Vacuum pump questions

[Paul Maxwell]

I have a co-worker that has an a/c evacuation vacuum pump that I could get on trade. I want to set up a vacuum chuck system, but a, unsure if this type of vacuum pump would work properly. It is a Robinair model #15400 with the following specs:



VacuMaster Pump Specifications
Model 15400
Free Air Displacement 4 CFM
Stages 2
Motor Speed 1725 RPM
Voltage +10% 115V 60 HZ
Factory Micron Rating 20 microns
Approximate Oil Capacity 15 oz.
Weight 29 lbs.
Width 55/8 in.
Height 93/4 in.
Length 151/2 in.
Intake 1/2” and 1/4”
SAE MFL
Min. Starting Temp.
(at 90% Voltage) 32oF
Motor Size 1/3 hp
Capacitor Start Capacitor Start
Operating Temp. 155oF

Note:

1. All motors are internally protected (automatic reset).

2. Operating temperatures are typical for normal operating
conditions.

Would this work ok for this application?

[Jeff Nicol]

It will work great! You will just have to make or buy some vacuum chucks and get an adapter for the lathe that works. Then some valves and tubing an you should be set!
I wish I could get one on a trade. I use an old compressor from a dehumidifier and that works great! It is not real pretty!

Jeff

[Steve Schlumpf]

Paul - I agree with Jeff - that pump should work just fine. Biggest thing to look for is the amount of air it can move. Yours moves 4 cfm and that should work great.

Don't know if you already have plans on how to build your system but there is a tutorial on a vac system in the Woodworking Articles and Reviews Forum that may give you some additional information.

[Joshua Dinerstein]

Where does one go about getting a vacuum pump if not lucky enough to find one for trade? I went to the website steve mentions and they didn't have the one he used.

Anyone got a good source for one?

Joshua

[Tom Klass]

you can try surplus center for the pump, I have a gast rotory vane type. They may also have a spare freon tank. I use it when I do veneering it sucks down the bag faster. good luck Tom,

[Max Acbuilder]

Try this place. [URL="http://www.joewoodworker.com"] Drill down into the web site and he has the very best low cost turner's vacuum set up. I ordered the pump and parts and it is one of the best deals on the web. Also look at the Oneway vacuum adapter and vacuum chucks. All great stuff and it takes the mystery out of vacuum chucking.:rolleyes:

[Ben Richardson]

Harbor freight tools has a nice looking vacuum pump for about $65.00 new. My advisor thinks it is a good deal.

[Paul Maxwell]

Don't know if you already have plans on how to build your system but there is a tutorial on a vac system in the Woodworking Articles and Reviews Forum that may give you some additional information.

Steve, Thanks for your thoughts on this pump. I have been looking at your tutorial for several weeks now just waiting to begin on my build. I think that my fellow "trader" may be asking a bit too much for this to work out for me. My realistic cost for the trade would come in around $200, and I am wondering if I can't find something for less. The trade would mean no additional cash out of pocket for me though and cash is not something I have a lot of lately!

Also, thanks for taking the time to put the tutorial together. It is a fantastic reference for those of us still trying to put a system together!

[Joshua Dinerstein]

Harbor freight tools has a nice looking vacuum pump for about $65.00 new. My advisor thinks it is a good deal.

Wow. That is a good find. $59 for the 1.2cfm vacuum pump and $75 for a 2.5cfm pump. Anyone, Steve?!!?, have a comment on how much of a vacuum is really need? For that I will build one of these. Would have worked perfectly last night for what the ring caddies I was turning!

I wanted to add my Thanks to Steve for his excellent write-up on building a vacuum chucking system!

Joshua

[Steve Schlumpf]

Joshua, I looked at the HF pumps and honestly feel that they would be underpowered to do the job. Please understand that I am basing this on gut feeling only and have no idea how to convert 10 Pascal to it's equivalent hg reading. The max of 2.5 cfm worries me more than anything. Your system, once built, will have air leaks no matter how well you seal it. All the little leaks, the porous wood, everything together - all subtract from the total amount of vacuum you can pull. I would think even the biggest one of these pumps would be overwhelmed with the job. Would make for a great veneering pump - but honestly don't think they would work for a vac chuck system IMHO.

[Joshua Dinerstein]

Joshua, I looked at the HF pumps and honestly feel that they would be underpowered to do the job. Please understand that I am basing this on gut feeling only and have no idea how to convert 10 Pascal to it's equivalent hg reading. The max of 2.5 cfm worries me more than anything. Your system, once built, will have air leaks no matter how well you seal it. All the little leaks, the porous wood, everything together - all subtract from the total amount of vacuum you can pull. I would think even the biggest one of these pumps would be overwhelmed with the job. Would make for a great veneering pump - but honestly don't think they would work for a vac chuck system IMHO.

Yeah. That was what worried me. That it just wouldn't be enough.

I found this website just now: http://www.onlineconversion.com/pressure.htm

That does a conversion from pascal's to ??? But I am not sure what inches means in this case. Inches of air? Water? According that site 1 pascal is 3.1 inches of air at 0 deg C and 3.28 inches at 15 degrees. So if 22 is what is needed then then 31 to 33 inches should be enough. But that doesn't account for leaks etc...

Perhaps it just isn't worth worrying about. Might be time just to find another source. But the price sure is tempting.

Any further thoughts after seeing the conversion?

Thanks Steve!
Joshua

[Steve Schlumpf]

Joshua,

The units used to measure vacuum is inches of mercury (hg) and when I ran the conversion of what the bigger pump can offer - it can in NO WAY work for your system. I run around 20 hg and this pump maxes out at 75 micron of mercury [0 °C] = 0.002 952 755 939 8 inch of mercury [0 °C].

Basically - means you need to keep looking - unless someone can prove the logic wrong!

[Larry Marley]

I have the HF 2.5 and it works great.
It quickly pulls down to 29hg.
The one thing to know is that it is an oil bathed rotary vane type which is why is pulls a high vacuum. The bad part is that it exhausts oil mist when bleeding air to reduce vacuum. I installed two of the filters Steve lists in his instructions in series on the exhaust side of the pump to filter the oil mist.
I made an adapter to connect the exhaust to 1/2" hose. very quiet.
Also runs on 120v, which is nice...

I also used the Beal tap that Steve recommends to make the vacuum chuck and it is slick as slick gets.

Thanks Steve!!!

[Steve Schlumpf]

Larry,

I stand corrected! Thanks for your input! Figured for sure that the 2.5 cfm would have been the limiting factor with the HF pumps. Glad to know that I was wrong and folks could use the pump! Can't beat the price! Thanks for setting the record straight!

[Ben Richardson]

Larry you are right I have a friend that has the small pump and he does large bowls on a large PowerMatic. He gets 20" HG very easily.

[Larry Marley]

Steve,
You are still the Vacuum Chuck king in my eyes!

[Joshua Dinerstein]

Steve,
You are still the Vacuum Chuck king in my eyes!
Thanks for posting your results. I think I need to start building mine. I could really have used it the other day!

And thanks again Steve for doing the work in the first place.

Has anyone spec'ed out the prices of the rest of the fittings? I wonder with the HF pump what the actual cost would be... I guess I will get started on doing just that.

Joshua

[neil mackay]

Paul,
Pretty wellany vac pump will do with in reason.


The significant questions are volume and % or hg of negative pressure [vacuum] that are achievable.


As long as you have a reasonable level of vacuum you should be alright. Whats a reasonable amount? Kinda depends on the area that its being applied too ie 20% [6.4hg] applied to 1sq inch aint much but on a sq yard its a lot.

So go for the highest vac number and vac chucks can get by with low volume.
ie 50% vac [16hg] and .5cfm would make a good vac chuck application. Volume affects the speed at which the vacuum pumps get to its maximum or set level.Unless you have a super porous work piece, then a higher volume pump is required, the higher the better.

As to leaks these can be remedied by going over your screwed joints with a good quality teflon pressure tape. Actually achieving a good seal on vacuum is easier than doing so on pressure. On sealing rubber,for on your chuck, look arond for "closed cell" foam. This will mould its self to your work piece with almost zero leakage.

Pascals come in kilopascals or megapascals 10 kp is around 2.95hg and 10mp is around 2952hg.

hope this helps

[Keith Outten]

Last year I purchased a Project EVS kit from Joe Woodworker (http://www.veneersupplies.com/vacuum_press.php) to convert a small Gast pump to use for vacuum chuck work on my ShopBot. This week I finally got around to finishing the pump assembly, the system will pull 21"hg but I don't know what the volume rating is on the pump. The little gast pump came with my laser engraver, I contacted the manufacturer to verify that it could be used as a vacuum source since it was designed as a compressor. Here (http://www.joewoodworker.com/video/video-evs-h.wmv) is a link to a video of the EVS system from Joe Woodworkers site.

I am in the process of building my first vacuum puck, I intend to use Corian for custom pucks and will be using the system to hold Corian material on my router table to machine small parts. I don't expect to have any leaks since the material is all non-porous unless I have gasket problems. I hope to be able to find a roll of O-ring material and machine the grooves in the pucks to fit but I haven't figured out how I can join the ends of the o-ring to get a perfect seal yet.

I could use flat rubber for gaskets I guess, possibly even cut them from sheet stock so there are no joints that would leak. I know this isn't lathe work but the principals are the same, anyone who has suggestions I would appreciate some feedback.
.

[Angus Hines]

What about screen splineing sealed at the ends with that yellow goopie stuff for car weather striping ?


Last year I purchased a Project EVS kit from Joe Woodworker (http://www.veneersupplies.com/vacuum_press.php) to convert a small Gast pump to use for vacuum chuck work on my ShopBot. This week I finally got around to finishing the pump assembly, the system will pull 21"hg but I don't know what the volume rating is on the pump. The little gast pump came with my laser engraver, I contacted the manufacturer to verify that it could be used as a vacuum source since it was designed as a compressor.

I am in the process of building my first vacuum puck, I intend to use Corian for custom pucks and will be using the system to hold Corian material on my router table to machine small parts. I don't expect to have any leaks since the material is all non-porous unless I have gasket problems. I hope to be able to find a roll of O-ring material and machine the grooves in the pucks to fit but I haven't figured out how I can join the ends of the o-ring to get a perfect seal yet.

I could use flat rubber for gaskets I guess, possibly even cut them from sheet stock so there are no joints that would leak. I know this isn't lathe work but the principals are the same, anyone who has suggestions I would appreciate some feedback.
.

[Tom Klass]

Keith, use super glue to put the ends of the o-ring material together. At my full time job we make alot of our own o-rings due to the size we need, works great.
Tom

[Keith Outten]

Thanks for the suggestions guys, I will try the screen spline material and CA glue.
.

[Paul Maxwell]

Back to my original question. I am going to speak to my "trade partner" tomorrow. Does anyone have any more feedback regarding this pump?

[Dave Halter]

What about this one from Surplus Center at $54.95?

http://www.surpluscenter.com/item.asp?UID=2008112820342351&item=4-1669&catname=

The specs say it pulls 4 cfm at 0" hg, with 20" hg maximum.