DIY Vacuum Chuck

[John C Bush]

Tired of the jam chuck efforts for bottom finishing and want to make a vacuum chuck. First question is do they work well enough for larger bowls.(Will eventually try vacuum bags for veneering, etc)
I have a repurposed Gast 522 pump that needs rewiring-condensers included. Wires from motor are labeled/numbered and label on motor lists hook-ups. Next ??--is polarity a consideration for wiring condensers. Appears there is one "common" for condensers. Seems to be straight forward. Confirmation would be a confidence builder.
??#2--pic of lathe shows outboard spindle handle. Thinking of getting an aluminum faceplate and milling(old Atlas metal lathe) a recess for a bearing and retainer. Want to keep handle "original". Is an internal style spindle adapter better?? Not sure where to get Delrin for less than a faceplate$$.
??#3--I have 1/4" ID quick disconnects for vac line hook-up. Do I need 3/8" to max " of Hg?
??#4--inboard chuck--Get a 6" steel chuck, mount MDF or hardwood, cut a groove for a 4" PVC coupler, seal in groove with epoxy, apply gasket seal foam tape -Is a rounded "official" gasket needed??
I will likely build a mobile cart like those shown in the Turners Forum here to tuck it away 'til needed.

Great Big Thank You to all for your help and to the author of A woodturners Guide To Designing, Building, & Using Chuck Systems. John477016477014477015

[Kevin Jenness]

Sorry, can't help with the wiring. 1/4" tubing will work, 3/8" is better as it will allow greater flow to overcome leaks. You want an inline dump valve to release/throttle pressure. I splurged on a Holdfast kit which works with my handwheel in place. https://www.packardwoodworks.com/110919.html

I used a Beall spindle tap to make wood faceplates rabbeted to accept 2 1/2" and 4" sched.40 pipe fastened with epoxy, as well as a 6" d. x 6"deep wood chuck. The rims of the wood mandrel and plastic chucks are rounded over and gaskets made of 1/8" closed cell packing foam are contact cemented on. The chucks need to be long enough that the bowl rims clear the headstock.

The holding force on the bowl varies with the chuck diameter - with a 22" hg vacuum level you can get about 10 psi.

[Gary Pennington]

I'm no help for wiring but for the chucks and associated plumbing check frugal vacuum chuck, Bob is a super resource.

Gary

[John C Bush]

I have a repurposed Gast vacuum pump that I plan to use for a vacuum chuck for finishing bowls and possibly vacuum bagging if it works!
The clipped wires are labeled/numbered and there is a wiring "menu" on the motor. I will need to wire in the start and run capacitors and not sure if polarity is a consideration.
The "menu" lists an individual wire for each capacitor and there is a single wire listed as "common. Not an electrician I would prefer to not make a smoke screen in the shop!!
Any suggestions on the best design for the chuck ois appreciated as well. Here are some pics of the pump. Thanks, John477047477048477049