Big close call in the shop

[Robert gree]

I had my craftsmen plunge router attached to my jasper jig. Making a 16" wide circle .5 inches deep in .75 MDF. cutting a 1/16 inch at a time. Nice slow rotation when my 1/2 straight bit grabbed and all hell broke loose. next thing i know im picking myself up off the ground the router is on and sitting on my belly. Im thinking i have a spinning mess inside me. till i look over and see my 1/2 bit laying on the ground.

I pick the bit up its bent and theres no sign of anything in the mdf that would cause a problem. and my jig is now cracked

[Victor Robinson]

Wowzers. Glad to hear you are ok.

One possible scenario is that the jig shifted slightly such that a subsequent pass was widening the cut in addition to deepening it. Depending on which side of the cut was widened ever so slightly, it might have been a climb.

But that wouldn't explain how your bit ended up on the ground...

[Robert gree]

Wowzers. Glad to hear you are ok.

One possible scenario is that the jig shifted slightly such that a subsequent pass was widening the cut in addition to deepening it. Depending on which side of the cut was widened ever so slightly, it might have been a climb.

But that wouldn't explain how your bit ended up on the ground...

maybe the bit grabbed enough Wood that it stopped turning. which would have slung the router into be and also loosened the bit? or i didnt have the collet as tight as i should have and it saved my behind

[Jason White]

Were you using a bit with a 1/4" shank? Those suckers are very prone to breaking if you push them too hard.

Jason



I had my craftsmen plunge router attached to my jasper jig. Making a 16" wide circle .5 inches deep in .75 MDF. cutting a 1/16 inch at a time. Nice slow rotation when my 1/2 straight bit grabbed and all hell broke loose. next thing i know im picking myself up off the ground the router is on and sitting on my belly. Im thinking i have a spinning mess inside me. till i look over and see my 1/2 bit laying on the ground.

I pick the bit up its bent and theres no sign of anything in the mdf that would cause a problem. and my jig is now cracked

[Fred Voorhees]

Wow, that could have been disasterous. Glad it wasn't. I guess none of us can ever lower our level of attention while working in our shops. Thanks for the reminder.

[Mike Heidrick]

Try a Whiteside RU4700 next time and ditch the 1/4" shank router bits.

[Bill ThompsonNM]

That could hurt. Glad you weren't. Interesting, though, for those of you who remember the thread some months back about cutting circular tabletops. If I remember correctly, many suggested a router rather than the OP's question about the jig for the tablesaw. Clearly no matter what the tool, if you've got sharp edges and horsepower... it can be dangerous! (usually it's the drill press that gets me...seems so benign...)

[Myk Rian]

I don't care what router or bit you were using. Taking a 1/2" cut at one time will do it to you every time.

[Robert gree]

I don't care what router or bit you were using. Taking a 1/2" cut at one time will do it to you every time.

1/16 inch depth 1/2 wide cut

[Robert gree]

Try a Whiteside RU4700 next time and ditch the 1/4" shank router bits.
going to finally buy the infinity bits ive been looking at

[Rob Holcomb]

I'm glad you are ok. Danger lurks everywhere in a woodshop! I am a bit confused though. The router bit into the wood at such a force that it actually knocked you down to the ground? I assume the Jasper Jig was still attached to the router but I wasn't aware that a router could cause that much force to take a grown man to the ground. I can see it being forced out of your hands, falling, getting sprained wrists etc. but WOW! I learned something today. I never would have thought a router could fly out of your hands and hit you hard enough to knock a person down! I now have a new respect for the power of routers!

[Andrew Gibson]

Think of a horse kicking you in the chest, that is the equivalent of a 1HP router in the right circumstances... :D

Really glad you didn't get hurt! That is some crazy stuff.



I'm glad you are ok. Danger lurks everywhere in a woodshop! I am a bit confused though. The router bit into the wood at such a force that it actually knocked you down to the ground? I assume the Jasper Jig was still attached to the router but I wasn't aware that a router could cause that much force to take a grown man to the ground. I can see it being forced out of your hands, falling, getting sprained wrists etc. but WOW! I learned something today. I never would have thought a router could fly out of your hands and hit you hard enough to knock a person down! I now have a new respect for the power of routers!

[Myk Rian]

1/16 inch depth 1/2 wide cut


Making a 16" wide circle .5 inches deep in .75 MDF.

Hence the confusion.

[Nathan Callender]

Can you post pics of the jig, router, bit and workpiece? That might help people figure out what happened.

[Lee Schierer]

I believe what happened is that your collet loosened and the bit came loose. The vibrations cutting MDF can be severe enough to loosen the bit. Most likely you had the bit extended a little too far out of the collet to get the desired depth of cut and the collet couldn't grip the bit properly. Check your collet carefully and make sure you didn't also bend the collet shaft.

When cutting grooves with a router bit you have to remember that half of the bit is climb cutting so they will tend to self feed which can lead to a pinch and the resultant throwing of the router (and operator).

[Neil Brooks]

I believe what happened is that your collet loosened and the bit came loose. The vibrations cutting MDF can be severe enough to loosen the bit. Most likely you had the bit extended a little too far out of the collet to get the desired depth of cut and the collet couldn't grip the bit properly. Check your collet carefully and make sure you didn't also bend the collet shaft.

When cutting grooves with a router bit you have to remember that half of the bit is climb cutting so they will tend to self feed which can lead to a pinch and the resultant throwing of the router (and operator).

I'm kinda' with Lee.

When a similar nightmare happened in my shop, the issue was an ever so slightly -- I'm talking maybe a 64th of an inch -- off centered router sub-base.

In my case, it allowed the lock ring on the bushing to contact the collet, unscrewing the collet, and ......

[EDIT: actually, it allowed the bit to contact the lock ring ... which ...... lived in the house that Jack was trying to build ;)]

Glad you're okay.

Yet another thing to go over ... thoroughly ... before hitting the ON switch!

[Michael MacDonald]

wow... really scary. aonther router come to life--glad it turned out all right. it is good to hear these stories every once and a while--a healthy sense of fear is motivational.

[Jim Rimmer]

WOW ! Having a spinning router on yuor gut is really scary. Glad you're OK.

[Mitchell Andrus]

Routerstop!
.

[Don Jarvie]

Glad you are alright Robert.

One thing we all probably over look is how we use our tools with respect to our body position. Depending on how the piece is clamped down on the table we may not be getting our body in a correct position to apply the correct pressure on the tool to minimize kick back, etc.

I'm not saying anyone is doing anything wrong but how much thought is put into body position regarding force and leverage.

Just something to think about.

[Chip Lindley]

Robert, Close Calls are Wake Up Calls! Glad you did not suffer serious injury!

Upon looking up the Jasper Jig on Google, I must say it appears a bit flimsy for large cuts. The many pivot holes may be convenient, but are very small. A small screw or nail can wiggle loose in the stock and throw the router off course, to grab lots of wood at the wrong moment. A larger bolt through the center pivot point would help lots.

Instead of hand-held, I do all circle-cutting on the RT, with a Ho-Made jig held in the miter slot. It can be slid in and out to pivot stock at exactly the right radius.

[Richard Wolf]

Which way were you feeding the router? You should be moving it clockwise.

Richard

[Chris Kennedy]

That sounds ridiculously scary. It definitely sounds like something failed -- the collet or the bit. When you figure it out, let us know. I would be hesitant to use that router until the reason is determined.

Chris

[mreza Salav]

Which way were you feeding the router? You should be moving it clockwise.

Richard

And why? if you are cutting a circle with a straight (or spiral) bit should it really matter?

[Ron Jones near Indy]

I'm glad you are ok.

[David DeCristoforo]

"And why? if you are cutting a circle with a straight (or spiral) bit should it really matter?"

If you are moving counterclockwise, you are "climb cutting" which means that you are moving the router in the same direction as the cutter rotation. This allows the cutter to grab and "run away" (or climb), taking the router (and you) with it. Very dangerous and quite possibly why you ended up on your ass.

[Richard Wolf]

I know it is difficult to visualize what David is saying, an internal cut seems like it shouldn't matter. After all,you are removing material from both sides of the cutter, but I know first hand, that once you try it counterclockwise you will never try it again.

Richard

[mreza Salav]

"And why? if you are cutting a circle with a straight (or spiral) bit should it really matter?"

If you are moving counterclockwise, you are "climb cutting" which means that you are moving the router in the same direction as the cutter rotation. This allows the cutter to grab and "run away" (or climb), taking the router (and you) with it. Very dangerous and quite possibly why you ended up on your ass.


I know it is difficult to visualize what David is saying, an internal cut seems like it shouldn't matter. After all,you are removing material from both sides of the cutter, but I know first hand, that once you try it counterclockwise you will never try it again.

Richard

Sorry, but I don't agree with these arguments.

Geometrically, the "line" at which the router bit is moving at any given point of time is perpendicular to the radius from the center to the contact point. I other words, you are always cutting from the "front" not the sides.
So, theoretically, I don't think the issue of climb cutting is really there as you are cutting from the half circle to the "front" of the bit.

I do this all the time (when cutting a circle in several passes I go one round clock-wise, lower the bit and go counter-clock-wise and so forth).
Never felt any difference either.

The only case I can say this might matter is when the radius of the circle you are cutting is small.

[David DeCristoforo]

"...I don't agree with these arguments..."

Sorry but they are not "arguments". They are facts. The cutter is round. There is no "front" or "back" or "sides". If you move the router in a counterclockwise direction, you are climb cutting. Period.

[Glen Butler]

Sorry, but I don't agree with these arguments.

Geometrically, the "line" at which the router bit is moving at any given point of time is perpendicular to the radius from the center to the contact point. I other words, you are always cutting from the "front" not the sides.
So, theoretically, I don't think the issue of climb cutting is really there as you are cutting from the half circle to the "front" of the bit.

I do this all the time (when cutting a circle in several passes I go one round clock-wise, lower the bit and go counter-clock-wise and so forth).
Never felt any difference either.

The only case I can say this might matter is when the radius of the circle you are cutting is small.

I cut circle circles the same way as you have described. I vote somewhere between Richard/David and Mreza. When using a jasper jig and the recommended 1/4" bit, I find that there is a difference cutting clockwise vs. counterclockwise, but not huge. The router does take off a little when working counterclockwise, but not uncontrollably. You can just feel the feed is easier. And it doesn't bother me working both directions. So, not as dramatic as a regular climb cut, but it is there.

Before I got the jasper I used a shop made jig and a 3/4" bit. I would only work clockwise with that and I agree with David and Richard. Even though it seems the cut geometry is the same either direction, it would throw itself running counterclockwise.

[johnny means]

Climb cutting or not, one should always have good footing and proper leverage and balance to deal with these unexpected events. Bits break, boards pinch, knots grab. One should always have control over their hand held tools. Cutting ¾ MDF with ½ flush trim bits is an everyday occurrence in my shop and the routers do like to jump and chatter, but they are hardly uncontrollable.

[mreza Salav]

"...I don't agree with these arguments..."

Sorry but they are not "arguments". They are facts. The cutter is round. There is no "front" or "back" or "sides". If you move the router in a counterclockwise direction, you are climb cutting. Period.

I think I respond to people with respect and try to reason, but this respond
sounds to me a bit condescending.I thought forums are to discuss things...

Here I try to explain what I meant by "front" of the bit being cutting.
In the picture below, if you assume you are cutting in a clock-wise motion and if you move the bit a little around the circle, the material that is being cut is the red eclipse that is to the "front" of the bit (the direction of move is the red arrow). If you rotate counter-clock-wise the direction of the move is the blue arrow and the material being cut is the blue eclipse.

146115

In either case the bit is moving straight into the material being cut.

As I understand, "climb cut" is when the bit tries to grab the piece and pull it, so if you are routing an edge with a router free-hand (for example) the bit tries to move more rapidly in the same direction it is being introduced to the wood. In this picture, there is no where the bit can move further forward except into the wood. So as long as you hold the router firm down on the piece (so that the bit doesn't move up-ward out of the cut) I don't see how you can "climb cut".

[Bill ThompsonNM]

Think of it this way.
1. You're cutting down the center of a board -- the board exerts a force on the router bit ghat is even on both sides -- you push and overcome resistance in the direction you are routing
2. Now on the edge of a board-- all of the force is on the 1/4 of the bit that is cutting. If you go one direction the force of you pushing counters the force of the board pushing the bit. The other direction the forces are added and you are climb cutting with less control. The big difference is your only cutting on one side of the bit
3. Now cutting the circle. Note that the outer 1/2 of the circular ring you are cutting has more area than the inner half. The rate your cutting at is the same (arc per time) for the inner and outer, though, so you must be doing more work on the outer side of the bit. It's very similar to cutting an edge but the difference in forces on opposite sides of the bit are less than the edge example. Since they aren't the same one direction adds to the difference and one subtracts When it adds you are climb cutting. Less difference for smaller bits since there is less difference between the areas of wood removed

[John Coloccia]

Because when you're moving left to right, the front edge of the bit (and the only part of the cut that's asymmetrical since the back edge is already cut) is pushing the router outwards. This is good since that's where you're pushing also, unless for some bizaare reason you use a circle cutter by pushing IN towards the center.

When you're moving right to left (i.e. counter clockwise) the leading edge of the bit is pushing the router IN towards the jig, while you're pushing OUT. Being that these are mechanical objects, and nothing is perfectly tight, if you happen to win the tug of war, you will suddenly be climb cutting on the outside edge of the circle.

Same with a fence. If you setup a fence, and try to cut right to left, you may find rather dramatically the the router doesn't really want to stay on the fence all that much, and buh bye router.

[mreza Salav]

Bill, I understand your explanation that in that eclipse that is being cut one half (closer to the outer edge) is so slightly larger than the other half (closer to the inner edge) but if the radius of the circle you are cutting is not very small (say larger than 3-4") and you are not using a very large bit that difference is next to nothing.
That's why in my earlier post #28 I said this (climb-cutting) is a non-issue unless the circle you are cutting is fairly small (or you are using a fairly thick bit, which you shouldn't be anyway).

[mreza Salav]

Because when you're moving left to right, the front edge of the bit (and the only part of the cut that's asymmetrical since the back edge is already cut) is pushing the router outwards. This is good since that's where you're pushing also, unless for some bizaare reason you use a circle cutter by pushing IN towards the center.

When you're moving right to left (i.e. counter clockwise) the leading edge of the bit is pushing the router IN towards the jig, while you're pushing OUT. Being that these are mechanical objects, and nothing is perfectly tight, if you happen to win the tug of war, you will suddenly be climb cutting on the outside edge of the circle.

Same with a fence. If you setup a fence, and try to cut right to left, you may find rather dramatically the the router doesn't really want to stay on the fence all that much, and buh bye router.

There is no pushing IN or OUT when I use a circle-cutting jig. If I am
going clock-wise the direction I push the router is in the direction of red arrow and if I go counter-clock-wise the direction of push is always the Blue arrow in the picture. In either case I am pushing the router "into" the wood since the area that is being cut (the eclipse) is *almost* the opposite side of the where I am pushing.

I tried to explain why this is different from using a fence: in that case the bit is cutting from one side and one other side of the piece (or bit if you are doing free-hand) is free.

[John Coloccia]

There is no pushing IN or OUT when I use a circle-cutting jig. If I am
going clock-wise the direction I push the router is in the direction of red arrow and if I go counter-clock-wise the direction of push is always the Blue arrow in the picture.

The red and blue arrows are tangent to the circle. If the jig did not exist, the router would go straight. The router goes in a circle because the jig exerts a force inward bending you away from the tangent. It's pulling in only because you're pushing away. You're biasing the cut towards "stretching" the jig, and the leading edge of the bit it also pushing the router outwards when you're going in a clockwise direction. This is why I said it would be bizarre to ever push inwards because everything is naturally setup to tension the jig and move outwards, even a "neutral" force like you're using.

The only reason why the situations aren't symmetrical is that there's play in any jig, and also that this particular jig is more stable in tension than compression because there's very little keeping it from buckling

[James White]

"The only reason why the situations aren't symmetrical is that there's play in any jig, and also that this particular jig is more stable in tension than compression because there's very little keeping it from buckling"

This is what I think is the relavant factor regarding weather you go clock wise or counter.

James

[Gene Crain]

CNC ;)

Gene Crain
plantasymaderas dot com
cnczacatitos dot com

[David DeCristoforo]

"... this...sounds to me a bit condescending....

Sorry. Didn't mean to. It's just that theory and reality in practice often disagree. That bit is spinning at twentysomethousand RPM in one direction. It's like a driving wheel if you move the router in the same direction as the bit is rotating. That's all I'm trying to say.