A couple of weeks ago I purchased a harbor fright tool grinder. At first it did not seem to be a bad machine except it did viberate more than I liked. Dressing the wheels corrected most of the viberation.
Than I decided that I wanted a diamond wheel and so ordered one from Enco for $83. 00. When I tried to install the new diamond wheel it would not fit the backing plate. The hub of the backing plate was 1.253 while the diamond wheel hole measured 1.251.
Also the orginal green wheels were mounted using 8mm shoulder bolts and they would not work with the diamond as it used a flat head screw diameter unknown but less than the 8mm. I don't have any way of measuring a metric female thread and I don't have any metric bolts.
Now on the backing plate are 4 extra tapped holes that a 1/4X20 screw would just try to start in.
So I pulled off one of the backing plates to make the 50 mile trip to the hardware store and get the correct bolts for the diamond wheel and ones that would work in the smaller holes as the 8mm would not go through the mounting holes in the diamond wheel.
When I pulled off the backing plate I looked at the bore of the backing plate. There was a great big void that had been bored across also the backing plate looked like it may have some cracks or could be just markings from the mold that they were cast in, it is hard to tell. The void was so big that I feel the backing plate is unsafe to use. I showed this to a friend that had his own machine shop for years and he felt the same way as I do, it is unsafe.
The backing plate have a keyway cut in them but the motor shaft is drilled and a spring pin put in and that is used for the key. One one side of the motor the spring is flush with the motor shaft and does not do a dam thing.
I know I probably should take the grinder back but the next one maybe just as bad or worse. I think that I will get some material and just make new backing plates. This way they will fit any of the wheels that are purchased in the future.
My advice to anyone that has purchased one of the grinders is to pull the backing plates and look them over real well.
Hope this was not to long winded and someone may get some help from this post and maybe avoid an accident.
Than I decided that I wanted a diamond wheel and so ordered one from Enco for $83. 00. When I tried to install the new diamond wheel it would not fit the backing plate. The hub of the backing plate was 1.253 while the diamond wheel hole measured 1.251.
Also the orginal green wheels were mounted using 8mm shoulder bolts and they would not work with the diamond as it used a flat head screw diameter unknown but less than the 8mm. I don't have any way of measuring a metric female thread and I don't have any metric bolts.
Now on the backing plate are 4 extra tapped holes that a 1/4X20 screw would just try to start in.
So I pulled off one of the backing plates to make the 50 mile trip to the hardware store and get the correct bolts for the diamond wheel and ones that would work in the smaller holes as the 8mm would not go through the mounting holes in the diamond wheel.
When I pulled off the backing plate I looked at the bore of the backing plate. There was a great big void that had been bored across also the backing plate looked like it may have some cracks or could be just markings from the mold that they were cast in, it is hard to tell. The void was so big that I feel the backing plate is unsafe to use. I showed this to a friend that had his own machine shop for years and he felt the same way as I do, it is unsafe.
The backing plate have a keyway cut in them but the motor shaft is drilled and a spring pin put in and that is used for the key. One one side of the motor the spring is flush with the motor shaft and does not do a dam thing.
I know I probably should take the grinder back but the next one maybe just as bad or worse. I think that I will get some material and just make new backing plates. This way they will fit any of the wheels that are purchased in the future.
My advice to anyone that has purchased one of the grinders is to pull the backing plates and look them over real well.
Hope this was not to long winded and someone may get some help from this post and maybe avoid an accident.
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