metric vs. imperial belts

Bearings/Motors/Belts/Gears/Etc.

metric vs. imperial belts

Postby generalsocial » Sat Oct 15, 2011 6:21 am

I was getting a little frustrated since I couldn't find an XL belt that was long enough for my z-lift.

I went into my parts box to see what kind of Nema 17 motors I had. I have some with 5mm shafts.

I went to McMaster and boo hoo, I didn't see any metric.

But when I went to sdp-si, yippie! They had lots. And belts as long as 7m!

Q1) If I go metric which pitch should I use?

Q2) Is it a common practice to drill pulleys? For example if I got some with 6mm bore for my z-lift, I could drill them to 1/4" so they will fit on my 1/4-20 shaft? Is that a good idea?




Darcy
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Re: metric vs. imperial belts

Postby BenJackson » Sat Oct 15, 2011 6:46 am

T5 is very close to XL (5mm ~ .196" while XL is .200") but the space/gap ratio is different so there is backlash if you use a T5 pulley on an XL belt. I haven't seen it but I suspect a T5 belt will not mesh with a XL pulley. Remember that tooth count and belt pitch will determine how far the axis moves. I mention all this because mixing up T5 and XL is common among 3D printer builders...

If you go all metric then T5 is probably fine. Boring out a pulley with a drill is probably fine for the Z lift since there's wobble (the threaded rods aren't exactly .25") anyway. Spur gears are commonly sold with min/max bore (to be modified by the buyer on a lathe) but they are solid metal.
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Re: metric vs. imperial belts

Postby generalsocial » Sat Oct 15, 2011 8:24 am

I'm finding that the https://sdp-si.com/ site has metric pulley bore with metric belt size and imperial belt size.

So I might be able to get everything there.

Also, they have lots of very long belts if you go to the metric stuff.
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