Treadmill motors - my modifications.

[Moby Duck]

1. I like this modification but have concerns over the heat generated, particularly if used for a belt grinder. A normal fan ventilated motor gets some respite from full load heat when the load is removed and the motor is still running and ventilating. A fully enclosed motor is subject to a continuous build up of heat, slightly less when off load, but still there, and it has nowhere to go. Sealed motors usually have fins on the outside and if necessary have a fan attached to cool those fins.

2. Fitting mesh filters at each end will do very little to improve cooling unless you retain the fan to draw the air through the armature area.

3. Lowering the speed by rheostat reduces the torque as you pointed out but I understand that there may be better electronic speed controllers available that allow a full range of speeds without torque loss. Those fitted on the more expensive treadmills tend to have no loss of torque with speed reduction.

4. Retaining the original flywheel fan for its flywheel effect and for the cooling air it might draw over the outside of the motor might help with the cooling. Heat sinks attached to the motor body and retaining the flywheel fan would help more. Many people utilise the treadmill speed controller and RPM indicators. The speed indicators are driven by a sensor on the flywheel, another good reason for keeping it. It is common to attach the drive pulley directly to the flywheel by bolting or welding and your way of truing it up would be perfect for this as well.

5. There is much debate on the web about whether the drive wheel should be crowned on a belt grinder. Suppliers of ready made wheels generally supply crowned drive and tracking wheels but that doesn’t make it right. There is an excellent explanation somewhere on the web, (I had thought it was your excellent website tonyfoale), that explains how only the tracking wheel should be crowned. If both wheels are crowned they tend to fight each other for alignment.

6. I wrote this assuming that you were building a belt grinder but now see pics of a tool & cutter grinder. Heat is going to be less of a problem with such a grinder and the relatively light loads involved. May it last you forever.