Thread: Vacuum Pump?

You could try this one:
Air Operated Powered Vacuum Pump Venturi System Power Vacumm | eBay.
Cheap enough to experiment with and says it will achieve 28" Hg (about 40 Torr or 90% vacuum) . The down side to venturi is the noise from your compressor.

Refrigeration pumps are ok. They don't pump refrigerant but are used to evacuate the system before charging. This one:
3 CFM Single Stage Rotary Vane Vacuum Pump R410A R134 HVAC A C Air Refrigerant | eBay
reckons it can achieve 5 mBar (about 95% vacuum). I've used similar to this in spectroscopy systems.

I wonder how much difference the higher vacuum makes given that 100% vacuum means 14psi (~1kg/cm2). For a 7.5cm circular chuck that's 44kg holding the job to the chuck or 22kg @ 50% vacuum. Would have thought that even 50% vacuum would be overkill for most work (and maybe even destructive in some instances).

Anyway, I'd be interested to see how you go as I've been thinking about doing the same thing.

Recon medical vacuum pumps come up occasionally on the Aust/NZ luthiers forum. Very good quality.

Vacuum cleaners work Ok but are noisy. Vacuum pumps work, but care needs to be taken especially with thin walled objects, full vacuum can collapse the timber object.

My vacuum pump, bought on ebay is rated at 4.2cfm and as others have said ,it is a pump to evacuate refrigerent lines not to pump refrigerent.I also found that buying the various pipe connections cost about the same as the cost of the pump.It was some time ago and I think about $300 all up.Have a look at TTIT's web site I think he has details of his vacuum system there. I got most of my information from him.
Ted

hi guys,
sorry i have not replied earlier,work keeps getting in the way of my hobby
the system i have is a ''holdfast'' vacuum generator,not sure of the technical
jargon but it pulls 20+in Hg,and the ''safe'' minimum is 12 in Hg,not sure what
that all means but i have never lost a piece yet,there web site is ,TMI Products woodturning tools cyanoacrylate adhesive sharpen gouge vacuum chuck hollowing carbide
sorry i am not sure how to do the linky thing!!!!!!!!!!
i am sure if you have a compressor already ,this is a good way to go
i will get some photos together on the weekend and send them
or post on here,as i have said this week has been a bit busy
cheers smiife

p.s. not sure how the link came up,but it is there now
just went on the website,and remembered i got it from craft supplies usa
went on there site and they are selling for $160.00
hope this info helps,i would recommend this system to anyone
certainly works well

Originally Posted by dai sensei

........... Vacuum pumps work, but care needs to be taken especially with thin walled objects, full vacuum can collapse the timber object.

?? Did you discover this the same way I did?

Originally Posted by smiife

....................not sure of the technical jargon but it pulls 20+in Hg,and the ''safe'' minimum is 12 in Hg,...................

I try to keep mine around 15Hg using the bypass valve - anything higher and! . . see note to Neil above

I bought myself one of those 4 cubic ft/min 2 stage vacuum pumps off ebay a few years ago when I wanted to do some fibreglass infusion molding and just connected it to a 300lt water tank heater which I picked up from a scrap metal merchant This gave me extra vacuum reserve if neccessary, it took about 20-25 minutes to get down to almost pure vacuum and then I just switched the pump off and closed the valves in the line. I have no idea how much vacuum you need for a chuck but I would imagine that a water heater would hold way more than you would require. At least this way the pump would not be running continously and if the vacuum was starting to run out due to leakage, you could always switch the pump on again.

Cheers

Ed.

Hey Scott,

Lots of vacuum pumps are available on ebay. Alternatively, you can have a look onto engineering supply companies. As I know they might have it on lower price. We have it on Tizaro also. You can check if you get any that meets your need.

FWIW I've had hours of use out of an ordinary domestic vac, just with a couple of 3mm bleed holes drilled in the line close to the headstock.

My scientific measure of load is the rise in pitch

hi scott,
sorry, i have been a bit busy,but did manage to get a bit of turning/photographing
on the weekend,hope these photos help to explain what setup i have
if you need any more help just let me know
sorry the pics are not great
cheers smiife


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Originally Posted by smiife

sorry the pics are not great

Nope, that's perfect Smiifie, thank you. Where did you get the holdfast from?

Originally Posted by Osbojo

You could try this one:
Air Operated Powered Vacuum Pump Venturi System Power Vacumm | eBay.
Cheap enough to experiment with and says it will achieve 28" Hg (about 40 Torr or 90% vacuum) . The down side to venturi is the noise from your compressor.

Refrigeration pumps are ok. They don't pump refrigerant but are used to evacuate the system before charging. This one:
3 CFM Single Stage Rotary Vane Vacuum Pump R410A R134 HVAC A C Air Refrigerant | eBay
reckons it can achieve 5 mBar (about 95% vacuum). I've used similar to this in spectroscopy systems.

I wonder how much difference the higher vacuum makes given that 100% vacuum means 14psi (~1kg/cm2). For a 7.5cm circular chuck that's 44kg holding the job to the chuck or 22kg @ 50% vacuum. Would have thought that even 50% vacuum would be overkill for most work (and maybe even destructive in some instances).

Anyway, I'd be interested to see how you go as I've been thinking about doing the same thing.

Thanks for the links Osbojo. Only problem with those pumps is that they're U.S. based, I'd have to get some sort of transformer. I'm interested in Smiifie's solution and will post a little more once I know where I'm heading.

Originally Posted by Scott

Nope, that's perfect Smiifie, thank you. Where did you get the holdfast from?

hi scott,
i got it from craft supplies usa,there web address is Pen Making, Bowl Turning, Wood Lathes, Wood Blanks, and Turning Tools for Woodturners | Craft Supplies USA
look it up just go to the chucks section and vacuum chucks
hope this helps
i tried to find similar in aussie but could not find anything ,i always
try to source tools etc at home first,but could not....
cheers smiife