Vacuum pump suggestions?

[stargategfx]

I'm finally ready to build a vacuum table for my Alpha/Columbo 'Bot.
What should I be shopping for in the way of a vacuum pump?
Any experienced advice would be appreciated.
Brands, types, power ratings etc.
Thanks in advance!

[richards]

Boyd,

What do you plan to cut? What size pieces? How deep and what speed per pass, etc?

On my Alpha w/3hp spindle, my Fein shopvac, four-zone, bleeder board setup does great for cabinet sized pieces. I use tabs to hold smaller pieces together. I can cut MDF, Baltic Birch and particle board one pass to a depth of 0.65 inch and then run a clean-up/tabbing cut to finish the cut. (On larger pieces that don't need tabs, I still run a quick pass slightly oversize and not quite to full depth, and then run a 'finishing' pass).

For small pieces, I use a 3/4-hp Gast pump with MDF masks sized to fit the piece being cut.

[elcruisr]

Boyd,a great deal depends on what you're trying to hold down and what size parts you need to hold and the size of your table. I run a 15 hp FPZ regenerative blower, the kind Shopbot sells. For me it's a minimum setup but I cut parts by the hundreds and thousands out of MDF, ply, melamine and the like. I tab my parts into full sheets and cut at full throttle! If I had my 'druthers I would go to a double stack of 10 hp Becker or Dekker oil ring pumps. Even a single would be a step up but that's not in the budget right now. I don't have alot of time to play with gasketed jigs and the like so I need lots of suction and a good high flow rate. I can still lose a part or two occasionally to suction loss on sheets with tons of small parts.

That being said many here are happy with a couple of shopvacs but then they have different needs than I do. There are also several setups in between.

[david_morris]

Mike,
I'm new to the forum and have just purchased a Alpha96 w/3hp and a Fein III. In your Fein Shopvac setup did you use the Shopbot four-zone file to cut your bleeder board in MDF?

[richards]

David,

I have a 3/4-inch MDF bottom board glued to 3-inch wide Baltic-birch stips that are bolted directly to the Shopbot supplied steel frame. On top of the bottom board, I glued a 3/4-inch sheet of MDF that is cut with the four-zone file supplied by Shopbot. On top of the vacuum board, I have a 1/2-inch sheet of MDF surfaced both sides that is 'glued' to the vacuum board with silicone for 'easy' removal when the board has been surfaced to too thin a point. The four zones of the vacuum board feed through a 2-inch PVC (white plastic) pipe manifold system with a plastic ball valve feeding each zone.

(Yesterday I cut pockets out of a piece of scrap 12x97 3/4-inch MDF that was held in place by the vacuum with no other covering of the exposed areas of the spoil board. Depending on the material being cut, the temperature, humidity and various gremlins that seem to like visiting my little shop, my vacuum system works much better than I expected. On particularly hot dry days, I might add a clamp near the corners because the material tends to bow. On cold dry winter days, I almost always add tabs because the material seems to be slicker than normal.)

[gerald_d]

Boyd, you also have to consider how much electricty you are willing to pay for, and how many amps you can draw at your location.

[elcruisr]

Pumps definately consume some power. On "big iron" machines with 40 to 50 hp pumps the consumption is pretty steep but then the holding power is incredible, which it needs to be if you're cutting around 1800 inches/minute. It becomes a question of how much production do you need because the more you need the more the electric bill will climb. Of course it also means the more money I can make per hour if I charge by the part....

Eric

[richards]

I agree with Eric. My little Fein vacuum works quite well, but I have to be careful about how the parts are laid out and whether to tab or not and how many passes to make per part - just to keep parts from shifting around. In a real production shop, my methods would cost much more in lost production than a large vacuum would cost to buy, run and maintain.

As Eric has written in a prior post, you have to consider the Shopbot, the router/spindle, the vacuum, the software, and proper work flow as a 'system'. Having a large vacuum with a router probably wouldn't buy you much productivity - since the router would be the weak link. In the same fashion, having a 5hp spindle with no vacuum or with the wrong kind of vacuum could be just as unproductive, since it's kind of hard to chase moving parts around the spoil board. However, if you're mainly cutting one pattern all the time, a little vacuum with a good vacuum mask would probably meet your needs. If the goal is to have a truely universal system, where you can virtually cut any part from any type of material in the minimum time with no special setup, then the largest possible vacuum might hold everything in place.

Knowing your customers and their needs is just as important as knowing your equipment and your abilities. Having the wrong tools or the wrong skills or the wrong attitude can sink a business just as quickly as having the wrong customers.

[mikejohn]

Mike
what a sensible post.
I missed Erics earlier post you mention, but in fact all these arguments about differing methods for hold down, table construction,spindle/router/ software have no relevance unless seen as part of the whole work flow system of the person involved.
Isolating and arguing about one single part of the system is pointless.
However, offering constructive advice is still very worthwhile, and I am sure welcoming to the questioner, I know it is to me.
(Which is why when I am repeatedly cutting the same pattern I construct a hold-down jig using some type of clamp
)
................Mike

[stargategfx]

Wow...thanks for the help guys!
Pierre Wessels, a local 'botter called me today and turned me onto regenerative blowers, something I had never heard about before.
Seems as though this would be sufficient for most of our work.
High speed production is not that much of a concern as we are using the Alpha to cut prop and set pieces which change with every episode.
We cut everything from SIP's to medite, aluminum, plexi, sign foam, pvc etc. both large and small objects.
Any suggestions on brands, who has best prices?

[elcruisr]

Boyd, some of those materials would stick like glue with even a 7hp regen while the more porous stuff like some foams and medite could be held but you would need to cut keep your cutting speeds low to keep them from wandering. I speak from experience!

Try the used market first, we bought our 15hp FPZ at 1 year old for half the price of new. Watch sites like ex-factory and M-MLS for used blowers. Another source we found was local industrial pump dealers. Many deal in air pumps as well and sometimes have used models taken in trade but you will need flow and vacuum numbers for them. For some baseline numbers I think the FPZ site has the flow rates and vacuum numbers for all their different models. Just vacuum alone is not the sole concern, you need flow capability to maintain it. I don't have my numbers handy but keep those values in mind while hunting. Don't be afraid to look at any oil ring pumps either, just remember you need to exhaust the air from some of them out doors or through a filter because some of them can "smoke" a little under some circumstamces. You'd be surprised at the prices you can find with a little patient searching.

Eric

[ron brown]

One needs to be careful and look at the specifications of the regenerative blower... or other "pump". The advantage of the proper regenerative blower is a high volume at very good vacuum pull. Some are built more for pressure than vacuum.

All need a sufficient filter system and the larger AND shorter the tubing runs the better. Most vacuum devices make more noise than I like to live with.

Ron

[andre]

I have not yet purchased a shop bot yet but am anticipating in the next year. There seems to be so much talk about vaccum systems that I must say I am confused. If budget were not an issue wouldn't it be best to purchase the system from shop bot or are they not worth the money? Can you get the same performance from shop vacs without spending the $6000? I am a cabinet maker and I forsee most of my usage will be to hold down 4x8 sheet goods. aLthough once I get it I'm sure the possibilities will be endless.
Any advice would surely be appriciated.
Thank you

[patricktoomey]

Andre, I've been using 2 shopvacs to cut cabinet parts from 4x8 sheets with no problems. I would like to have the bigger vac system just to have it and I'm sure it would let me cut deeper passes and smaller pieces but I have not had any incentive to spend all that extra money. If I get to the point where I need to squeeze every last ounce of speed out of my setup I may consider the big vac system so I could cut a little faster but at this point it's not worth it for me.

[elcruisr]

"Can you get the same performance from shop vacs without spending the $6000? I am a cabinet maker and I forsee most of my usage will be to hold down 4x8 sheet goods. aLthough once I get it I'm sure the possibilities will be endless. "

For large cab parts you can use the vacs to a point. For full on production of whatever comes through the door even my 15 hp FPZ is sometimes not enough. With it though I single pass up to 1" sheet goods at 10" / sec. Holding smaller parts requires gasketting, tabbing or a combination of tricks.

If I had money to spare I'd go for two 10 hp Beckers or Dekkers in parrallel and run either one or both as needed.

[joe]

Thank you Eric for a cogent and savy explaination of Vacuum's.

I visited the MultiCam CNC website for their recommendations. They have two units. The smaller is a 10hp, that pulls 15hg of mercury at 200 CFM. There larger unit is ,20hp and pulls 420 CFM at 15hg. I believe Eric was suggesting this type of vacuum presure is necessary for production work. That isn't for everyone but more and more Shopboters are looking in that direction.

Many of us are trading in our routers and Fein's for more professional equipment. That's not to say everyone should change out their equipment, but it's note worthy to notice big changes are afloat.

One option to condiser. If you ever think a spindle would be a good move, consider having it with the tool changer pickup. I'm not talking about a tool changer. It's the replacement of the collet system for a tool changer. With it you twist the bit holder counter clockwise and tug downward. Bit installation is in reverse order. O yes, there's no need to zero a bit again, ever. Well, not with the router.

joe
www.normansignco.com (http://www.normansignco.com)

[pierre_wessels]

I posted a pic somewhere here a while back of an unbelivable vacuum pump that I bought on ebay. I am pretty sure the specs were...50hp 800cfm and 28.6" of mercury!!!!

someone here called it a black hole generator i think...

It was the most powerfull unit I could find and it was a bargain at $3800usd. It went onto a dual 5'x5' table Thermwood c42. The reason I bought such A powerfull pump was that we were cutting 5/8" mdf into smallish shapes (6" x 6" and bigger) and the original "turbotron" 10hp 400cfm 14" pump could not hold the small cut pieces in place. The Thermwood uses a bleeder board arrangement were the vacuum pulls straight through the mdf table top and we were having trouble with the pieces moving while cutting. After installing the bigger pump we could turn up the cut speed but still not as high as we would have liked. At some point the cutting force against the mdf exceded the vacuum force on the small pieces surface area and the pieces would move a little. So at the end of the day it is not only the size and capability of the pump but more about how you plan your complete holding strategy. We ended up going to a combination vacuum and jig combo to eventually get our speed to where it needed to be.
Pierre

[joe]

Very informative post Pierre,

I've been watching Ebay as well. There seems to be some great buy's but I will wait until I understand more about these pumps.

Were you cutting the 5/8" MDF in a single pass?

[mziegler]

If still a problem of parts moving with the mega pump, why not tab the smaller parts together. Then make a tool path to rout out the tabs. If the tabs are thin then there will not be much cutting force on the small parts and vacuum should hold. Have your cake and eat too! Mark

[woodworkseb]

If you are looking for a complete vacum system for under $2000 check this out
http://www.oriontechproducts.com/index.html

[Brady Watson]

Steven...Most of us own CNCs. We can easily make our own pucks!


-B