Finally got the milling machine home.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Steviegtr on 16/03/2020 18:47:57:

So can I ask in the order of strength. Which is the weekest to strongest. I.E I take it R8 is stronger than MT2 but what above that, MT3 etc ?????? +all the old sizes .

Steve.

That's a really interesting question!

I'm not sure the question is on target in the sense that I don't believe holding strength is the main design criteria. The main purpose of tapers and other holders is quick tool changing. MT tapers grip well, but their simple drawbar arrangement slows down tool-changes and – incorrectly adjusted – they're prone to slip. Hence other designs that either improve speed and/or reliable setting up.

I'd guess the main limitation of a machine would be it's spindle strength rather than the taper type, and the spindle should be designed to take at least the power of the motor plus a safety factor. So in the case of MT, motor power determines spindle size, and spindle size determines the taper.

I've got books explaining the maximum power that can be transferred by a shaft, but I don't think I've seen anything giving the power handling capacity of a friction grip taper. Machinery's Handbook let me down, I shall do some more digging.

Given that tightening a stone-cold male taper into a hot socket can require a big hammer and heat to release it, I'd guess the power handling capacity of tapers is high – better than a single key, not as good as splines.

Dave

[SteviegtrParticipant @steviegtr]

Thanks guys I knew I would get an answer I can understand. I will await the arrival of the cutters & then find out the size of holder I need. It could be a few weeks I guess before I can try them. I have ordered some EN1A mild for a job to do. I need to order some Aluminium for the 1st try. All tips greatly appreciated & thanks again.

Steve.

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