MIT Tech TV Videos on Machining....

Pete link=topic=256.msg2741#msg2741 date=1295052217 said:
Those videos are good but they do contain quite a few suspect methods. Some of them would get that instructor banned from my home shop. MIT could and should do better. I certainly don't know it all, But for certain things I do know more than that instructor.

Pete
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Can you elaborate? Granted, guards have been removed in the interest of being able to film the operations.

It's been way too long since my Jr. High School wood and metal shop classes, and we never used lathes. About the only thing that really bothered me was his use of a band saw, and not lowering the "foot" to the peice being cut. There's a bearing that the blade should get pushed into, and the closer that bearing is to the piece being cut, the less likely the blade will break and/or derail (and break). There are a few comments made by reviewers that point out some other errors, but honestly, if you can point out something that I can learn from, I'd appreciate it.

Thanks,
- Arved
Newbie Sieg SX2 Mini Mill Owner (and S/N 00666 at that!)
 
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I appreciate your comments. Thanks. Some are things that irked me, too.

Pete link=topic=256.msg2745#msg2745 date=1295067846 said:
-Buffing wheels set up and used in the same areas as the grinders. Airborn grinding dust WILL contaminate that buffing wheel, Why try to polsh parts with a contaminated wheel? Your wasting your time.
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Yes, and also using one buffing wheel for multiple polish grits. A buffing wheel is only going to produce a finish equal to the coarsest grit in the wheel. And your right, if the coarsest grit is the junk from the nearby grinding wheel, that's what it's going to produce.

Pete link=topic=256.msg2745#msg2745 date=1295067846 said:
-He say's drill presses drill very accurate holes.Depending on the defination of accurate, In machinist terms, drilled holes are not very round, on size or even all that straight. If you want a fairly accurate hole then reaming is required. Better yet you drill the hole, Single point bore it to get it round and straight and then ream it for size. Were not even talking about what some industrys use for real high precision. Drills are very efficient at metal removal but their not real accurate.
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Lots of issues. I wouldn't want the quill extended like that one is. Minimize extension to increase accuracy - the same reasons a milling machine is recommended for more precise drilling, but you covered that below. Some will probably argue that a keyless chuck may be less accurate than a keyed chuck.

Pete link=topic=256.msg2745#msg2745 date=1295067846 said:
-I certainly wouldn't use a pair of dial calipers to scribe parts. Scribes cost a few bucks. Good 6" dial calipers can cost $100 or more. Would you buy a Ferarri to haul gravel? Your just putting wear and tear on those dial calipers doing that.
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Yes, I was shocked at that. There are calipers for doing that, but not that type. Divider style calipers, for instance.

Pete link=topic=256.msg2745#msg2745 date=1295067846 said:
-While showing the X.Y table no mention was made about using the table axis locks. If your depending on the leadscrews to provide accuracy and hold the table in position then your mistaken. All leadscrews have backlash. Those table locks would be a lot better than the leadscrew.
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I'm not sure what's the bigger "oops" - drilling into the table, or drilling into the vise. I guess I learned to use a lot more sacraficial material (like wood or scrap metal) to protect the equipment.

Thanks for taking the time to share your thoughts.

- Arved
Extreme Newbie ;D
 
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You used to be able to down load these a few years ago. Wonder what happened to that?

Paul
 
The thing about brushing away the chips with his hand also bothered me. From first hand experience. You only need to get a metal sliver in your hand once, I think. At least, for me. Yeah, that's what those "chip brushes" available everywhere (even Walmart has them) are for. That and a shop vac.

There are a bunch of different cutting/coolant fluids out there. Even virgin motor oil is fine as long as you don't eat or drink the stuff. It's only bad against your skin when it's been used in a motor, and collects blow by gases from the combustion process. But yes, even with something that is toxic (and even not), good shop practice and the use of Personal Protective Equipment (PPE) is a must. Funny how he'll show how to stand when using the bandsaw, but doesn't give much other advice during the rest of the presentation.

That said, the video is for robotics lab students. It's not a trade school turning out machinist apprentices. Most of these kids will go into industry and sit in front of a computer working CAD/CAM all day. If they're lucky, they'll be called down to the shop floor when there's a problem. Otherwise, machinist will probably fire off an e-mail to them asking them why they did something bone head like reference all dimensions to the edge of a casting (and forget that there just might be a draft angle on the part). ;D

I wish the local high school or community college offered machine shop classes as part of an adult ed program. I'd take it. But they don't.

Thanks again,
- Arved
 
Pete,

Common sense has become an oxymoron. What makes sense isn't common, and what's common doesn't make sense. :D

Have fun,
- Arved
 
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