Post by Beamer on Nov 29, 2009 18:54:17 GMT -6
Hey all...
I posted about this a few weeks ago and teased you all with the sketchup drawing so I'll start there:
So that's what i started with. It's to replace this:
A little back story, first ... I knew this guy named Allan. He thought of me as his son. He was diagnosed with colon cancer in '07. It's a very long story that some of you have heard, but I'll spare you the details. He passed away in September and saw fit to give me this:
He had bought it from a fellow ww club member this past spring but didn't really get a chance to use it. He thought I'd get plenty of use out of it ... it's still pretty heavy on my heart but I'm doing my best to use it with his intentions in mind.
Anyway ... this new saw is about triple the size of my previous one. I had a Powermatic 64a contractor saw with a 30" rip capacity. This is a Powermatic 66 cabinet saw with a 52" rip capacity and an Excalibur sliding table. Very much a big present ... and a big footprint.
Well the blade guard I had been using worked fine for several years. This new saw, though, moved the blade over to the left about a foot and a half. Right under a light fixture I really didn't want to move. I'd been holding on to a few improvements I wanted to make to the old guard anyway, so this was a good time to build a whole new one.
One of the things I wanted was more rigidity so I built a tripod base that straddles the light fixture. It gave me a great excuse to use my steel glue gun (Welding is FUN!). So once it was all designed in SketchUp, I set about makin' it. First i made the mounting system:
With T-track there so I can move the whole mess left and right depending on my needs (for skinny rips or something). Couple that with the plate on the bottom of the mount:
... and I can put the guard just about anywhere within a 18" diameter circle above the blade of the saw. I learned this trick with the first guard - it was nice to be able to nudge it over once in awhile.
The next bit I set out to do was the mechanism. So far, it's all been steel, but I already had some 1/4" x 1" aluminum bar stock that I had hoped would be rigid enough. Turns out it is ... so I cobbled together the parallels:
Fully retracted:
Fully Down:
Once that was done, I set about building the actual guard. One big change was the independent sides. I didn't like having the entire guard lift up when only doing a narrow rip, for example. That destroyed the dust collection somethin' terrible. So the independent sides came to me in a vision (probably someone else's guard I'd seen somewhere).
Example of a crosscut:
Example of a narrow-ish rip:
And here's a shot of it raised off the table - showing it fully bottomed out:
The hardest part about this whole build was the counterbalance system. The old one had a single C-clamp hangin' off the back tail. Well this new one wasn't just wood 'n aluminum. We had steel all over the place. I worked out that it'd take about 34lbs of downward force at the tail point to get close to equal balance. 34lbs of counter weight? ack.
So I set about finding a way to get some more active balancing. Springs! After trying various configurations of heavy springs, light springs, tail-side, front-side, etc, I landed on this one:
These get me nearly all the way there. The two C clamps that hang off the back nearly perfectly balance things now. They weigh just under 6lbs so now I just have to find 6lbs of ... something ... to hang off that tail. I'm thinkin' lead shot or something like that so I can tweak the weight settings if need be. I've found that DC hose stiffness varies with temperature so when it's 80 in there in the summer, it might need more weight.
Does it work? Heh. Yes. Quite well. I had it going with both the arm and the cabinet ports open and then I did that famous "edge" rip - you know where the blade just takes off enough to eat maybe 1/8 (or less) - lotsa sawdust and a big rooster tail, right? NONE. ZERO. I mean ... not a speck of dust sat on the table. You could actually see the dust changing direction as it left the blade. 4" is WAY better than the 2 1/2" i had been using before. YEE HAW!!
Some of the finer points are that each and every point of motion uses bushings made of Delrin that I turned on my metal lathe - lots of VERY thin, VERY small bushings. Lots of repetitive tasks, too. Counting cross-slide cranks and parting off these super teeny washers. It was fun ... tedious, but fun.
I had a blast making it. I decided to paint it because it would look nicer. Plus it would hide the grinding I did on all my welds.
If you wanna see the full-sized versions of all the pics (and a handful more shots of various views), check 'em out here:
Version 1:
gallery.sawdusters.org/v/Beamer/randomtools/guard1/
The New One:
gallery.sawdusters.org/v/Beamer/randomtools/guard2/
Thanks for looking!!
I posted about this a few weeks ago and teased you all with the sketchup drawing so I'll start there:
So that's what i started with. It's to replace this:
A little back story, first ... I knew this guy named Allan. He thought of me as his son. He was diagnosed with colon cancer in '07. It's a very long story that some of you have heard, but I'll spare you the details. He passed away in September and saw fit to give me this:
He had bought it from a fellow ww club member this past spring but didn't really get a chance to use it. He thought I'd get plenty of use out of it ... it's still pretty heavy on my heart but I'm doing my best to use it with his intentions in mind.
Anyway ... this new saw is about triple the size of my previous one. I had a Powermatic 64a contractor saw with a 30" rip capacity. This is a Powermatic 66 cabinet saw with a 52" rip capacity and an Excalibur sliding table. Very much a big present ... and a big footprint.
Well the blade guard I had been using worked fine for several years. This new saw, though, moved the blade over to the left about a foot and a half. Right under a light fixture I really didn't want to move. I'd been holding on to a few improvements I wanted to make to the old guard anyway, so this was a good time to build a whole new one.
One of the things I wanted was more rigidity so I built a tripod base that straddles the light fixture. It gave me a great excuse to use my steel glue gun (Welding is FUN!). So once it was all designed in SketchUp, I set about makin' it. First i made the mounting system:
With T-track there so I can move the whole mess left and right depending on my needs (for skinny rips or something). Couple that with the plate on the bottom of the mount:
... and I can put the guard just about anywhere within a 18" diameter circle above the blade of the saw. I learned this trick with the first guard - it was nice to be able to nudge it over once in awhile.
The next bit I set out to do was the mechanism. So far, it's all been steel, but I already had some 1/4" x 1" aluminum bar stock that I had hoped would be rigid enough. Turns out it is ... so I cobbled together the parallels:
Fully retracted:
Fully Down:
Once that was done, I set about building the actual guard. One big change was the independent sides. I didn't like having the entire guard lift up when only doing a narrow rip, for example. That destroyed the dust collection somethin' terrible. So the independent sides came to me in a vision (probably someone else's guard I'd seen somewhere).
Example of a crosscut:
Example of a narrow-ish rip:
And here's a shot of it raised off the table - showing it fully bottomed out:
The hardest part about this whole build was the counterbalance system. The old one had a single C-clamp hangin' off the back tail. Well this new one wasn't just wood 'n aluminum. We had steel all over the place. I worked out that it'd take about 34lbs of downward force at the tail point to get close to equal balance. 34lbs of counter weight? ack.
So I set about finding a way to get some more active balancing. Springs! After trying various configurations of heavy springs, light springs, tail-side, front-side, etc, I landed on this one:
These get me nearly all the way there. The two C clamps that hang off the back nearly perfectly balance things now. They weigh just under 6lbs so now I just have to find 6lbs of ... something ... to hang off that tail. I'm thinkin' lead shot or something like that so I can tweak the weight settings if need be. I've found that DC hose stiffness varies with temperature so when it's 80 in there in the summer, it might need more weight.
Does it work? Heh. Yes. Quite well. I had it going with both the arm and the cabinet ports open and then I did that famous "edge" rip - you know where the blade just takes off enough to eat maybe 1/8 (or less) - lotsa sawdust and a big rooster tail, right? NONE. ZERO. I mean ... not a speck of dust sat on the table. You could actually see the dust changing direction as it left the blade. 4" is WAY better than the 2 1/2" i had been using before. YEE HAW!!
Some of the finer points are that each and every point of motion uses bushings made of Delrin that I turned on my metal lathe - lots of VERY thin, VERY small bushings. Lots of repetitive tasks, too. Counting cross-slide cranks and parting off these super teeny washers. It was fun ... tedious, but fun.
I had a blast making it. I decided to paint it because it would look nicer. Plus it would hide the grinding I did on all my welds.
If you wanna see the full-sized versions of all the pics (and a handful more shots of various views), check 'em out here:
Version 1:
gallery.sawdusters.org/v/Beamer/randomtools/guard1/
The New One:
gallery.sawdusters.org/v/Beamer/randomtools/guard2/
Thanks for looking!!
