Minimax sliding saw dust collection above saw blade

[Frank Martin]

I have a Minimax CU300 Smart with a 5.5 ft slider. Really like it with one exception; above blade dust collection through the supplied blade guard is not sufficent and results in a lot of dust escaping behind the saw blade.

I use an Oneida 2.5 hp cyclone and believe that is not the limiation.

I am curious to see if there are owners of this (or similar machine) who have made modifications to improve dust collection.

Previously, I had a Unisaw with a sharkguard and it was much better in collecting dust at the blade.

[mreza Salav]

Without seeing it I suspect the blade guard is narrower with smaller hose; that doesn't work well with a DC. You either should use a shop-vac for a narrow guard/narrow hose or you should use a guard with a bigger hose. The static pressure of small diameter hose is too much for a DC to have enough air volume.

[Jim Becker]

The standard over-blade guard with collection is stopped down pretty severely and as you note, doesn't provide great collection...I honestly don't use mine much for that reason, but plan on making a replacement that hangs down from above and is independent of the riving knife. That way, I'll get better collection and can leave it in place 100% of the time while at the same time improve my ability to see the cutting action. There are many machines that have the same issue...it's not a unique feature of the more modest Minimax machines.

[john lawson]

I have the exact machine as the OP and have the same issue. I use a 4" drop for my dust collection but the hole size in the blade guard is just too small. Jim, when you make your replacement be sure to post pictures. I need some good ideas, I'm not that good of a designer. I just made a zero clearance insert and the problem got much worse.

[Bill Adamsen]

As others have indicated ... with a small inlet and body, the static pressure of the collector is simply too great. I use a vacuum on mine (somewhat similar Knapp slider) and that works. The other option is to upgrade to overhead dust collection with a larger body/inlet and less resistance. When cutting sheet goods especially, mine with the small head/inlet and vacuum significantly improves dust collection.

[Chris Parks]

It should be noted that when the blade is in the guard a considerable amount of inlet opening is blocked because the guard is so narrow. It is narrow for one reason and that is to allow the crosscut fence to be as close to the blade as is practical and a wider guard would have to sit above the cross cut fence unless the clearance between the end of the CC fence was increased considerably. All this adds up to the narrow guard which is supplied with sliders and to overcome the small inlet area the more expensive saws have guards which are much longer. Of course if you allow the guard to ride directly on the material being cut then there is a whole lot less airflow happening.

it has been found with some testing that if trimming wood and just taking maybe the width of the kerf off then the dust gets blown sideways and then lays on the table, I have tested this and if a piece of wood is laid close to the guard's length the problem dust is trapped and mostly picked up by the overhead guard. it has also been found that on cabinet saws leaving the back of the guard open to the atmosphere the dust collection is always improved.

Another big problem on the Hammer saws and maybe the MM is hidden and that is they cheaped out on the cabinet dust collection. I have no way of knowing but the EU equipment all have 125mm ports so I guess it is a regulation. What hammer did was use a 100mm flex hose from the port to the under blade collection chute and that chute is too narrow restricting air entry anyway. Between the two issues the DE on this style of saw can be marginal. I drive my DE with a Clearvue and I always have debris in the cabinet. I know of another user who got sick of it and pulled all the under guard collection out of the saw and built his own and that fixed the whole problem.

[Jim Becker]

Chris, my MM S315WS has a 120mm port and that connects directly to a hood that surrounds the blade in the cabinet. Under-blade is pretty effective...it's just the small overhead collection/hood that doesn't perform well, at least for DC. It's certainly qualified relative to the safety reason for the hood/guard.

[Chris Parks]

Mine has a 12mm port, it is what leads from the port to the under blade chute and including the chute that is the problem on mine. I don't even think it is 100mm more like 90mm hose which is ludicrous and and cheap arsed attempt by Hammer at dust extraction.

[Frank Martin]

Looks like it is time to look for an alternative guard / hood. Other than Sharkguard, are there any options that may directly be installed to the riving knife on MM300? Specifically, are there guards / hoods made with a larger port made for euro machines?

Regarding below the table dust collection, I am actually not thrilled with it either. I end up with bunch of dust inside the cabinet. I tolerate it a bit more because dust is contained inside the machine and less of a health hazard. When I had a Unisaw with a Sharkguard I had little dust inside the cabinet and above the blade was near total extraction. This was with the same Oneida cyclone.

[Orlyn Gaddis]

The original dust collection hood provided by MM didn't work very well. I replaced it with a Sharkguard and it works great for my MM SC4 Elite unless I'm cutting very narrow pieces. Don't think anything will solve the problem with narrow pieces. My under blade dust collection works fine as is. The Sharkguard has the added advantage of covering the scoring blade which is a very good safety feature.

[Jim Becker]

Frank, the ideal replacement is going to be an overarm guard, not one attached to the riving knife. The reason is clearance with both the miter fence and the rip fence when it's in "high" position. Adjustable height independent of the blade allows much more flexibility.

[Matt Mattingley]

Static pressure and cfm work hand in hand when trying to move dust or lift a bowling ball, no mater what the diameter is.

My dc has a high water column and high cfm and I am going to try a 2” reluctantly(20” and 1900cfm in 6” pipe.) https://www.convertunits.com/from/Water+Column/to/psi . With out a high water column and you restrict diameter, cfm goes way down. This is where a shop vac comes in. Shop vacs have high water column in a 2” dia. Most 80 to 120” with 300 cfm ish.

[Frank Martin]

Frank, the ideal replacement is going to be an overarm guard, not one attached to the riving knife. The reason is clearance with both the miter fence and the rip fence when it's in "high" position. Adjustable height independent of the blade allows much more flexibility.

Jim, great point. In my case, it would have to be ceiling mounted. Of course I can make something myself, but I was hoping for a direct bolt-on solution. I will see if I can come up with something that is not very hard to make.

[Jim Becker]

Frank, I also have to go with "ceiling" mount with the additional challenge of that ceiling being sloped because it's the bottom of a stairwell. :) :D

[Chris Fournier]

Please show me the stock guard/collection unit on your machine. I designed and with the help of a talented friend created a proper unit for my Minimax 410 Elite. I may be able to help. I'll get images on the weekend.

[Frank Martin]

Please show me the stock guard/collection unit on your machine. I designed and with the help of a talented friend created a proper unit for my Minimax 410 Elite. I may be able to help. I'll get images on the weekend.


Chris, below are the pictures of my guard. I believe it is standard as I remember seeing pictures of exact same guard on some other MM machines as well. Would be great to see what you came up with as a solution.

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[Jim Becker]

Chris, the OEM unit I have is pretty much the same as the one that Frank illustrates, more or less.

[Erik Loza]

I don't have any photos but Sam made an oversized guard out of plexiglas and plywood that was suspended from the ceiling. Obviously, this only makes sense if you keep the combo in one spot. IMO, the riving knife-mounted guards supplied by any of the Euro combo makers are pretty bottlenecked as far as dust collection goes. If you go into a pro shop, lots of them don't even have it hooked up.

Erik

[Jim Becker]

Erik, I pretty much don't notice much difference in collection with the riving knife-mounted guard between when I have the port turned on to it and when I conveniently forget to turn on that port. :) :D So what you describe makes perfect sense to me!

[Chris Fournier]

Sorry guys, I dropped off the face of the Earth there. Those guard/collectors mount differently than the unit on my CU 410 Elite S. My solution won't help you I'm afraid. Getting a good guard/collector designed and then made was worth the effort but it took a few iterations and plenty of time on the computer, in the plastics and machine shop.

[Frank Martin]

Sorry guys, I dropped off the face of the Earth there. Those guard/collectors mount differently than the unit on my CU 410 Elite S. My solution won't help you I'm afraid. Getting a good guard/collector designed and then made was worth the effort but it took a few iterations and plenty of time on the computer, in the plastics and machine shop.

Chris, it would be nice to see what you came up with in case it gives some ideas even if it does not work directly on my saw.

[Matt Mattingley]

Frank, what size is your flex hose? What are the sizes of that step down adaptor you are using? What is the diameter of the crown guard port? What material is your crown guard made out of aluminum or metal? What is the inside width of the crown blade guard?

What I’m guessing is you can modify what you have or make new.

This is my modification idea... transition from 4 inch diameter to a 5 1/2 x 1 oblong. This would require cutting the top of the existing guard. Some fabrication... The flex hose might actually take the new shape if calculated properly.

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[Jim Becker]

Matt, as noted previously, I have the same guard for my S315WS Slider and there really isn't any kind of direct modification that can be done to it to improve performance as the whole guard is quite narrow...necessarily so to clear the miter/outrigger fence(s) and rip fence when in the "tall" position for a narrow cut. I feed mine from a 3" drop, but the area inside the guard that has to provide air just isn't there. The best modification is replacement with a wider guard that can flow the equivalent of the 3-4" drop to said guard.

The other issue with the riving-knife mounted guard is that it requires you to have the blade raised quite high to clear the miter/outrigger fence(s) which can actually limit thickness of cut even with a 12" blade which is the normal size on my saw. That further's my desire for an independent guard that can be positioned exactly for a given cutting situation as well as flow a lot more air for better collection.

[Matt Mattingley]

Jim, have you tested your CFM and water column at the blade through the overhead guard with your present set up? If so, what are your numbers?

Just because it’s narrow doesn’t mean CFM cannot be improved greatly. But this also works hand-in-hand with the capacity of the DC and static pressure implied.

Have you made any modification that have yielded better results?

I’m guessing this is your set up?

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CFM is a flow rate through a particular size pipe after its smallest reduction(applicable) . It is measured at that point. The water column can be measured at that point too... but both CFM and water column are affected by any other ports that may be open. You can increase the CFM by increasing the minimum port Area (in cubic inches). You will achieve more CFM. This ultimately improves your static pressure.

What is the crown guard made out of? Aluminum or plastic? Can you take and post a picture of your present set up? What is the max CFM and horse power of your DC?

Sorry for asking so many questions (maybe eight). Are you truly looking to improve your situation too?

[Frank Martin]

Frank, what size is your flex hose? What are the sizes of that step down adaptor you are using? What is the diameter of the crown guard port? What material is your crown guard made out of aluminum or metal? What is the inside width of the crown blade guard?

What I’m guessing is you can modify what you have or make new.

This is my modification idea... transition from 4 inch diameter to a 5 1/2 x 1 oblong. This would require cutting the top of the existing guard. Some fabrication... The flex hose might actually take the new shape if calculated properly.

385822

Flex hose in my setup is 4" diameter. The inside width of the existing guard is less than 7/8". So, a 5 1/2 oblong would create an area that is about equal to a 2.5 in diameter connection.

The current connection narrows down to 7/8” x 2” at the narrowest part of the guard. Basically, very restricted.

I will see what I can find to test this idea. In theory it should significantly improve. Not sure it will get near total dust extraction, which is what I had with the Shark Guard on my Unisaw.

[Matt Mattingley]

Flex hose in my setup is 4" diameter. The inside width of the existing guard is less than 7/8". So, a 5 1/2 oblong would create an area that is about equal to a 2.5 in diameter connection.

The current connection narrows down to 7/8” x 2” at the narrowest part of the guard. Basically, very restricted.

I will see what I can find to test this idea. In theory it should significantly improve. Not sure it will get near total dust extraction, which is what I had with the Shark Guard on my Unisaw.

so a full transition would be 4”dia to ==>>>7/8 x 5 1/2” (or more) to get full CFM. I am looking for plus transitions...

Is the cubic inch much differant? Or did I screw up on my math?

[Chris Parks]

I had a narrow flexible line the same size as the port on my Hammer K3 overhead guard hooked up to the 6" main duct which is driven by a CV1800 @ 65hz fan speed. it sort of worked but nothing spectacular so I then replaced that hose with 4" and wondered what the strange noise was when I turned on the DE for the first time with it hooked up that way. What I could hear was the air rushing through the hood, it was damned noisy and obviously flowing as much as it could manage. I expected some improvement in air flow but not that much.

There is another issue with overhead DE that is applicable which occurs on all saws when trim cutting and the blade is not buried in the wood. What happens and this has been documented is that the debris tends to get blown sideways from out under the hood if say a kerf width is being trimmed instead of a cut where the blade cut is contained in the wood and the off cut prevents this behaviour. I have laid a piece of wood parallel with and up against the hood to contain this debris sideways spray and that seems to be fairly effective.

[Jim Becker]

Matt, I'm familiar with all of that, but I do not have the gear to do any formal testing.

The hood I have is pretty much what you show in that photo. My DC is an Oneida cyclone with a 7" main to a 6" trunk. Drops to the saw are 5" to the 120mm port on the saw shroud and a 3" drop to the blade guard when it's in use.

Honestly, I wouldn't consider trying to modify the OEM guard over making a new, truly overhead guard with superior collection. I did this years ago for an old UniGuard before moving to an Excalibur setup for the cabinet saw I owned before the slider. That type of guard would be usable for 95+% of my cutting and only be out of the way for "tall cuts" I sometimes make for beekeeping woodenware. Otherwise, I'd move from 5% use to 95% use with a guard independent of the blade/riving-knife. It's on my list...but the list is long and my priority is to get up to speed on my CNC since that's what's going to make money for me in my business plan.

[Frank Martin]

I think I am going to go with Shark Guard. Lee also provides hardware (optional) for ceiling mount using unistrat. He has some pictures of setups on his website. I will start with riving knife mounted setup and convert to ceiling mounted later if I feel I prefer it.

[Rod Sheridan]

I think I am going to go with Shark Guard. Lee also provides hardware (optional) for ceiling mount using unistrat. He has some pictures of setups on his website. I will start with riving knife mounted setup and convert to ceiling mounted later if I feel I prefer it.

That sounds like a good plan Frank.

I used a riving knife guard for 6 years, finally converted to an over-arm type so I could dado and rebate. The only time I go back to the riving knife guard is when I use the feeder on the saw.......Rod.

[Chris Parks]

For most of the work I do a riving knife is useless and if I made a guard support from the ceiling it would spend 99% of it's time off the saw.

[Rick Potter]

Woodsmith magazine had an interesting overhead design a few years ago. They used layers of plywood band sawed to shape for the body, and put simple flat plastic sides on it. It could be made any width by adjusting layers of ply.