3.12.2021 Mitre saw: New dust collector guides and hose.

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Friday 3rd. 34F. Overcast. I haven't done a thing on the dome for days. Snow, gales and continuous rain don't allow me the freedom, nor desire to do much outside.

I have discovered some useful ideas for containing the aluminium swarf flying off the miter saw blade. One YT poster has cleverly used rubber sheeting to guide the swarf to the back of the saw where he uses a workshop vacuum for wood dust. 

I'd prefer to guide the metal swarf into a container beneath the saw stand. As his guides are attached to the saw they aren't affected by the saw being angled for miters. 

 https://youtu.be/viRRYmIfzC8

Many of the rigid box ideas on YT simply won't fit into my shed. I have lots of heavy, rubber, pond liner I can use for the swarf guides. It took me ages to tidy up the swarf last time. It sprays literally everywhere at very high speed. Worse than that, it has much more weight than wood dust. So gains momentum as it is accelerated by the teeth of the blade. One slight worry is the flammability of aluminium dust.

First I removed the DeWalt, dust collection, plastic tube from the saw. Then discovered that a 60mm corrugated hose would just about slip through the triangular cutouts in the saw castings. The original tube is tiny. A smooth bore, 65mm hose would probably just be able to go through the saw. Though it would require the hose was made triangular to fit. 

An alternative would be 60mm PVC, gutter down pipe. This would need to be warmed with a heat gun to make it fit the triangular openings. Getting it back out after it has cooled might be a real struggle! Note how the sliding mechanism distances the blade from the collector. [Two lower images.]

The main problem with changing the extractor pipe to a larger one is the blade fence latch. It is bulky and lowers directly into the path of any extraction system. Total idiocy on the part of DeWalt designers. I use the term "designers" loosely.  

A screw top cleaning fluid bottle would make a good directing funnel. It would have to be slotted for the saw blade and a cutout made for the fence latch. Even so, it would be several orders of magnitude larger than the original collector area. Which blocked continuously in normal use. 

I am still trying to discover the real purpose of what I have mistakenly called the "fence latch." It has no connection to the saw blade or its protective shielding. DeWalt calls this thing a "rear guard" in its spares catalogue. Does it prevent kickback in a jam? It seems not to have any spurs to prevent kickback. Its removal would certainly simplify my collection funnel ideas. 

It is hinged and lightly spring loaded. Yet rides well above any material being sawn. I found a reference to it on a forum where a user had a kickback and destroyed this "rear guard." Other than it having been modified at some point I haven't discovered any more details. My wild guess is that it is a shield for the exposed part of the blade but little more. Though that doesn't explain the hinge or return spring. 

UPDATE 6.12.2021: A long experienced, woodworking machine repairer has warned me to leave the rear guard in place. It catches small pieces of wood which occasionally splinter off the item being sawn. This prevents them from being caught in the blade and flung around. He shared dire warnings about bloody stumps of fingers and thumbs. Being found in machines returned for repair after an accident.  

I was further advised that a larger, dust collection hose will just slow down dust collection by reducing air velocity. My crude DIY collector wasn't properly aligned with the saw blade exit anyway. So would probably not work as desired. If the saw were fixed, rather than sliding, it would have been far easier to guide the swarf into a container. I'll have to look again at outer rubber shields to help contain flying swarf.

 

 

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