Building my own blade guard - nothing exciting but a real challenge for me

[Bob Davis]

I got all hyped up about building a European style Riving knife for my saw. This naturally meant that I would have to do something about the blade guard. More importantly, dust collection on a table saw seems to be a fruitless quest, if you don't do something about the saw dust above the table. I was extremely disappointed when I connected a 2hp collector and installed a zero tolerance blade insert at the same time, only to discover that I still got a heaping helping of sawdust when I ripped with a high blade.

I am combining designs from multiple sources to achieve my own personal priorities, with extremely good dust collection being at the top of the list. I'll report progress as I muddle through this.

The biggest unknown to me was the cost and availability of Lexan -- seems this is a must for blade guard. Today I went to a local plastics supply house and was pleased to be introduced to their cutoff stock. I had drawings of the parts I needed and a gentlement in the sawroom helped me search the cutoffs. He also gave me some advice on cutting and routing the stuff. Overall it was a good old fashioned top service experience.

For those of you thinking about something like this, Lexan (GE brand of polycarbonate) sells for roughly 14-15 cents/cubic inch in my area (Houston, Texas). I got a 1/2 inch x 23 inch x 12 inch piece for $20 and a 1/8 inch x

10 1/2 inch x 23 inch piece for $4.

So what am I going to do with 1/2 thick lexan? Well, in case someone shoots a bullet through my shop, it might have a chance at stopping it. Otherwise, I figure I'll have one heck of a blade guard.

Bob

[Plane Truth]

I'm thinking of doing the same thing. I found this web site,

detailing one design. I'd be interested in seeing pictures of yours. Will you post some pictures on ABPW when you're all done?

Thanks, Gary in New Tampa, FL

[Bob Davis]

Hi Gary,

The site you referenced is one of the inputs into my design. Yes, I'll post pictures. My brother suggested I make a mockup of the guard before making the real thing. Boy, am I glad he suggested. I built a 1/2 plywood model and learned all kinds of things by actually putting it on top of the table saw. I also learned that I am lousy at setting up non-standard angles and getting it right in the first 3 cuts. I would guess that many of these homemade systems are copied from commercial ideas and there area few that have original thinking. Some of the variable dimensions I've seen on various guards:

1. What is the leading angle on the guard? The website you referenced uses an especially low 40 degree angle. The factory guard on my jet saw uses a

45 degree angle. I suspect the 40 degree angle is used to make rising up over wood as easy as possible. It sure contributes to a "pointy" front end on the guard, though.

1. Is the second angle cut at the top front of the guard really necessary? I suppose it may add some visibility by creating a little window to look through. But it makes the other angles and heights really difficult to get right. One degree here and a quarter inch there and you end up with the guard sitting on top of the blade.

2. Should the guard be tall enough to clear the blade, even if it falls on the table? Several guards I've seen are not tall enough to meet that criteria.

1. Is dust collection efficiency worse on a tall blade guard than a short one?

Regarding my primary quest of dust collection, I'm very intrigued by a design shown in the Workshop Book by Scott Landis. It has sliding sides and a flexible plastic flap at the front and rear of the guard. The idea is to make as tight a seal around the blade/wood stock for getting good dust collection. These moving parts really do not add any protection to the already intact guard housing underneath. I'm going to build these features. If they don't work, I can just rip them off and will still have a functional blade guard.

The Workshop Book design also has a really strange suspension, dust collection pipe set up. I'm separating the guard into two pieces - the guard and its suspension system. I figure if I get the guard right, I can always monkey with the suspension system later. Anyway the suspension system I reference has a vertical column suspended from the ceiling. The column is hollow with 1/2 devoted to a hardwood counterweighted slider to which the guard is attached. The other 1/2 is a hollow square dust collection duct. The original builder of this whole thing made good use of common materials that are cheap.

Darn, I write too much. Sorry to bend your ear. I'll save other detailed stuff for a website, assuming this is successful as I anticipate it to be.

Bob

[Larry C in Auburn, WA]

There are several home-made guards on the web. I thought I had bookmarked them, but I either didn't or I stored them in a place where I could easily find them and now I can't. I've thought about building one myself as it seems pretty easy to do. I think we're just talking about a little plastic box with a hole in the top. I would make it tall enough to clear the blade even if the blade is at full height and the guard is on the table. Also wide enough for you widest dado setup. Raise your blade to full height, put a piece of plywood against the side of the blade and trace around the blade. Isn't this the minimum size of the box sides? Add yourself another inch or so around the perimeter and square it up. Then you can add the angle on the front edge if you want without worrying about the 1/4 inch here and there that you're concerned about. I have a hunch you are worrying too much about completely sealing the guard up. Experiment with a plywood guard and see if you get most of the dust, I bet it won't be too hard to do.

In my thoughts, the trickier part is how to hold the guard up. I move my saw around so having something attached to the ceiling is out of the question. It has to be attached to the saw and I'd like it to be spring-loaded so I don't have to fiddle with it everytime I change wood thickness.