Results 1 to 9 of 9

Thread: Vacuuming forming

  1. #1
    Join Date
    Jun 2008
    Location
    GTA Ontario Canada
    Posts
    12,264

    Vacuuming forming

    I have a couple of projects i want to do that involves vacuum forming some trays.

    Finally got hold of a suitable sheet (4x8) of the correct plastic and now been researching how to make a unit. So if anyone comes across some great ideas please post here.

    Here is one that i found that goes all the way even down to making the element part.

    http://blindsquirrelprops.com/suppli...rming-machine/


    If you interested in model making check out the rest of the guys website, he makes some amazing models and takes commissions and now has a backlog of 18 months work.

    When it comes to people wondering where 3D plastic printing will be used, well if you look at some of what this guy makes i imagine he could sure make use of one in his future.

    For me i want to make tool trays shaped specifically to the tool so each tool in a draw has its own place. I know there is foam one can get but it don't appeal to me to have foam trays cut out and i don't want wooden trays with parallel dividers.

    Once setup vacuum forming is a piece of cake and if you layout your tools as they would be in the draw boom and you got a tray in one go.

    My real need is for a business project that is justifying the effort. Searched hi and low to find exactly what i am looking for in off the shelf storage and nothing available to my required size so i am going to make my own.

    Was going to outsource the project which i believe in but the price to get going was horrific and some small businesses did not even want to reply. There are days i wonder just how some do any business when they forget everything starts at some point as a requirement for 1. I started with a batch of 20 to 100 and still got no sensible bites when these people did decide to reply, so i reluctantly decided to diy and on the bright side will use the same equipment to make tool trays for my woodworking and mechanical tools.

    Once you have any exposure to the concepts of "lean" manufacturing its hard not to subscribe to Glenns point of having dedicated places for each item. That fastcap video should have proved that point to any skeptics.
    cheers

  2. #2
    Join Date
    May 2007
    Location
    Kansas City, Missouri
    Posts
    13,464
    Mine isn't as elaborate as that guys, but I built a simple one for forming kydex. I use a toaster oven for the heat source and quickly move it to the vacuum former when it's up to temp.

    http://familywoodworking.org/forums/...ighlight=kydex
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  3. #3
    Join Date
    Mar 2007
    Location
    Escondido, CA
    Posts
    5,176
    Oh, yeah!



    Will be watching avidly.
    ++++++

    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

  4. #4
    Join Date
    Jun 2008
    Location
    GTA Ontario Canada
    Posts
    12,264
    Well moving along with this whole vacuum thing. I say thing because i see vacuum as something i would like to dabble with many applications. (note i am a dabbler not a pro).

    Way i see it i want to try vacuum chucks on the lathe, vcauum hold downs on the bench, veneering and forming in vacuum bags and finally the motivation that is going to fund it all is vacuum forming plastic for both a business need and for tool storage.

    So far i have managed to pick up one component in my rounds yesterday and that was an air tank. Decided on trying a metal air tank 5 gallon size. Going to place a significant online order with Joe Woodworker today for loads of bits and pieces to make up his EVS system will add foot pedal control as well.

    Over time have done a fair bit of research on the pumps and this is where i need some family input. Research without experience is in my view pretty useless. I read in a Gast (significant vendor in vacuum pump industry) document on the various types of pumps manufactured (and they do the whole gambit so there is no bias) that the difference between the types has to do with how low a vacuum they can draw. Trouble is the document was rather out of date by a few evolution's of the technology compared to where the sizes of the pumps are today. Its not hugely out of date just does not take into account the capacity of some types today.

    Here is the salient extract from the Gast write up as to the various types.

    Reciprocating Piston Pumps -The primary advantage of the piston design is that it
    can generate relatively high vacuums from 27 to 28.5 in. Hg-and do so continuously under
    all kinds of operating conditions. The major disadvantages are somewhat limited capacities
    and high noise levels, accompanied by vibrations that may be transmitted to the base
    structure. In general, the reciprocating piston design is best suited to pulling relatively
    small volumes of air through a high vacuum range.

    Diaphragm Pumps -The diaphragm unit creates vacuum by flexing of a diaphragm
    inside a closed chamber. Small diaphragm pumps are built in both one- and two-stage
    versions. The single stage design provides vacuums up to 24 in. Hg, while the two stage
    unit is rated for 29 in. Hg.

    Rocking Piston Pumps -This design combines the light weight and compact size of
    the diaphragm unit with the vacuum capabilities of reciprocating piston units. Vacuums to
    27.5 in. Hg are available with a single stage; two-stage units can provide vacuums to 29
    in. Hg. Air flows, however, are limited, with the largest model available today (a twincylinder
    model) offering only 2.7 cfm.

    Rotary Vane Pumps -Most rotary vane pumps have lower vacuum ratings than can be
    obtained with the piston design: only 20 to 28 in. Hg maximum. But there are exceptions.
    Some two stage oil-lubricated designs have vacuum capabilities up to 29.5 in. Hg. (Also
    see the section on medium-vacuum pumps.)
    The rotary vane design offers significant advantages: compactness; larger flow capacities
    for a given size; lower cost (about 50 percent less for a given displacement and
    vacuum level); lower starting and running torques; and quiet, smooth, vibration free, continuous
    air evacuation without a receiver tank.


    Rotary Screw and Lobed Rotor Pumps - Vacuum capabilities of rotary screw
    pumps are similar to those of piston pumps, but evacuation is nearly pulse-free. Lobed
    rotor vacuum pumps, like the corresponding compressors, bridge the gap between positive
    and nonpositive displacement units. Air flow is high but vacuum capabilities are limited
    to about 15 in. Hg. Capabilities can be improved with staging.


    PS Note to Admin . Tried to upload the pdf file of pump info there was more than this extract, unfortunately our 150Kb restriction on this size doc restricted it. Would have liked to put a link in but have no idea now how i got to it in the first place. It was not on Gasts website but some other parties that sells Gast pumps. Cant find them again. Any chance we can arrange to add this doc somehow.?


    Of this list the two that i have found most commonly available that fit the bill for least noise, oilless and small size i have highlighted in Blue above.

    Joe woodworker sells primarily the rocking piston type and says the rotary vane types will work for the EVS system but it needs some additional parts to be a continuous vacuum set up to prevent chatter.

    The two chief criteria i want given I am trying to make a flexible machine and invest once are being able to draw as low as possible a vacuum and then the flow of air to be the most possible within reason of the pump range.

    That's where i tripped myself up again. My target price for the pump component is $200 US. I am not buying a new pump when i see so many refurbished units available and know that they are able to be serviced and the ones i am looking at have already been refurbished (as in seals etc).

    The thing i find about the rocking piston type are the CFMs are lower as in 2.7cm to 3 cfm and some 5 cfm but then they get more pricey. The rotary vane unit i can get my hands on is $169 and 10cfm rated.

    Now just to clear things up for everyone that reads this and dont know. That CFM rating is when the pump is sucking free air no closed off system. This drops as it draws vacuum but every pump is rated at the open pressure specs. There are graphs available if one can get to a manufacturers spec sheets and the manufacturer is reputable that show decline of cfm as vacuum increases.

    Its not that big of an issue if one builds a EVS system and has a holding tank given it only then affects the time to draw down the tank to the vacuum one wants.

    Naturally as a male and a woodworker i want most for least, add to that my frugal nature and i want the most for nothing not least. That has me looking at the rotary vane 10 cfm pump for $169.

    But my brain is buying into paying a bit more and buying a rocking piston as per what Joe sells just from a different source for about $70 less. This is based on herd mentality i figure i am safe going with what so many have bought from Joe to use.

    The thing that i need help on here is the practical side of all this. and the feel for vacuum. Gast says a two stage rocking piston can get down to Hg 29 while the rotary vane down to 20 to 28 hg

    The only application i am concerned about how low i can go on is the aspect of forming of wood in a vacuum bag. I have no idea what the practical implications here are.

    For veneering i can see either of these doing adequate jobs, for vacuum forming definitely there will be enough vacuum for my needs given the tank too, but clamping and holding wood on a form i have no sense for i just see loads of force being required.

    Can anyone shed more light on this topic for me from their experiences or knowledge. If i was buying new and the pump manufacturer was down the road, (well if they were down the road i probably would be buying new) then I would have a different view given i can go talk to real supplier and return the part when i get bs results. But buying via web i need to take some risk out of the equation given shipping costs versus pump value.

    The rocking piston design also says longevity to me kind of comparing the idea of compressors where the pump is a piston type versus the other non oiled compressors.

    BTW i missed out yesterday on a great deal on ebay would have had a really great vacuum forming system all in for $800 if i had kept bidding. It would have meant a trip to see Larry too as the pickup was in Michigan not far from grey beard. Should have used a bidding site to do my bidding. Would have saved me such a large amount of time and headaches.

    As usual any input will be appreciated.

    Oh and if you have built an EVS system like i know Mike H has, can you comment on the experience please... the good the bad and what you would do differently and which pump you used thanks.

    EDIT: Attached is the PDF: vphb_s4.pdf
    Last edited by Darren Wright; 10-23-2014 at 06:40 PM. Reason: Adding PDF for Rob
    cheers

  5. #5
    Join Date
    May 2007
    Location
    Thomasville, GA
    Posts
    6,000
    As to the pump, that's between you and your wallet. My pump is a RobinAire that was made for AC evacuation. A friend who was downsizing had bought it at a pawn shop a couple of years earlier - sold it to me for $80.

    You'll get all kinds of comments about how much vacuum is needed to be successful. Then, you'll hear from folks like me who have some practical experience in various situations. The bottom line is you do NOT need to pull an absolute vacuum to be successful.

    I built my system with a vacuum controller so the pump doesn't run all the time. You'll hear different arguments about this but having the pump cycle is a good way to build a system. I have the controller set to shut off at about -21inHg; it will drift down to about -16inHg before turning back on. I could set it for a deeper vacuum but this is more than enough for everything I do, including bentwood lamination.

    A side note: When I became "semi-retired" and worked in a cabinet shop for a while, we did a ship load (literally) of veneering and vacuum forming. One item we had to form was too big to bag, so we taped plastic material over the bending ply to seal it off. The vacuum system could only take it down to -8inHg but the material was securely pressed to its form.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  6. #6
    Join Date
    Mar 2007
    Location
    Escondido, CA
    Posts
    5,176
    Some years ago, when I was still teaching, I developed a class on using vacuum for clamping in the wood shop. The pumps we used were what we could find surplus and mostly rotary vane types. I personally still have have a diaphragm, a rotary vane, and a piston pumps. The rotary vane pump will serve you well for the applications you listed. Some things you might chew on here to help you better understand what you are dealing with:

    1. Vacuum is the result of removing air from a confined space (bag, chamber, container, etc.).

    2. Vacuum pressure is the affect of removing the air, and it is exerted on EVERY (inside and out) surface of the object within the confined space.

    3. Adding a tank to the system is suspect in that it is another space with more air that must be removed, i.e., more opportunities for leaks.

    4. There is only one size of a vacuum leak. If it lets air in, there is no vacuum. A pinhole is as effective as a fist sized hole. A tank cannot overcome a hole. It may take a bit longer to return the confined space to atmospheric pressure, but we are talking mere seconds here. Makes you appreciate the complexity of space suits!

    5. CFM in vacuum systems only addresses the speed at which the air is removed from the confined space. That's why there are systems that utilize a shop vac to remove lots of air quickly and then a quick switch is made to a vacuum pump to remove the balance to achieve vacuum pressure. This is not practical in a production environment.

    6. Vacuum alone in a small shop is not effective in bending or forming material. Usually heat is also involved, especially in forming. This was not a part of my class for that reason. Except for steam bending and that was clamped conventionally. Different class. Wood bending was done with thin strips clamped to a form. The form ( a two piece male/female form) was sandwich style with the end product in the middle.

    7. I see the difference between bending and forming as defined by the degree of angles. Bending would be relatively gentle bends and forming could go around 90º or more edges. See #2 above.

    8. Vacuum forming would be fun. I may try it some time! I envision four things: the form, the material, heat and vacuum.

    Hope this was helpful. Based on my experience. I would not be too concerned with the date of the information you are finding. Vacuum is a force of nature. Not much new there! And FWIW, a vane pump is very easily and inexpensively repaired, if you need to go there.

    BTW, we got a lot of pumps from Surplus Center in Nebraska. Another place to look is an industrial surplus supply. I have seen vacuum pumps piled high against the wall in those places. Those pumps are pulled out of service, usually from medical and scientific applications, where the measure of vacuum was critical or because a usage date had been reached. They will work perfectly for your application.

    Oh, yeah. Why do I have all three of those pumps? I was teaching the subject! Which gets the most use? Short term application, like clamping to the bench, the diaphragm pump. Longer term application, like shaping, the rotary vane pump. The piston pump? Well, because. It is a hoss in terms of weight. I don't know that it has any advantages over the first two in my applications thus far. I think I will try it with the lathe when I get that set back up.

    When you get around to vacuum chucks, clamps, forms, etc. Let me know. There are some 'rules' there, too.

    Finally, Joe Woodworker. He provides good information and materials. I helped a friend build one of his systems. It was more complex than what I had my students build, but it worked fine. Thus also a bit more expensive. Remember this is his business and he will ( and ought to) address his customers concerns, regardless of the degree of understanding on their part. We buy more than parts. We buy assurance and convenience. But then you know that!
    ++++++

    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

  7. #7
    Join Date
    May 2007
    Location
    Thomasville, GA
    Posts
    6,000
    Carol makes good points, as always. I'd like to address her item 3 - the tank. The purpose of a tank, no matter how it's constructed, is to act as a buffer providing more volume of vacuum. When a system is set up to cycle after reaching the desired maximum point, the tank gives the pump time to breath, if you will, before having to cycle on again.

    As to potential leaks in a tank, there's no question it's possible. I built my system with a buffer tank made from two 2-foot sections of 4" schedule 40 PVC. Each piece has a cap on each end. I drilled holes in the side of each piece of pvc to join them together with a 1/2" brass fitting, securing it with pvc cement and silicone. I then drilled a hole in the side of one section of the tank and inserted a brass tee with one side going to the pump and the other going to the bag side of my system. I also have a vacuum gauge, air filter and check valve in the line as well as a valve at the bag end of the hose. I can pull a vacuum on my system and will hold for hours without having to run again. If there are any leaks, they are insignificant.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  8. #8
    Join Date
    Jun 2008
    Location
    GTA Ontario Canada
    Posts
    12,264
    Wow again thanks for the info need to get back to read and digest it all.

    Sent from my SGH-I337M using Tapatalk
    cheers

  9. #9
    Join Date
    Feb 2007
    Location
    Catalunya
    Posts
    4,632
    I did quite a bit of plastic vacuum forming while I was at school. It is amazing the good results you can get with a domestic or shop vacuum and a heat gun. You have to make sure that the shape you want to form has positive angles to be able to remove it from the mold.

    Manual vacuum forming machines are not so expensive ( I think) and they can hold a sheet of 1x1 meters.
    Best regards,
    Toni

    __________________________________________________ __________________________________________________ _________________
    web site:http://www.toniciuraneta.com
    I also dream of a shop with north light where my hands can be busy, my soul rest and my mind wander...

Similar Threads

  1. Vacuum forming
    By Darren Wright in forum Off Topic Discussion
    Replies: 18
    Last Post: 04-15-2016, 08:21 PM
  2. New North Houston/Woodlands, Texas Area AAW Club Forming...
    By Steve Russell in forum Off Topic Discussion
    Replies: 0
    Last Post: 01-19-2008, 05:37 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •