Thread: Band saw port grills

I think I did make mention of the cross hair lump stoppers some time back, I have since taken them out, don't know if it has made any difference to airflow but as Bob says, cant hurt



Pete

One would think if a manufacturer felt the need to put them in the port that they would at least put the thin edges to the airstream.

Pete

Originally Posted by QC Inspector

One would think if a manufacturer felt the need to put them in the port that they would at least put the thin edges to the airstream.

Yep, and while they are at it they might also think about offering larger ports. It's much easier to adapt down that to have to tear into the machine to enable larger ducting to be added.

Larger ports will happen but everyone will be a lot older when they do. I was part of an online move to change things in kart racing and I reckon that the change took about 8 years in all before the manufacturers worked out that we were right and actually knew more than them. The current attitude is lip service to the problem and they are quite happy with the status quo and think they have done what is required and we should be happy with that. The Europeans are leading the charge and they have at least gone to 125mm ports which is something in the right direction.

Why do the manufacturers do such dumb stuff? The pic shows a plate welded over half of the cabinet port on my bandsaw. The grinder soon removed it, but why is it there?
IMAG0032.jpg

In the picture above showing the blue port with the cross hairs, could their thinking be for safety? What I mean is, is the blade traveling in the versinity of the port? If it were not there could someone remove digits by twaddling them in the port? Just a thought. But even if for saving fingers, exposing the 3mm edge to the flow of air would be better

Originally Posted by John Samuel

Why do the manufacturers do such dumb stuff? The pic shows a plate welded over half of the cabinet port on my bandsaw. The grinder soon removed it, but why is it there?

Here is my take on what probably happens.

The manufacturer makes a product and then (if we are lucky) says, "what is my best guess as to what size/type DC will be hooked up to a specific machine?"

Tiny band saws like my baby ryobi have a 2" port suited to a vacuum cleaner hose. BTW this was 45% blocked with a crappy cast metal which I cut away significantly removing the air flow.

Small 14" BS usually have one 4" port and manufacturers might assume a 1HP DC and say ~2 m piece of flexy will be used on such a saw. When manufacturers try this out they visually see a build up of chips inside the BS cabinet and correctly interpret this as the air speed being too low to pick up the dust so they stopper down the port to increase the air speed. Increasing the air speed helps clear the visible chips but the lower flow doesn't help the invisible dust much. The lower flow is however most likely caused by the lower cabinet being too air tight.

On larger machines they might add extra ports and assume the user will have a bigger DC but they don't really seem to think about location or cross flow too much. Nevertheless the stoppered down ports are a real nuisance particularly to those users who have access to more suction.

Here is what I did with my BS as I found the flow out of outlet of the main BS cabinet to be woeful (<200 cfm). This flow does not refers to the port visible in the photo on the RHS of the BS but to another low down near the floor of the cabinet on the other side of the door. The port visible in the photo has its own probs - which have been discussed by any others before.

Removing the cross hairs in the middle of the port made no difference which told me it was definitely the sealed cabinet that was blocking the flow. When I removed the door the flow increased to 280 cfm but I did not want to leave my door off and I could not leave it just cracked (as others have done) as the door interlocking system prevented this so I added a grille as shown.

The majority of the dust on my BS seems to be collected by a third 4" flexy that I just jam under the table right where the bottom band rollers are located.

Bob,

My best guess is that you are correct.

However, even my 1 HP dusty struggled to get enough air into the bandsaw cabinet to do a decent job. The original design is just plain poor. This problem is not limited to cheap Asian machines. The dust extraction system on my German made jointer/thicknesser is not a lot better, and fixing/replacing the ports on this machine will be a major job.

The silly part is that the amateurs have solved most of these problems. Folk like you know how to modify the machines to make dust extraction work well. What, in the name of all that is holy, are the professional machine designers doing? I am certain you and I could sit down and design dust collection ports for a wide variety of machines that would not increase costs for the next model, and that would work well. This is particularly true for my Electra Beckum jointer/thicknesser, where all the DC ports are moulded ABS. Even if we stuck with 100mm ports hooked up to a dusty, the design and airflow could be improved vastly.

I am forced to conclude they just don't care; don't think its important.

In Saudi Arabia for work right now ... suffering severe shed withdrawal symptoms. This may account for my GOB (grumpy old bugger) attitude.

Why do they use ports the size they do? Someone somewhere decided that 4"/100mm was a good sized port to use on dust extractors so that is what they put on the machines to match it. The reason they chose that size was probably due to a couple of factors, affordability and access to 100mm is good and if they did use 6" then they would have to uprate the DE to match the duct size. I can sympathise with them a bit, if they did go to 6" everyone who buys one would scream bloody blue murder when they found out what the ducting was going to cost them. Most of the buyers of these DE's are budget conscious and to have to put in 6" ducting would mean that they might not be able to afford any sort of DE. Of course there are those who could shop at a higher level but through lack of education do not which is another issue altogether.


Once you look a bit deeper than the port problem you then see that the basic design to facilitate good DE performance is completely ignored. I guess this came about due to the lack of knowledge in times past or even the lack of any need because people simply did not see dust as an issue. From that base the need arose so they simply put a port in and declared the job done. In my conversations with a couple of people re this issue they simply do not understand what the fuss is all about. When I started to explain it went in one ear and out the other and in my experience you can't talk to deaf people.


Any effective ideas on changing this attitude would be gratefully accepted by the woodworking community but I doubt that the manufacturers will listen. I also doubt that most woodworkers will tolerate a wholesale change to 6" ducting as the education process has not convinced them that the benefit to cost ratio is tolerable. Indeed a lot of them simply could not afford it, end of story. The sad part is that these same woodworkers will buy a dust making machine before they have the DE to protect their health but that is human nature.

Originally Posted by Chris Parks

I can sympathise with them a bit, if they did go to 6" everyone who buys one would scream bloody blue murder when they found out what the ducting was going to cost them.

I don't think it would be that dramatic. It is much easier to adapt ducting down than up as no one is forced to use 6" ducting on a 6" port. If the manufacturers made their machines with at least a 6" ports and included a 6 - 4" adapter as standard (my guess is they could supply one with the machine for <$5) then everyone would be satisfied.

Port size on most machines is only one half of the problem. Neither of the 95 mm siam ports on my BS are well made and neither do their locations appear to be well thought out - not that I have much better on more expensive saws. Collection of invisible dust is problematic on a BS so some innovative solutions are sorely needed on that front..

Bob you are talking to the converted, what you need to do is convince the manufacturers and sort them out. We as interested participants know what the issues are, or at least we think we do.

My point exactly. Even if we chose to stick with 100mm ports, the design on most machines is terrible.

We three are all singing to the choir. Bob's point about 150mm ports with a 100mm adaptor is a great idea and would help, but it would be even better if the designer thought about small issues like airflow.

I think I'll hop off this horse for now. It has been flogged to death. The likelihood that manufacturers will provide good designs and 150mm ports in my lifetime is so slim it can be ignored.

Still, if you hear a faraway voice cursing the Germans who designed the ports on the Electra Beckum jointer/thicknesser in the near future, that will be me, flogging the dead horse out of frustration.

If we machinery buyers start looking at machines and buying ones with larger ports/allowance for air movement it won't take long before manufacturers offer the larger ports as standard, a paradigm shift in thinking will be in order but we have to keep pushing for it. Keep up the fight!!!



Pete

Originally Posted by Chris Parks

Once you look a bit deeper than the port problem you then see that the basic design to facilitate good DE performance is completely ignored. I guess this came about due to the lack of knowledge in times past or even the lack of any need because people simply did not see dust as an issue.

Chris I agree that it is something that the manufacturers are currently ignoring. I posted on here a while ago about my belt and disk sander with the 2" port on it but it sucks through a hole about a third of that size to collect from either the belt or the disk and as such it was effectively useless. The manufacturers seem to just add on dust ports that "look right". I doubt that most manufacturers have conducted any testing on dust extraction. They are put on there so that they look good, not so that they will work efficiently.

Since the bottom cabinet on a bandsaw is fully enclosed with very little allowance for inwards airflow I believe that if you could only do one modification you would be better off opening up more ventilation and leaving it with a 4" port rather than keeping the cabinet almost airtight and adding a 6" port. Obviously doing both would be better, I am just saying there is no sense in increasing the size of the port without increasing the source of available air.

When was the last time you saw a manufacturer's recommendation on what size dusty or even a CFM figure they recommend for their equipment? It doesn't happen because they have no control over how the equipment will be used and in what environment. To make such a recommendation may somehow leave then legally liable. Instead they just put on a dust port here and there and leave it up to us to make it work. To reach the required standards they would probably have to recommend a minimum of a 15 amp machine which would render it impractical for most back-yarders.

I also think that this is "evolution in progress" and one day we may see well thought out dust extraction capabilities built into machines. I think that 4" ports are the industry standard right now partly because 4" ducting is more affordable but also because it will reasonably efficiently extract chips and most people were until comparatively recently more interested in a clean floor than in clean air. I think that Bob's point about 6" ports with a 4" reducer is a good one and is likely to be coming up in the "Evolution" process.

For the foreseeable future however, I think that we will be continuing to improvise and modify.

Doug