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Thread: Vacuum chucks

  1. #1
    Join Date
    Jun 2008
    Location
    GTA Ontario Canada
    Posts
    12,260

    Vacuum chucks

    Anyone here use a vacuum chuck on their lathe and care to share a few pics and know how on how they hooked it up and use it?

    My lathe has a hole all the way through the spindle last time i looked at this i came unstuck at the other end on the exterior side with how to hook up.

    I have not as yet resolved this but trust me this is going to happen somehow even if it means i mangle that end.

    What i need to see is how that is done on a decent lathe, i laugh because there is nothing decent about my lathe, we have a love hate relationship.
    cheers

  2. #2
    Join Date
    Aug 2014
    Location
    St. Mary's, Georgia
    Posts
    398
    Rob I got one when I got my Lathe but I have only used it once an that was like 5 years ago, but when I get a chance I dig it out an hook it up so you can see how it is setup. I haven't had a need to use it even when I do platters I just use my chucks , but I turn a lot of lamp shades for the last year or so an hollow vessels


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    https://www.facebook.com/BgCouger

    If you are going to make something nice, make it with a statement, use quality an do it right the first time

  3. #3
    Join Date
    Dec 2007
    Location
    Tellico Plains, Tennessee
    Posts
    4,353
    Rob,
    I don't have a commercial vacuum chuck, but my local turning friend does... I use a homemade one that I hook up to my shop vacuum to use... it works pretty well, but I'm a little skittish about using it... probably a trust issue... it's a little disconcerting having bowls flying around the shop.

    Mine is made using a round disc of MDF covered with a sheet of closed cell foam. I've drilled a hole in the center to take bearing and glued the mdf to a tapped piece of poplar that screws onto the threads of the spindle. There are also four screws through the mdf in case the glue comes loose... the bearing goes over the end of a lamp rod and the lamp rod goes through the spindle shaft. on the hand wheel side of the headstock the lamp rod sticks out and is covered with a length of plastic tubing that is fitted in one end to a turned block of wood that fits in the intake port of the vacuum chuck. The purpose of the bearing is to let the lamp rod stay static while the spindle and chuck turns around it. I usually put a spring clamp on the tubing to ensure that it stays on... I've had occasions where it will slip off the lamp rod and I lose vacuum.
    The vacuum will pull only about 2 or 3 atmospheres(or whatever the term for the hold is) so the hold is a little tenuous, but with light cuts and a light bowl, will work. A heavier bowl sometimes will not hold as the vacuum is too light ... my friends venturi pump will pull about 18 or 19, so his has a much better hold. His vacuum works off the compressor and he also has a much bigger compressor than mine.

    I don't have any pictures of my set up, but if I remember when I go to the shop later today, can do a run up and take a couple for you.

    If you want to see a shop vacuum working, look up Bob Hamilton's U-Tube videos... He's a Canadian turner that has several good videos up... and one that shows how he made his vacuum chuck. He uses what looks like a Home Depot Ridgid vacuum... about 6 gallons..... mine is a Shop-Vac 16 gallon and since most of the vacuum is developed in the reservoir of the vacuum, should be stronger than his ... not sure that it is.
    Last edited by Chuck Ellis; 10-23-2014 at 02:15 PM.
    Chuck
    Tellico Plains, TN
    https://www.etsy.com/shop/TellicoTurnings
    My parents taught me to respect my elders, but it's getting harder and harder to find any.
    If you go looking for trouble, it will usually find you.

  4. #4
    Join Date
    Mar 2007
    Location
    Escondido, CA
    Posts
    5,172
    Uhhh...guys. The strength of vacuum is not in the reservoir. It is in the lack of air in a confined space and the connection between the inside space and the outside space of that confined space. The atmosphere provides the pressure. A reservoir simply adds size to the confined space - not always helpful. There are applications for reservoirs in very large and production environments. Our shops are not that environment.

    Why are systems available with tanks? Because we confuse vacuum pressure with air pressure and air pressure requires a reservoir to replenish the air for continuous use. Introducing a vacuum to a confined space takes less than a second (unless you have to evacuate a whole tank first). Vendors supply us not with just what we need, but also with what we think we need. Remember, a vendor is tasked with selling his product or service. A customer is tasked with using what he bought. Two very different agendas here! In other words, a tank is not 'wrong' but I present the argument that it is not necessarily helpful.

    Air pressure is surplus air with a pressure higher than the atmospheric pressure. Pressure is provided by the surplus air. Vacuum pressure is negative air pressure, with an internal pressure less than atmospheric pressure. Pressure is provided by the atmosphere. Air pressure is measured in pounds PSI. Vacuum pressure is measured in Hg, (inches of mercury). These are two very difference physics. And most easily confused in their respective properties.

    Do not test vacuum pressure against your thumb or hand. A quick blood blister. Think hickies in the back seat of your car when you were a teenager. Breaking the vacuum is simply allowing air into the confined space. First shot of air, and the pressure is broken. Instantly.

    That said. Chuck Ellis has described a homemade system pretty well. Various sizes of chucks can be mounted to hold various sizes of turnings. Craft Supplies has parts if you want a more elegant system.

    Here is the caveat. Sheer force (sideways or slipping force) is the force that most easily defeats vacuum clamping pressure. Sheer force is the force applied with turning tools to the turning blank. Thus vacuum clamping on the lathe is most effective when reversing the turning and completing the bottom with light cuts. I know many, many turners who have a vacuum system and use it sparingly.

    Why do I know all this? I developed the syllabus and taught a class on vacuum pressure for woodworkers years back. Vacuum is a force of nature. Not much new about that over the years! See my other response to Rob in his other vacuum thread.
    ++++++

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  5. #5
    Join Date
    Aug 2008
    Location
    Reno, Nv
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    3,632
    The amount of vacuum that can be achieved is limited by two factors, pump strength and altitude. You can't pull more vacuum that is available in positive atmospheric pressure.
    It is 100% possible to suck the middle out of a thin bowl or platter. I'll say this as a must but take it however...NEVER use a vacuum chuck without the tail stock in place!!!
    Your Respiratory Therapist wears Combat boots

  6. #6
    Join Date
    Nov 2006
    Location
    Austin, Texas
    Posts
    1,448
    Two parts...

    My vacuum adapter is just a sealed ball bearing that fits into the center of the handle in the headstock. Through that bearing, I can either put a large adapter for my shop vacuum hose, or a small adapter (like a tire valve) for my vacuum pump. In fact, the shop vacuum is sufficient for many uses - I haven't taken my vacuum pump into the shop in years.

    The second part is the faceplate. I screwed a 12 inch piece of plywood to my faceplate, turned it round, and drilled a small (1/4 inch) hole in the center. I got some closed cell shelf "paper" foam padding, and stuck it on the plywood. A ball point pen was used to draw numerous concentric circles on the foam - easy hand turning it on the lathe, and very helpful when putting something on the faceplate.

    Now the zinger. I often turn small bowls (I think my wife must eat them, but she loves a lot of them for herself and friends). A small bowl (2-3 inches in diameter) doesn't have a lot of area for the atmosphere to hold it against the faceplate, so doesn't stick very well, even with the vacuum pump. But put a 5-6 inch plate on the vacuum "plate" and it sticks very well with only the shop vacuum. Lots more area for the air pressure to hold it.
    Charlie Plesums, Austin Texas
    (Retired early to become a custom furnituremaker)
    Lots of my free advice at www.solowoodworker.com

  7. #7
    Join Date
    Oct 2009
    Location
    Near Gassaway,West Virginia
    Posts
    105
    Rob you have got a lot of good responses. I use a Hold Fast system that works off my air compressor. There is an adapter from JT Turnings to connect it to the handwheel of the lathe. There is a vacuum chuck (also Holdfast) that screws on the spindle. I have a three inch and a six inch chuck and use the three inch much more than the 6. I have thought about getting a vacuum pump but the Hold Fast system works pretty good. I use it to reverse just about all my bowls to do the bottom. I have other systems like Cole jaws and donut chuck but I use the vacuum the most. It is just easier. I use the tail stock till I get all the turning done except a small tit in the middle and then back off the tailstock and just cut it off gently with a gouge. Clear as mud?
    Fred
    steercreekwood.com

  8. #8
    Join Date
    Jun 2008
    Location
    GTA Ontario Canada
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    12,260
    WOW wow i am overwhelmed. Have not had a chance yet to read all replies yet, but will and will respond again. Time not on my side today. Thank you all for the info.


    Sent from my SGH-I337M using Tapatalk
    cheers

  9. #9
    Join Date
    Dec 2007
    Location
    Tellico Plains, Tennessee
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    4,353
    Quote Originally Posted by Carol Reed View Post
    Uhhh...guys. The strength of vacuum is not in the reservoir. It is in the lack of air in a confined space and the connection between the inside space and the outside space of that confined space. The atmosphere provides the pressure. A reservoir simply adds size to the confined space - not always helpful. There are applications for reservoirs in very large and production environments. Our shops are not that environment..
    I may have said that wrong, but the reservoir in the shop vac does play a part in creating the vacuum... you're correct that the hold is created when the air is sucked out of the inside of the turning, but with a shop vac, there needs to be a place for that air to go to... also you with a shop vac vacuum chuck, you need a continuous air flow, otherwise you dead head the vacuum and it will burn out.

    I told Rob I would take some pictures of my home made vacuum chuck... keep in mind that it's pretty rude and crude, but it does work... and Jim Burr is 100% correct, it's safest to keep the tail stock up as long as possible...

    Here are a few pictures showing my crude homemade vacuum chucks... one is a flat faced mdf disc with closed cell foam for pading, the other is a pvc fitting mounted on a mdf disc attached to a tapped piece of mdf that screws on to my spindle.
    This is the front face... lines are for assist in centering the piece..
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    This is the back side of the mdf disc... I didn't round the mounting - I did say it's a little crude.... second picture is the disc mounted.
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    My vacuum tube is a length of clear plastic tubing, 3/8" id, the wood piece is turned to fit the intake port of my shop vac.
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    I should have made the lamp rod a few inches longer, it sometimes has a tendency to come off now, so I usually to add a clamp to hold the tube on the rod.
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    These pictures show my pvc chuck... used for flat pieces or an inside hold on a bowl with an uneven edge.... the black is a rubber gasket material to create a cushion... sometimes you can get a black rubber mark on your piece if it slips any... may have worked better without the gasket... the pvc fitting is a 4 inch coupling that is recessed into the mdf disc and glued in place with epoxy... silicon might work just as well, but didn't have any at the time when I made this.
    Attached Thumbnails Attached Thumbnails 14-side view pvc chuck.JPG   10-pvc vacuum chuck.JPG   11-back view pvc chuck.JPG  
    Last edited by Chuck Ellis; 10-24-2014 at 12:46 AM.
    Chuck
    Tellico Plains, TN
    https://www.etsy.com/shop/TellicoTurnings
    My parents taught me to respect my elders, but it's getting harder and harder to find any.
    If you go looking for trouble, it will usually find you.

  10. #10
    Join Date
    May 2007
    Location
    Thomasville, GA
    Posts
    5,998
    Continuing on the question of using a reservoir (buffer) tank in a vacuum bagging/forming system, here are two items I found:

    This presentation from Gast, who know a bit about vacuum systems.

    This blurb that Joe Woodworker has on his site.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

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