Tooth Profile for HTD 5M pulley ( NEED HELP)

ESK8 Mechanics
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21

here you have the full explanation http://www.gatesmectrol.com/mectrol/downloads/download_common.cfm?file=Belt_Theory06sm.pdf&folder=brochure

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22

Looks really good. I replicated your equations in SW, but I am missing the equations for TPR1, TPR2 and TPD1. Are they constant regardless of number of teeth? And what about different pitch? I would be very happy if your share this information.

23

Thats a good question. Let me check.

24

I checked. They are fixed values in my equation. Maybe that’s what I got from the cad from the websites.

25

Thank you very much for your effort.

It is a little odd, because your values are just a little different from the ones downloaded from sdp-si.com.

The reason I ask is that I downloaded and printed some wheels from a German website and they performed terribly, but they had quite different geometry from what I later purchased. So now I want to know, what is “correct” if anything is.

26

I don’t exactly remember which website I followed, but the designs have served me well. Haven’t had a belt broken in 2 years, riding roughly 2 miles daily. This is a new pulley that I printed and this is how the belt fits.

MVIMG_20180918_121535

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27

Great, thank you. I will go on with your values :sunglasses:

28

printing gears is also a bit trial and error imo, nozzle diameter and slice settings can change the gear tooth profile so it’s not exactly the same like in your cad software.

29

Also keep in mind that if you got the diameters right but the teeth fitting is tight, just run it anyway, a few minutes ridding the belt will wear the pulley and make a perfect fit

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30

Hey, I’ve tried to replicate your sketch and have double checked the dimensions but it’s still not evaluating as your’s has. Pulley%20Sketch

What is the tangent relation to the outer circle? (tangent symbol below TPR2 dim) I would have thought the R0.45380 would be tangent to the “OD” (24.32) circle but it becomes over-constrained if I do that.

Any hints?

Thanks

31

Perhaps there is a short straight line (0.29 mm for 16T) hidden back there?

Pulley%20Sketch%202

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32

You are much better off importing a 3d model from sdp-si.com and using that as a basis for your pulley if this is a one-off kind of part.

33

Seem like you are using solidworks. PM me with your email. I’ll send you the part.

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34

Thanks! Unfortunately I can’t for the life of me find where to send a PM, perhaps I don’t have that privilege yet. but you could send it here [email protected] thanks again.

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35

I would, but I need a pulley with hundreds of teeth for an e-bike and spd-si only go up to 72.

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36

I just send it to you.

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37

Oof, that’s a dousey.

Keep in mind, they typically don’t go to very high tooth counts because any small error in the tooth profile will compound over each tooth. For hundreds of teeth you’re going to need a very very precise profile, and likely many tests to tune it.

38

my profile is almost, if not completely, identical to sdp-si.com profile. I would be more worried about the 3D printer limits/tuning. image

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39

Yeah, Ill be printing in 4 to 8 (TBC) sections & can add shims between the sections to adjust out any pitch errors that may accumulate. OF course, shims will make it out of round but the effect will be very small.

Although this guy prints a 180 tooth pulley with a poor sketch and seems to do OK:

(Of course, perhaps he was lucky and the error in his sketch could have been corrected by the error in his printing )

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40

In my experience you will have to tune the profile for your 3D printer, print just a thin ring with no infill and adjust as needed

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