bx2750d set screw threads

PeterK · Feb 3, 2011

I went to oil the chain on my blower after a good workout over the last couple of days and noticed that the upper chain gear is missing both set screws. No wonder I suddenly started breaking shear pins on the fan.

I looked down the threaded holes with a flashlight and can see a shiny spot from previous pins so I know they're supposed to be there - also the gear moves back and forth a bit with a screwdriver.

Can anyone help me with the thread size/type. I've tried 5/16-18 and it starts to thread then stops. Also tried an 8mm-1.25 bolt. Maybe a tapered pin? Allen head set screw?

dennisgw · Feb 3, 2011

Can't remember if it is a keyed shaft. It is keyed, then the set screw will just keep the key in place. You might want to take the gear off and run a tap through first. Should be std thread. Ordinary tap will bottom out if you leave it on shaft.

yooper jim · Feb 3, 2011

Parts diagram says 2 pc. They are 5/16 - 18 X 1/2"
Jim

PeterK · Feb 3, 2011

yooper jim said:
Parts diagram says 2 pc. They are 5/16 - 18 X 1/2"
Jim

Thank you Jim. My manual states "obtain locally" but I was leaning towards 5/16-18 vs metric.

New ones are going in with loctite, like they should have been to begin with.

Thanks again.

Oh. One set screw to hold the key in and one 90 deg on the shaft.