Radial Arm Saw Blade Coming Loose

[jack forsberg]

I don't know what to look for. Everything seems to be square and flush. The threads look good. It takes 7 seconds for the blade to slow down to a complete stop. Is that an excessively aggressive brake ?

I've had the saw for 3 or 4 years. I can't remember when the problem started but it doesn't seem to be getting more frequent. Usually, I don't even know the blade has come loose until I turn it on the next time and I hear a terrible screeching noise. Ronald, does your DeWalt have a brake ? Could you tell me how long it takes to come to a stop ?

Mine is designed to be held with an allen wrench in the end of the shaft and I tighten it down pretty well.

Regs in the EU are 10 sec for braking . Is this a single phase with DC braking?

[Erik Loza]

Try a fresh arbor nut?

Erik

[John TenEyck]

An Allen wrench in the end of the shaft? Never seen that. Can you post a photo of how it looks with the blade on and another of all the components that go on the arbor?

John

[Yonak Hawkins]

Yes, single phase. I don't know if it's DC. It's a DeWalt 7790 with "Lectrostop", serial number : 80230355. I'll have to look it up later this evening.

[Matt Day]

I had that saw for about 4 years, sold it a month or so ago after I restored a delta. Mine was the B&D vintage, with the same Allen key design. Never had a problem and it had probably the same spin down time. You have the arbor washers on right? Have you simply tried tightening the arbor nut more?

[Rick Potter]

Mine is a 1980, type 7, Dewalt 7790. It has the Allen wrench hole in the end of the shaft. The Allen wrench holds the shaft from turning while you tighten the bolt. There is an arbor flange (thick washer) between the nut and the blade.

I just timed it, and the electric brake (Lectrostop) takes 13 or 14 seconds to come to a complete stop. Someone on this site told me that 30 seconds is within spec.

No problems with the blade coming loose. I do have a 4" blade stabilizer on the machine, but I never had a problem, with or without it.

Hope this helps.

[Yonak Hawkins]

Thanks, Rick. Any idea how to adjust the timing of the brake ?

[David Eisenhauer]

I bought a new early-mid 1980's 10" saw (Model 7770? 7700?) that says "Lectrostop" on the side so I guess it is electric braked. It does not use a lock washer, just the collar and the brass looking arbor nut. It uses the Allen wrench in the arbor as already described. I have never had a slip in all the time I have owned it.

[Rick Potter]

Sorry, no idea how to adjust it. I don't think there is anything I the manual, but I will check.

[michael langman]

It could be possible there is something wrong with the blade. Warped, out of balance, just enough to cause the nut to vibrate loose when blade is slowing down. An accident with the blade?
If the saw uses a domed washer I would replace it, and the nut as recommended above.
Bearings could be going in the motor or vibration from the saw itself.
Not an expert but just some thoughts.

[Matt Day]

Good thought on the bearings. If the bearings are going bad and getting crunchy, they would cause more friction and make the blade spin down faster.

[David Eisenhauer]

Assume you have confirmed that the arbor nut and washer are flat, correct? Maybe a little rub on a stone for them? Then look at the makeup of the blade face to the domed washer face (as in plane iron back to cap iron) to confirm flat makeup.