Need input on a possible way to make a T5 belt pulley

[Zoltar]

Youre Welcome!

Stacking of 2D parts is a idea too, but maybe harder to get right/straight

The advantage of two halves is that it can simply be combined on the hub,
You've got your rim giving extra support next to the belt,
and it could look good too on the side

Ive been exploring CNC-cutting aluminium on my hobby machine for some time.
With good Alu and a decent cutter its actually pretty easy.
So if you have a Fab-Lab in your neighberhood or some CNC-addict...
it should not be that hard to get a decent result.

Looking forward to your final solution!

Chris.

[etard]

Very Cool Zoltar! Can you post a pic of your CNC?

I wonder what happened to the OP"s belt pulley drive?

[Kin]

Just want to subscribe here in case people post some more useful links.

[Zoltar]

Hi Etard,

Just check the URL under the avatar....

OP?

[Miles]

OP?

"Original poster", I think.

[Zoltar]

"I wonder what happened to the OP"s belt pulley drive?"

Indeed OP, learned a new shortcut (SC)

I also do wonder how Wheazel's the Pully did work out.
Was its strong enough for this purpose ?
How the flanges on the gear where solved.
(an aluminium rim -bolted trough-on both sides would provide sufficient strength/body I guess)

Overhere Ive modified my HTD pulley a bit and also found that
even the belts have a slight variation in pitch.
Could be caused because its a (China) non brand.

Testing it wit a longer HTD belt proved to work fine.
Now that Ive received a short one wich I am actually gonna use...
the fit of the HTD 5 on the pulley is just a tiny bit to tight.
So slight tooth change and gonna have to cut another pair.




Greetings, Chris.

[Zoltar]

A member came up with this idea:

http://www.cnczone.com/forums/epoxy_granite/135197-make_your_own_timing_pulley.html

Casting a HTD-Gear from epoxy.....Idea??

-chris-

[Miles]

Hi Chris,

Interesting. Thanks for the link.

This is a similar method which seems to work well:
viewtopic.php?p=171685#p171685

[bobc]

My experience making a "stacked laminate" pulley - 1st, the tensile members in the belt are inside it, not on the surface, so the outside of the pulley needs to be a somewhat smaller diameter than the belt pitch and N-teeth might lead you to suppose - on the gates carbondrive belt i needed to subtract 1.8mm (!) from the calculated diameter. This might explain why the belt pitch seemed wrong on the pulley (?).
2nd - Zoltar - your CNC'd pulley made from 2 halves - why nottaper the hole in the middle and compress a tapered 'olive' onto the shaft by screwing the 2 halves towards each other. I've made a number of such "home-made taperlock" pulley fixings with 100% success (you could CNC the taper but I suspect you'd be better served popping it into the lathe). The tapered fixings are guaranteed central, no backlash, no damage to shaft, unlikely to come loose etc. etc. - I've stopped using grubscrews ;^)

[Zoltar]

Hey hello Miles,

Thats also a good suggestion!
Thanks for pointing this topic out.

A granite -epoxy pulley would be too heavy also - that is, on a bike....

"home-made taperlock".... This is a valid solution to go for Bob.
Ive tought about that option for a moment, then this is a quick way to test and cut these pulleys.

Grubscrews are indeed not very favorable but can do the job for some light duty tasks.

-chris-

[Miles]

A granite -epoxy pulley would be too heavy also - that is, on a bike....

Indeed. You could, though, have a large alu. inner, spokes and rim, then cast the teeth plus a shallow intermediate layer using this "outer former" method. It would remove the need to ascertain and machine the exact rim diameter, which is essential for the example I linked to. Might be more robust, too. The retaining flange could be turned as part of the rim.

[ZOMGVTEK]

Does anyone have a vector drawing of a gear that mounts to the brake disc?

I want to cut one out of Acrylic/Polycarbonate and see how strong they are.

[Miles]

Does anyone have a vector drawing of a gear that mounts to the brake disc?

Bob has worked out a tooth profile for Gates Polychain: viewtopic.php?p=533008#p533008 That particular one is for the 11mm pitch belts, though...