ss350 knocking

[dow]

Hello, long time no post

I've got a Delta SS350 that's about five years old. It's never given me any trouble, until last night. I changed blades, and when I started it back up, the darned top arm was knocking on the body housing on the downstroke. Do you have any idea of what might have caused this and what I can do about it? I see that the Delta scroll saws are no more, so I need to figure a way to fix this.

Thanks for your time,

Dow Mathis

[Jim McDonald]

Is it possible that the tensioning control broke so that no matter what position the lever is showing, it is just like leaving the lever flipped up??

Take off the right side housing and make sure everything is connected along the rear vertical channel.

[dow]

Originally Posted by Jim McDonald

Is it possible that the tensioning control broke so that no matter what position the lever is showing, it is just like leaving the lever flipped up??

No, the tension control works just fine.

Take off the right side housing and make sure everything is connected along the rear vertical channel.

Did that. The rear linkage looks good, as do the rocker bearings on the upper and lower arms. As a matter of fact, I'm not seeing much slop anywhere in the saw. With the side off, I checked movement and ran the saw to see if it was still doing it. There was some vibration due to the housing being off, but other than that the saw ran fine. So I put the housing back on, and it didn't knock any more. I cut some 1/8" scrap and it cut just fine. Then I threaded the blade through a starter hole in a stack of Christmas ornaments and all of a sudden it started knocking.

Unfortunately, I didn't have the time (or patience) to keep messing with it today. Does anybody have any other thoughts?

[DBourdon]

Dow,

You might try taking off the black plastic cowl on the end of the upper stationary arm. My SS350 had the same problem and when I took them off no more knocking.

Don

[dow]

Hi Don,

That's a great idea. However,when I got mine, that piece was broken,and I took it off then. I'll keep trying stuff as I get time.

Anybody else have any thoughts? The upper arm is knocking on the bottom of the opening of the housing where the arm comes out.

Thanks,
Dow

[Rick-H]

My guess is that the link arm at the back of the arms has worn holes. And the screws may also be worn. Normal for the older models to wear those parts and they were out in the open where they could be lubed once in awhile. Now the same link and screws are inside where you cannot get at them to lubricate them at all.
Take the screws out and the the link arm out and inspect the holes in the link being oval showing wear. Check the screws for wear where the link arm rides. Try Delta for parts first. Or a good machine shop should be able to make the link arm. Then by filling with weld the worn area of the worn screws and then machining back to size again.

[dow]

Thanks Rick (and everybody else). Turns out that was the problem. The link arm was wollered out a little bit, but the screws were in pretty bad shape (especially the upper one).I hunted around and found both the link arm and the screws at MikesTools.com, so I ordered three link arms and half a dozen screws. I hope this is a good outfit. The parts were priced pretty good, but the shipping seemed a little bit high, expecially since the whole shipment shouldn't weigh more than a pound.

Anyway, they're ordered, and hopefully will be here by this weekend.

Thanks, everybody. Hopefully that'll get this saw back up and running.

Dow

P. S. What are your thoughts about greasing those points with high temperature lithium grease?

[Rick-H]

Grease will work. But you do not want to use very heavy grease because it can cause some drag that may effect the saw working. Had the same problem on the main arm pivot bearings. People were using too heavy of grease and the saw would not start. Also grease will attract dust.

[dow]

Hmm... What about graphite or teflon? Ideally, I'd like to find something that'll stay put, lubricate, and not gather dust and crud.

Since things don't wear out instantenously, here's what I suspect happened in my case. I had been meaning to oil the saw for a looooong while, but since I hadn't been using it that much, it was easy to forget. So last week, my son wanted to use it, and I was going over the saw with him, and I thought, "This'll be a great time to oil it and he can see where the oil goes and how to do it." So that's what we did. Anyway, I suspect that by oiling the rear linkage and then running the saw, the fresh oil flushed out all of the metal bits and crud that had been holding the linkage tight, and allowed it to flop around on the worn screws. Make sense?

[Rick-H]

It comes down to there is steel on steel with friction. The parts are going to wear, the lube will just slow the process down. Your saw just finally made it to the point you noticed it, it has been gradually headed that way over a long time, not something just just started going bad last week.