circular saw sudden jam - gave me quite a shock

[AJB Temple]

Was using large hand held hilti 110v circular saw yesterday, a tool I am quite familiar with. I was doing parallel cuts in green oak to take 70mm deep tenon cheeks off a 9" post. Suddenly the saw stopped dead with a jolt. A chunk of oak had broken away from the beam and jammed the saw blade against the guard. This was the last cut of the day anyway.

(after unplugging the saw) I've removed the jammed piece and originally thought the blade was bent, but it appears to have sprung back into place once I took the jammed pice out.

In 30 years of woodworking such a thing has never happened to me before. This timber framing malarky puts you in close contact with some big tools.

I have not tried to restart the saw yet or checked properly if the blade is OK. Slightly unsure what precautions to take when checking it. Any advice?

 

[Blister]

I think it will be fine , its a mechanical jam not motor related , When trying it make sure the blade bolt / fixing is tight , and that the blade cover is in place , BEFORE plunging it in spin the blade and make sure it runs free and that the blade is not bent , Then Pull the trigger and see what happens after applying power

 

[CHJ]

Before using it in anger slacken off the blade fixing bolt and retighten, you may find it is currently over tightened and difficult to undo. (may not be relevant if blade has an anti-rotation locating spigot hole, I don't know machine)
Better to do this when you have time than on a time limited job when you need to change the blade quickly.

 

[Eric The Viking]

Check all teeth are intact, just in case*.

Assuming it runs, without excessive vibration coming up your arm, make a shallow cut progressing _slowly_ and running against a straightedge, and check the kerf width against the spec. of the blade with digital verniers in several places. If it's wider than normal, either the saw plate or the spindle may be bent (it'll be as if you're using wobble-washers).

That won't tell you which is damaged, but substituting a known good blade will do. If the width gets narrower, ditch the blade from the incident (the spindle is most likely fine).

Hilti are usually really well made, so I'd be surprised if either has been harmed.

E.

*your own teeth are irrelevant in this context.

 

[otter]

Has it got adjustable speed control? If so, I'd turn it right down before starting it up for the first time and then when happy slowly increase the speed whilst it's running.

 

[AJB Temple]

Thanks guys. Blade has been popped off and checked for any unevenness, refitted and saw run. Much to my surprise all seems fine. I thought a mechanical dead stop would damage the motor but apparently not. Otter. it is not variable speed. This basically a saw for commercial use. Very easy depth adjustment etc and capable of dealing with some quite tough stuff. Some bits of this green oak are rock hard though!