Vacuum pumps

[Keith Blaine (Unregistered Guest)]

I am looking to get a 7.5 to 10hp vacuum pump. I don't have $5K to spend on shopbot's setup. Is there a place that sells a ~150cfm pump for around $2-3K? Thanks.

[Ryan Patterson]

Look into regenerative blowers http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2125847&PMT4NO=4544065 If you are are in no rush try ebay you will find one or two bigger one at good prices. http://cgi.ebay.com/Regenerative-blower-5-5KW-7-5HP-vacuum-pressure-process_W0QQitemZ7509603111QQcategoryZ106436QQssPa geNameZWD1VQQrdZ1QQcmdZViewItem

[patricktoomey]

Do you think the 10 HP version of the regenerative blower linked to in the post above could handle cut throughs? In other words, can I use LDF as a spoilboard with a plenum under it and then cut through my plywood parts without losing the vacuum? I have seen 10 and 15 HP pumps of other types (and higher prices) do that but I'm wondering if the regenerative blower is capable of that kind of thing.

[Keith Blaine (Unregistered Guest)]

Thank you Ryan.

I started looking at alternatives and saw this.

http://www.amazon.com/gp/product/B00004TI1T/qid=1139375202/sr=1-6/ref=sr_1_6/103-2854000-9107049?%5Fencoding=UTF8&v=glance&n=228013

This is an Amazon link to Milwaukee's 8912 3-state wet/dry vac. According to the specs, it does 92CFM and has a "sealed suction in water" of 134 inches. Does that mean 134 inches of water, aka ~9.5inHG? If so, that would be pretty impressive. The Fein vac only goes to 105 inches of water.

Do you think a pair of these would be sufficient to work with 4x4' bleeder boards?

[richards]

Keith,
If the Milwaukee is like my Fein, you can have EITHER 92CFM of air flow OR 134 inches of water suction. When you have air flow, you lose suction and when you have suction you can't have air flow.

The bleeder board on my vacuum setup helps to reduce air flow, but I can't do one-pass cuts on cabinet sized panels without some slippage; however, if I leave a 0.020 or 0.030 inch 'skin' on the melamine coated particle board, everything works. (My goal is to have 2-1/2 minute cut times per sheet when cutting cabinet panels. I've optimised the tool path so that the cut time is obtainable, but the lack of adequate vacuum means that I have to break apart the panels and then run a clean-up pass on each panel at the router table.)

At a trade show in L.A. last week I visited four CNC router booths that all used 15hp - 18hp regenerative blowers. Two of the booths cut only melamine coated particle board and the other two booths were cutting MDF. At one of the booths cutting MDF, they were having serious problems holding the parts because the MDF wasn't being held securely - which is understandable since MDF lets air bleed through. The booths cutting melamine had no problems - since the melamine acted as a barrier to air flow. (The other booth cutting MDF was demonstrating a door cutting program where they were making multiple passes on the through cuts.)

[Ryan Patterson]

Patrick
Yes the 10hp should handle through cuts with out a lot of small parts. I had used a 7.5HP and was able to hold 12 x 12 without a problem.

Keith,
When I first got my Shopbot I use a shopvac for hold down it worked but the when I got a regenerative blower (the first blower a got was 4.5hp) and could not believe how much stronger it was then the shopvac a was using. It all depend on what you are going to be cutting.

[Keith Blaine (Unregistered Guest)]

Thanks Ryan,

I did some more searching and I think I'm going to end up with either the 10hp Gast Regenerative blower or a similar 10hp Fuji.

As for the spoilboard material, I haven't found a source for LDF yet (california). Does particleboard work at all?

[Brady Watson]

Keith,
You can use Trupan, which is available in CA.

-Brady

[billp]

PALS (Plywood and Lumber Sales)in Richmond,CA has 5-6 different thicknesses of it in stock usually...

[Keith Blaine (Unregistered Guest)]

Thanks.

How does trupan compare to typical BORG MDF?

Richmond is about 30-45 minutes away. Perfect!

[Brady Watson]

Keith,
What is 'BORG' MDF?

-Brady

[Keith Blaine (Unregistered Guest)]

BORG = Big Orange Retail Giant = Home Depot.

[Brady Watson]

Oh..that BORG...It is a totally different animal. If you get the ultralight version, it is 40% lighter than MDF, makes a decent chip with no fine dust, is easy on cutting tools, very little formaldehyde and sands like butter. It is only a few $ more than MDF...and worth every penny.

The problem with BORG MDF is that its resin content fluxuates too much to know if it will work or not as a bleeder.

-B

[ckurak]

Mike,

You mentioned leaving an onion skin on your panels, then having to break them apart and clean them up on the router table. Have you considered/tried making it a two-step process: 1) Make an almost full pass leaving the onion skin, and 2) cutting the onion skin with your CNC? There should be very little lateral force when cutting the onion skin, so the parts may not move.

I know this will increase your per sheet time, but overall it may be better than all of the hand-work to break apart pieces and run them through the router table.

Just a thought...

Charles

[greg_russell]

Charles,

I am using a low powered vacuum system (shop vac) and as such do exactly as you suggest. I cut material almost through leaving about a 64th. I then go back with a final pass to remove that last bit of material. It works very well. As you state, there is very little lateral force and parts do stay in place. Occasionally small parts move but this is far out weighed by the time savings of having to cut off tabs or a skin.


Greg