blower -vac

[dan_nelson]

What is the difference between a blower or a vaccum hold down system? Alot of vacs and blowers are 3 phase I have only single phase. Will I need a converter? My spindle ( columbo) says its 3 phase but is it converted thru the delta speed control or what? thanks.

[bleeth]

Regenerative blower is the technical correct phrase for what many call a vacuum system. This is the industrial version rather than what many botters use successfully in the form of Fein Vacuums (Well made shop vacs that don't burn up quickly) or home built rigs using Universal vacuum motors originally designed for residential central vacuum systems (Brady Vac). Most regens are 3 phase as the motors are pretty hefty. Anywhere from 7.5HP up is used. If you don't have 3 phase available you can get a phase convertor.
The 3 phase columbos that run on single phase (I have one too) uses a 3 phase VFD that is rated for twice the HP of the motor but has half the electricity going into it from your 1 phase supply. So the Columbo 5HP motors use a 10HP VFD.

[dana_swift]

Before you spend any big bucks on vacuum systems, learn a lot about them. There are many ways to go at it, some very inexpensive and well documented on here.

It depends somewhat on what you want out of a vacuum system, if you are holding large sheets that you will never cut through, you dont need much. However if you cut through the material it doesn't take a very big hole to let 20 or 30 cfm of air leak through. The vacuum level drops then also, and may drop quickly.

Dedicated fixtures with gasketing may be able to hold high vacuums with almost no leakage at all. For my first several years that was my preferred method, I used air-conditioner vacuum pumps and got remarkable hold-down for reasonable prices.

Later I wanted more tolerance for leaks, so I went to an industrial pump so I get the best of the high flow and high vacuum worlds. Most of the time the system operates above 20"Hg. Much as it was with the cheaper a/c pumps.

I have not used a blower, they are good when you are going to be cutting through a fair amount. You can look up on the forum where there are several designs using vacuum cleaner blowers, which by switching between series and parallel operation allow you to switch between high CFM and "better" suction.

Blowers usually peak out at about 15"Hg while offering 150+CFM open flow. This costs 15hp of electricity and noise in your shop. The pump I use is a 5hp Becker which offers 28"Hg and 75CFM open. Two of these combined would give 28"Hg and 150CFM open, better performance than the blowers for only 10hp of electricity.

No matter what you go with there are advantages and disadvantages.

If you are new to botting, consider just using mechanical hold-down until you have visited a few shops and seen what other folks are using and the results they get. Nothing beats mechanical hold down for the price, its cheap and very reliable compared to vacuum. I still use mechanical hold for many parts.

Hope that helps-

D

[gene]

I also have a 3ph spindle on single phase power and a 7.5hp roots blower for a vac. it was purchased from shopbot , the only thing i dont like is the noise level, I also have a becker vac pump but it is on my vac panel lift . A vac system needs to be fit to what you are cutting. If yon only cut small parts then a fein vac will work good, but if you are cutting full sheets in alot of parts at one time then the blower will work better. What are you going to be cutting and what size table do you have?

[dan_nelson]

I cut mostly sheet goods. I have a 60 x120 with 8 zones. on the small stuff I screw/clamp down. We have tried to onion skin but not with much luck. To much cuppage around thesse days. bot came with 2 shopvacs which work but only with the spoil board under 1/2". like the idea of tandom regen vacs trouble is I only have single phase. thanks.

[cip]

I took a page from Gary C's book, bought 4 central vac system motors @ about $140. ea. setup 4 zones and forget the rest. Works so good that I wish I'd done this from the start. Uses about 20 amps total @ 220v is very quiet with muffler attachments. I cut a lot of sheet goods and very seldom does anything move.

By the way I have a roots 15HP 330 cfm 14hg pump I would part with pretty cheap.

Mike

[HansDef]

Mike

can you give us the model, maker and where to buy info of your vac motors.

thanks
Hans

[Brady Watson]

You might want to start your vac motor journey here (http://www.talkshopbot.com/forum/showthread.php?t=545) & see where it takes you. Keep in mind that the community has made lots of mods and improvements on the setup over the years.

-B