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Vacuum Chuck & Plumbing Recommendations???

Brodie Brickey

Brodie Brickey

Joined
Jun 7, 2004
Messages
128
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Location
Long Beach, CA
Website
www.smoothturning.com
I've got a 3520A lathe and I want to start seriously looking at vacuum chucking. What do I need to know?

Strength of pump?
Particular type of pump?
Vacuum chuck preferences?

Good sources or references?

Anything would be helpful. While I'm handy, I'm not an engineer. I wouldn't mind building my own, but knowing what I'm really looking for would greatly help.

Thanks,

Brodie
 
Brodie,
Check out the suggestions in the earlier post "GAST vacuum pump" and other posts on vacuum chuck systems. You can buy it or build it yourself. All you need is the right pump, a sealed bearing, and some plumbing. Others (J.T. are you reading this?) will jump in here and lead you in the right direction.
 
You might want to look in the subforum How To's and Tips. There are a couple of vacuum articles, and one is on vacuum chucks. You can also use the search button to look at previous threads on vacuum.
 
Brodie,

Check out eBay for used vacuum pumps. The type that you should get is a dry (non-lubricated) rotary vane vacuum pump. GAST makes a model that is very popular and it is the model that Craft Supplies sells for $360. I got my used one on eBay for $25. The GAST pump is capable of pulling 26 inches of mercury vacuum with zero flow and has an open port flow rate of 4.5 CFM. The motor is 1/4 HP and can be wired for either 120 or 240 VAC, but there is not any reason to use 240 VAC unless that is the only voltage available close to yor lathe.

In addition to the pump, you will need a needle valve for fine tuning the vacuum to the chuck, a vacuum gauge (get one with a large dial), a filter to catch any of the stuff from the chuck (put it close to the headstock), a couple ball valves (to shut off vacuum to the chuck and to dump the input to atmosphere), an electrical switch, a manifold (to mount the filter, gauge, and bleed valve), a quick disconnect, heavy walled reinforced hose, a vacuum chuck, and a rotary vacuum adapter.

I built my own rotary vacuum adapter using a double rubber sealed bearing (it has to be sealed and not shielded or else there will be way too much air leakage), some PVC filltings, some UHMW, brass plumbing fittings, rubber gaskets, and all thread lamp rod. The cost was around $20. You can buy one for about $70.

I built my vacuum chuck from a faceplate, rubber washer, fender washer, MDF disk, 4" heavy duty PVC coupling, a brass 1/8NPT nut, and some wide closed cell foam weatherstripping. The cost was around $30. You can buy one for around $80.

I found that the UHMW, PVC, and brass can be turned on the lathe very nicely using your regular turning tools, but I wouldn't use a bowl gouge.

It was a lot of fun and took a couple weeks of spare time, but I also saved a few bucks.

Bill
 
Check out the diagram at this link for a basic view of the system. You can make changes to suit your needs.Vacuum System

Where rigid pipe is called for, you do not need to use brass. Black iron pipe will do fine. Black iron fittings work as well but are not as pretty and compact.

Use Teflon tape at all your joints and you will have no leaks.

Use a tough flexible hose such as rubber air hose for abrasion resistance.

Ed
 
I have been using vac pumps for about 5 years now and have gone from an air compressor venturi (god awful noisy) to a car airconditioner pump (cheap , effective, a little messy from the oil it may spit out) to a rotary vane vacuum pump.

There are several easy sources for vacuum pumps, like ebay (do a search on "vauum pump" to www.surpluscenter.com to Bill Nobles site http://www.wbnoble.com/forsale/vac-pumps/gast.htm . Bill has been selling used pumps for years and has written a very will laid out (very long) treatise on vacuum pumps that can be found here
http://www.woodturners.org/tech_tips/frame_1.htm

But what you have read here is all true and tested. You will need some method of drawing a vacuum, a dedicated pump is the most efficient. The pump shold be capable of at least 3 + cfm free air flow (with no draw), and should be capable of at least 22" Hg (vacuum is measured in inches of Mercury and not PSI). The higher the CFM, the quicker it can evacuate the woodturning and create a seal, compensate for leaks and recover from the seal at the chuck being broken.

You will need a vacuum guage in line, some sort of way to pull the air through the headstock, and ball valve. Bassically, run them all through a block and you are golden.

As far as a vacuum chuck, I used to dedicate a faceplate to each one, whihc gets real expensive, now I make them out of mdf, as told by Johnny Tolly in this article
http://www.turningwood.com/mdfchucks.htm

The photo shows the more "complex" parts of the setup
 

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plumbing issue

I would suggest looking at oneways site and click chucks then vacuum chuck then vacuum kit assembly. You will see a complete diagram of what is needed ( whether you choose to buy from them or not). The picture shows the placement of parts. One of the most important parts of the system is the blow off value which should be either mounted on the lathe or somewhere really close. You will use the blow off to release and control the amount of vacuum sent to your turning. This value in invaluable in centering your piece on the chuck. You can use the valve to set a vacuum level that will allow you to bump the piece around until centered then close the value to obtain the proper vacuum for turning.

www.oneway.on.ca
 
This model vacuum pump will work real good:

http://www.surpluscenter.com/item.asp?UID=2005120310521153&item=4-1540&catname=

Surplus Center has them new, you can also find used ones on eBay with filters and a regulator of sorts attached to them that were used in the Dentistry offices.

These models were or are an OEM Gast pump, meaning they built them to spec for a specific customer. They work just fine for our use. The only odd thing is they are 220v which could cause a problem for some shops.

I got a new oil filled vacuum gauge off eBay, some quick disconnect fittings from McMaster-Carr and some hose, a valve and made my own manifold system. I use Oneway’s chucks and the E-Z Vacuum adaptor that is found in Packard’s and other catalogs. I can try and add a picture later if it will help you.

I keep the pump in the attic (I never hear it) above my lathe with a switch on the wall to turn it on and off. A hose comes through the ceiling and attaches to the manifold when I want to use the vacuum chuck.

Bill
 
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