Hey, I just got some new pulleys for a new build and wonde how they look.
While they were quite expensiv I would like to know if this is a sign of poor quality or ist it just because they are bigger? The smaller ones I have also have that pattern, but much finer.
You can barely feel it, so it might look worse on the picture than it is, but I just wonder if that is normal at all.
Can someone tell?
I made a photo of them compared to smaller GT2 ones
Those look like tooling marks. If that is what they are, it would explain the expense. Someone put the blank on a CNC mill and drove an end mill down the length of the edge.
Generally, given that the shape of the “teeth” is important, a machine shop will have a special cutter with the profile expected and using a rotary table cut the slots that way and then either assemble or weld on the “sides.” In your case you can see the edges of the teeth are perpendicular to the center (not shaped) and that is why I conclude someone just used a straight sided end mill.
For what it is worth they will not transfer energy to a timing belt as efficiently as one which has the proper profile.
they look fine! if available I suggest using locking devices for connecting them to the shaft.
@Chuck_McManis The tooling marks look more like hob scallops than a milled profile which is the standard method for generating that type of profile. If cleaner profiles are required the parts would require a shaper cutter or would need to be shaved after hobbing.
That profile may be designed to work with a silent chain instead of a cogged belt, but there shouldn’t be much difference in efficiency unless the loading is so high it causes slippage.
Just make sure which ever pulley you use matches the belt 100%. If they don’t, the belt is going to jump and that is the last thing you want. Different sizes of pulleys will give you different operational speeds. You also want to use the same size on all axis.
Good luck.
Those look good to me. I bought T2.5 pulleys and every one was bored off centre. Needless to say I won’t be using that supplier again
Thanks everybody, so it seems that is not poor quality but normal processing.
And by the way those are HTD profile, I dind’t told, sorry.
Belt fits perfectly,theres just a very little gap to from the belt tooth, but the pully tooth looks good.
@Abi_ghafari I have two screws to lock it on the shaft. But i think you mean something diffrent. Would you share a link with me please?
Why can’t everything be nicely extruded or possibly EDM.
@Joe_Morrison I don’t know much about gear cutting. Know of any good web or reading material with explanations and examples?
@Dwayne_Knight_Dark_C I don’t know if I would completely class this as a good place to learn. As a trade magazine it can be either very basic or super technical. However http://www.geartechnology.com/ is worth looking at. I have a free subscription so I skim the print version monthly, I think the same content is available online without a subscription.
Because extrusions and EDM cost a lot? The finish of EDM might prematurely wear out belt teeth too. It’s the texture of sandpaper, maybe 220 grit.
It seems like those pulleys could have been machined better, but I bet they’ll do the job fine.
@Jeff_DeMaagd
I thought EDM could have a nice finish and then the part would be rocket science expensive.
Hihi, that just remembers me of a friend of me who worked on the eurofighter and he actually build up a very nice bbq grill with some nose parts of the jet.
The grill would cost over 500k if you would buy those parts. But he also told they aren’t worth it, it’s just criminal how they calculate and manufacture those parts.
@Dwayne_Knight_Dark_C EDM has a nice finish, but it’s not a polished finish. It cuts material with strikes of electrical arcs, so there is a surface roughness that is easily visible. I can ask the EDM guy that I know if changes can be made though. But I’ve seen many parts made with the process and I’d be concerned that it would wear out the belts.
Maybe the teeth are polishable with fine tumbling media. But yes, it would be an impractically expensive part.
@Jeff_DeMaagd
That’s fair I didn’t think about post processing. I just know EDM is used in some very high precision applications I don’t normally have to deal with.
Depending on the material used EDM also leaves a remelt layer at the surface so you can end up with some pretty undesirable material properties.
