Thursday, 10 July 2014

When is a belt not a belt?

When its the wrong length!

The Mi1.5 project has been going along quite nicely. I've had a couple of meetings with it with the new center pulley mount and Mi5 pulley and spur. I've made a few small changes like swapping the mount from the left side to the right side (closer to the motor). The main reason is to make changing the spur easier. A little stuff up on my part meant that, previously, I had to remove the whole mount to change a spur but now I just need to removed 3 screws. Fortunately, I haven't had to make anything new at this stage but I will have to clean it up and make something that looks a little more "professional".

Ignore all the spacers and stripped spur - it is a prototype after all

The most frustrating part at the moment has been finding a suitable front belt. Those of you that have read my ramblings before will remember the initial trials with finding a suitable belt, well now that I have some track testing under my belt, it has become obvious that the front belt is far too tight and needs to change. After much re-visiting websites of both RC manufacturers and general timing belt manufacturers I decided to buy a 507mm belt, originally an optional XRay belt but also used on some HPI models. The original choice was 501mm.

Now given how tight the 501mm belt was, I was thinking that 507mm would be close to perfect. After all, its only 6mm longer. How wrong I was. Extremely floppy is the first description that comes to mind. Several hours of consternation, more web searching I determined that I had to make the 507mm belt work. I had the original Mission belt tension-er sitting in a box of stuff and, as I was looking through another box of "junk", I found a piece of carbon fiber that just happened to have a slot cut into it that would be a perfect mount for it. A bit of dremel work, a couple of holes drilled and the tension-er was mounted and seems to work exactly as needed, taking out the extra belt slack.

 The drive line has much less drag now and feels smoother. Track time will confirm if I have everything right and that should be happening this weekend.

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