DIY Vacuum Fixtures

Hi,
lately i have been doing a lot of repetitive stuff plus i need also for sanding, so i decided its time to make some specific vacuum fixtures plus 1 more universal.

So i decided to use the second compressor i have. Bought programmable digital vacuum pressure switch, its on the way. Will fit that near the CNC or on it to avoid vibration from the compressor, it outputs 5v on off signal, so its easy to wire it to input pin. Then will switch the compressor via some relay on the BOB

Mean while i looked at all the design solutions all over the net. Some were very interesting.

I will start making 2 specific fixtures to hold down 200mm OD circle pieces of wood. Here i will use thicker gasket, to compensate if the wood is not perfectly straight.
Now another thing to have in mind is that when i finish the big machine i am building, then i would like to make much more fixtures, so i would like to stick with one size.


While i have it almost all clear, there still remains a question.

What size tubing? Having in mind i will use always compressor directly. No shop vacs , ventury, no pumps or whatever. I am thinking of something minimalist like say 4mmx2.5mm. M6 at the other side.
http://www.mycncuk.com/attachment.ph...id=14349&stc=1

-Am i right that the smaller the tubing the faster the vacuum will be achieved? And that small is good for my specific case?
-Also i will most possibly do it 2x 6-8mm aluminum that will sandwich 10-12mm plastic. So not a lot of space for connectors in the plastic




Below is a table for quick hose connectors. Left is the tube, right is the fixtrure side thread.

http://www.mycncuk.com/attachment.ph...id=14347&stc=1

For those interested here is the piece that is needed at the compressor side . Note that its not like the one i bought so it does NOT have 5V TTL output i believe. Though is the cheapest best buy at 40euro shipped.

http://www.ebay.es/itm/180987591897?...84.m1423.l2649

http://www.mycncuk.com/attachment.ph...id=14348&stc=1 http://www.mycncuk.com/attachment.ph...id=14350&stc=1

Will down pressure from the cutting tool compress the thicker gasket and make Z0 lower ?

I'm also very interested in making some vacuum fixures soon so I'll be watching your progress keenly. I have not done any real investigation yet but I guess the thinner the ID of the tube the better because I don't think high flow volume is required and keep tube lengths to a minimum. I mean long thick tubes will need a bigger vacuum tank to handle the initial suction. Not sure but I don't think all types of quick connect couplers that are designed for pressure will seal properly when used for vacuum so maybe just confirm that with the vendor.
I'm curious when you say "compressor", do you mean vacuum pump or will you be using a compressor with one of those compressed air vacuum generators or is there another way?

Hi Guys
Found some kits
http://www.toolpost.co.uk/pages/Wood...rkholding.html
Regards
Mike

Compare the price to this; http://www.trend-uk.com/en/UK/produc...make_kit_.html

Much more better Eddy
That was the first one i found on my search and was going to see if Trend carried spares for the vacuum pad.

Thanks for that Eddy
Just bought one for the come in handy box
Regards
Mike

Quote:

---

Originally Posted by mekanik

Hi Guys
Found some kits
http://www.toolpost.co.uk/pages/Wood...rkholding.html
Regards
Mike

---

Someone (I think it may have been Eddy) posted some similar kits that Trend had on clearance. I bought two kits, can't remember the price, but less than a tenner a kit. I have not yet tried to make them up as I wanted them for my other router re-build which is still a project - not yet started!!! G.

Here using the left side bar menu, you could see all types of vacuum systems used on CNC.

I like the VAC-MAT and tried to purchase only the mats which are sacrificial but still no response. This is one very clever product but its price is prohibitive. Though i still hope that the mats could be at reasonable price.
http://www.mycncuk.com/attachment.ph...id=14351&stc=1


I especially like the FLIP-POD Vacuum System and parts for it could be made at home or purchased. Especially nice for a big machine.

http://www.mycncuk.com/attachment.ph...id=14352&stc=1

The Metapor Chucks are also favorite of mine. I will make something similar for starters, cause that's what i need, 2 of them. Of course i don't have sintered breathing aluminum so i will use some breathing mat in the middle or nothing at all. cause as i said they will be job specific.
http://www.mycncuk.com/attachment.ph...id=14354&stc=1


Simple Vac clamps also will do the job

http://www.mycncuk.com/attachment.ph...id=14353&stc=1


Here they have some materials, i will buy my self the Vill MIll mat for small details , if i don't find something similar where i live.

http://www.mycncuk.com/attachment.ph...id=14355&stc=1

Had to split the post, too many images

The universal table i am going to make will be grid and perforated at the same time.Similar to what they sell here. By the way the best ones i have seen for the buck. So if you are lazy...
They seem quite a deal. What i like is the small air holes 0.6-0.3mm so it will still suck if holes are open. They can be surfaved /3mm/ and if you dig by accident, repaired.
But if i make something similar will add grid and make it compatible with the VAC-MAT mats.

It will be 2 or 3 parts, look down at the photo , so can be bolted below, at the same time clamped from the sides and at the same time made like the last photo bellow with multiple connectors at 4 sides like these so i can chain them together of needed.

http://www.mycncuk.com/attachment.ph...id=14356&stc=1http://www.mycncuk.com/attachment.ph...id=14357&stc=1http://www.mycncuk.com/attachment.ph...id=14358&stc=1

The ones with multiple connectors that can be stuck together, thats nice:

http://www.mycncuk.com/attachment.ph...id=14359&stc=1 http://www.mycncuk.com/attachment.ph...id=14360&stc=1http://www.mycncuk.com/attachment.ph...id=14361&stc=1


:pirate: So are we ready to make some vacuum tables or what :hysterical:

PS. I will use the compressor directly. It will suck from where the filter goes. Will disconnect the normal pressure regulator. Still not sure if i will need a vacuum deposit or not. Will try both ways. I read on the Zone, so many people are using setup like that and report no compressor heating even after 8h constantly working. You know its easier to suck than to compress

Also there were these threads about the subject;
http://www.mycncuk.com/threads/6710-...a-vacuum-table
http://www.mycncuk.com/threads/7824-...-cutouts-edges

Ok, just tried running the compressor for half an hour and it did not heat at all. Unscrewed the outlet quick connector and screwed a connector where the compressor sucks air.Then taped the inlet :redface:. 30 min was ok. Just was going to report here and it turned off. Waited 5 min tuned it on and it run again. It was almost cold to the touch but obviously something heated. But before i rip it apart and search for a termistor or something , i would like to see if it will work for the fixture or not.

Yeah, i read all the threads here and at the zone. However my conclusion is that i have better have fixture for each job or for the universal table, to have a mat for each job. That covers all unused holes and produces enough friction at the borders and may be inside the job too if needed. Some plain cheap mat will be perfect. Later will go on shopping.

Silyavski, its great news to know that using the compressor inlet works well. Would it not make sense to use an old 9kg or 12kg LPG gas cylinder as a reservoir + a simple one way valve then you don't have to run the compressor all the time?

Be careful with compressor tanks they are designed for positive pressure not negative and they DO implode under high vacuum esp if they are old rusted and not vented correctly.

I'm not scare mongering here it really does happen. My son builds and tests tankers and you'll be amazed at how destructive Vacuum can be on what seem like strong tanks. Watch the Video.!
The Lad in the Green jumper connecting the pipes at 3:19 is my Son he was also the one who crushed the tank hiding behind the tanker while filming and venting the tank . This was an old tank with it's internal baffels cut out to help crush (Your compessor also doesn't have these braces or baffels.) and you'll be amazed how little Vac pressure was needed to flatten that thing.!! . . . . Don't under estimate Vac pressure it's a Killer.!
https://www.youtube.com/watch?v=HCTn3gm7VMQ

If your planning on using the compressor has Vac tank then suggest you weld exterior rings as braces to strengthen. Like this. Attachment 14365

EdIt: Oh by the way those Numpty's weren't acting either they really thought they'd crushed the tank. . .Lol (Serieously)

Any tank that will withstand 14.7PSI positive pressure(@ sea level) (29.4 PSI absolute)will withstand a vacuum attainable by any compressor you CNC chaps will be using.
I was going to buy a vacuum device for changing my engine oil but they were a bit pricy for a plastic tank and a bit of a hand pump so i modified(or should i say hacked) a 5Ltr pressure sprayer that stood up well on a dry run however when i tried using it on the car the hot oil weakened the plastic and it did collapse, the pucker units are obviously made from a different type of plastic and they have internally moulded rings as per a submarine pressure hull. buddy down the road gave me a small butane tank and i will be converting that shortly. all i am trying to say is if you are using a pressure vessel for vacuum storage you should be fine.
Regards
Mike

Quote:

---

Originally Posted by mekanik

all i am trying to say is if you are using a pressure vessel for vacuum storage you should be fine.
Regards
Mike

---

Yes and No Compressors by there nature are water storage units and rust internally so old pressure vessels can be dangerous when used as Vacuum storage.
So all I'm saying is just be aware the pressure vessel may look strong but is it really.? . . You got Xray eyes.!

Appreciate what your saying Dean, and i would suggest that a gas cylinder was used as opposed to a second hand compressor tank. The one i have is prestine internally.
Regards
Mike

Quote:

---

Originally Posted by mekanik

Appreciate what your saying Dean, and i would suggest that a gas cylinder was used as opposed to a second hand compressor tank. The one i have is prestine internally.
Regards
Mike

---

Yep I agree just don't weld it up.! . . Thats another playing with fire thing I've experienced first hand and very scary.! Pocket of gas in metal exploded and just looked like it had been shot with a bullet I shite my self. . .:onthego:

Boyan I did some playing around with vacuum a while ago and found that the small pipe was ok if your just pulling and maintaining high vacuum but soon as the vac dropped IE drilling just a few holes the Vacuum would drop and part would loosen.

Noticed Larger pipe held longer and allowed more holes before dropping I think due to more volume thru the pipe but it didn't allow the same high vacuum.
So I'd say if your not cutting thru then small pipe for better higher vacuum and if you plan on cutting thru in a few places then larger volume needed.

I'm a fan of Vac pods they can be placed any where and can work around them, esp good for profiling.

I will be welding a small threaded adaptor to the base to take a valve for the extraction pipe, but i cut the valve out with a 50mm hole saw and it's been sitting around for over a couple of month so should be OK.
The youtube vids i have seen for window and door manufacture seem to use the movable pad system with various stops for alignment.

I will never let at once 6 people in my garage that are reciting "Bend, Bend..." :victorious:

That was quite impressive collapse on a large scale.

This bellow is my dust separator, made from 200l tank which is 1mm thick. So my 2000w shop vac will not bend it at all when all closed. You can not lift the top either when vac is working, though it just rests there, is not screwed. Pads ring is from old yoga mat. Of course the compressor will pull much more vacuum than the vac cleaner.
By the way this thing works really well. The plastic conical thing is from Aliexpress.

http://www.mycncuk.com/attachment.ph...id=14367&stc=1


What i did learn these days browsing the web, is that:
-from new to old some compressors worked 4 years non stop in that setup
-in order to work well, the compressor needs to have the pistons checked, the gaskets checked, the reed valves on the head checked and everything cleaned. Air filtered well at the input side. Plus liquid separator , if on a mill.


In fact i started preparing and first checked one compressor, which was in like new state, at least from outside. It was dirty there, the reed valves copper gasket was bad, so i ordered new sheet of copper. The valves were dirty, so wouldn't close well. Luckily the pistons seem new and the piston rings ok at first glance..

This is the biggest one i have/330LPM/, so maybe i will be using it for both purposes. I discovered that all that is needed is to leave the output open. Some people on the net say that even if it is closeed, the air is not building enough to stop the compressor.

Quote:

---

Originally Posted by EddyCurrent

Compare the price to this; http://www.trend-uk.com/en/UK/produc...make_kit_.html

---

I bought one of these...Yet to get enough round tuits to actually make it tho... Wish they'd sent a CNC template idea and not the paper hand router templates :-(

I made some test jig from wood. Works perfectly.

One thing is clear to me now. All hosing from compressor up to the CNC must be industrial 1/4 or 3/8, cause i will step on it, solder over it and so on. It must be strong so no cheap PVC hoses here. Added bonus is that i use the same hoses and extensions like for air. So the only thing i bought is the 3/8 quick connector which i fitted at the compressor inlet side.


Decided to save on connectors :-) so i drilled the vacuum fixture and just pushed the PVC hose inside, it works perfectly. Recessed all the necessary areas 3mm. Drilled hole to the back so the vacuum fixture is self fixing to the table. Hole could be closed and instead fixture clamped.

The mat is non slip mat from chinese shop -2euro. 15mm wide rings, i wanted a superb friction.

Next step will be when i have time to fit the Vacuum switch to the compressor, check the negative pressure achieved and test if using vacuum reservoir/the compressor tank/ is better in any way.

Video : https://plus.google.com/111571569713...ts/BHSTDvFBjks

http://www.mycncuk.com/attachment.ph...id=14432&stc=1

http://www.mycncuk.com/attachment.ph...id=14428&stc=1

http://www.mycncuk.com/attachment.ph...id=14431&stc=1

http://www.mycncuk.com/attachment.ph...id=14429&stc=1

http://www.mycncuk.com/attachment.ph...id=14430&stc=1

Just measured the compressor suction- 94Kpa = 705 mmHg = 27.7 inHg= 0.927 Atmospheres , not bad for an old sucker :victorious:

Now i still have the problem about the compressor switching off after 15-20 min of run, without obvious heating. Any ideas? I am going to use the bigger compressor when repaired the gasket, but i want already to use my fixtures . I read on forums people use 8h non stop the compressor without problems for years, why then this old sucker stops?


By the way i have 2 more micro digital vacuum switches, i bought a lot, used , perfect condition, made in japan, very small size, so PM if interested. 25euro each

has the wood been sealed ?

Quote:

---

Originally Posted by Blackrat

has the wood been sealed ?

---

No, but it seems is not necessary. Its very dense. I made it from wood as a test to understand better how it works, before making some stuff in aluminum. It seems though it will perfectly work if wooden. it made from a solid kitchen cutting board. however sealing it is recommendable, due to humidity so it would not twist when dry or humid

it will suck probably more air from the actual part, which is has 3mm bottom /pine/

very useful thread thanks.

a few questions

i know nothing about compressors, can you provide any details incuding photos of how to connect up for sucking/to create vacuum?

a compressor turns on for 5 mins till its full then stops, how do you keep it ogint for an hour without stopping? release air whilst is drawing air in?

Hi andy
A compressor is controlled by a pressure switch,Tank empty switch it on and compressor will run filling the tank, when it's upto the set pressure the pressure switch kills the supply to the motor, as you use air the tank pressure drops below the switches set point,the contacts close and power is supplied to the motor increasing the pressure.
If using as a vac pump all you need to do is open the outlet valve on your tank so the switch will never see the cutout pressure.
There is usually a filter of some sort on the inlet, use this connection for pulling a vacuum.
Regards
Mike

I see so leave the drain valve open or something

Time for update.

Bought from ebay an Alcatel 2010 vacuum pump from Lithuania. WOW what a sucker! 7cfpm , 2 stage, 350W. So these days i have been finishing my new Vacuum Pump Station.

Attachment 18943


Basically the pump is mounted on old air compressor tank, driven by VFD as its motor is 3 phase 350w. The pump is fitted an original exhaust and DIY inlet filter and separator. The pump sucks -filter-hose-tank-quick connector. There is an vacuum sensor switch fitted to see pressure and eventually when i figure how to connect it to my VFD. May be i need a relay or sth. This is the part that i always don't understand...

Attachment 18944Attachment 18945




will post a video later, just uploading it now

here is the video where i show the details of the vacuum system, if you are ready to bear with my gibberish for 5 min

https://www.youtube.com/watch?v=DbSztc4T26c&feature=youtu.be

Hi,
one more video. The final result. Using the vacuum station with the aforementioned vacuum fixture. That saves me a couple of operations when fabricating the top and bottom of the small musical instruments i make. Avoiding tabs, cutting the tabs, sanding the tabs, sanding the shape. The pull is incredible, i can not move it with all my force.

The video is a timelapse of the 15 min process. The cutting is done using 3 flute 1/4" carbide at 17k rpm and 90IPM. I tried full length cut and no problem with that as the fixture is strong and the machine is rigid, but fire starts inside the dust, so no additional 5min savings for now. Maybe time for a new dust shoe and a bigger cutter.


So all cost me not so much, looks nice and is useful to the point that i see starting to use vacuum fixtures for anything i make. Made from cheap wood, it saves additional operations. As far as i see it the key being here is make properly specific vacuum fixture to maximise pull, universal table will be nice, but specific fixtures are simply perfect and easy to make.

https://youtu.be/MiEdiqFYAfc

Some follow up after 2 weeks of 8h per day continuous use.


All works like a charm. Super strong holding force when fixture designed with laws of physics in mind, meaning as big as possible vacuum suction cap area.



But:

Somewhere hidden in the vacuum pump manual is that - When in continuous use oil heats, goes out of pump and travels from exhaust out!!! Discovered that the hard way. Good that i always monitor first time setups. So there is a need of another expensive device that separates and recycles the oil. Or in exhaust there is a spring valve that makes back pressure of 1-2 bars to pump. Remove that and all is cured. But smoke starts then. Dangerous for health smoke.

"No way" i though. More money? The solution - after the exhaust, either you have it or you don't, a pipe must be fitted, vertical for at least 50cm .Oil goes up and when stopped goes down. That ventilates gases far away from your workshop. I left the backpressure valve so i don't produce a lot of smoke. Without this it becomes impossible in workshop after a couple of minutes.Anyways i was wearing a gas mask / for the fine dust. Care should be taken for dust or humidity not to enter back as it sucks all when cooled. When pipe long enough that's not a problem. Plus i bent it at the roof downwards so rain stays out of it

After trial and error i discovered that 35-40Hz from VFD /when 50 is max, remember its a 3 phase / works best so pump makes fast enough negative pressure, no need of valves and pressure switches to control in case of too much vacuum and at same time pump is cool to the touch. That keeps it from consuming oil also.
I think that's the best discovery i have made so far and i think that the pump in this mode will need no repair soon even if working nonstop.


Here is how little smoke it makes now with this setup. No windows or neighbours near, dont worry.

https://www.youtube.com/watch?v=NgR9HZ9nKeM