HPLV or LPHV for CNC / Table saw

[Thedog]

Hi,

I know this has been discussed so many times on many forums but I I find a lot of the recommendations are very conflicting.

Anyway, I have a Camvac CGV286-3 (Twin motor 2kW) which from what I understand is a HPLV system?
In general it works very well with my tools, including a thicknesser, which produces lots of large chips.

However, it seems to be pretty poor when used with my table saw. The ports are all 4".
I was thinking about buying a dedicated extractor for my table saw and possibly for my CNC machine.

I understand this this is a subject in itself with so many variations of what can and cannot help with the performance, but really my question is what type of dust collection is best for a table saw / band saw and maybe a cnc machine. My initial ideal was just to use the Camvac with fixed pipes / blast gates etc but now I am not so sure if this is a good ideal.

Can anyone recommend a suitable stand alone dust collector for a table saw / cnc (Maybe one for each) and should this be HPLV or LPHV?
It would be nice to hear from someone who actually has a particular model or type of extractor with real life reviews etc.

Thanks

Paul

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[Keith 66]

I had quite a bit of experience with this working in a school as a technician, We had separate extractors for each machine namely Numatic NVD 750's which are a common HPLV extractor often installed into schools by service providers under supply & maintenance contracts, Each bandsaw had its own vac extractor & the Circular saw had two one underneath & one pulling from the crown guard.
They were pretty useless with the air getting thick with dust in no time if cutting a lot. In our case the Machines all had 100mm (4") ports but had standard sized 35mm bore vac hoses to the extractors.
This lead to a protracted battle with management & service provider & they never accepted their system did not work.
When a machines Spec sheet says Min requirement 850 M3 per hour a Vac extractor that pulls 144 M3 per hour isnt going to do the job!
They kept on saying but the duct velocity is over 20m/sec so it complies. All very well but you got to have a pipe big enough to move the stuff!

 

[Sachakins]

Table saws benefit from having both rear extraction plus a crown guard extraction. Try running a 50mm hose to this and 100mm to rear. Can yse a splitter, or use a separate wet/dry vacuum type to crown guard.

 

[Thedog]

Hi,

Thank you for your replies. the table saw crown guard has about 30mm hose which connects directly down to the 4" port on the back of the saw which is supposed then take care of the dust from under and around the blade. these just seem useless withe the Camvac fitted running both motors. under and inside the saw is a mass of sawdust which builds up very quickly. The blade also spits out a dust stream from under the crown guard while cutting.

Might as well not have the Camvac turned on. Is this a common problem?

So, if I have a separate extractor for the 4" port and one for the 30mm crown guard what would you recommend. As in the type of extractor etc. or even makes and models to consider.

Thanks.

Paul

 

[Jameshow]

I'd get a hvlp one for the underside and your camvac for the crown guard.

Any hvlp will cope with a saw p/t.

More of an issue is the space / ducting to suit.

 

[Sideways]

Totally agree with James.
As soon as you are working through a skinny 30mm hose to a crown guard, attaching it to a High Volume extractor is a waste of time. HVLP doesn't make enough suction to move air through narrow hoses. Connect the camvac (or a shop vac if you have one) just to the crown guard and that will work as well as anything can. You need high suction / high velocity airflow to capture chips and dust coming off the blade tips at over 100 mph.

The camvac is actually good for this job but if it is also connected to a wide open 4" dust port at the back of the saw, all the suction collapses at that point and it's powerful vacuum never makes it to the crown guard..

Also, think about where the chips are being ejected as they break through the top surface of the wood. Often the extraction port is at the back end of the crown guard. If you have the blade set just say 10mm above the wood, the point of breakout may be well ahead of the dust port with the chips having a lot of velocity up and forward that needs to be overpowered by the extractor. The most efficient place to extract from a crown guard is actually the front but few guards are made like that.

My own (work in progress) plan for my big tablesaw is a shop vac dedicated to the crown guard extraction and a High Volume extractor to the 5" port that pulls from the shroud below the blade.

 

[Sachakins]

30mm hose will kill suction.
Just try your house vac on the crown guard with camvac on 4" only.
See if it works before investing on another vac.

Also try bigger hose if you have one.

 

[Doug71]

Only posted this pic a couple of days ago but here it is again as relevant!

I have a Record DX 4000 to the bottom of my saw which I think is very similar to the twin motor camvac, the saw is meant to have 125mm hose going to it but I only have 100mm and it works fine. I originally tried using the Record on both saw base and crown guard but there was a definite drop in performance.

I have a shop vac going to the crown guard with I think 62mm pipe as that is the size needed on the crown guard.

This set up works really well for me apart from the Record vac fills up a bit quick sometimes, I hardly ever have to empty the shop vac so not much dust makes it back round.

I guess a lot of it is to do with the internals of the saw, mine seems to have a kind of funnel right around the blade which looks like it will catch all the dust and send it all off in the right direction straight down the pipe.

 

[Nic Rhodes]

Can I suggest you look at the problem slightly differently. The dual extractor ideas above are good here but rather than buying a new unit just yet to replace the Camvac, try sealing up some of the 'holes' underneath the table saw. You could do this with gaffer tape initially. This is to limit the air ingress / leak paths and to optimise airflow. Saws are notoriously bad here. What you don't want ti do is seal it totally, there needs to be an air path. This will increase the velocity and dust pick up. Longer term might be a box underneath, new zero clearance insert (look on Hooked on wood channel for an excellent idea there) but for now cost of a roll of tape. The only time I can't get my Camvac to clean stuff like this is when the bags need changing so that is worth a check also. They can be quite capable, if they are pulling large shaving from other machines, it indicates the right airflow is not around the dusty areas in the saw..