View Full Version : Which Gast pump for strong air assist?

Rich Harman
02-18-2012, 2:24 AM
I have currently ditched the air assist pump that was provided with my laser. It is not too bad as it is a large 220V model but since I tried using the output of my large vacuum pump there is a huge difference in the amount of airflow. It's hard to quantify but I would guess that it is five to ten times stronger. The air blast is sufficient enough that I now have zero smoke residue on the top surface next to the edge of the cut. It is completely clean. It wasn't bad before but this is obviously much better.

In searching through the many threads that deal with air assist I have read that Gast comes highly recommended. However, I am having trouble finding which Gast pump would be best as I have only found one mention of a partial model number.

I do have a Badger airbrush compressor that I experimented with. It is no better than the Chinese pump that came with the machine. 95% of what I do is cutting at full power so I am looking for something substantially more powerful than an airbrush compressor. Quiet would be nice too. My vacuum pump is quite loud.

I also have a regular shop compressor (ex-military compressor built in 1944) that is very quiet but I don't want to have to run lines across the shop and deal with the water issues. Even though it still runs great I don't want to have it running as much as would be needed for the laser.

Daniel Wolanski
02-18-2012, 1:01 PM
Hey Rich!
I ditched the junker that didn't work when you came over to help setup my machine. I bought one of these on AmazonActive Air Commercial Air Pump with 12 outlets - 110 Liters Per Minute


It's prewired as 110v and it improved my cut rate tremendously... it REALLY BLOWS!:) I also tried the harbor freight airbrush pump and it doesn't even compare to this thing. In fact, I just ordered another one for the other cutting head.

FYI, I don't use the 12 outlet manifold that comes with it unless I want to regulate the air flow lower. For most of my cutting, I just hook up the line direct to the single pump outlet.

john banks
02-18-2012, 2:17 PM
I have the Hailea ACO500 at the bottom of this page for a UK supplier with a great price:

I'm sure searches for the product will find it in the US.

Check the voltage but I find it fantastic with thick wood. It runs about 5 PSI and I get no benefit from running three times that from a much bigger/noisier/oily compressor. It doesn't need a reservoir and can run 100% duty.

Rich Harman
02-18-2012, 3:49 PM
Dan, that pump looks exactly like the one that came with my machine.

John, yours look the same too, although I don't see the 500 model, just the 420. That 420 claims nearly four times the flow of Dan's, which I guess makes sense since it is 220V.

My old one is 220V also but there are no markings indicating what it's flow is.

I sent off an email to Shenhui to see if they can tell me the specs on it.

john banks
02-18-2012, 4:56 PM
They all look the same but when you see pictures of the higher flow models next to the ones typically supplied with a machine they are considerably bigger. The ACO 500 is 420lpm and the biggest in the range.

There is a thread here which motivated me to buy it. oplaser.co.uk/opsupport/viewtopic.php?f=5&t=3

Pic from that thread for those not registered showing standard vs the ACO500 is attached.


Rich Harman
02-19-2012, 2:24 AM
The one supplied to me by Shenhui is the larger size, and it's performance is acceptable.


john banks
02-19-2012, 6:10 AM
But you get better results with something bigger? From the photo I think the one you showed has a different number of fins and if that is sitting on CW5000 it looks smaller. I will post some measurements so we can be sure as if you find an economical upgrade that is better I would possibly also try and keep existing as spare.

john banks
02-19-2012, 12:46 PM
12x6x7". The 12" length included the black cylindrical cover but not the unscrewable hose barb at the outlet.

Rich Harman
02-19-2012, 4:02 PM
Thanks John.

Yes, there is a big difference when going to a more powerful air assist - at least when cutting plywood. Absolutely no cleanup is required on the face and no residue surrounding engraved areas. I can't tell any difference when cutting acrylic so I use the supplied pump for that since it is much quieter.

My pump seems to be a bit smaller than yours. Mine measures 9.8" x 5" x 5" not including the feet.

Daniel Wolanski
02-19-2012, 6:14 PM
I think one of the best things we could do is increase the diameter of the tube going from the pump to the nozzle. This would give a greater volume of air available without as much friction loss as we are encountering. I need to find a source for that tank track looking stuff that the tube / wires go in so I can buy a bigger one.

john banks
02-20-2012, 8:26 AM
0.738" (18.73mm) wood being cut at 90% power 3mm/s 3" (75mm) ZnSe lens with this 5PSI air assist.


Rich Harman
02-20-2012, 8:40 AM

This is an old video of cutting 14mm cedar at 4mm/s with the 50mm lens. The air assist is from the pump provided by Shenhui (pictured a few posts up).

john banks
02-20-2012, 1:40 PM
I tried 22 PSI through a big compressor and the charring almost disappears even without tape. But it is a noisy and vibrating nightmare of a thing.

Mark Sipes
02-20-2012, 4:27 PM
"I need to find a source for that tank track looking stuff that the tube / wires go in so I can buy a bigger one."

Try Grainer (4930 3rd Ave S, Seattle http://cableorganizer.com/igus/echain-series-e08-chain.html

Energy Chain (Cable/Hose Carrier)

or an Electrician's Supply Source like Platt Electrical , 2757 6TH Ave S, Seattle

Daniel Wolanski
02-20-2012, 4:35 PM
Thanks Mark!

Rich Harman
02-20-2012, 4:58 PM
Or you could just print some... http://www.thingiverse.com/thing:11978 :)

Rich Harman
02-22-2012, 3:38 AM
Shenhui says that the air pump is rated at 110 liters/min @ 4.6 psi.

That makes it comparable to Dan's new pump. I think I will try the 420L/min one that John has.

Rich Harman
02-22-2012, 7:47 PM
Yikes, I was mislead. I easily found the Hailea ACO 500 pump on eBay for $160 but I did not notice the $160 shipping charge until I went to order it.

Still looking for another source...

Kimmy Armstrong
02-22-2012, 8:19 PM
Any photos of the before and after when cutting plywood?

Rich Harman
02-22-2012, 11:23 PM
I will try to get some photos posted soon.

I have made a decision (more like a guess) on which pump to purchase. A Thomas 2685 (http://www.cfpwarehouse.com/thomas/compressors/pump_data/2685pe40.pdf).

Rich Harman
10-08-2012, 2:59 AM
A follow up;

I didn't actually get the Thomas compressor. After I bid on it (eBay) I noticed the picture was not of a Thomas but a Gast. The seller claimed they were made by the same factory and were identical. He was an idiot. I went ahead with the order because the Gast 71R(twin cylinder) is a good compressor and they are hard to find for a good price.


I have been using it for several months and it works great - no problems. It may be less than 70dB like they claim when there is no resistance but I think 80dB is closer to reality under use. I made a post a while ago where I state what the actual dB levels are.

I rigged up a simple way to vary the pressure. From the compressor I have the line going into a tee. One branch goes to the laser, the other has a ball valve with a five foot length of hose attached that I have routed behind the laser, not attached to anything. Ahead of the tee I also have a pressure gage. If the ball valve is open then most of the air is dumped through the hose behind the laser. I put it behind the laser because it can get a bit noisy with all the air rushing out of it. The more the valve is closed the more pressure goes to the laser. When cutting wood the valve is all the way closed for maximum pressure (30psi) to the air assist. When cutting acrylic I open it up a little to about 20psi - it runs quite a bit quieter that way too.