Fairly terrifying - Stepping back to revaluate what happened

[HMH]

So documenting a fairly terrifying event from last weekend for the group as A) a conversation starter re: what went wrong/ better ways to prevent, and B) a PSA of sorts to remind us to all stay on our toes...

FORTUNATELY - I WAS NOT HARMED. I still have all of my fingers, and no carbide bullets lodged anywhere. Definitely woke me up though!

The scenario/ backstory:

I was making a few tool holders/ etc for various frequently used tools to hang on a recently built French-cleat wall, using up various scraps I've had lying around forever. The task at hand was cutting 45 deg miters on some short scraps (the short length being primary culprit here in my view), of purpleheart. The scraps in question were again, very short/ small, (~1.5" square piece of 4/4 stock), so I had a stop block/ backboard hold down in place to keep my hands well clear. my backstop/ hold downs were all friction fit - no mechanical connectors. First cut on piece #1 = no problem/ results as intended. Cut on piece #2 = EXPLOSION, counted my fingers, and patted myself down for holes, (no holes found fortunately).

The 2nd piece grabbed somehow, and apparently shot into the guard around the blade, BREAKING 1 tooth off completely, (physically breaking both the steel and the carbide) and stripping the carbide tooth off of a second, (the blade in question was a freshly sharpened Forrest Chopmaster, so I'm somewhat ruling out the blade as the culprit here), and then continuing it's path and bouncing off the right hand fence of the saw, (Bosch slider), physically breaking, and bending the removable aluminum fence wing).

Other factors - I recently installed a "popular Etsy purchased dust shroud" for the saw - brand/ maker deliberately not named to protect the innocent. That said, this particular dust shroud has a fairly heavy rubber "mouth" to collect *& funnel the dust coming off the back of the blade. I'm thinking that this piece contacted the wood, and lifted it somehow?

So for part A) Group discussion of what I did wrong here - let me have it. Was the culprit the short pieces, or is there validity to the dust shroud contribution? In any case, I'll be removing the shroud on all but 90 degree cuts on standard/ more substantial/ less prone to being lifted. Other thoughts?

 

[Mike Davis]

Little square is entirely too small for a mitersaw.
I would use either a bandsaw or a sliding jig with clamps for the table saw.

 

[creasman]

I agree w/Mike that the piece is too small of the tool. I'd also check that dust collection shroud to see if lowering this creates enough suction to actually lift the piece of wood. That could lead to unintended consequences like you describe. Maybe try it with the saw off to see if the vacuum lifts the wood.

 

[Bas]

I know the dust shroud you're describing. He has a video on his channel about people reporting that the offcuts caused the shroud to explode. I don't think that this was the issue in your case (or only issue), since it wasn't just the offcut that was small. But I'd email him anyway in case the improved suction caused the problem.

I've cut small pieces like that, but used double stick tape to attach them to a piece of sacrificial plywood.

 

[ssmith]

Sounds like you took precautions but +1 on the workpiece being too small to cut safely.

When you say "stop block / back board", do you mean a sacrificial piece of stock you don't cut through, laying on the table between the workpiece and fence (the point being to bridge the gap in the fence)? That would minimize the chance the blade would pull the stock thru the fence, which image 8819 seems to show happened. You'd still need to secure the workpiece though and if your miter saw is like mine, that's really tough with such a short workpiece.

 

[FredP]

I cut small stuff like this a lot. I attach a sacrificial wood fence to the saw so that the saw curf is just that, a saw kerf. Most miter saws have a wide open hole in the fence where the blade goes through. There lies the problem. Also let the saw spin down to a stop before lifting out of the cut.

 

[Wilsoncb]

Thanks for sharing, interesting situation.

It looks like you have a two piece fence on the side that broke? I have one that will fold away from the blade so when it is folded out (away from the blade) it leaves you with a lower fence closer to the blade. Can you clarify what what that relationship was. Also how close the blade and blade guard were to the fence that broke. For example, if I cut 45 degrees by tilting the blade vs. pivoting it, mine would cut through the fence if it was folded in (toward the blade).

I’m asking because I’m surprised the blade broke only from the wood piece. Also a little bit surprising that wood scrap broke the fence. However the fence break does not look like it was due to blade contact…but not ruling it out.

Otherwise, the “friction“ holds only provides side pressure. Not enough downward pressure to hold the piece. It broke the fence piece which flew into the blade and metal part of blade guard…and broke the blade.

 

[jfynyson]

Glad you're ok...other than your shorts I bet. I agree w/ Fred if you must cut short pieces; but add the ability hold down the off cut and long cut pieces if possible using a holder like this:

Sorry! Something went wrong!

 

[bowman]

Wrong tool for the job, even with using a hold-down like @jfynyson is showing.

 

[Mark Johnson]

I think the shroud is a bigger contributor than you may think; however, the small stock is still the biggest trick. When cutting small stuff on a miter saw, I use a piece of plywood with sandpaper attached to reduce wood movement; zero clearance slot in ply and the wood back stop. I also us the hold down device shown above, but I think that a diagonal on a block the size you describe does not leave room for the hold down to fit. I have had a block get caught in the flexible dust shroud on my saw and on steep angle cuts, I remove the shroud. In my opinion the best practice would be to cut close on a bandsaw and sand to final dimension on a disk sander. You can make a "perfect" 45 jig without much trouble and eliminate a whole lot of anxiety.

 

[HMH]

Thanks all - yes, I see and agree w/ the prevailing wisdom here that the piece was way to small for the miter saw. I thought I was compensating for that by having the piece on a scrap of plywood for a base, w/ a plywood fence on both the back, and opposite face from the miter saw fence, (in my mind, capturing it on 3 sides), but w/ no attachment to the plywood base, (double sided tape or sandpaper would have been a great idea), apparently either the suction from the dust shroud, or some tension in the purpleheart itself was enough to lift the second piece and cause the carnage. The sliding miter fence to the right, (the one that was damaged), was well clear of the blade, but I'm thinking it may have caught on the rubber boot portion of the shroud and potentially lifted the lip enough to move the piece - at this point who knows.

Regardless - the bigger take away here is to slow down and think. Mike's suggestion of using the bandsaw, (that was literally 10' away), and dressing up the cut w/ a disk sander, (that was literally 15' away), is the obvious correct answer here in hindsight - but in the heat of the task, I didn't even look in that direction, and just used what was laying around me on the bench to cobble something together quickly. Thank god that I was smart enough to keep my hands well away from all of that, but catching a piece of carbide somewhere at that range/ RPM coming off of the blade, would come pretty close to being shot I imagine. Super lucky it didn't come back at my body or face, (I have no idea where it went actually, still haven't found it).

This concludes the safety PSA for the day, w/ the moral of the story being: THINK, and use the right tool for the job.

It has now been "3" days in Heath's shop w/o an accident, ha.

 

[Bill Clemmons]

Some good advice in this thread, Heath. I especially agree with the crosscut sled on the TS; a sacrificial wood fence on the miter saw to close the kerf gap; and a back saw or pull saw in a small miter box.

 

[Linc H]

Thanks for sharing your experience and details. This helps us newbies to avoid disasters. I am glad you are not harmed Heath!!!

 

[bob vaughan]

I go along with the sacrificial fence idea. I made a fence for my saw that will slide left or right, according to the angle and thus keeping a very narrow slit for the saw. The first few little piece kickbacks got my attention and compelled me to consider an alternative.

Like they say, "No pictures, didn't happen."

 

[Rick_B]

I did he same thing as Bob on a PC 12" miter saw. Worked great. That saw is now gone - gave it vto my son

Rick

 

[pop-pop]

This thread makes one realize how safe a handsaw is for small parts (with no added doodads).

 

[SabertoothBunny]

As far as what caused the failure, do not rule out the possibility that the Forrester blade was faulty. It is perfectly plausible that the tooth that broke off have a flaw assisting with the failure and flying parts contributed to other damages. Mass production does allow for these potential flaws to occur. It is just hard to believe that this small piece of wood caused that kind of damage alone almost regardless of species.

Lesson learned though right? Bandsaw or small parts jig on tablesaw. Sand it down with the sander, go old school like pop-pop and use a handsaw. Glad to hear you were not hurt.

 

[mpeele]

I have the same saw with the same dust chute and seem to be making a lot of small pieces. All of the suggestions have been great but I'll add that you have to control the material on both sides of the cut. That small off cut can do damage.

I use this on my miter saw with clamps/bars similar to Bob's.


I always stop blade before raising the blade out of the cut.

Then sometimes the off cut is the part and its just to small to control.

Small cut of 3/16", small blade and small sled to make 2000 small parts.

 

[bob vaughan]

I like that vacuum box idea for those little fussy parts. For making 2000 parts, its well worth the effort.

 

[creasman]

This thread makes one realize how safe a handsaw is for small parts (with no added doodads).

I do most of my crosscuts now on an old-fashioned miter saw. This is mostly because I enjoy working with hand tools, but like Mike this makes me realize how much safer it is. Also, I get exercise and there is a lot less dust.