Bolts on Edger blade collar keep breaking

[JSR]

 I have been breaking cap bolts on my WM edger. The bolts are to lock the collar on the fixed blade, these are 5/16 x 24 tpi. The blades are sharp, so I do not think that I am shocking them. Most of the lumber is 4/4 that is run through the machine, mostly cedar, pine and hemlock. Once a bolt breaks, the blade moves out of position on the shaft and next board through is messed up. I am considering Lock-tite on the threads, though it might make it harder to extract broken bolt from collar. My reasoning here is that bolts start to become loose and then snap. Have any of you come across this problem?
Thanks Jim

[docinstein]

I taped mine out to 3/8" and haven't had a problem.

Doc

[bandmiller2]

Jim,kinda hard not seeing the ofending parts but are you using socket head hardened cap bolts.??Those seem to hold better than normal hex head.If the holes are tapped through prehaps longer bolts and a jam nut behind. Or what doc. says go larger,space permitting. Frank C.

[JSR]

Thanks, I am going to incorporate both of your ideas. The new edgers use 3/8" bolts, just going to make sure I use the proper grade of bolt. I am sure this will help me out.