Well, I made the purchase of the Hold Fast V810 Vacuum Chuck system at the end of last year, and I finally had a chance to put it through the test. And all results are coming back as OUTSTANDING!  You know, I was the one that once said I would never trust air pressure to hold a piece of wood spinning at over 1000 rpm's.  But now I know what I have been missing.  I read several reviews of the V810 model, studied the pros and cons, and knowing that I don't have the time nor the patience to build a system from scratch, I decided to invest in this relatively inexpensive system.  At the time, it was on a clearance sale at Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or for $172 for the complete setup, minus the compressor.  The fine people at Hartville were very helpful and answered a few questions I had about it.  BTW, it arrived at my door 3 days later, and the shipping at the time was free.
I decided to purchase a dedicated compressor, since all I had was a small pancake style that probably would run continuously to keep up with the air requirements.  I found this one Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or at the local Harbor Freight and it has proven is worth.

Setting up the V810 was not difficult at all.  Just had the install it through the headstock, cut the rod to size I needed, and the rest was hose connections to and from the compressor.  I decided to purchase a combination regulator/drier to place between the compressor and vacuum generator, since moist air is a major culprit of poor vacuum seals.  And I'm always good about serious compressor maintenance.

I tweaked the incoming air pressure to around 60 psi and held my finger on the end of the vacuum rod and was able to tweak the regulator until I was pulling 24 in/Hg.  The manufacturer recommends you to have at least 12 in/Hg for safety reasons.  The chuck has a 6" diameter head (recently ordered the 3" head for smaller items) that screws directly to the spindle and has a double seal that is replaceable.  Finally, I have a system that will enable me to be as creative as I want to be with finishing the bottoms of bowls, especially cleaning up the foot of a bowl.  That was once my biggest struggle, but not anymore. 

The chuck has a great seal and I have often been able to pull up to 24 in/Hg on the Oak bowls I have to finish from Gustav trees.  Since Oak is porous, and some of the bowls have drying cracks, I occasionally have to apply masking tape on the outside in strategic positions to help ensure a good vacuum, but as I have learned is common with all vacuum systems.  My compressor cycles every 8.5 minutes at full vacuum, a little more during a weaker vacuum pull due to more air being lost.  Overall, straight out of the box, this system has won me over, hands down.  I have turned about 15 bowls on it so far and have not had one slip from center yet.  Now, the possiblities are endless.  Just gotta find more time to turn.  Holler if you have any questions.

Hey,glad its working for you Leo.I have been gonna email ya just to see how it worked,just kept forgetin to,but I can't use mine till I get back to NC anyway.Glad it works good.Can't wait till I get back up there to test it out.

Great review Leo!
Here are some pictures of my setup.


This is of the hand wheel with double sealed bearing, O ring, and brass fitting(put on lathe and turned with scaper to 3/8 dia. and glued in with super glue)The hand wheel was chucked up on lathe and turned to 1 1/8 od. x 1/4 deep and bearing glued in.Oring goes in hand wheel against spindle.

Back side of chucks.Face plates caulked and screwed on.Seal mdf with paint or lacquer.Use foam for gasket.
Mike

I use mineral spirits and rub the black ring out.  Most of the time the ring will vanish.

If you are trying to get a soft or porous piece to stick to the HoldFast, swirl a few coats of poly on the inside to develop a seal.  This has worked for me almost all the time unless there is a hidden void.