Vacuum Chucks

[gketell]

Dave_M asked about vacuum chucks in our June Meeting thread. Since I didn't want to pollute that thread I thought I would start a new one.

Here is a crappy drawing of how to assemble a Vacuum Chuck.

The filters are just big fuel filters. They can be had on ebay pretty cheaply.

The vacuum pump can be almost anything depending on the wood you are using. The more porous the wood the bigger the CFM rating you need. For really dense wood the Harbor Freight turbine vacuum pumps would work but the noise would be atrocious. Most people go hunting for a used Gast 0522 or 0523 pump. They are oiless and quite and STONG.

You can make your own Rotary Adapter (mis-labeled "spindle adapter") if you want but after 2 home-made versions broke I finally bought one. If you want to know how to make them just let me know.

The blue line is pretty much any flexible air compressor hose or thick-walled PVC hose you want to use.

If you have any questions I'm happy to talk about it. I'll post later about the actual chucks.

GK

 

[PaulDoug]

I've read somewhere that you can get vacuum pumps from old refrigerators. Is this true and are they hard to set up for a lathe vacuum system or a vacuum chamber for stabilizing wood?

 

[gketell]

Yes the compressor from a refrigerator will work as a vacuum pump too. And it would work great for a vacuum chamber function. But it probably won't work for the Vacuum Chuck because it is a fairly low CFM so it wouldn't be able to maintain the vacuum as you turn the wood thin and it becomes porous.

 

[Dave_M]

Thanks Greg. Drawing looks great to me. Although you should have airbrushed a 3d version for us. Now that would have been impressive. Have you played with the airbrush anymore?

 

[turn4fun]

Greg.. thanks for the info. I've been thinking that a vacuum chuck might be something we could use. Craft USA shows a Holdfast Vacuum System in their catalog that sells for $285. The system includes a "Holdfast Vacuum Generator", but still requires you to have your own standard shop compressor to make their system work. I'm not sure what their vacuum generator does exactly. It looks to me like it converts air pressure from your shop compressor into a vacuum. Is that what it's doing? and Have you heard anything good or bad about the Holdfast System?

It looks like the system you diagrammed might cost a lot less money to put together. What do you use for your vacuum generator.. a shop vac? I think you shared some home made vacuum chuck heads at one of our previous meetings. I'm curious what it costs to put together a home made system?

Thanks Again.. Larry

 

[gketell]

Greg.. thanks for the info. I've been thinking that a vacuum chuck might be something we could use. Craft USA shows a Holdfast Vacuum System in their catalog that sells for $285. The system includes a "Holdfast Vacuum Generator", but still requires you to have your own standard shop compressor to make their system work. I'm not sure what their vacuum generator does exactly. It looks to me like it converts air pressure from your shop compressor into a vacuum. Is that what it's doing? and Have you heard anything good or bad about the Holdfast System?

It looks like the system you diagrammed might cost a lot less money to put together. What do you use for your vacuum generator.. a shop vac? I think you shared some home made vacuum chuck heads at one of our previous meetings. I'm curious what it costs to put together a home made system?

Thanks Again.. Larry

Larry, ANY vacuum generator that relies on an air compressor to generate the vacuum is a turbine based system. The air compressor air spins one end of a dual-ended turbine and the other end creates the vacuum. These work but are VERY noisy and VERY high pitched (which makes the noise seem worse).

Besides the noise there are two other issues with this system.
1) Your air compressor has be big enough to run "uncapped" constantly since when the compressor stops or slows the vacuum stops or slows. Even my 5-HP, 30-gallon compressor wasn't big enough to do that.

2) While the vacuum created is potentially strong (I developed nearly perfect vacuum using my Harbor Freight turbine system) it can't handle high CFM of vacuum leak. Great for casting but for this use, if you have porous wood it won't hold. Having something come off the vacuum chuck at speed is potentially deadly. (We lost another turner this week when a bowl broke off the lathe at speed.)

Other than the vacuum pump itself you can build the entire system you see in the diagram yourself and it will cost less than $50. The actual chucks that I made are MDF, ABS pipe fittings, and a bit of closed-cell foam from Michaels. Probably $8 or less each. But you do need to buy a tap that fits your spindle OR buy nuts that fit your spindle and glue them into the back of the chuck. I bought the spindle-tap because I trusted it more than glued in nuts.

The vacuum pump can be had off ebay or craigslist, usually.

 

[Dave_M]

Great info Greg. Thanks for sharing.

Dave

 

[kenlicciardello]

Any way we can build one of these at the meeting? I would be happy to shop for the parts if you give me a list. Sounds like a fun project.

 

[gketell]

Hi Ken,

Are you on SawMillCreek? They have a great turning section (for bowls, vases, etc. not much pens) and that is where I got the instructions and parts list to make mine.
http://www.sawmillcreek.org/showthread.php?75579-Vacuum-Chuck-System-%96-How-I-Built-Mine

If you aren't a member then I can type things out tomorrow.

GK

 

[kenlicciardello]

Hello Greg,

Thanks for the link. I am on sawmillcreek and didn't think to check there. They have so much information it is easy to miss.

Ken

 

[MesquiteMan]

Larry, ANY vacuum generator that relies on an air compressor to generate the vacuum is a turbine based system. The air compressor air spins one end of a dual-ended turbine and the other end creates the vacuum. These work but are VERY noisy and VERY high pitched (which makes the noise seem worse).

Actually, Greg, all of the air compressor attached vacuump generators that I am aware of are venturi type pumps. I know the ones from HF are. There are no moving parts in the system, just a greatly reduced orifice or venturi that creates the vacuum via Bernoulli's Principle. Not saying that there are not any that are turbine based but I have never seen one and have done a lot of reading on vacuum generators. I know the HF compressor types are venturi based since I have taken one apart! You are right about the noise and the drain on the compressor.

 

[gketell]

Thanks for the clarification, Curtis! The HF ones sure Whine like a turbine! But having never disassembled one I will take your word for it.

GK