Question about vacuum gauges…

[JeffSmith]

The other day I discovered that the oil-filled vacuum gauge that has done yeoman’s service on my lathes for about 15 years has decided to start leaking. I thought initially it was leaking from the o ring around the inlet fitting at the bottom, but after checking closer, it’s leaking from the screws on the back.I gingerly tighten it a little - it barely moved - but the leak is still there. This is a wika gauge - can’t find a lot of information on it in terms of whether anything is serviceable on it. The replacement runs about 4 times what a gauge from Veneer Service costs…

For now I’ve replaced the gauge with one I bought from Veneer Supplies about a decade ago to use with the vacuum pump I use on a carving stand. It’s a dry gauge, but has worked fine for years now. It functions just fine, but I’ll need to replace it so I can still use the carving stand.

My question is - is there any benefit to the oil-filled gauge in either of these applications (lathe vac chuck or carving stand)? The cost difference is 4x - the Wika online runs about $80 - the one from veneer Supplies is $17…not entirely sure how I wound up with the oil-filled version - my Scottish blood doesn’t allow reckless spending, but it’s been many years now…and veneer supplies has everything needed for vac chucking at reasonable prices.

 

[Dennis J Gooding]

IMHO, there is little need for accuracy here. Mostly, you want to assure that there is a good seal between the chuck and the workpiece.

 

[Dave Landers]

IMHO, there is little need for accuracy here. Mostly, you want to assure that there is a good seal between the chuck and the workpiece.

Yeah. My gauge reads about 3 or 5 with no vacuum - so I know the numbers don't mean anything, except that I know about where the needle is for "good", "maybe", and "nope".

 

[JeffSmith]

I agree with you both - still curious that there is such a difference between these two solutions. Dave - I got a chuckle from your “good, maybe and nope” - I’ve been oblivious to the numbers, just look for which ‘sector’ the needle is in.
Still, I hate to send this thing off to the landfill if there’s a way to salvage it.

 

[Tom Gall]

@JeffSmith I prefer the oil/glycerin filled gauges because the needle doesn't bounce all around - not a big deal of course. Mine leaks very slowly. Most have a little plug on the top to refill or top it off - don't remember but I think I just used 3-in-1 oil. The last one (2-1/2") I bought from Amazon for $15. Amazon & Walmart have many options ... just noticed Walmart has a 4" gauge for $20+. Look around.

Robot or human?

????

https://www.amazon.com/s?k=vacuum+gauge+0-30+hg&crid=2GD5ZKMSDFZ1J&sprefix=vacuum+gua%2Caps%2C90&ref=nb_sb_ss_ts-doa-p_8_10

 

[Tim Connell]

Glycerin or oil filled gauges are used when accurate readings are needed in high vibration/movement situations. They dampen vibrations of the mechanism and prevent the "bouncing needle". Because they dampen vibrations, wear and tear on internal mechanisms is reduced and they last a lot longer than unfilled gauges. Unless you want accurate vacuum readings, save some money and get an unfilled gauge.

BTW, most gauges are filled with glycerin unless it is to be used in a high temperature situation then silicone oil is typically used.

Also, don't know if your gauge has glycerin or oil? Mix a little with water, glycerin will mix with water, oil obviously won't.

 

[hockenbery]

I just use enough vacuum to pull the piece away from the tailstock center a 1/16”
Our guage had been broken for years. Didn’t need it.

I bought a new gauge when Al Stirt was going to teach in our shop.
When Al was doing a pre- class walk through. I showed him the new guage and said something about not really using it.
He said “you shouldn’t have bothered, mines been broken for years too”

 

[JeffSmith]

Does anyone know what the screw on the back is for? That’s where the leakage is coming from.

This one is glycerin filled - easy enough to refill, but the manifold with the gauge mounts on my headstock when being used - and even though the glycerin itself is relatively benign stuff, it still drips down onto the headstock - slowly, but it’s there.
I went ahead and ordered another one from Veneer Supplies - same as the one (dry) I moved from the carving stand vac pump. They are a great small company (husband and wife) that have good products and lots of information on using vacuum in woodworking.

I do like having a functioning gauge - even if I don’t pay attention to the actual numbers, I check it fairly often when finishing bottoms to make certain the vacuum is staying consistent. Doesn’t happen often, but once in a while the thinning bottom will leak through its pores and lose hold.

 

[Richard Coers]

You can still use an empty wet vacuum gauge even if it's dry. The diaphragm and needle still work fine.

 

[Tim Hunter]

Screw on the back holds the housing shell to the inner works.

Tim

 

[JeffSmith]

I’m considering draining it and storing it away as a backup - already ordered a new one (dry version).