RedDirt
Gold Member
- Joined
- Dec 4, 2007
- Messages
- 469
- Location
- Northern Idaho
- Tractor
- Kubota BX23, Wards 16HP HST Garden Tractor, (previous) D2 Logging Cat
Arnie,
Yes, you are correct to measure your impeller diameter at the tips of the blades.
Another discovery I made at TBN is for efficiency in throwing snow (distance) the critical item is the gap between the impeller blades and drum. This is especially true with wet snow. One members who is extremely critical in this regard keeps his clearance to the thickness of a dime and claims to throw snow (as I recall) 100ft.(!) My clearance is about 5/16" and if I end up not throwing far enough I'll look here first. I think 1/8" clearance would be what I would shoot for.
To reduce the gap there is a product available (I don't recall the name) comprising of rubber type flaps with backing plates that can be bolted onto the existing impellers. Some have welded a bead on their impeller edges and milled (grind/file?) to fit. Others have added sheet metal liners to their drums. So there's several options and approaches.
My feeling regarding reducing the impeller/drum gap is that the critical location for the closest tolerance would be in the last third or quarter turn of the impeller rotation before it reaches the chute outlet. A larger gap up-rotation from this would only be slightly detrimental. It is just before the snow exits where the clearance needs to be tight. With this in mind it may even be possible on some blower designs to shift the impeller shaft in the correct direction to achieve the required gap for the quarter turn before the chute. On my design the impeller shaft is held in place with a flange block through bolted to the back of the drum. I could slot the mounting holes and adjust the impeller clearance that way then roller pin the block to the backing plate to hold it in position. Of course I'd then have to adjust my gear backlash but I made provisions in my design to do just that.
Yes, you are correct to measure your impeller diameter at the tips of the blades.
Another discovery I made at TBN is for efficiency in throwing snow (distance) the critical item is the gap between the impeller blades and drum. This is especially true with wet snow. One members who is extremely critical in this regard keeps his clearance to the thickness of a dime and claims to throw snow (as I recall) 100ft.(!) My clearance is about 5/16" and if I end up not throwing far enough I'll look here first. I think 1/8" clearance would be what I would shoot for.
To reduce the gap there is a product available (I don't recall the name) comprising of rubber type flaps with backing plates that can be bolted onto the existing impellers. Some have welded a bead on their impeller edges and milled (grind/file?) to fit. Others have added sheet metal liners to their drums. So there's several options and approaches.
My feeling regarding reducing the impeller/drum gap is that the critical location for the closest tolerance would be in the last third or quarter turn of the impeller rotation before it reaches the chute outlet. A larger gap up-rotation from this would only be slightly detrimental. It is just before the snow exits where the clearance needs to be tight. With this in mind it may even be possible on some blower designs to shift the impeller shaft in the correct direction to achieve the required gap for the quarter turn before the chute. On my design the impeller shaft is held in place with a flange block through bolted to the back of the drum. I could slot the mounting holes and adjust the impeller clearance that way then roller pin the block to the backing plate to hold it in position. Of course I'd then have to adjust my gear backlash but I made provisions in my design to do just that.