What I'm workin' on ...

[Beamer]

Hey all ... just thought I'd start a thread on my current project..

I recently acquired a new table saw that's significantly bigger than the one I've been using the last 4-5 years or so. I'm a huge fan of the over-head blade guard system.

Well this new saw moved the blade over about a foot, right under a light fixture! Naturally. Well, I didn't want to move the light, really, because it's very well placed and I'd been wanting to make some changes to the guard I made a few years ago anyway.

So .. that's my latest project. A new blade guard and mounting system. Here are some pics of the old guard:





A couple things I don't like about this one:

1) The dust collection port is too teeny. The new one will have a 4" port.

2) Related to #1, the suction isn't so good if i'm taking off less than 1" from the edge of a board - once the whole guard moves up, the airflow is reduced such that it doesn't grab much of the dust off the rooster tail. The new one will have independent sides to help keep the suction up a little better. It needs to keep airflow, but not TOO much. Hopefully this will do that

3) It was a little too flimsy - the wood mount worked okay, but she really wobbled side-to-side a bit much. The new one is going to have a steel base and thick aluminum arms.

Here's a SketchUp image of what i've modeled:



The mount is done. I got to glue steel together last weekend. This weekend I've spent time painting all the metal parts. The parallel mechanism works fantastic and is MUCH more rigid than the wood one. I've made a couple small changes to the design which enable me to adjust the whole works both left-to-right and back-and-forth to get right over the blade as I need it.

Yesterday I cut most of the polycarbonate pieces to shape. Today I began doing all the crucial drilling needed to make the independent sides operate.

I'll be adding more pics when the new guard's done ... but I figured I'd share what i've got so far

[TDHofstetter]

Verra' COOL, ya materials maven you!

What'cha gonna' use for counterbalance?

[Stretch]

Very cool. I gotta get my shop done so I can start working tweaking all my tools with cool stuff like this.

[Beamer]

Counterbalance ...

The jury's still deliberatin', to be honest. I didn't want a super long tail on the back because my workbench may end up back there and i'd like it to be unobstructed. Of course, that means i'll need more force to accomplish the same balancing act.

I'm currently leaning toward a stout spring from the tail end to the bottom of the top arm that gets me 80-90% of the counter force I need. Then I'll figure out a weight system that lets me fine-tune the balance. Maybe a little square-tube between the aluminum arms with a nut welded in the end so I can hang some weights off a length of all-thread. That's my current scheme ... if I can find a suitable spring that isn't too strong or too weak.

I think I'll need about 30lbs of force back there if my maths have come out right. I'd hate to make that ALL static weight so if i can get a spring to work, that'd be fantastic.

[TDHofstetter]

And we're lookin' at... lessee. Four to six inches of vertical travel, which would translate roughly to maybe two to three inches of spring extension? I think that should't be too hard to accomplish - if ya run into trouble getting one spring badazz enough, use two - one on each side.

Spring's a good approach; the higher the guard lifts, the tougher it gets to lift it... unless you cross a sine line & it gets easier, like a compound bow.

[fredbelknap]

Looking good, if you use a spring it would be good if you had some way to lock it in down position like maybe a friction knob. Lock it down when needed and loosen and raise for when it's not.

Fred

[Beamer]

Thanks for the encouragement, fellas

My hope with the spring is to still have it weak enough not to pull the whole mess up automatically. Mostly, i want it to take up enough weight to allow me to add a little more to the tail and find "neutral buoyancy" such that it'll stick anywhere i set it along it's travel.

Tim, as-built, the end result from the bottom of the top post and the end of the tail in fully UP position is about 4" and in the fully DOWN position is about 12" - I was thinkin' about even puttin' that spring on the front side, which has a better mechanical advantage AND a longer span which just might be long enough to take a porch door spring ... you know, them 12" long jobbies? ... it wouldn't have to be nearly as strong on the front since it's 3x longer than the tail is.

I wonder if there's a fish scale out there somewhere I can put on this rig to see how many lbs of force i really need. That'd sure help me pick out springs


One handy benefit is the guard itself will have independent sides so I will likely not need to move the whole thing very often. I just got a trial run of those sides and the final travel is around 2 1/2" before it bottoms out and would lift the whole guard.

I'm at the finicky stage of machining delrin parts to act as my bushings on all the pivots. It's handy havin' that lathe!

[Joe Lyddon]

That looks like a very clever way to get the dust out!

Seems like I've seen something like it... David Marks or Scott Phillips... someone... Excaliber rings a bell?

Look good... Very interesting...

[TDHofstetter]

K - in lieu of a fish scale... tie a string to where you'd prefer a spring to be attached. Clamp a C-clamp to the other end of where you'd like it to be attached, and run the string over that. Tie an empty paint pail to the loose end of the string & start piling stuff into the bucket. When the guard has about the right amount of loft, you know how much spring tension you want with the guard at rest.

[sawduster]

Nov 8, 2009 20:04:52 GMT -6 TDHofstetter said:

Verra' COOL, ya materials maven you!

What'cha gonna' use for counterbalance?

Wassa matter with the C=clamp counter weight of the old one? ;D Gotta love that ingenuity.

Tell ya Jason, bet you could move some of those blade cover thingies if you were of a mind to, and maybe even entire set-ups if you were to go into making them.

[Joe Lyddon]

It kinda reminds me of how these adjustable table lights work... where there is a Base that clamps to a lip... it has a round hole in it about 1/2"... Another piece sticks into the hole which has two sections with some springs connecting them as well as knobs, etc. that can be tightened to get desired angle / height with the light also movable via a swivel...

Yes? ;D

[Beamer]

Oh you know what ... right there inside the arms - i know what yer talkin' about, Joe ... that has the wheels turnin ... compact ... elegant ... i'm gonna take a good look at tryin' something like that.

Thanks for the spark of inspiration!

[Joe Lyddon]

No problem...

My advice is ONLY worth what you have to pay for it...
... remember that... If it dunt work... OK? ;D

[Beamer]

oh heck no. If it don't work, I'm holdin' YOU responsible, buddy! LOL!!!