressed.
It's not quite that easy in the real world. You would need an expensive benching DMM and even the wires and connections come into play when measuring that. It's not something you could feasibly do, especially if you aren't an EE.
@@xenonram Yes, the capacitance is probably in the range of picofarads perhaps below the range of most multimeters. This device: www.ebay.com/itm/L-C-Meter-LCR-LC200A-Handheld-Capacitance-Inductance-Multimeter-Electric-Bridge/182584739286?hash=item2a82e605d6:g:pkwAAOSwusdcJuFA claims to be good down to 0.01 pF. At $35.59 it might be worth a try. (Yes, I know that the spec's are from you know where. ;-) )
That's to exclude oxygen in order to prevent "scaling". Yes, there will be _some_ oxygen inside the package (unless you do the wrapping inside a purged glove box), but (practically) no additional oxygen will be able to reach the part once the oxygen inside the package has done its worst. You could also use an exclusion coating (such as boric acid), or heat treat in a vacuum or inert gas oven.
@@stanrogers5613 thanks! I'd still like to know how the oxygen contributes to this "scaling" you're talking about.. Would the expanding air cause deformation on the piece or what?
@@tohtorizorro Wrapping also prevents loss of carbon (I presume it combines with oxygen to form CO and CO2). Carbon is essential to tool steel and its loss will inhibit austentite formation when the steel reaches a bright red heat . Quenching is the method whereby the steel is trapped in the austenite structure, as there is not enough time for the face centered atoms to migrate back to the body center of the fundamental cubes of the crystal structure. This is why there is a risk of cracking, because the change in structure causes a change in volume of the workpiece.
It was (Tom mentioned) a very free cutting wheel, specially for hard tool steel. With coolant, and a small stepover, it's usual to use quite "heavy" cut depth with such a wheel. This resulting wheel wear is thereby concentrated at the leading edge of the wheel, leading to longer intervals before the entire wheel loses diameter and has to be re-dressed. As a side benefit, the finish is better.
@@Gottenhimfella interesting, thankyou. So, to pick your brain, the term free cutting refers to the 'self sharpening' properties of the wheel; like having a soft matrix allowing wheel wear expose new abrasive grits, and/or friable properties in the abrasive, so is breaks down into a sharp edge after use, or have I got that wrong? And if you had to guess at the appropriate cut depth, what would you say? So he's working the wheel hard and that helps the cutting action, is that correct?
@@ASP1NALL Yes, counterintuitively, you need a "soft" matrix and somewhat friable grains to grind hard material for the reasons you give: As soon as a particle of grit gets dull, it needs to either fracture or be released. As with cutting tools, it's essential to use a sharp edge for hard materials, otherwise you are just burnishing and the cutter will push away from the cut. You can to some extent manipulate the characteristics if you can vary the spindle speed; running slower makes the wheel behave as if it is softer. If you plunge grind (downfeed only, with a wheel as wide as the work) you have no chance of achieving a flat surface because the entire width of the wheel will be reducing in diameter, unevenly. So the best plan is to downfeed a decent amount before commencing a new pass (perhaps as much as 0.2mm, if you have the right wheel, a decent-sized spindle and a rigid machine, and of course enough motor power) with the wheel beside the work, and then use small increments of stepover so that most of the periphery of the wheel is only sparking out, and all the work happens at the leading edge (which will quickly 'dress' itself to a radius followed by a slope) Use a rapid traverse, and flood coolant, which (with a suitable wheel) will keep the workpiece cool. Never stop, or even slow down, on the work. Grinding hard material is easier than soft, if you follow guidelines like this. This is also the best way to true your magnetic chuck. It's (by definition) the largest workpiece your machine can cover, so it's important that the effective diameter of the wheel does not reduce by the time you get to the far corner.
@@Gottenhimfella I was just reading on Norton's website some general things about grinding. They said the opposite, faster wheel behaves harder. This makes sense to me as one time I tried grinding a carbide scraper with a green wheel on a slow speed grinder.. all it did was chew up the wheel
I know for a fact I should never attempt hardening, or at least without gloves. I would have reached over there and grabbed that foil packet with my fingers by accident without a doubt.