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Please Help,
What is the difference with these vacuum pumps. High vac, low vac, low, high pressure, 15″ HG, 29″ HG?
I am a going insane.
Andy,
this is too much information for a public forum.
Shouldn’t you be discussing this in private with your doctor?
P.
Andy,
Try http://www.usvacuumpumps.com
They have information on quite a few pump types and the ranges of vacuum they can obtain. They also explain about about HG and a few other terms.
Paul
Ok, First a little bit of vacuum fundamentals.
Atmospheric pressure is about 14 PSI (lbs per square inch). This is a natural pressure that is exerted on all bodies on the surface of the earth by the atmosphere above us. In a vacuum system some of the atmosphere below a sheet of material is removed by pumping out some of the air, thereby creating a vacuum. The most common way to measure vacuum is in inches of mercury (HG).
If all of the air was pumped out from underneath the material, you would have a perfect vacuum and the gauge would measure -29.92 in Hg. This means that there is 0psi underneath the sheet and 14psi on the top. On a square foot of material that translates to 144sq in x 14 lbs/sq in. 2016 lbs of pressure on the part!
So, HG is the amount of maximum pressure your pump will apply to your material. 15HG = 7 psi = 1000 lbs of pressure per square foot of material. 5 HG = 2psi = 300 lbs of pressure
So High Pressure/Low pressure is the same as 25HG or 15HG
High Vac/Low Vac refers to the amount of CFM that is drawn through the intake of your vacuum.
A High Vac system will have a huge capacity to pull air though the intake. Think in the thousands. (2000-4000CFM)
Low Vacs pull a much smaller amount of air. (50-500CFM)
Now there are three main types of Vacuums.
Fans, Blowers, and Pumps.
Fans are high vac systems pulling thousands of CFM through the intake valve, but usually at under 5HG or 2psi.
Blowers are in between high and low vac systems. They pull between 200-1000CFM, but usually only up to 15HG or 7psi.
Pumps are low vac (50-300CFM) but with very high pressure (20-29HG or 10-14psi.
Andy,
For example we run an AXYZ 5012 with a 10HP Dry Vane Vacuum Pump. When our spoilboard is new our gauge reads at 25HG. When it gets all cut up and full of score lines, or when there is some dirt underneath our material, etc.. Our gauge usually still reads 12-15HG.
I believe you said that you had the TurboVAC from Multicam. The TurboVAC is only capable of 15HG at max vacuum, so when your spoilboard starts to get cut lines, or dirty, your pressure could possibly be dropping as low as 5HG.
Another consideration, is how many vacuum zones you have on your table. When we were considering a CNC we looked at MultiCAM as well, but their table only had 2 vacuum zones as opposed to the 8 that our AXYZ has. Our pump only has a CFM rating of 173 while yours has 425. This allows you to keep your vacuum up over a larger area than ours. But we can simply shut of areas of the table that we are not using to prevent our vacuum from falling to fast.
Hope this all helps. Let me know if you have any other questions.
– Dennis
Perfect. Now is the Dry Vane Vacuum pump going to be better system than what I got? I have 4 zones and I would like to be able to shut some off when only cutting half a sheet or just one sheet.
What brand and model number is your vacuum pump. I want to buy one.
Thanks for all the help.
I found this page from AXYZ. CLICK HERE
Andy, Although I know little about vacuum as compared to Dennis i just bought the cam-wood and it also comes with the 10hp dry vane pump. After much research I have discovered that it is better even though it has less hp.
I am bummed out. My easy button broke at work and the countertops quit building themselves..
Andy, We have a Becker 10HP Oil-less Rotary Vane Pump. Model #VTLF250 SK.
Here is the link for the Becker Web Page: beckerpumps.com/vacuum_pumps.asp
A referral by a company using an Andersen CNC and Becker Pumps: beckerpumps.com/downloads.asp
I love our pump because we can shut off our unused zones and concentrate the vacuum on smaller parts / half sheets.
I know that there are many companies out there besides Becker, You may want to look into some of those companies.
I know that usvacuumpumps.com sells the Becker pump that we have, although it looks like it is priced a lot higher than what we paid. I also know that MultiCAM offers a line of Rotary Vane pumps, so you might want to look into that as well.
You can often find used/new equipmen on Ebay for decent prices.
Does anyone know if I could piggyback a smaller vacuum pump onto the one I already own? I don’t want to spend a ton of money on a new pump when I already have one. But, if I could buy a smaller 5hp unit that would pull more like 27hg, would that work, or is it a big waste of time?
Dennis, I am having my CNC built at the moments and they had planned to install a 25hp vac with 15″hg. I was informed by a tech that works on CNC and other big equipment that the Becker 10hp vac at 27″hg is all I need. Being that you mentioned you love it, will this be all I need for a two sheet hold down? Just worried abount losing the vacuum during routering. Do you make one pass or two, and does it matter with the Becker 10hp pump?
I have a 10HP Becker on my table. Yesterday we had zone three on my table open, 2’x4′ with a one aquare ft piece of SS at the front of the table with 1″ spoil board. Even with 7 sq ft of open surface the pump was still pulling 27hg and I opened another zone so that the pump didn’t lag as much. Still pulled 25hg with 16 sq ft of open surface. With two sheets on the table and all zones open we still pull 18hg.
It’s a great pump.
Paul
Andy,
That worked for me (piggy back ie in series rather than parallel) in China, but I was sucking air out of a chamber.
B Rgds,
Lenny
pjb wrote
I have a 10HP Becker on my table. Yesterday we had zone three on my table open, 2’x4′ with a one aquare ft piece of SS at the front of the table with 1″ spoil board. Even with 7 sq ft of open surface the pump was still pulling 27hg and I opened another zone so that the pump didn’t lag as much. Still pulled 25hg with 16 sq ft of open surface. With two sheets on the table and all zones open we still pull 18hg.
It’s a great pump.
Paul
Paul, I have the same pump as you. I have noticed that when cutting my edge build up they move at the last moment. I do organize my sequence and my start points to compensate for this. But when I spoke the the guy from Becker at the AWFS show he said it should not move. Do your small parts move?
Enroute Pro Wood, I have an option in enroute called Bridges. This is a way cool feature that leaves a bridges( you specify how many, how thick and how wide). Using this feature I cut every letter for a sign and nothing moved at all. I will upload the picture of the sign in a little bit.
Travis,
More often than not my edge buildups don’t move, but my scribe strips always move. The Last 1/8 or so of SS usually breaks from the lateral pressure from the bit and it forces the piece to move. On the build ups I have been making sure the last cut is on the long side. It always moves if the last cut is a short end. I have tried tabs in Toolpath but the software is not very versatile in that regard. The tabs are always the depth of the last pass requiring multiple passes to achieve tabs and you can’t choose where you want them. I have had much better success with cutting small parts with multiple passess and slower speeds on the last pass resulting in less lateral pressure on ther part.
Paul
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