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Tablesaws 101 Question: How do I cut this safely?

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Forum topic by Ted Ewen posted 11-21-2015 10:51 AM 1600 views 0 times favorited 29 replies Add to Favorites Watch
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Ted Ewen

187 posts in 533 days


11-21-2015 10:51 AM

Topic tags/keywords: table saw safety beginner 101 how to cuts

Hi,

Last week I got my first ever tablesaw. Until then, all my experience of a table saw was watching them being used on YouTube or TV. Last week I made some test cuts and a couple of working cuts, but nothing taxing. Just some ripping and crosscutting. Turned a 2×4 into a 45mm x 45mm pole, cut some sheet stock.

I have worked up a 30° A-frame coop in SketchUp. The ridge pole is made out of a 38mm x 57mm cut to a 30° angle on both long sides, and is 1.5m long:

I used sketchup to work out, geometrically, how the cut needs cutting:

The physical reality of my saw set up this way leaves me with some doubt. There is about 1.5cm clearance between the fence and the teeth, and the blade height is about co-planar with the top of the fence:

My current thinking is to screw another piece alongside it to give me more depth to work with. Or get a bandsaw ;) How would you make a piece like this?

Thanks.

-- Show us a man who never makes a mistake and we will show a man who never makes anything. The capacity for occasional blundering is inseparable from the capacity to bring things to pass.


29 replies so far

View rwe2156's profile

rwe2156

2198 posts in 947 days


#1 posted 11-21-2015 12:27 PM

You’re certainly jumping right in to a fairly complicated cut for a beginner!
But you can do it the main issue is SAFETY.

First off, you need to have the blade tilting AWAY from the fence or you are setting yourself up for a binding and/or kickback potential. Easily accomplished by simply moving fence to other side of the blade.

The waste will fall of the outside of the blade instead of being trapping between the fence and the blade.

You’ll be making the cut upside down from what you’re showing there.

I would use some kind of featherboard or guide blocks to keep the piece stable on the second cut.

Not to mention a push stick (or two).

It’s still gonna be a little bit of a hairy cut.

-- Everything is a prototype thats why its one of a kind!!

View greatview's profile

greatview

110 posts in 2624 days


#2 posted 11-21-2015 12:34 PM

A ridge pole doesn’t need to be beveled at all. Use a one by ten instead of a two by ten (or whatever size is needed). The rafters normally oppose one another and, in theory, you can build a structure without a ridge pole bu simply putting the rafters against one another.

-- Tom, New London, NH

View Tennessee's profile

Tennessee

2410 posts in 1981 days


#3 posted 11-21-2015 12:38 PM

I don’t think I would ever try the second cut with it upside down with the fence on the other side. Upon the first tooth hitting air when finishing the cut, your piece is riding next to the blade, now on a pointed edge and could slip one way or the other, despite trying to hold it to the fence.

I’d make that cut with the riving knife off, guard off, with the blade just at the top of the point, no more. Just the top tooth peeking through the top of what would become the peak.

Use a push stick to make it go through with the blade tilted toward the fence, or better yet, see if you can get a helper to pull it through when it gets close and you both are away from the blade.

Agree, that is a tricky cut no matter what.

-- Paul, Tennessee, http://www.tsunamiguitars.com

View ThomasChippendale's profile

ThomasChippendale

244 posts in 399 days


#4 posted 11-21-2015 12:43 PM

I would cut it upside down, leaving a small1\16flat on top.

-- PJ

View Paul Bucalo's profile

Paul Bucalo

626 posts in 826 days


#5 posted 11-21-2015 12:50 PM

Cut the ridge pole on its side, with the blade angled away from the fence. This way, you are always undercutting the pole, bevel cut facing the table. Once a cut is done, flip the piece over, end for end, then run through again.

-- -- Paul Bucalo, Norwich NY USA

View Tennessee's profile

Tennessee

2410 posts in 1981 days


#6 posted 11-21-2015 01:01 PM

Paul, I thought about that, but wouldn’t a 60’ angle be needed on the blade? My saw won’t go beyond 45’.

-- Paul, Tennessee, http://www.tsunamiguitars.com

View hotbyte's profile

hotbyte

844 posts in 2442 days


#7 posted 11-21-2015 01:11 PM

As already mentioned, you probably don’t need to cut ridge that way but if you want to, fence should be on opposite side of blade and board cut upside down.

One thought I have is to start with board about 2’ longer than needed. As you make the second cut stop short and turn off saw before removing board. This will leave board better supported feeding into blade and not involve the most dangerous part of cut – feeding final end of board past blade. Then cut to final length.

Also, be sure to have sufficient infeed and outfeed support.

View athomas5009's profile

athomas5009

293 posts in 1084 days


#8 posted 11-21-2015 01:25 PM

I would you the opposite side of the blade as mentioned and some sort of push block like the gripper. It’s resembles a 4×4 with a handle and a tab that hooks over the end of your workpiece. It allows one to put downward pressure, pressure against the fence and is user friendly the way it’s just pushed through the blade.

If you don’t feel like spending the 60$ on the gripper just make one. All you need is a block off wood, a handle and some hardboard screwed to the back for the tab/hook.

-- Sometimes you're flush and sometimes you're bust, and when you're up, it's never as good as it seems, and when you're down, you never think you'll be up again, but life goes on.

View Paul Bucalo's profile

Paul Bucalo

626 posts in 826 days


#9 posted 11-21-2015 01:30 PM



Paul, I thought about that, but wouldn t a 60 angle be needed on the blade? My saw won t go beyond 45 .

- Tennessee

If the blade is set at 30 degrees, cutting the underside of a piece on one side will have the same angle as the top side cut from the other side of the blade. Consider how a French cleat is made. Both ends are reversed of each other and bear a cut at the same angle. Make sense?

-- -- Paul Bucalo, Norwich NY USA

View Kazooman's profile

Kazooman

628 posts in 1419 days


#10 posted 11-21-2015 01:58 PM

Paul, I thought about that, but wouldn t a 60 angle be needed on the blade? My saw won t go beyond 45 .

- Tennessee

If the blade is set at 30 degrees, cutting the underside of a piece on one side will have the same angle as the top side cut from the other side of the blade. Consider how a French cleat is made. Both ends are reversed of each other and bear a cut at the same angle. Make sense?

- Paul Bucalo

Just starting in on my second cup of coffee, but that isn’t making sense to me. Can you draw that out showing the fence, blade, and workpiece like the OP did above? A hand drawing with a cell phone pic would do fine, nothing fancy needed. I just can’t get my head around what you are trying to say.

By the way, I woke up to about three inches of fresh, wet snow on everything. Expecting up to five more inches throughout the day. Actually very pretty coating on all of the tree branches. Time to put the golf clubs in the basement.

View Paul Bucalo's profile

Paul Bucalo

626 posts in 826 days


#11 posted 11-21-2015 02:03 PM


Just starting in on my second cup of coffee, but that isn t making sense to me. Can you draw that out showing the fence, blade, and workpiece like the OP did above? A hand drawing with a cell phone pic would do fine, nothing fancy needed. I just can t get my head around what you are trying to say.

By the way, I woke up to about three inches of fresh, wet snow on everything. Expecting up to five more inches throughout the day. Actually very pretty coating on all of the tree branches. Time to put the golf clubs in the basement.

- Kazooman

Heh-heh. I was on my first cup of joe when I replied, so who knows what universe I was in at the time. ;)

I’m off to the box store to get some new plumbing—got a kitchen remodeling job that is behind and must be done by the end of this weekend—so I’ll try to get back to you later in my day. For now, think of the letter “Z”. If the blade is the riser on the letter, and the top and bottom are being cut by the ‘blade’ on opposite sides of it, the only difference is the top is being undercut, the bottom is an overcut. I hope that helps. :)

-- -- Paul Bucalo, Norwich NY USA

View Kazooman's profile

Kazooman

628 posts in 1419 days


#12 posted 11-21-2015 02:05 PM

If you really need to have the ridge cut like that, the safest way would be to have the blade tilted away from the fence as mentioned, make the first cut and then mount the piece to a second 2×4 or other wood with screws being certain to keep the screws above the blade. Make the second cut and the nicely pointed piece is securely held by the attached wood. If the screw holes are a problem, then make the piece a few inches longer than required and put the screws in the ends. Cut off the excess wood with the holes when you are done.

View Ted Ewen's profile

Ted Ewen

187 posts in 533 days


#13 posted 11-21-2015 03:11 PM

Thanks for all the replies.

What I’ve gathered is this:

1) Fence goes on the other side. I’d swear the advice I saw said the offcut should ride above the blade, such that if it releases stress and bends, it is unlikely to cause a bind since it would curl away from the blade….

Yup, as here:
Kickback while bevel ripping. On a right-tilt saw, your material is trapped between/underneath the blade and the fence. Any “movement” in the wood will increase the friction between the material and the blade, increasing the likelihood of kickback. On a left-tilt, the material is between/above the blade and the fence. Any “movement” of the material and it simply rides up on top of the blade.

Also this:
Again intuitively, I keep the rip fence on the right side of the blade. Since my Unisaw is the left tilt version, I can rip a narrow bevel (for example on the edge of sheet goods) without having to move the fence to the left side of the blade in order to avoid trapping the cutoff against the fence, risking it becoming the proverbial “hidden arrow” should it kickback.”

That just added a little more understanding of the problem – as long as the cutoff is not trapped between the fence and the blade I am fine. Am I understanding it better?

I whipped up a few more illustrations of the suggested methods for the cut:

Turning the piece 90° won’t work. I’d need a 60° bevel (I had the same thought, Paul… but wait – it would work with the fence on the left, right?).

Inverting the cut looks…precarious:

If I do make the cut, I will add a batten to increase the depth of stock, and use an overlong blank as suggested, cutting it free from the pole:

2) Ridge Beam? We don’t need no steeking ridge beam…
I think the simplest thing to do will be to just butt the joists together.
So, when does one actually need a ridge beam? Does it ever need to be beveled to match the slope? Is there a better way to incorporate a ridge beam than this? I just used one because the plans I’d been looking at used one.

-- Show us a man who never makes a mistake and we will show a man who never makes anything. The capacity for occasional blundering is inseparable from the capacity to bring things to pass.

View splatman's profile

splatman

563 posts in 866 days


#14 posted 11-21-2015 08:53 PM

Leave your stock square, and cut sloped-bottomed notches where the rafters will go. OK, 2 passes through the TS is easier and quicker.
Practice on scrap material first.
As mentioned, set the blade elevation to just a fuzz above the top of the stock. (if cutting upright) or just a fuzz out the side (if cutting upside down).

View ThomasChippendale's profile

ThomasChippendale

244 posts in 399 days


#15 posted 11-21-2015 09:00 PM

Scew back the removed corner flush with the table !

-- PJ

showing 1 through 15 of 29 replies

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