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i have some questions about material thickness and bolt sizes.

what thickness of aluminium plate is needed for certain bolt sizes

For example i want to tap some 10mm plate of whatever size is m5 the biggest i can fit while still retaining strength

For example i think this was m5 into 10mm thick plate but could m6 been used? talking about tapping into the TB mounting plate not the cable adjustment plate



would like to know for m3 m4 and m5

Clear as mud?

Edited by wolfie on 29th Jan, 2011.

It would depend on what you want to hang off the screw.

"Commercially pure aluminium has a tensile strength of approximately 90MPa and can be improved to around 180MPa by cold working. The heat treatable grades can develop a tensile strength of around 570MPa and even higher in some alloys (7001). This figure compares favourably with mild steel which has a tensile strength of approximately 260MPa."

The number before the dot on a metric bolt is the tensile strength of the steel in 100's of Mpa. The number after the dot gives the relative yield strength in tenths i.e. 8.8 means 800Mpa & 8/10ths (or 640Mpa) to put it in to yield

http://www.tech.plym.ac.uk/sme/desnotes/boltb.htm

It'd be just as easy to copy what's used on similar components or rig up a test by screwing whatever it is to some ally scrap.

Edited by TMF interloper on 30th Jan, 2011.

Thought I'd have another go, for if you're just thinking of up sizing the existing screws?

Obviously a bigger screw will be stronger (more thread area) but it will be relatively easier to pull the threads out of the flange as the ratio of length to diameter will be less.

You could use this to roughly calculate the difference for going from M5 x 0.8 (32tpi) to M6 x 1 (25tpi) http://www.riverhawk.com/boltloading.php

or better

http://www.futek.com/boltcalc.aspx?mode=metric

Edited by TMF interloper on 30th Jan, 2011.

Ive always taken an aproximate thickness from a nut for whatever size thread you want to use and add half again for aluminium. It is only a rough guide though but good enough for anything Ive done

Paul

I seriously doubt it!

TMF
I am currently making something and it can be made with a wall thickness of 8mm but would prefer 6mm, looking at it my best bet is m3 bolts i think

Edited by wolfie on 30th Jan, 2011.

thanks guys its given me something to think about

when you drill the tapping hole wolfie go under size 0.25 mm it will make the the threads a little more especially in ally

drilling slightly under size is a good tip, but how much will depend on the thread size. The "thread minus pitch = tap drill" thing gives about 85% thread engagement iirc. Of course in the real world you might go under size 'cos that's the closest drill bit you have.

Build it 'n see, if you pull the threads you can always retap 'em bigger.