Author Topic: Vacuum pump or my maddest modding project yet.  (Read 8176 times)

Offline Henning

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Vacuum pump or my maddest modding project yet.
« on: October 25, 2011, 04:25:15 AM »
Hi all!

I sincerely hope there's someone with an understanding of vacuum and vacuum pumps out there, as i am utterly lost!
Here's what i'm trying to achieve or the design brief if you will:

Make a vacuum pump setup that will enable me to vacuum form wood, plastics and cf/fibreglass. In addition a vacuum holding setup. Something along these lines: http://www.axminster.co.uk/bagpress-pro16-electric-vacuum-press-prod810324/

I have already managed to source a pump. I got this one free from a friend of mine, it's a Busch industrial quality rotary vane pump, where the vanes are running in oil.

 :worthless:

Here's the main pump:



and the other side:



All signs on the pump:

Switch (or something?)



Motor:



and pump:




Here's the main questions i have this far:

1. Would this be a pump for continuous running?
2. What does the Bürkert 3/2 solenoid valve do? Does it redistribute the vacuum to the open port when the vacuum is reached or?
3. Would this pump be suitable for vacuum forming? I have read on the 'net some suggestions this is one of the worst pumps to use for this...
4. What does the 20 mbar on the pump mean? Is this the vacuum pressure? In which case it's waaaaay to low, isn't it?

ANY and all help would be most appreciated as i'm clearly out on deep water here. It seems i lack even the most basic knowledge of vacuum pumps and vacuum...  :doh:

Thanks in advance!

Henning

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Offline Bernd

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Re: Vacuum pump or my maddest modding project yet.
« Reply #1 on: October 25, 2011, 07:15:15 AM »
This may not be the answer your looking for but I made a quick vacuum pump using a refrigirator compressor/vacumm pump. Here's the link to my web site.

http://www.kingstonemodeleng.com/MachineShop/vaccum/vaccum.htm

Might give you some ideas. Oh, and it was cheap too. :clap:

Bernd
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Offline fixerup

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Re: Vacuum pump or my maddest modding project yet.
« Reply #2 on: October 25, 2011, 01:14:07 PM »
Hi,


1. Would this be a pump for continuous running?

Has long has there is no major leaks, I think it would be ok to run continuous.  Touch the casing, you should be able to leave your hand on it.  Make sure the pump oil is topped up. Note: you need vacuum pump oil, not motor oil.

2. What does the Bürkert 3/2 solenoid valve do? Does it redistribute the vacuum to the open port when the vacuum is reached or?

no idea

3. Would this pump be suitable for vacuum forming? I have read on the 'net some suggestions this is one of the worst pumps to use for this...

Maybe they say it is the worst pump, because they are forming very large  mold. For smaller stuff I can't see a problem, from your specification tag picture I can see 1370 L/min and that is not bad.
 
4. What does the 20 mbar on the pump mean? Is this the vacuum pressure? In which case it's waaaaay to low, isn't it?

That is correct.  20 mbar is equivalent to about 8 inch of water of vacuum.  Most rotary vane pump can pump to 20 mbar the difference  between pump is how fast.

Hope this helps,

Cheers!
Phil

Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #3 on: October 25, 2011, 02:29:02 PM »
Thanks for the replies, chaps!
Nice work, Bernd!

Hi,


1. Would this be a pump for continuous running?

Has long has there is no major leaks, I think it would be ok to run continuous.  Touch the casing, you should be able to leave your hand on it.  Make sure the pump oil is topped up. Note: you need vacuum pump oil, not motor oil.

There's special oil for this? 

2. What does the Bürkert 3/2 solenoid valve do? Does it redistribute the vacuum to the open port when the vacuum is reached or?

no idea

I found a user manual for the solenoid. It seems to me it takes the vacuum off the chamber when it's reached the setting. This is set for a specific pressure, presumably, but can probably be taken off it can run continous.

3. Would this pump be suitable for vacuum forming? I have read on the 'net some suggestions this is one of the worst pumps to use for this...

Maybe they say it is the worst pump, because they are forming very large  mold. For smaller stuff I can't see a problem, from your specification tag picture I can see 1370 L/min and that is not bad.


would that be how much air it evacuates on max?
 
4. What does the 20 mbar on the pump mean? Is this the vacuum pressure? In which case it's waaaaay to low, isn't it?

That is correct.  20 mbar is equivalent to about 8 inch of water of vacuum.  Most rotary vane pump can pump to 20 mbar the difference  between pump is how fast.


Any chance you can tell me how much that would be in Torr or inches/mercury?   

Hope this helps,

Cheers!
Phil


Helped a whole lot! Thank you very much!
Henning

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Offline DaveH

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Re: Vacuum pump or my maddest modding project yet.
« Reply #4 on: October 25, 2011, 04:39:04 PM »
Hi,

15torr = 20mbar.

Because 1torr = 1.333mbar = 1mmHg (near enough)

 :beer:
DaveH

PS. 1 Standard Atmos = 760torr = 760mmHg =1013mbar
(Ex Leicester, Thurmaston, Ashby De La Zouch.)

Offline picclock

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Re: Vacuum pump or my maddest modding project yet.
« Reply #5 on: October 25, 2011, 05:46:30 PM »
Hi Henning

Vacuum pumps often have a limited flow rate which is why this may be deemed unsuitable. However you just need to get an empty gas cylinder (say butane/propane and definitely empty like with brass valve removed) and connect the output of the pump to it to form a vacuum reservoir. Then when you apply the vacuum the pressure will stay low long enough despite the inevitable leaks to complete the forming successfully. 

I have a machine which generates its own vacuum from a compressed air supply and a venturi arrangement which also seems to work quite well.

Best Regards

picclock

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Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #6 on: October 26, 2011, 02:44:16 AM »
Hi,

15torr = 20mbar.

Because 1torr = 1.333mbar = 1mmHg (near enough)

 :beer:
DaveH

PS. 1 Standard Atmos = 760torr = 760mmHg =1013mbar

That would actually be quite a lot of vacuum. i've been thinking the wrong way  :Doh:

Thank you very much!
Henning

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Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #7 on: October 26, 2011, 02:53:51 AM »
Hi Henning

Vacuum pumps often have a limited flow rate which is why this may be deemed unsuitable. However you just need to get an empty gas cylinder (say butane/propane and definitely empty like with brass valve removed) and connect the output of the pump to it to form a vacuum reservoir. Then when you apply the vacuum the pressure will stay low long enough despite the inevitable leaks to complete the forming successfully. 

I have a machine which generates its own vacuum from a compressed air supply and a venturi arrangement which also seems to work quite well.

Best Regards

picclock

My thinking yesterday evening was along the lines of this. If i add a vacuum switch and a tank, i will be able to run up vacuum and then let it off without pressure in the system and with the pump turning off. In addition, for vacuum clamping i may be able to utilize the pressure in the tank without having to start the pump?

Thank you very much all of you who have replied so far! I appreciate it!

Here's a couple pic's from yesterday when i took of the motor to see if it could be traded for a single phase:

Stubborn gear:



Had me bring out the "if it doesn't want to budge, i'll make it"- kit:

Henning

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Offline DaveH

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Re: Vacuum pump or my maddest modding project yet.
« Reply #8 on: October 26, 2011, 10:32:03 AM »
That would actually be quite a lot of vacuum.
Thank you very much!

Hey that's quite good - a lot of nothing :) :) :)
 :beer:
DaveH
(Ex Leicester, Thurmaston, Ashby De La Zouch.)

Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #9 on: October 27, 2011, 07:27:20 AM »
That would actually be quite a lot of vacuum.
Thank you very much!

Hey that's quite good - a lot of nothing :) :) :)
 :beer:
DaveH

Not allowed to make fun of non-native speakers  :hammer: :D :)   :beer:

After a lot of thinking (probably due to a bad case of  :proj:) about this project i decided yesterday to use a capacitor and run the 3- phase motor directly from my single phase, not least to get some progress. I got it figured out and had it running yesterday evening.
Then i built a small cart for it, which will be upgraded with panels to hold quick couplings, wiring etc. in due course.

Here's where we are now:



I'm going to see if i can get some more bits tonight and start on the elecktrickery part. Need a box of some sort to hold the cable connectors and capacitor first, though. And a 24V power supply...
Henning

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Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #10 on: October 28, 2011, 02:34:33 AM »
Magnetic switch seems to be dead, so i quickly decided to discard completely, and then sorted out the electric box which has the main switch, all connections and the capacitor:



Need to add to the cart to get somewhere to put it now! And source some more parts.
Henning

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Rob.Wilson

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Re: Vacuum pump or my maddest modding project yet.
« Reply #11 on: October 28, 2011, 03:06:43 PM »
Hi Henning

What will you be making once you have the vacuum machine sorted ?



Rob 

Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #12 on: October 28, 2011, 04:32:52 PM »
Hi Henning

What will you be making once you have the vacuum machine sorted ?



Rob

It's primarily to be able to make curved bits out of that hideous brown stuff (wood), but i see no reason not to use it for other interesting projects like gun stocks from glassfibre or carbon fibre, maybe even stabilizing wood with the right accessory.

Sourced some parts today, an old fire extinguisher for pressure tank, some fittings and some hose.
Pic's tomorrow. I did find a filter type of thing completely filled with crud which i had to break to get out, and as this is right above the chamber for the rotary vanes, i took the part off to avoid dirt getting into the chamber.
That means a rebuild of that part will need to be done including making a new filter (piece of stainless mesh)  :doh:, and the powder from the fire extinguisher needs disposing of  :loco: and then i can start to look into making the pressure chamber and a thousand other small jobs. Plus the odd mishap, this project should keep me off the streets for a few more days i think  :dremel:
Henning

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Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #13 on: October 30, 2011, 04:50:52 PM »
Well, i have done a few more things.

After a lot of procrastination, cunningly disguised as "design process" i decided to get a move on yesterday after having sourced some parts on friday.   

A little thinking, drawing and figuring out later i produced a scheme for how i wanted it to look and work. I then set out to start on the pipe and hose side of things.

I figured a tank would come in handy. A rummage around in my friends barn produced several different variants, and after a little thinking i took off with this:



Taken apart and emptied it looked like this:



Now everything that passes my bench which i haven't seen or otherwise learned how works before will be picked apart and inspected until i fully understand how it works, why it works and how it looks inside. I am also not very good at throwing stuff away, but squirrel it away somewhere in my ever increasing pile of "that'll come in handy some day"
This is the mechanism from the fire extinguisher soon to be completely picked apart:



Now i had a small problem. The threads on the fire extinguisher was not very standard. Which meant i would need to make a new fitting for the tank  :wonder: , then drill a hole, tap that and make another fitting for that  :headsl: and then connect the various inlets and outlets.
Not a job i looked forward to, i admit, but then lightning struck and i had one of my brighter moments. The fitting from the extinguisher already had three threaded holes, one with a hose connection already and it would be quite simple to drill them and just make two new fittings for the last two holes.
Off we go! This is the top of fitting where the push valve used to be. I drilled and tapped for a regular thread, and this will, as soon as i manage to source a vacuum manometer be used for that. In the meantime i'll just plug it:



Then i drilled up the two holes in the mechanism which where already threaded but only had very small holes (manometer and safety valve):



And made two fittings on the lathe (Not my prettiest, but they'll work, i guess):



As luck would have it, i of course didn't have the right size threading dies (M10x1 would maybe not be a completely impossible one to find, but M14X1??? The only place i've seen that thread before is on old Citroen cars... In which they were left handed as well)  so i will order them tomorrow and then get them threaded and then drilled  through. These will accept hoses for the two separate outlets. A tame engineer i know said that it was no problem to do it like that, what do you all think?

Lastly, i had to rebuild the outlet part of the pump after a small mishap with the coarse filter in there.
The filter consisted of very fine stainless steel mesh, something i couldn't produce after an hour of going through my "that'll come in handy someday"- piles anyway, i was a bit lost as to how to produce the holder for the mesh (Small steel ring to the back right of the picture).
So, i've tried something different, and i will be sure to keep an close eye on this, as i am not at all sure it will work, but this is how it looks now:



It's hard to see, but i made a coarse filter out ofa piece of fabric from an old thin woolen sweater, then forced that with an o-ring and the lock ring which held the old filter.
Not sure it  will work, but if it does, it will probably be very good! My main concern is that it will be sucked into the pump, but as air passes freely through, i hope that will not happen. Anyone have any thoughts on that?

 Here's the rest of the innards of the part in question:



Tomorrow, i will try and continue on the cart, after having geared my shop back from metal working to woodworking, something which is no small job with my very, VERY limited space!
Henning

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Offline BillTodd

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Re: Vacuum pump or my maddest modding project yet.
« Reply #14 on: November 04, 2011, 08:30:04 AM »
Quote
    Hi,


    1. Would this be a pump for continuous running?

    Has long has there is no major leaks, I think it would be ok to run continuous.  Touch the casing, you should be able to leave your hand on it.  Make sure the pump oil is topped up. Note: you need vacuum pump oil, not motor oil.


There's special oil for this?

Apparently, the oil is formulated to have less/fewer short chain molecules that would otherwise evaporate/boil-off in the low pressure area of the pump and cause the oil to thicken.

I have an unopened 1litre bottle of Edwards Hi-Vacuum oil in the shed that you can have for the cost of postage (and an small optional donation to the Royal British legion - given it's November)

Regards,
Bill
Bill

Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #15 on: November 04, 2011, 09:06:29 AM »
Quote
    Hi,


    1. Would this be a pump for continuous running?

    Has long has there is no major leaks, I think it would be ok to run continuous.  Touch the casing, you should be able to leave your hand on it.  Make sure the pump oil is topped up. Note: you need vacuum pump oil, not motor oil.


There's special oil for this?

Apparently, the oil is formulated to have less/fewer short chain molecules that would otherwise evaporate/boil-off in the low pressure area of the pump and cause the oil to thicken.

I have an unopened 1litre bottle of Edwards Hi-Vacuum oil in the shed that you can have for the cost of postage (and an small optional donation to the Royal British legion - given it's November)

Regards,
Bill

Bill,

Thank you very much for your kind offer. Considering i'm in Norway, i'm not entirely sure it would be wise to send this though, as that means airmail.
I'll source some locally i think.
I will, however, make a donation to the British Legion, just for the kindness. (And a little due to the fact i'm ex- forces as well.)

Thank you!


Update on the pump:

All parts are coming togheter, i amassed a load of threading taps in the process, due to a mentioning in the right place and at the right time.
Ordered the dies in M10X1 and M14X1. When i got it it seems i managed to include both M8 fine, m4, 5 and 6 fine and forgot to order the M10 :Doh: :doh:
So, my brother is now running around trying to fix that so that hopefully i'll have something to show after the weekend.
Henning

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Offline Henning

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Re: Vacuum pump or my maddest modding project yet.
« Reply #16 on: January 28, 2013, 04:55:34 AM »
Well, that took some considerable time, but at least i have something working...

Here's the pump now:



And here's the first test to see if it worked:



It did, not least thanks to the great help i got here. So, as it stands i need to attach the vacuum switch (which means i need to rid myself of the NVR- switch), i need new oil and a general cleanup and i need to find some leaks and fix them.

Thank you again to all who offered help during the initial stage!
Henning

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Offline dsquire

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Re: Vacuum pump or my maddest modding project yet.
« Reply #17 on: January 28, 2013, 03:02:44 PM »
Henning

Thanks for the update. Glad to see that you got it working. Hopefully the next update will not be quite as long.   :D :D

Cheers  :beer:

Don
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