> We are a husband and wife engineering team with over a decade of combined experience developing high-performance products for the aerospace and energy fields. Through our YouTube channel, we break down complex engineering topics into entertaining and informative videos. We hope to democratize access to mechanical engineering knowledge via the internet in the same way that others have made electrical and software engineering approachable.
> The effort you and detail you have put into your videos is beyond anything I have seen anywhere else. I can’t thank you enough for taking the time to put this together. By the way, the juxtaposition of your two voices really adds to the professionalism. I am a home machinist but I want to do as close to professional quality work as I can and your videos are a great part of that.
Much can be learned from their approach, e.g. providing templates and other actionable references for students to apply the techniques.
> We designed this ruler with the engineer and machinist in mind. Made of tempered 301 Stainless Steel with a natural brushed finish and photo etched markings, this ruler is a high-quality measurement tool that will not wear with use. Additionally these are made in the USA // 6" Steel Rule with Imperial and Metric Units // Machinist's Ruler // Engineering Ruler // 1/32" and Decimal Inch & 1mm and 0.5mm Graduations
I don't think people would get used to having a nice day being 300 degrees, and water freezing at 273.15. You've got to pace yourself in these metric conversions, tenths of an inch is something that wouldn't get undone the next day.
??? Metric, not scientific notation. Water around my place greezes at 0c and boils at 100c, both of which are far easier to understand than any other system.
This is an excellent site. I have some machinery and grew up in a machine shop so I know my way around but lack the nuanced experience due to circumstances well beyond my control.
I am also VERY thankful they transcribed their videos otherwise I would have skipped the site entirely as video is not a format I enjoy. We need more quality content like this that isn't locked up behind some crappy walled garden guarded by commercials and flanked by ads.
This is an excellent and concise video on the subject. It's while since I've had to bore precision holes and ages since I was taught how to do so, so it was an excellent refresher course.
Its comments on measurement and metrology are particularly strong and well worth listening to.
On that point, I wouldn't use calipers to measure the ID of a precision hole but I'd almost forgotten that scaling error requires the ID jaws of calipers to be a thou or so smaller than the OD ones. Stands to reason when you think about it. Raising that issue shows how useful this video is, it shows that its authors pay careful attention to detail.
Similarly so, their comment in respect of plug gauges and the trouble in differentiating between them during hole measurements due to burrs etc. (I'm a bit obsessive about deburring workpieces properly and I get pissed off when I see others failing to do so - so this comment rang bells with me.)
I'd strongly recommend this video to just about everyone in the machining game.
Some additional comments and opinions:
1. Precision drilling with a 3 flute stubby carbide drill is a good way to achieve +/- 0.001 size tolerance in certain materials and size ranges, close to what you can get with a reamer and blisteringly fast speeds.
2. For long holes, guide drilling with a stubby drill is superior to spotting for orientation, and does just as much for position.
3. Spotting at 75% of the finished diameter isn't usually necessary, it's better on small sizes to pre-chamfer using the spot drill to 130% or spec rather than post-chamfering. Most holes would want to have a chamfer.
4. Optical comparators are useful for profile measurements.
5. Go/no go gages are not well characterized as a cheap and easy way, they are the final say and represent both the state of the art in metrology and the actual geometric definition of the tolerance limits for size and any other geometric control that you care to specify. For metrology of very tight tolerance holes and bores at small sizes, precision ground gage pins are the most expensive way to go and are irreplaceable. For larger bores, 2- and 3- point bore gauges and micrometers are to be seen as a necessary evil. I view 2 point spherical gages or micrometers as superior to 3-point cylindrical mics, because they tell you much more information about the bore shape.
6. The best designers avoid tight tolerance features except where strictly necessary.
7. I would tend to avoid straightness, cylindricity, and circularity, when tolerancing holes, and focus on the more general concepts of size, position, and surface profile.
8. Diameter compensation offsets are usually easier to adjust in the machine control than adjusting the boring tool, and can usually get close enough, especially on a horizontal CNC milling machine.
Thank you for posting this video. I've been working for 12 years as a mechanical engineer learning so much of this video piecemeal and usually through "the hard way". Thanks! Can't wait to watch the entire series.
24 comments
[ 3.7 ms ] story [ 57.1 ms ] thread> We are a husband and wife engineering team with over a decade of combined experience developing high-performance products for the aerospace and energy fields. Through our YouTube channel, we break down complex engineering topics into entertaining and informative videos. We hope to democratize access to mechanical engineering knowledge via the internet in the same way that others have made electrical and software engineering approachable.
As one commenter said, https://tarkka.co/2019/04/28/engineering-drawings-how-to-mak...
> The effort you and detail you have put into your videos is beyond anything I have seen anywhere else. I can’t thank you enough for taking the time to put this together. By the way, the juxtaposition of your two voices really adds to the professionalism. I am a home machinist but I want to do as close to professional quality work as I can and your videos are a great part of that.
Much can be learned from their approach, e.g. providing templates and other actionable references for students to apply the techniques.
Took a couple decades before I knew exactly what I had done wrong.
If I were King for a day, all inch rulers would have at least one decimal scale. 8)
> We designed this ruler with the engineer and machinist in mind. Made of tempered 301 Stainless Steel with a natural brushed finish and photo etched markings, this ruler is a high-quality measurement tool that will not wear with use. Additionally these are made in the USA // 6" Steel Rule with Imperial and Metric Units // Machinist's Ruler // Engineering Ruler // 1/32" and Decimal Inch & 1mm and 0.5mm Graduations
I am also VERY thankful they transcribed their videos otherwise I would have skipped the site entirely as video is not a format I enjoy. We need more quality content like this that isn't locked up behind some crappy walled garden guarded by commercials and flanked by ads.
Its comments on measurement and metrology are particularly strong and well worth listening to.
On that point, I wouldn't use calipers to measure the ID of a precision hole but I'd almost forgotten that scaling error requires the ID jaws of calipers to be a thou or so smaller than the OD ones. Stands to reason when you think about it. Raising that issue shows how useful this video is, it shows that its authors pay careful attention to detail.
Similarly so, their comment in respect of plug gauges and the trouble in differentiating between them during hole measurements due to burrs etc. (I'm a bit obsessive about deburring workpieces properly and I get pissed off when I see others failing to do so - so this comment rang bells with me.)
I'd strongly recommend this video to just about everyone in the machining game.
2. For long holes, guide drilling with a stubby drill is superior to spotting for orientation, and does just as much for position.
3. Spotting at 75% of the finished diameter isn't usually necessary, it's better on small sizes to pre-chamfer using the spot drill to 130% or spec rather than post-chamfering. Most holes would want to have a chamfer.
4. Optical comparators are useful for profile measurements.
5. Go/no go gages are not well characterized as a cheap and easy way, they are the final say and represent both the state of the art in metrology and the actual geometric definition of the tolerance limits for size and any other geometric control that you care to specify. For metrology of very tight tolerance holes and bores at small sizes, precision ground gage pins are the most expensive way to go and are irreplaceable. For larger bores, 2- and 3- point bore gauges and micrometers are to be seen as a necessary evil. I view 2 point spherical gages or micrometers as superior to 3-point cylindrical mics, because they tell you much more information about the bore shape.
6. The best designers avoid tight tolerance features except where strictly necessary.
7. I would tend to avoid straightness, cylindricity, and circularity, when tolerancing holes, and focus on the more general concepts of size, position, and surface profile.
8. Diameter compensation offsets are usually easier to adjust in the machine control than adjusting the boring tool, and can usually get close enough, especially on a horizontal CNC milling machine.