We are continuously learning about precision machining, surface grinding, and other topics in making and engineering. Talking with those who are experts is a great way to learn, and putting what they suggest to the test is a common theme on this channel. SUBSCRIBE and join us on this journey!
Kinetic Precision grew out of the need for prototyping specialty antennas in support of AntennaSys, Inc. and its consulting and low-volume production needs. We have produced antennas which have been thousands of feet deep in the ocean and to the edge of space.
We make and sell the famous PFG Stones®. Others make stones, but ours are PFG!
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Links for products/designs mentioned are at pfg.gg/links
Follow me on Instagram at "spencer_webb_nh".
("PFG Stones®" is a registered trademark of Kinetic Precision)
Now you need to put a reminder in you phone to change the batteries next year or at least I do as I wouldn't look at that stick until there is a problem.
Sadly. Work says enyrhing with Bluetooth is not allowed as its causes distractions from us machining and dont allow us to hear the machines running. Yet hearing protection is required.
Why not use compressed air around grinders ? I do cylindrical grinding in the aerospace industry and I havent heard that before now. Am I missing something?
It's an old adage, and is to prevent operators from blowing grit into the grinder ways. Of course, if you know what you're doing, there's no reason not to do it. Though sometimes you'll hear me joke about never using compressed air around the grinder, as I am doing just that.
I *think* you're referring to the book _The Perfectionists_, by Simon Winchester. Which is not specifically about gun barrels, but the evolution of precision in machining and measurement. Highly recommended in printed or audio format.
Also, the elephants foot is caused by two different things: Expansion of the resin due to high over-exposure and build plate squish during exposure due to too fast a retraction speed that doesn't allow sufficient time for the resin to completely squeeze out from the 0.05mm (typical) initial gap between the LCD screen and the build plate. Long exposure delay after retraction finishes also is necessary to minimize elephants foot.
I almost exclusively print directly on my build plate with my Elegoo resin printers (Mars 3 Pro and Mars 4 Ultra 9K). I use a chamfer as well, but you have to change the angle and the height of your chamfer to match your base layer and transition layers. I typically only use 1 base layer and 10-ish transition layers and thus you chamfer height needs to match the height of your base + transition layer and the angle is calculated based on the base and normal exposure times. This helps the thickness issue, but to solve that completely you need to slow the retraction speed way down for all the layers, but mostly for the base + transition layers. The details are specific to the resin being used since the amount of elephants foot depends on the resin.
Sorry I missed the live stream - one thing I use all the time is vented screws. When designing anything that bolts together that has to live in vacuum, we use vented screws to prevent those little pockets of atmosphere in the bottom of blind holes from "wrecking" your vacuum. (think big cameras in astronomy)
Given how cheap USSR flats are and how expensive monochromatic sources are, do you have any advice on budget-friendly light sources for the home gamer?
@@howtoguro Yeah that's kinda what I've been thinking. My biggest concern is how to know if you've spread the laser light enough to be safe. But I'm pretty conservative with regard to injuries, especially with my eyes.
@@ParallelTransport You could just wear laser shades. Even really typical clear safety squints provide some protection against lasers. Full nuclear mode would be to view it from a secondary camera and monitor. Sadly, powerful lasers are too common. I actually bought a red laser point for a “Cat Toy” because I figured it would be weaker, but it was a class 3R so be really careful.
An additional point: the molten salt bath definitely does not mean sodium chloride which melts at 804º C (bright red heat). I don't know which salts are recommended, and it may well be a mixture that melts at lower temperature than any of the components. GIven your low tempering temperature, molten salt may not be an option.
@@KPNH Agreed, the salts I've seen are a mixture of sodium and potassium nitrate which are the oxidizers in black powder. Nothing you want in your home.
Hi Spencer, sorry to miss this but I was snoozing after drinking Easter brunch in one of the very picturesque clip joints in very picturesque Newport RI. I agree that a quantitative analysis of the quench process is likely to induce nausea, vomiting and collapse, but we can do some useful hand waving. The two major factors are the volumetric heat capacity of the liquid and its viscosity. You want the former should be high so less liquid is needed to remove the heat. The latter should be low to assist convection. Professor Lipton's non-intuitive recommendation to heat the oil probably serves to reduce its viscosity. Don't forget that Larrin Thomas is mainly interested in knives which are no thicker than 1/4", I'll bet your hardness pattern of softer in the center is due to inadequate heat soak. I doubt your hardness measurement is deep enough to sense the difference in quench rate between the thick and thin parts.
Whew, that is an intense heat treat cycle! I think once upon a time we talked about using those non-contact IR guns in shiny surfaces: if you're trying to get a truly accurate temperature you'll end up having to take the emissivity of the target in to consideration (which might be pretty hard to do on a treated surface like that). In other words you might not have even been off by the 5 degrees, just the reading on the fluke. I'd bet that lab oven uses an RTD sensor and you could use that as your emissivity calibration? Looking like a very nice tool already, can't wait to see it get to the point you can ring a jo block to it!
Thanks! Yes, emissivity is important when using an IR thermometer. Basically, it's accurate for a "black-body radiator". Conveniently, our oxidized, blackened part is essentially that. BUT, a shiny ground part is the opposite, and the surface of a liquid is even worse. I'll try to post a link to an article that explains this. Thanks for your feedback! 👊
Your longer soak time will help. Keep in mind the inner section has more mass than the outer section due to the groove therefore different heat and cooling times on thin and thick sections. It is always nice to be able to heat treat the part to a higher RC then Draw back to the desired RC. At 65 RC you may be pushing the limits.
Hey, Steve, thanks for the input. Yes, I think the adjustments I'm going to try (soak time, quench temp) are going to help, but the cross-section is what it is. It not super-critical to have perfect uniformity, but it's a goal!! If I went crazy about it, I think I'd clamp on some filler material into the groove. But, that's beyond the scope here. Thanks for your wisdom!!
Steve, did I hear you say that you have changed from D2 to DC53 as your material of choice for steel parts? If so, how has this changed your heat treatment protocol?
@@carltauber2939 I use to make tools out of A2. D2 was to brittle for my projects. DC53 is a little more wear resistance than D2 and about the same toughness as A2. I send my parts to Hansen Bulk in Grand Rapids Michigan for heat treatment and have them do Cytogenetics treatment as well. The parts are even more wear resistance and tougher after Cryo and much more stable.
I made 3 lapping plates inspired by Tom Lipton using 3 plate method. Cast iron 8 inch dia 1 inch thick. I of course did not grind them by hand but programmed my CNC mill. It took hours of grinding but got a magnificent result measured by laser interferometer. You might consider mechanized lapping. In High School I made a telescope mirror but made a machine to do the work first. Watch you regularly. JY
@@KPNH I was talking about the T nut part of the video. I thought an option there may have been to Tig weld 2 pads instead of the shim, then file them down until you have a nice fit. It was just what came to mind, Probably because I had been Tig welding the day before lol. Its probably a classic case of "The Law of The Instrument" P.S. love the video's
@@KPNH Yes, I saw it. At some point I was also concerned with that, but after I tested it a couple of times and it was within 0,5HRC all around everytime, I stopped worrying about it. But I usually work with quite highly alloyed steels like ESR D2 (1.2379) so that could also make a difference.
Nice job, I disagree with your measurements however, and it’s a very typical outcome. If you get the right answer you move on, if you don’t you check again, and again. One result disagreement and recheck of that result, undermines every other single check measurement. I recognise at this point your feel on the parts over many process you know what is ultimately there or not. But it is interesting how tradespeople process these situations.
@@KPNH probably the same to be honest because if you handle the part enough you get a feel for it. I find it interesting that we question wrong answers more then right ones, despite the methods of acquiring the result being the same. High precision is not my field I am a general machinist, so I cannot provide a better method with actual experience to back it up, but the issue of judgement affects us all. I don’t know if a dial indicator on a stand would offer a less subjective result?
