Improving Dust Extraction: Does hose size count? Are CamVac's the best solution?

[Atomic_Sheep]

One idea that has floated about the head of late is to have four air jets arranged to blow the chips out of those deep slots. Of course this implies an air compressor. With four jets you can only be effective with one jet at a time and then only when a movement is parallel to an axis. To cut down on air usage you might want to tap the direction signals to your step and direction drives. That would allow you to shut off two of the jets depending upon direction. On the other hand on the second pass it might pay to have both jets blowing.

Just some ideas!

The thing I don't like about this idea is the fact that compressed air will blow a lot of dust outside of the curtain thus creating a health hazard. Just reading Bill Pentz's site at the moment and I'm not sure how to solve this problem.

If you have a fine dust issue, you'll see dust on everything in your shop when you come back the next day. I can make a single cut on my table saw, and there will be fine dust on every flat surface in my shop. I never get any dust in the air with my CNC.

This is a very good point... Bill Pentz mentions on his site that the amount of dust produced is roughly equal at all sizes i.e. 1/3 of dust created is invisible... so you won't see it collect the next day, but 2/3 is visible, so that means that as ger21 pointed out, if you don't see any dust the next day, you're golden.

[ger21]

The thing I don't like about this idea is the fact that compressed air will blow a lot of dust outside of the curtain thus creating a health hazard. Just reading Bill Pentz's site at the moment and I'm not sure how to solve this problem.

That's the purpose of the brush around the dust shoe - to contain dust and chips and keep them from being thrown outside of the area that they can be sucked up by the vacuum.
Even without compressed air, a router is capable of throwing dust 2 meters away if you don't have a brush around the tool to contain it.

[Jon.N.CNC]

That's the purpose of the brush around the dust shoe - to contain dust and chips and keep them from being thrown outside of the area that they can be sucked up by the vacuum.
Even without compressed air, a router is capable of throwing dust 2 meters away if you don't have a brush around the tool to contain it.

I have just built a shoe like fretman idea. It stays at a fixed height. Works much better a than a brushed boot and I think you could introduce compressed air and still contain it. A brushed shoe not so sure.

[ger21]

The brush needs to reach down to the spoilboard. This will require different length brushes, if you use tool with a large length difference.

[520052]

The brush needs to reach down to the spoilboard. This will require different length brushes, if you use tool with a large length difference.

Or you could make a dust shoe that is adjustable in height.

[Atomic_Sheep]

That's the purpose of the brush around the dust shoe - to contain dust and chips and keep them from being thrown outside of the area that they can be sucked up by the vacuum.
Even without compressed air, a router is capable of throwing dust 2 meters away if you don't have a brush around the tool to contain it.

My logic dictates, there is much less CFM required to achieve high pressure sufficient to blow chips away than the CFM required from the dust collector so by that logic, we should be ok in terms of the possibility of high pressure building up within the curtain.

[daniellyall]

I have one like the one above they work very well

[fretman_2]

Jon...do you have some pics of your shoe?

I have just built a shoe like fretman idea. It stays at a fixed height. Works much better a than a brushed boot and I think you could introduce compressed air and still contain it. A brushed shoe not so sure.

[Atomic_Sheep]

Purchased a cheap 1250w vac from the local hardware store for 60 dollars... can confirm, this was not a sufficient solution.

Don't have a dust shoe yet so was manually holding the vac up to the drill bit as it made the cuts. It had sufficient power to collect all the dust so at least I can confirm that you don't need 5hp to collect all the dust... although I was holding the vac hose right up to the drill bit, so perhaps it won't be enough if you create a dust shoe that has the intake a bit further away.

However the filter on it was not fine enough, so all the fine dust got blown out the back and coated my room, so if you're collecting dust internally, you definitely need some good filtration system.

I guess the next logical step for this setup would be to attach an exhaust hose out the back of this vac and send it directly outside and see where that takes me.

EDIT: LOL didn't read the instructions fully... looks like I forgot to install a dust bag that is supposed to collect all the fine particles. So looks like for 60 bucks I sort of solved the dust collection problem. I will buy a hose and stick it onto the exhaust system of the vac and push direct it outside so that I don't have to constantly replace the paper bags however. But overall looks like ger21 was right... his suggestion that 1HP is enough might be correct... albeit mines about 1.6HP.

[shujaa]

HI 520052,

can you show me your 6" dust shoe ??

please

[shujaa]

HI 520052,

you are the only person i have met on this site who has done it with 3 HP, 6". Like me although i am venting outside.

[520052]

HI 520052,

can you show me your 6" dust shoe ??

please

Sure. I cut the parts out of 3/4" acrylic flat stock and sawed some acrylic tube for the hose attachment and spindle clamp. Cemented a couple of blocks to the tube (milled to match tube radius) and drilled for clamping lever. whole thing is easily height adjustable. Also drilled both base plates for micro drop coolant as I machine aluminum mostly.

[520052]

HI 520052,

you are the only person i have met on this site who has done it with 3 HP, 6". Like me although i am venting outside.

Kept mine venting inside as I don't cut stuff like MDF or have to worry about too fine of particles even though they would not be a problem. With the filters I have there is really no pass-through of fine particles and 1000 cfm pulling through the 6" shoe I do not have anything escaping the collectors draw.

I have a small 4158 cubic foot space, so if I vented outside, the collector would pull all my conditioned air out in about 4 minutes.

[shujaa]

Hi,
Is the hose connector for 6" ? Because if it smaller the CFM will drop as Bill Pentz said.

[520052]

Hi,
Is the hose connector for 6" ? Because if it smaller the CFM will drop as Bill Pentz said.

Yes, 6 inch connection, 6 inch flex to 6 inch spiral pipe to very short 8 inch main.

[shujaa]

Hi

Is it necessary to channel the suction directly at the cutting point ??

I feel more air will be sucked from the front part of the brush than from the direction of spindle. Or maybe I am wrong. Can you clear up my point.

By the way your design is real neat. ....

[520052]

As long as your brush seals to the top of the work piece and your moving enough air, the vacuum sucks all the dust from within the brush sealed area, especially when moving 1000 cfm. Most of the designs you see on here that channel the suction from the spindle end of the shoe probably are not moving sufficient air because of under powered vacuums or too restrictive of piping. Which is fine if your trying to get by with a shopvac or an under powered dust collector. I learned a long time ago it takes money to collect dust properly and with my health at stake, I am willing to spend what is necessary to do the job right.

I am fortunate in the respect that my machines are my source of income, so I usually have a little more to invest in this kind of stuff than someone who is just doing hobby work.

[shujaa]

Thanks. Lot of.
In order to be on the safer side I plan to double the layer of brush on the front side.

[legendarylarry]

I am using a 600 cfm vac with a 2.5" hose on a brush type boot. It works Ok but my 3hp spindle is air cooled so the air blowing down through the spindle into the dust boot is more than my vac can pull so I feel air blowing out between the brushes and with it I get fine dust. If I went to a larger hose would that help any?

[wizard]

I am using a 600 cfm vac with a 2.5" hose on a brush type boot. It works Ok but my 3hp spindle is air cooled so the air blowing down through the spindle into the dust boot is more than my vac can pull so I feel air blowing out between the brushes and with it I get fine dust. If I went to a larger hose would that help any?

Probably! The first question you need to ask is this are you actually getting that 600CFM through the 2.5' hose? I kinda doubt it, a quick way to check would be to unplug the hose while the vac is running (pulling nothing but air) and see if there is a huge difference in volume or a significant uptick in motor RPM. If there is a noticeable difference then the hose itself is causing a pressure loss.

The trick with vacuum systems is to keep large masses of air moving quickly. If you vac is too small it won't have the volume capability to keep velocity up in a larger hose. If the vac supports a larger hose go for it, after all you really won't know until you try.