Re: Timing Belt styles/sizes

Chris,

As you know, I am a proponent of the htd belts FOR cnc drive usage.
Here's a link as to why:

http://www.sdp-si.com/herb/spk/sdp-si/D260/HTML/D260T004_4.html

Notice near the bottom the info about backlash.

Also, a quick web search mentions that the Gates HTD patents have run
out, so you may be on to something re: Gates motives...

Their bifurcated style HTD tooth (gt2?) works well also, being
essentially an update of the older HTD tooth form.

Until your post, I had never considered backlash to be a
consideration, having seen this type belt used in the drives of $250K
cnc routers, VMC's and mills...

I can say that in practice, it has never been an issue; whereas I
HAVE had problems with the xl trapezoid tooth form.

Hope this helps.

Ballendo

Gates "newest" is the polychain, of which I have no direct
experience. It is however, deemed inferior to the htd for automotive
to aircraft engine conversions.

--- In CAD_CAM_EDM_DRO@y..., ccs@m... wrote:
>
> While trying to pick a timing belt style for the long feed leadscrew
> drive on my lathe, I downloaded a manual from Gates.
>
> In this, they mentioned that the HTD style of belt is designed to
> be stronger, but the tooth shape used to accomplish this requires
> greater clearance than trapezoidal belts, which results in backlash.
> In short, they do not recommend HTD belts for precision positioning.
>
> I had the sense that some here did like these belts for this
purpose.
> Gates may have a vested interest - they are trying to sell their
> new shape, the GT2, but that does not necessarily void their
argument.
>
> What belt series in practice is good for a 600 oz-in motor? A 1000
> oz-in? I used XL on the crossfeed stepper, but assume I need
> something bigger such as H or L for the long feed given that I'm
using
> servo with much more power. I've been able to find a few figures
for
> allowable working tension, but it is unclear if that is installation
> pre-tension, or the tension due to power transmission.
>
> Chris Stratton
>