# Vacuum Pumps



## thenodemaster (Jun 14, 2015)

I am almost ready to pull the trigger on a vacuum chucking setup but was wondering which type of vacuum pump I should use: diaphram, rotary vein, etc. What are the pros/cons of them? I see diaphram being more expensive and oilless but quieter while rotary vein has been noted as being louder and uses oil but a much better price for a given CFM. Looking at between a 4 and 6 CFM pump.

Right now I am leaning towards this pump with the plumbing kit below on the same page: http://jtturningtools.com/vacuumpumps-kits

Just trying to get the best deal I can find for a good setup.

Thanks for your insights!


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## thenodemaster (Jun 14, 2015)

I found this pump on ebay and wonder if it is work a shot for the price. Would say it is made in China, but considering: http://www.ebay.com/itm/5CFM-1-2HP-...d=100010&rk=4&rkt=19&mehot=pp&sd=231702288123


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## Bill Boehme (Feb 9, 2014)

thenodemaster said:


> I am almost ready to pull the trigger on a vacuum chucking setup but was wondering which type of vacuum pump I should use: diaphram, rotary vein, etc. What are the pros/cons of them? I see diaphram being more expensive and oilless but quieter while rotary vein has been noted as being louder and uses oil but a much better price for a given CFM. Looking at between a 4 and 6 CFM pump.
> 
> Right now I am leaning towards this pump with the plumbing kit below on the same page: http://jtturningtools.com/vacuumpumps-kits
> 
> ...


*Dry* rotary VANE is the preferred type for woodturning because of the high flow capacity and good vacuum performance even wit some air leakage. Oil type rotary vane pumps are less desirable because of oil contamination from wood dust and also because they produce an oil mist.

DIAPHRAGM pumps are less tolerant of air leaks and are slower to recover vacuum although the one that you indicate seems to be better than average. Diaphragm pumps are generally the lowest cost of the three main types. Typically, diaphragm pumps do not produce as strong a vacuum as rotary vane or piston pumps.

Piston pumps are for pulling a hard vacuum, require oil, and have lower open port flow rate than rotary vane and diaphragm pumps.



thenodemaster said:


> I found this pump on ebay and wonder if it is work a shot for the price. Would say it is made in China, but considering: http://www.ebay.com/itm/5CFM-1-2HP-...d=100010&rk=4&rkt=19&mehot=pp&sd=231702288123


The main drawback is that it is an oil type rotary vane pump.


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## thenodemaster (Jun 14, 2015)

Thanks for the info, Bill. I appreciate the clarity.

My minion at my day job has a couple of rotary vein pumps he is going to check on the CFM. If they are not more than a 4 or 5, I will pass them on since everything I have read says that 4CFM is the minimum for reliable hold even when the wood allows for some leakage. I understand the issue with the oil filled pumps. That was one of my concerns as well. As far as the oil mist or noise, it is not much of a problem as my minion at work has let me know of what sort of performance and noise he had from these pumps. I was going to give me a deal of $35 if one of them met my CFM requirements. We'll see what happens--had my budget slashed rather severely and I am trying to salvage my chance of doing this. Otherwise I would have just gone with the setup at jtturningtools.com for the pump and plumbing.


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## Bill Boehme (Feb 9, 2014)

I hope that I'm not being too "vain" when I say that it is rotary "vane" and not "vein". :laughing: Sorry, I couldn't help myself. 

The internal workings has four vanes that slide in and out of slots in the rotor as centrifugal force pushes them outward against the edge of the oval (maybe elliptical) chamber somewhat like a Wankel engine combustion chamber.

I think that the Gast series 0523 pump has an open port flow of about 4.5 CFM which has been fine for everything that I have done over the past 7 or 8 years. A rating of 3 CFM would be marginal I think.

I'm not sure where my minion is now. I donated him to Beads of Courage.


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## 9thousandfeet (Dec 28, 2014)

Just for the record, the JT pump which nodemaster linked to in the original post has been around for a while and is both durable and quiet.

Although it pulls less vacuum than a rotary vane unit like the Gast (just like any diaphragm pump will), it still pulls plenty for woodturning purposes. I've never once suffered from inadequate vacuum causing a lack of holding power.

It has only slightly less flow rate than the Gast pump too. (4.2 vs 4.5 cfm)

And you can buy two of the JT pumps for the price of a single Gast and have enough money left over for a decent bowl gouge.


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## thenodemaster (Jun 14, 2015)

Well, I pulled the trigger on this chuck kit: http://www.chefwarekits.com/woodtur...its-any-mt-2-lathe-woodturning-hold-fast.html

I also added the reverse chuck mount.

Still waiting for my coworker to find the pumps he has to see if they have a high enough CFM before I go out and drop another chunk of $$$ for a pump.


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## johnep (Apr 12, 2007)

When using a vacuum bag to pull down a veneer my friends used an old pump out of a fridge.
johnep


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## thenodemaster (Jun 14, 2015)

I was also looking for that functionality as well as for vacuum pot stabilization. If the one from my coworker is not up to the task, I found a 5CFM unit online that I will go with.


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## Bill Boehme (Feb 9, 2014)

I ought to mention that if you get a vacuum level of about 18 inches of mercury that should be plenty adequate for most things. Holding smaller things is more of a challenge than larger pieces where you can use chucks with a larger diameter.

The EZ rotary coupler is OK, but it seems to be a bit pricey. Also, it uses only a single bearing which means that any side loading where the vacuum line connects to the hose barb fitting will probably lead to some leakage through the bearing and some loss of lubricant from the bearing.

I built several single bearing type rotary couplers before it occurred to me that was the main reason that all of the grease was being sucked out of the bearing and resulting in early failure as well as excessive air leakage. The best rotary couplers have at least two bearings and shaft seals so that overhung loads are much less of a problem. I found that I can buy a really excellent rotary coupler from JT turning tools for about $100 or I can make one myself for about $50 and 100 hours of work that isn't as good as the store bought one from JT Turning Tools.

Something that you can do to minimize any overhung loads is to insert a *street ell* between the coupler and the hose barb fitting and then clamp the hose to your lathe in a way that insures only minimal side loads are being placed on the coupler. Flexible hose is also better than stiff hose in this respect.

If nobody has mentioned it yet, tailstock pressure should be used in conjunction with vacuum chucking to help keep the piece from shifting around and help save the day if vacuum is suddenly lost for some reason ... and it can happen when you least expect. My vacuum pump suddenly shut off in the middle of vacuum chucking. Fortunately the tailstock pressure prevented a flying bowl. The problem was that I had been using vacuum chucking for several hours without stopping long enough between bowls to let the pump cool and it was a hot summer day. When the motor reached the point of egg frying temperature, the thermal overload switch shut it off and I had to wait about an hour or so before the thermal cutoff finally reset. So now I pay much closer attention to how hot the vacuum pump is getting ... and the Gast dry rotary vane pumps do get really really hot.


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## thenodemaster (Jun 14, 2015)

Thanks for the info, Bill. Yes, I do plan on using the tailstock for support and have ordered a reversing mandrel for the 4 jaw chuck--it was an option for the chuck kit I ordered from Holdfast. The kit I got has aluminum ends with bearing in each for the vacuum adapter. I also ordered extra seals and such. It comes with a 3" and 6" chuck cups with the 1 1/4" x 8TPI of my lathe. I should hopefully know Monday if I will be ordering a vacuum pump or getting a second hand one form a coworker--he is just having a bit of trouble locating it at home. Once the pump and everything arrives, I will get the plumbing fittings locally and see what happens.


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## 9thousandfeet (Dec 28, 2014)

It's interesting to compute the holding power of a vacuum chuck.

Roughly speaking, you get almost 1/2lb/sq in of holding force from every 1" of mercury of vacuum. (It's a tiny bit less than that, but not much less)

So 20" of mercury pulling on a 6" diameter chuck adds up pretty quick;

0.5 x total inches of Hg vacuum (20) x area of chuck (3.142 x radius squared)

0.5 x 20 x 3.142 x 3 x 3 = about 280 lbs or so. 

Quite a bit, which is why a bleed valve is an absolute necessity so you can back off on the vacuum for fragile work, otherwise it's entirely possible to have the workpiece simply implode.

Like Bill mentions, when the chucks get smaller the holding forces drop in proportion to the square of the diameter, so if you halve the chuck diameter to 3", you get only one-fourth, about 70lbs in this example, of holding force. 

That's plenty for a smallish workpiece, but kinda spooky for a larger one.

So it's important that the chuck diameter matches the piece being turned. Much more so than with mechanical chucks which tighten on a spigot or tenon.
It's usually not a problem to hold a 12" diameter bowl with a 3" tenon in a 4-jaw chuck, but trying to hold that same bowl with a 3" vacuum chuck is asking for an adventure you probably don't want.


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## thenodemaster (Jun 14, 2015)

@9kfeet: That was why the set I bought came with a 3" and a 6" head.


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## 9thousandfeet (Dec 28, 2014)

thenodemaster said:


> @9kfeet: That was why the set I bought came with a 3" and a 6" head.


 Understood.

It's quite easy to make vacuum chucks bigger or smaller than that, as you find you need them, and very inexpensively too. 
Especially if you have a tap the size of your spindle thread — 1 1/4 x 8 or whatever.

I think I might have something like 8 or 9 homemade ones, the smallest being barely 1.5" and the biggest around 10" or so.

You're going to like vacuum chucking. It's really versatile.


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## Bill Boehme (Feb 9, 2014)

As 9K' said making a vacuum chuck is easy and can save you a bundle of money. The details depend on how you connect the plumbing from the rotary coupler at the hand wheel to the nose of the spindle. The two most common choices are using a lamp rod and just using the hollow spindle. The sealing requirements are different for those two methods. Here is a link to a thread on Wood Online where I describe *my solution* for building a chuck for my Robust. Since I am using a JT Tools rotary coupler, I can't use a lamp rod for the plumbing through the headstock. As a result, I needed a way to create a seal at the spindle nose. You can skip posts 9 through 18 since they are about rotary couplers including how I did it for my old Delta 1440 Iron Bed Boat Anchor. Posts 19 through 22 provide more details about my chuck design.


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## thenodemaster (Jun 14, 2015)

9thousandfeet said:


> Understood.
> 
> It's quite easy to make vacuum chucks bigger or smaller than that, as you find you need them, and very inexpensively too.
> Especially if you have a tap the size of your spindle thread — 1 1/4 x 8 or whatever.
> ...


I figured there would be in between and outside sizes I would need for those short bus special projects. At least with this set starting out, a wide swath of bases would be covered. And with the vacuum adapter, I can easily add my shop built versions as needed.

Can't wait to get my toys. Might even make one for the misses.......:blink:


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## thenodemaster (Jun 14, 2015)

Bill Boehme said:


> As 9K' said making a vacuum chuck is easy and can save you a bundle of money. The details depend on how you connect the plumbing from the rotary coupler at the hand wheel to the nose of the spindle. The two most common choices are using a lamp rod and just using the hollow spindle. The sealing requirements are different for those two methods. Here is a link to a thread on Wood Online where I describe *my solution* for building a chuck for my Robust. Since I am using a JT Tools rotary coupler, I can't use a lamp rod for the plumbing through the headstock. As a result, I needed a way to create a seal at the spindle nose. You can skip posts 9 through 18 since they are about rotary couplers including how I did it for my old Delta 1440 Iron Bed Boat Anchor. Posts 19 through 22 provide more details about my chuck design.


I like your pic for the expansion plug for the #2 morse taper. Very cool. I did my homework on the adapter that came with the starter kit I bought and the initial version had its issues but the current version I bought is made out of aluminum and has a lot of very happy customers. I saw the exact kit on Carl Jacobson's YouTube channel and got the same kit less the venturi vacuum generator. From what I saw, it is a great kit to start with.

At the moment, I have 3 or 4 bowls that are in need of the vacuum chuck so I can make the recess for my branded medallion--That is the first and main reason I ordered a vacuum chuck was so I could make that recess.:thumbsup:


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## thenodemaster (Jun 14, 2015)

johnep34 said:


> When using a vacuum bag to pull down a veneer my friends used an old pump out of a fridge.
> johnep


I have my minion from my day job checking the 2 vacuum pumps he has (used to do refrigeration stuff in his dad's auto shop) to see how many CFM they handle. If they are above 4, I will go that route because of the great price and I trust his knowing they are rather expensive and good quality pumps that work. If they don't meet my CFM needs, I have an alternative lined up but would prefer to go with someone I trust--and KNOW WHERE THEY WORK! :laughing:


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## thenodemaster (Jun 14, 2015)

9thousandfeet said:


> Just for the record, the JT pump which nodemaster linked to in the original post has been around for a while and is both durable and quiet.
> 
> And you can buy two of the JT pumps for the price of a single Gast and have enough money left over for a decent bowl gouge.


Those were the reasons I was really looking at those.

My minion in my day job is a submarine hydraulic and HVAC engineer who mentioned his complaints about the diaphragm pumps--which, after his explaining to me everything, I completely wrote off diaphragm pumps as an option.


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## thenodemaster (Jun 14, 2015)

Bill Boehme said:


> I hope that I'm not being too "vain" when I say that it is rotary "vane" and not "vein". :laughing: Sorry, I couldn't help myself.
> 
> I'm not sure where my minion is now. I donated him to Beads of Courage.


You donated your minion? Was it incompetent? If not...what a horrible evil genius...wait a minute...I guess you would be exactly as intended at that point.

And, yes, I get it: vein. Vane. :laughing:

Had both spellings on the sites I was checking and used what looked right. Guess I was wrong. Left?


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## 9thousandfeet (Dec 28, 2014)

thenodemaster said:


> ...who mentioned his complaints about the diaphragm pumps--which, after his explaining to me everything, I completely wrote off diaphragm pumps as an option.


 Fair enough.
I have no complaints about the JT pump though. It's been a real solid performer in a production situation for several years now.


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## Bill Boehme (Feb 9, 2014)

The suitability of a vacuum pump depends on both the intended application and the specs of the particular model regardless of the type of pump. For vacuum chucking on the lathe, where the requirements aren't very stringent you can find suitable pumps in all three categories. But, you can generalize about the characteristics of the three categories. Piston pumps are capable of pulling a hard vacuum and are the best for HVAC use, but the flow rate isn't high and lubricant is in the flow stream. Diaphragm pumps pull a soft to moderate vacuum with a flow rate that is between the piston and rotary vane pumps. Rotary vane pumps pull a high vacuum that typically isn't quite enough for HVAC applications and they have a high flow rate. Rotary vane pumps come in two flavors ... lubricated and dry. You can find a lot of performance variation in each category as well as a lot of overlap between the three types of vacuum pumps. While on average the dry rotary vane pump looks like the best fit for woodturning vacuum chucking, we can't exclude all diaphragm and piston pumps because there are plenty of models that will fit the needs of vacuum chucking. Also, the "requirements" of vacuum chucking are soft requirements that are somewhat overstated to give a lot of safety margin. In the early days of vacuum chucking some people used shop vacs and found them to be perfectly suitable (soft vacuum, but huge air flow that can overcome lots of leaks) ... the problem was that the shop vac motor, starved of cooling air, would burn up from lack of adequate cooling air. These shop vac systems also used simple rotary couplers that were just a slip fit between two cylinders.


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## thenodemaster (Jun 14, 2015)

I looked at the shop vacuum setups and was not impressed. While I do not have a lot of money, from what I have seen, I have enough of a budget to allow for a decent quality pump...just waiting to see if I can get off cheap with my coworker's of if I need to hit the store. Not really a bad thing if I have to buy a pump at the store, but, I can't think of anyone who would be opposed to saving $$$ when they can. I have been burned by cheap chinese garbage before which is why I am being careful with something that holds a chunk of wood which would easily rearrange my pretty face!


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## Bill Boehme (Feb 9, 2014)

Have you looked at the refurbished Thomas vacuum pumps from *FrugalVacuumChuck.com*. He has been at SWAT for the last two years and there has always been a crowd around his booth buying vacuum pumps. He rebuilds them to essentially new condition. Everybody has been very pleased with the vacuum pumps that he has refurbished. You can buy just the vacuum pump or a complete kit if you wish.


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## thenodemaster (Jun 14, 2015)

Bill Boehme said:


> Have you looked at the refurbished Thomas vacuum pumps from *FrugalVacuumChuck.com*. He has been at SWAT for the last two years and there has always been a crowd around his booth buying vacuum pumps. He rebuilds them to essentially new condition. Everybody has been very pleased with the vacuum pumps that he has refurbished. You can buy just the vacuum pump or a complete kit if you wish.


Never heard of them. Gonna go check it out! Thanks Bill!


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## hwebb99 (Nov 27, 2012)

Here is a testament to the power of vacuum chucking. I have vacuum plumbed into my work bench. I use foam gaskets to hold smallish work piece mostly cutting boards for sanding. 









Here is a piece of 1/2 plywood with vacuum applied over a 11x13 inch area. That is a 5 mm drill bit to show the scale of the gap. 









Vacuum is turned off in this picture.


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## hwebb99 (Nov 27, 2012)

Here is another testament to the usefulness and power of vacuum. This is a 43x8 inch board with an even smaller gasket which means less holding power. That is 75 pounds of lead shot on the end. I assure you that vacuum is the only thing holding this board down.


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## thenodemaster (Jun 14, 2015)

Wow! Nice demo.


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## thenodemaster (Jun 14, 2015)

Well, I pulled the trigger on the Holdfast kit with the 3" and 6" chucks. My cohort at work failed to come through on the pumps he had as he had family health issues to contend with, so, no big deal on that. I got a 5CFM vane pump which fit nicely within my budget. It is an oiled on, but I have it on a hose setup that allows me to have it at the opening of my shop. My Grizzly's headstock was a bit on the longer side of the spectrum and the rod that came in the Holdfast kit was long enough--barely! LOL. Anyway, played around a bit with it once I picked up a few plumbing fittings and a bypass ball valve. Pulls about 26" of Hg and has a quick vacuum grab with the valve closed all the way. I was surprised at how quiet the pump is when in use. I was expecting a heck of a lot louder, but it ended up being slightly louder that the aeration pumps I used back when I had a reef tank. Gonna have fun with this one!


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## hwebb99 (Nov 27, 2012)

I have compressed air fittings on my pump and I use a compressed air hose. Some people will tell you that the hose will collapse, but I have never had any trouble. I even use a flexzilla hose which is pretty soft.


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## thenodemaster (Jun 14, 2015)

hwebb99 said:


> I have compressed air fittings on my pump and I use a compressed air hose. Some people will tell you that the hose will collapse, but I have never had any trouble. I even use a flexzilla hose which is pretty soft.


That was what I used as well. The extension hose I bought was much more rigid than the blue transparent one that came with the kit, so, I think it will do just fine. Will give it a go with actual turning this weekend--depending on how much the misses wants to party at our concert tomorrow night...


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