Vacuum???

[Jerry Marcantel]

I see a lot of people use a vac system, but would like to know in the process of turning, when do you start to use it? Do you use it to rough turn, shape, or is it used at the end when the tenon is turned off???? Jerry (in Tucson)

[Doug Wolf]

When the tenon is turned off

[Thom Sturgill]

The PRIMARY reason for a vacuum system is to turn the bottom of natural edge bowls. While Jamb chucks can be used, they generally require the use of the tailstock which is in the way and donut chucks, longworth chucks and cole jaws will not work for natural edge.

That said, once you have one, it tends to be the go-to solution for reversing.

[Richard Jones]

Jerry,

for bowls, I use my vac to turn the tenon off, and to do final shaping to the bottom or a foot, if it has one. I also use mine for boxes, repairs of whatever, etc. I use mine a lot more than just for bowl tenons. It has become a very important piece of equipment, used far more than I ever imagined. Mine pulls about 22 inHg,seems adequate for what I've done, zero complaints.

[Faust M. Ruggiero]

Jerry,
Aside from the obvious uses; removing tenons from finished bowls, I often use mine when I second turn bowls I have cored. When I core bowls, I don't take the time to form a tenon on the cores. I core from smallest to largest. The only bowl with a tenon is the largest. I clean up the inside of the next bowl after removing a core but don't bother with the outside. I just put them away to dry. One thing I do is to move the tail stock up after cleaning out the inside and use the center to mark the middle of the next bowl to be cored. You will see why as I describe my procedure. After the drying process I install the morse taper extension and mount the bowl in vacuum chuck properly sized to the bowl. I use the mark I made when coring to exactly center the roughout in the chuck. The inside of the bowl is facing the tailstock. The morse taper extension gives me enough room to true a section of the inside of the bowl. I also true a small area near the rim on the outside. Once I have a true surface the size of the vacuum chuck, I turn the bowl around, center it in the vacuum chuck. The true area near the rim gives me a reference point to know when I have it perfect in the chuck. I run the vacuum but also keep the tail stock in place for added security. Now I finish the outside, including finishing the bottom and sanding. Then I flip the bowl around and finish the inside. There are two big advantages to this process. First of all, I don't like fitting the inside of a roughed out bowl against a jam chuck. All the pressure is in two opposing spots and there is a chance the bowl can split. Not so when the outside is forced in. Secondly, with a large enough face plate almost all the vibration is removed from the turning bowl and the feeling is super solid. The down side is you cannot use calipers to check your thickness. That's not usually a problem with cores because their wall thickness id uniform.
You asked what we use vacuum for and I answered. It is a somewhat limited use since I do it only for cores but for that purpose, it works for me.
faust

[Thomas Canfield]

The PRIMARY reason for a vacuum system is to turn the bottom of natural edge bowls. While Jamb chucks can be used, they generally require the use of the tailstock which is in the way and donut chucks, longworth chucks and cole jaws will not work for natural edge.

That said, once you have one, it tends to be the go-to solution for reversing.

I tend to agree with Thom except that I turn off the tenon on natural edge bowls using jam chucks with pad and also my donut chuck using some extension to gain the clearance for the wings or rough edge. PVC pipe sections or large couplings have been used on the donut chuck and my 1 1/4" shaft extension and even adding a 1 1/4 x 1" to that (about 4" total) have helped. Needless to say, I do not have a vacuum system or any plans to aquire one, but do see their merits.

[Jerry Marcantel]

Thanks to the few people who answered this question. The reason it was asked is I have invented a tool that can possibly eliminate Vacuums, donuts, Longworth chucks, and possibly any other type of hold down for completely removing the tenons plus that little annoying nub that we all experience... A large plate is required, as is a jamb chuck.... It's not for public release just yet, but in one of my posts, I gave you all a sneak peak, but no one took the time to noticed it. tsk, tsk, tsk. ............ Jerry (in Tucson)

[Richard Jones]

And here I thought you needed help with a vacuum issue...................

[Jerry Marcantel]

Richard, I really did want to know if that's all it was used for or do some people rough out with it.......... Jerry (in Tucson)