Getting started with Vacuum turning/chucking

Discussion in 'Tutorials and Tips' started by Jeff Jilg, May 20, 2005.

  1. KEW

    KEW

    Joined:
    Jun 9, 2005
    Messages:
    340
    Location:
    North Metro Atlanta
    Steve,
    The situation I am thinking of is where you have a complete power outage. The lathe will take awhile to coast down (especially since the motor will not brake the way it does under power - if I understand it correctly). The vacuum pump will quit running. Since air is compressible, it should take a (very) slight amount of time for the suction to go out of the lines and tubing as air leaks into the system.
    If I lose power in my basement shop (which is, thankfully, rare) I have some emergency lights, but but they are dim enough, I think I would lose vision for maybe a half second.
    Based on Dave's experience, with the addition of a 5 gal tank, I would have a second or two to gather my wits and drop to the floor (take cover behind the toolrest/lathe bed) before the project got launched!
    Does that make sense?
    The likelihood is low, but for $25, it seems like a worthwhile addition.
     
  2. Steve Worcester

    Steve Worcester Admin Emeritus

    Joined:
    Apr 9, 2004
    Messages:
    2,629
    Location:
    Plano, Texas
    Home Page:
    In that situation, I would say it would work.
     
  3. Malcolm Smith

    Malcolm Smith

    Joined:
    Jun 27, 2005
    Messages:
    173
    Location:
    CarmelHighlands, California
    Thankfully, I don't often have power outages but find the comments interesting. A system that works by the employment of a vacuum tank to provide time to duck is going to add a similar delay to creating the vacuum that holds the bowl in the first place. Will one duck is the question I have to ask. I'm not convinced that one would. The slow down might mean that the bowl departs with less thrust. As for the solution to this, I believe one should be wearing a full face shield when turning anything of size. There are a lot of other causes for one being hit in the face with possible injury. To mention a few while we are on this subject: the wrong speed, often the result of not checking what pulley a belt is on after doing spindle turning. Having one's face in the line of fire when reaching for the power switch (thank you Oneway for not putting it on the headstock). It's also the case that a bowl can simply break loose from a regular chuck, particularly if it's use is not by compression. Usually the bowl goes somewhere else but there have been severe injuries to turners.

    Malcolm Smith.
     
  4. Wyatt Holm

    Wyatt Holm

    Joined:
    Apr 30, 2008
    Messages:
    212
    Location:
    Southern Utah
    Thanks Jeff,
    You say people use a mdf base plate for the chuck. However I have a preference for acrylic/plastic whatever you want to call it. I went to a counter top shop that makes Corian counter tops, and they had some scraps of 3/4" plastic. They were also kind enough that they used there special glue and laminating it making it a perfect size. Then I took it home and made a great vacuum chuck.
     
  5. Steve Worcester

    Steve Worcester Admin Emeritus

    Joined:
    Apr 9, 2004
    Messages:
    2,629
    Location:
    Plano, Texas
    Home Page:
    Simply cost.
    I can get MDF for next to free, glue it up, thread it and make a chuck.
    Corian would be great, but it would be expensive if I had to buy it. I used to use a dedicated faceplate for each, and that gets expensive also.

    Once you buy some neoprene, some contact cement and a tap, you can make your own pretty easy.
     
  6. Bob Chapman

    Bob Chapman

    Joined:
    Feb 24, 2007
    Messages:
    81
    Location:
    Bingley, West Yorkshire, England
    Home Page:
    When I built my vacuum chuck (see: http://www.bobchapman.co.uk/html/for_woodturners.html) I built a five gallon milk churn into the system.

    It takes a little longer to reach the maximum vacuum, but it gives time for the lathe to stop if there is a power cut. I tested it by putting a solid wood blank (approximately 12" x 3" thick) on the vacuum chuck and turning the lathe up to maximum speed (it's a Vicmarc 175). I then walked to the far end of the workshop and switched of the power at the master switch. The lathe stopped completely long before the vacuum gave out. I had time to walk back after the lathe had stopped and still hold the blank before it fell.

    I wouldn't normally be using a lump of wood that size at that speed on the vacuum chuck, so I'm happy my system will hold onto the pieces I do actually use.

    Hope this may help

    Bob
     
  7. Pablo Gazmuri

    Pablo Gazmuri

    Joined:
    Oct 8, 2012
    Messages:
    3
    Location:
    Needham, MA
    Vacuum chuck

    I just got the adaptor to set up vacuum turning the one sold by Holdfast. Do I have to take it down when I am not using vacuum or can it be left in place permanently?
     
  8. Tom Coghill

    Tom Coghill

    Joined:
    Mar 20, 2013
    Messages:
    32
    Location:
    Anchorage, Alaska
    Vacuum Chucking Filters ??

    This is a question for all those who are already set up and using a vacuum chucking system:

    Do you put a filter on the bleeder valve to keep it from sucking up dust and debris?

    I am in the process of installing a vacuum chucking system on my lathe. Mine is set up very much like the attached diagram, however I have installed an additional in-line filter just before the vacuum pump (see attached photo) to stop anything from damaging my pump.

    As I was looking at the system, I couldn't help but notice that the bleeder valve (immediately to the left of the gage in the diagram) has nothing to stop it from sucking up dust from sanding or small wood chips from turning. This bleeder valve is SUCKING in additional air to lessen the vacuum force on the turning. Since it is SUCKING in air, it is also sucking in dust / debris. Why no filter?!?! it seems like installing an inexpensive filter here is a no-brainer!!

    The filter I added just before the pump will work to remove debris and dust, but it seems like having a filter up at the bleeder is also a good add to the system.

    Anyone comment?? Am I getting too carried away (again)? :eek:

    PS - the filter I installed just before the pump is a FRAM G-3 fuel filter. I found that this flows air freely, it is the correct port sizes (3/8 inch) it is easily monitored (clear) and it was only $3.50 at Walmart!
     

    Attached Files:

  9. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,116
    Location:
    Dalworthington Gardens, TX
    Home Page:
    Absolutely, yes.

    If the cheap filter you found is suitable for filtering out dust in the air then it should be good for your purpose.

    However, your filter installed just before the vacuum pump is in the wrong place. It should be located close to the rotary adapter on the lathe so that dust from the vacuum chuck does not get into the lines and the vacuum gauge.

    Hopefully, you have two filters -- one on the bleed intake and the other close to the rotary adapter.

    On another note, the diagram that you posted is too low resolution to make heads or tails out of it.

    One other thing -- if you have not read the Gast instructions yet, there is a shut-down procedure that requires several minutes of operation with the pump input port blocked and several minutes with it open. This is most easily accomplished with a brass T and two ball valves installed directly at the intake port. Following this procedure will add many hours of life before the vanes to be replaced.
     
    Last edited: Jun 11, 2013
  10. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,116
    Location:
    Dalworthington Gardens, TX
    Home Page:
    Interesting that if I click again on the diagram, it becomes readable.
     
  11. Tom Coghill

    Tom Coghill

    Joined:
    Mar 20, 2013
    Messages:
    32
    Location:
    Anchorage, Alaska
    Bill,

    Thanks for the reply and advice. I have found a very good, inexpensive filter for the bleeder valve. I will take a picture tonight. It is another FRAM gas filter, this one being a "G2". I have removed the housing of the filter, leaving the filter core in place attached to a 3/8 inch hose attached to the bleeder valve. The gas filters are less than $4 each.

    Tom

    PS - I have no affiliation with FRAM etc...
     
  12. Peter D'Attomo

    Peter D'Attomo

    Joined:
    Jan 19, 2009
    Messages:
    33
    Location:
    Illinois
    I have assembled a vacuum system where the pump shuts off once it reaches a given number.
    The system drops almost immediately and I'm guessing it's the bearing. I have used a sealed bearing, but not a double sealed. Is this a great factor? I'm using a 3/8" lamp rod and a 1.1/8 diameter bearing on the headstock end of a chuck, epoxied in place. Any advice would be appreciated.
     
  13. Dwight R Rutherford

    Dwight R Rutherford

    Joined:
    Sep 19, 2010
    Messages:
    139
    Location:
    Sacramnto Ca
    Every vacuum set up for woodturning I have ever seen runs continuously. The original post you attached to uses a system that runs constantly to hold at a given level.
     
  14. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,116
    Location:
    Dalworthington Gardens, TX
    Home Page:
    The vacuum should be controlled using a bleed valve. The pump has to run continuously because there are several sources of leakage and even a very tiny amount of leakage with the pump off would cause the vacuum to be gone very quickly.

    There is some leakage through the bearings. If your rotary coupler has only one bearing, that is a design flaw because that would allow flexing between the inner and outer races and result in a huge increase in leakage. Double rubber seal means there is a seal on both sides of the bearing. A single rubber sealed bearing would be open on one side. I've seen single "shielded". Bearings, but not single "sealed" bearings. Your rotary coupler should have at least two bearings and three would be better. Also, you should be using shaft seals on the high pressure side of each bearing. The seals on bearings are there to protect from contamination and loss of grease, but not to provide a vacuum seal. Shaft seals are what you need for that.

    There will always be leaks. Wood is very porous and a surprising amount of air leaks through the wood. Also, the seal on the vacuum chuck won't be a perfect seal and will be a major contributor to leakage.
     
  15. hockenbery

    hockenbery AAW Advisor Staff Member

    Joined:
    Apr 27, 2004
    Messages:
    4,304
    Location:
    Lakeland, Florida
    Home Page:
    I agree with Bill & Dwight.

    About 99% of the vacuum Chuck work is finishing the bottoms of bowls and platters. That takes 5-10 minutes of running the system.

    I do some spherical hollow forms held in a vacuum Chuck and I hollow some spheres held in a vacuum Chuck too. This takes on the order on 30 minutes. The pumps are built to do that.
    Wood leaks air. So one of the major considerations in a vacuum pump is air removed per minute to keep up with the leakages.
     
  16. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,116
    Location:
    Dalworthington Gardens, TX
    Home Page:
    I edited Jeff Jilg's tutorial to update most of the broken links that reference the old vBulletin forum. Unfortunately, some of the links are to files that no longer exist or have moved.
     
  17. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    8,116
    Location:
    Dalworthington Gardens, TX
    Home Page:
  18. Peter D'Attomo

    Peter D'Attomo

    Joined:
    Jan 19, 2009
    Messages:
    33
    Location:
    Illinois
    Thank you all for your replies.
    Peter
     
  19. Steve Worcester

    Steve Worcester Admin Emeritus

    Joined:
    Apr 9, 2004
    Messages:
    2,629
    Location:
    Plano, Texas
    Home Page:
    he was referring to something like this (photo credit: Harbor Freight).
    I use one inline when I am doing vacuum forming as I want to evacuate the space very quickly while the plastic is still hot. Because of the small space in woodturning, I don't think it is necessary. But in his case, he was using it for a safety feature, in case of a power power outage. Although I do not approve of his way of testing it (chucking up a piece and running full speed!) it seemed to work.
    image_23178.jpg
     

Share This Page