Replacing internal DC hose on a Hammer K3

[Matthew Springer]

Gang,
Recently the DC on my K3 went from OK to terrible. I opened up the saw and discovered the 4" internal hose from the blade shroud had gaping holes in it from where little crosscuts had been launched into the sidewalls. I really need to get a ZCI but that is another thread.

I have a full 5" hose headed to the back of the machine from a 6" PVC drop down, but I'm curious if anyone has replaced the 4" internal hose with a larger 5 or 6" hose. I have already removed the back plate and the dust port from the cabinet to take out the old hose. But the 5" hose will not at all fit through the hole in the cabinet of the original dust port. For a quick experiment I ran the 5" hose straight to the shroud in the back of the cabinet through the giant access panel in the back. Collection seems to be much much better.

Has anyone swapped out the internal DC hose and if so how/did you enlarge the DC port in the back or did you knock a new hole in the back access plate?

[Patrick Kane]

I just did this on a 14 year old KF700. Hose was nonexistent. I replaced it with a 4" hose, and didnt think to modify the cabinet for a 5" hose. Sounds like a decent amount of work for a little better DC. Frankly, the collection with the 4" isnt too bad. I get some accumulation of dust in the cabinet, but the shroud is designed pretty well. The problem for me is i would need to enlarge the outer cabinet hole as well as the inner cabinet opening, and that inner cabinet would be tough to cut the opening well. Up to you if its worth the time and effort to make it happen. I would mock up an adapter and 5" hose and then tilt the blade 45° to confirm it works. That should be the only limiting factor, im guessing.

[Erik Loza]

..Sounds like a decent amount of work for a little better DC...

My thought as well ^^^

Believe it or not, the Europeans actually put a lot of thought into correct dust collection diameters, volumes, etc. How's your actual dust collector working? Close enough, in good shape, etc.?

Erik

[Christopher Charles]

I'll echo Erik's caution. Bernoulli's principle dictates that increasing the opening size will reduce the velocity of the suction at the mouth of the opening, potentially reducing the capture of particles. This is assuming the total cfm stays (approximately) the same.

Good luck,
Chris

[Jim Becker]

There are a couple of threads about this very thing here at SMC, if I'm not mistaken.

[David Stone (CT)]

I have replaced the internal DC hose on my K3, after the original basically disintegrated after some 15 years or so. Admittedly I am not super particular about dust collection, but I can't see much virtue to upsizing the ducting. As far as I can tell, most, if not all, of the dust that my saw sends out into the shop has to do with a lack of collection above the table, not any deficiency in the oomph down below. ...In replacing the failed hose, by far biggest challenge I found was that the clear, flexible woodshop-type dust collector hose I used as a replacement was nowhere near as easy to form around, and fasten to, the connection point on the blade shroud as the cheapo vinyl dryer vent type product installed at the factory. ...Also, as Jim said, there has been at least one prior thread on this exact topic within the past year (I participated in it) where people offered thoughts on this issue. ...BTW, yeah, a zero clearance inset is basically a necessity IMO. Otherwise, the blade will grab thin cut-off strips and shoot them down the hatch at super high speeds, which at best results in time wasted fishing them out of the hose lest they plug it up (which they will) and, worse, is startling and potentially quite dangerous.

[Mark Bolton]

Not machine specific by any means but the velocity issue to me with any type of a euro slider is directly dependant on volume of air moved not necessarily velocity. DC are high volume low velocity so the instant you get below a 4" diameter if your any distance from the DC your shot. There is a reason why people run 6" drops to a saw, planer, modest shaper. The more air you can move the better. My slider had a 4" port on the side of the machine that was internally reduced to a 3" flex running up to the blade boot. DC was ok but not great. Same as you, no ZCI (I never bother because right tilt/slider/zci is pretty much useless). I ditched the 3" internally and custom fab'd 4" right to the boot and it makes a huge difference. It will never pull off the top of the blade, but more air is just better.

I have a 6" leg running right to the saw with a 4" takeoff for the saw then running on to two other machines. My slider at least will never be perfect internally and I dont run an overarm guard/pickup which I have threatened to build for some time, but the larger run to the machine made a world of difference at 4" and I can only imagine 5" would be even better as long as your DC is up to it.

Creating as as large a bubble of vacuum as you can is a good thing but those pesky thin rips that fly down into the boot will always foul you.

[Jim Andrew]

My K3 hose went bad soon after receiving it, and thankfully, it was just a standard 4" hose. The fitting on the saw required an adapter to use a 4" connection, so thought it might be a metric size hose, but thankfully it was not.

[Ed Stengel]

Even though this is an old thread, I had the same problem with the internal hose becoming useless and was searching for how others might have solved the problem. I own the Hammer k3, in fact it is my second, the first was ruined when Hurricane Harvey put 6' of water in my garage/shop number of years ago. The dust collection problem that I have fought till recently was the flimsy hose used to connect the dust shroud around the blade to the export flange on the back of the saw. It had multiple tears and holes in it from thin cutoffs being sucked into the 4" hose even though I usually keep a zero clearance insert on the saw. I tried connecting a sturdier 4" hose, but try as I might, I couldn't get the hose over the blade shroud. After hours of messing with it, I bought a section of 5" hose, a few 5" hose clamps and a rocker PVC 5" to 4" reducer. I got the hose on the shroud with some difficulty, tightened down a 5" hose clamp on it, attached the reducer to the 5" hose and a short piece of 4" hose, and then the 4" hose to the flange on the back of the saw. It kind of looks jury rigged, but since Im the only one opening the saw, it will be my secret.

The blade still moves all the way to 45 degrees for bevel cuts and the dust collection is better than when I first bought the saw. I don't use above table dust collection and my collector is a Jet 1 1/2 hp.

Maybe someone doing a search in the future will benefit.