Why M6 for leadscrew?

Hi Nophead,

Why M6 threaded rod for leadscrews on the Z axis?

It works great on my kit, but other companies use bigger acme or M8 leadscrews. Just wondered why you went the M6 route. I'm guessing that price and the pitch of the M6 was a benefit.

Also, was M5 just too small?

Thanks for your answer.

Mendel90 is still making great prints!

Chris

Hi Chris,
The decision was fairly arbitrary but mainly for cost reasons. Smaller screws need less torque to turn them but also have a smaller lead so the speed stays about the same. However smaller ones tend to be less straight. M5 has the advantage of being the same size as the motor so I experimented with coupling it just with tubing, like the Prusa I3. I found it wasn't concentric enough and too slow, so I stuck with M6 as a compromise. M8 is probably best, but more expensive.

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[www.hydraraptor.blogspot.com]

M8 rods cost 77 eurocents/meter in the metalshop around the corner and till now they have worked beautiful, so I wouldn't call it expensive

Stainless or BZP?

Try buying hundreds and find out how many are straight enough to use!

Try cutting up hundreds of 1m rods into the right length, grinding off the burr and re forming the thread with a die.

I am on my fourth supplier of lead screws and now buy them the right length with correctly formed threads on both ends. I still have to reject about 5% and scrap them and they cost me a lot more than EUR0.77 per metre.

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[www.hydraraptor.blogspot.com]