Vacuum chucking hazard

[Larry Copas]

Don't use quick connect fittings in a line from the vacuum pump to the lathe. A small wood chip can easily clog the fitting shutting off vacuum to the lathe. This can cause a 50 pound wall art piece to be launched into low earth orbit.




The reason for the quick connect is I use the vacuum pump for vacuum chucking, bag veneering and clamping.
The quick connect made it easy to switch between applications.

 

[Richard Coers]

How do you get a chip from the inside of the bowl into the system? You don't blow off the bowl to get rid of sawdust and clean it before pulling the vacuum? I think you have been missing a critical step to successful vacuum clamping all along. No issue in my shop for the last 25 years.

 

[hockenbery]

That is one rare experience.
Not sure how avoiding quick connect prevents the clog problem. Those chips have to stop somewhere in the system.
I’ve been using quick connects since 1999 with no problem.
Thats a close match to @Richard Coers 25 years..
I have a dust filter in my line I”m thinking chips like those would get caught there and stopped the system if they made it through the quick connect.

vacuum chucking is a closed system so those chips must have been in the system when you started up the vacuum.
Maybe you had chips in the spindle. Maybe in the coupling. Maybe in the chuck but you probably would have seen them in the chuck.

 

[Alan Vandergriff]

Are those standard air line quick disconnects? When I was building my system I bought some from Veneer Supplies that are made for vacuum lines. So far they have worked well. Joe is good to work with and it may be worth checking them out.

Quick Disconnect Fittings for Vacuum

Check out our inventory of exotic and domestic wood veneers. We also offer a full line of vacuum pressing kits, vacuum bags, and veneering essentials.

www.veneersupplies.com

 

[Larry Copas]

Are those standard air line quick disconnects?

Yes, and I think that is part of the problem as the air is going in the wrong direction.

One small chip probably in the spindle. Without the quick connect it would have easily made it through the air hose and stopped at my filter at the vacuum pump. Would never had even been noticed.

 

[john lucas]

I had a different problem. I was turning in a basement shop with 2 small windows. It was night time and the power went off to our entire block. The piece flew off and bounced all around my pitch black shop. I didn't even know where to duck.

 

[Doug Rasmussen]

Situations like described here are why OSHA requires guarding to prevent injuries from spinning parts coming loose.

At the the Seattle area JPW scratch and dent discount center I saw one of the PM 42xx lathes that actually came with the guard. That lathe was discounted to $5295. I've seen the smaller PM's with the guard bracket, no guard included though.

 

[Lou Jacobs]

I understand a clog resulting in sudden, catastrophic loss of vacuum, but I’ve always experienced a few seconds for my vacuum to release a piece when the power is intentionally turned off to it. I’ve assumed (I know what they say about assuming), that if I had an unexpected power interruption, I’d have a couple of seconds to apply pressure to the back of the piece to hold it on the chuck. I suppose not, but I wonder why…

 

[Larry Copas]

I understand a clog resulting in sudden, catastrophic loss of vacuum, but I’ve always experienced a few seconds for my vacuum to release a piece when the power is intentionally turned off to it. I’ve assumed (I know what they say about assuming), that if I had an unexpected power interruption, I’d have a couple of seconds to apply pressure to the back of the piece to hold it on the chuck. I suppose not, but I wonder why…

When I first built my vacuum system it was totally for veneer work using a bag. To make sure I had a fast draw down I plumbed in a tank which also acted as a trap for anything coming out of the bag. The tank would also provide a reserve vacuum supply for a short time if the power went off. Lots of pictures of vacuum systems with a reserve tank on the Joe Veneer website.

 

[GRJensen]

Situations like described here are why OSHA requires guarding to prevent injuries from spinning parts coming loose.

At the the Seattle area JPW scratch and dent discount center I saw one of the PM 42xx lathes that actually came with the guard. That lathe was discounted to $5295. I've seen the smaller PM's with the guard bracket, no guard included though.

When I bought my PM3520C six years ago, it came with the mounting bracket for the guard, but the guard itself was listed as an accessory that I opted not to buy. Currently you can find them for around $300.

 

[John K Jordan]

Joe is good to work with

I second that endorsement. He took the time to answer my questions on the phone and by email.

I think I ended up with a spare guard for Jet 1642 if anyone has a need for it. I’ll trade for a good story or a good joke.

JKJ