Taperlock HTD -vs- AT5 with setscrew

I have ballscrews with plain 12 mm journals (no flat, no keyway) and I need to attach timing pulleys. The two types of pulleys that seem to be available are AT5 pulleys with a setscrew and HTD5M pulleys with taperlock. Would you get the HTD taperlocks or would you file a flat and use the AT5 style?

The screws are ground and fully preloaded. Torque will be limited to about 1 Nm.

My concerns are 1) intrinsic backlash of HTD profile (there seem to be wildly opposing views on the suitability of HTD for accurate positioning) and 2) longevity of using only a setscrew to attach the pulley.

The AT profile is probably optimal; it's supposedly optimised for low/zero backlash. The question is what is most likely to cause problems on a mill: a taperlocked HTD pulley (possibly backlash from the HTD profile?) or a zero-backlash AT5 pulley attached using only a setscrew on a filed flat?

Edit: That is, if I could find AT5 pulleys with taperlock then I would get that, but alas...

I would never use a std setscrew on a shaft unless it had a brass pad, as otherwise it always seems to damage the shaft and makes removal difficult. In contrast, if you can find a suitable Taperlock, it doesn't require a key or set screw and doesn't damage the shaft.

Many of the off the shelf pulleys are machined from lengths of toothed stock from China. I ended up making my own HTD3 pulleys after giving up trying to procure OTS pulleys with the correct tooth profile, due to the loose fit with the belt. That loose fit was translating into fairly significant backlash between the motor and axis.

Muzzer wrote:

Wow, if that's the amount of backlash one gets with HTD then that is out of the question for sure! Great illustration - thanks!

.... my 5cent suggestion .... HTD is for hight power transmission where AT is not .... AT-T and some of 0 backslash (actually there are some special AT with double profile in same section fore reduce backslash) is built for servo or similar ... HTD for direct drive without special control .... plus, check these variable: "maximum force allowed for the belt tension at same belt size"/"money" .... and you will understand the differences ...

bkt
 

tommylight wrote:

I have some mounted on a non finished mill, HTD5,

Quite sure .... think you use a little bit force for tensioning ( think you have some power on your hand ) .... Seriously I have to congratulate you for the work you do here on the forum .... in these days to remind me of the work I left halfway through I followed back the posts of grotius, yours (your thanks have become synonymous with posts to follow for me) and udos .... for more I also found mine I work a year ago on a stick with peek written ..... until I saw the udos comments I didn't know what it was for ....

Thanks
TommyLight ...
      

arvidb wrote:

The AT profile is probably optimal; it's supposedly optimised for low/zero backlash. The question is what is most likely to cause problems on a mill: a taperlocked HTD pulley (possibly backlash from the HTD profile?) or a zero-backlash AT5 pulley attached using only a setscrew on a filed flat?

Edit: That is, if I could find AT5 pulleys with taperlock then I would get that, but alas...
 
 

Is the lack of taper-lock or QD bushing AT5 availability due to location?

Do you have a lathe available?  If so, there are some fairly easy options available way better than a set screw.

And yes, AT5 is significantly better for positioning than HTD.