Oops. Really screwed this one.

[LCHIEN]

gotta be more careful.

[Jim Frye]

????????!

[LCHIEN]

Now that's weird. I'm looking at this post on my PC and there's no pictures. But I have opened it my smartphone and I see all the pictures.

so ??????????
so I put them in via the PC. Now looking at the site from my phone they're on there twice. I dunno.

[d_meister]

The post was empty for me yesterday; OK now.

[leehljp]

Sorry about your accident, but thanks for showing it. What can WE do to prevent the same thing from happening?

I see the picts fine, but what is the story? Was it something you were trying to do on the router table with the Forstner insets?

What could you have done to prevent it? Hold downs?

Small object holder to keep fingers away?
( https://www.amazon.com/Holder-Router...s%2C175&sr=8-4 )

[dbhost]

So how did this happen so we can avoid it...

[mpc]

My reply initially had a couple guesses on what might have happened and what was being attempted... but they were just guesses and don't deserve to be public. Like the other folks, I hope to read the real story. I have a couple long-distance friends that I've been trying to teach woodworking too, one has a teenage son also interested in learning. So I've been writing stuff on tools with routers and router tables one of my most recent write-ups. A big part of it is "safety" - how far bits should be inserted, proper feed directions, proper router speeds/RPMs vs. bit diameter, how to inspect bits for damage prior to use, do's and don't-do's (with the "why" explanation included), etc. I hope to teach them enough to avoid surprises/accidents caused by not knowing "this is a bad idea."

Fortunately the injury doesn't look too severe.

Meanwhile: I see you have the JessEm router lift assembly. How do you like it? I have the Incra lift which I believe is built by JessEm. I can't imagine going back to a simple router + router plate that didn't have the "above the table bit height and bit change capability" provided by the lift. The Bosch 1617 series router, in its fixed based, does allow "above the table bit height changes" but not "above the table bit changes..." still gotta take the router + plate out of the table to swap bits. When Bosch introduced their new MRC23EVS series router both myself and the then-manager of my local Rockler store were dumbfounded that it couldn't extend the collet and motor shaft far enough for "above the table bit changes."

mpc

[Jim Frye]

What were you attempting to do? Were you trying to route the inner edge of the bored hole? Glad you only did the damage you did though.

[LCHIEN]

yeah trying to enlarge the bored hole a small amount using a oval template. In the end I failed to secure the template properly and the bit grabbed and spun the whole thing disastrously.

[LCHIEN]

...

Meanwhile: I see you have the JessEm router lift assembly. How do you like it? I have the Incra lift which I believe is built by JessEm. I can't imagine going back to a simple router + router plate that didn't have the "above the table bit height and bit change capability" provided by the lift. The Bosch 1617 series router, in its fixed based, does allow "above the table bit height changes" but not "above the table bit changes..." still gotta take the router + plate out of the table to swap bits. When Bosch introduced their new MRC23EVS series router both myself and the then-manager of my local Rockler store were dumbfounded that it couldn't extend the collet and motor shaft far enough for "above the table bit changes."

mpc

Yes, I have had the Jessem lift plate for quite a while. I had two Bosch 1617, one a fixed speed and one an EVS, I put the fixed speed one in the table permanently and have an external speed controller on it. I like the lift. I do all my changes above the table.
I have a bent collet wrench like the one shown below; I just have to raise the router enough to get it on the lower nut.

Removing the plate is a PITA, usually the fence covers the plate, if you want to retain the fence position, you can't get the plate out. When I first used the table, I changed bits by taking the plate and router out laying on its side and changed the bit. Taking the plate out required removing the fence. Or, optionally, dropping the router out of the attached table mount base. Once I got the lift, I found I could crank the router up, getting a bent wrench made it possible to change the bit from above the table easily. As I got older, bending to reach stuff under the table became more tedious.

Search google for offset router collet wrench (I find I only need one, not a pair.)



oh here's a sneak picture of mine (16 mm): The large nut visible, takes a 24mm but I don't use an offset wrench for that.

[LCHIEN]

The back story. I got a Bauer HF electric screwdriver and wanted to make a vertical stand for it.

It had a 1.56 x 1.76 oval base i was determined to cut a close fitting hole.

I don't have 1.56 dia bit... but used a 1.5" Forstner then enlarged the hole by using a 3/4" bottom bearing template bit with a 11/16 bearing making a 1/32" step. Then used the same bit with a stock 1/2" bearing to take off the step making a 1.5" + 1/16" dia.

more to come.
.

[Jim Frye]

Could not you have just used the Forstner bit to elongate the hole? I have done this by clamping the workpiece in position to the drill press table and letting the bit cut away the edge of the hole. You would have had multiple pilot holes in the bottom, but not sure that would have been a problem.

[LCHIEN]

well, Jim, I have never had much luck cutting with Forstner bits when the center point was not anchored in wood - especially is the cutting was really thin.. I wanted this to be near perfect in size, too. I mean the target size was just over 1.56 and I got 1.562" by my calipers. There would also have been the other axis to cut. I just can't use Forstners that way. They tend to shift even when clamped.

[Slik Geek]

I feared an even worse injury. I was relieved when I saw your hand photo. Hope you are healing well and aren't in pain.
A co-worker had a router accident that required surgical repair.
I look forward to your details - they may be a cautionary tale for the rest of us.

[LCHIEN]

I don't have a picture, I cut three 3"x3" squares of I'm pretty sure maple. Two I cut 1.5" FOrstner holes, the third piece I cut the hole 3/8" deep. I.e.
one template. All the holes were cut 0.1" to the side of center to allow the .2" shift to make the long axis of the 1.56 x 1.76" oval hole.
One top
One bottom layer.

I had to search high and low for this bearing. The one on the left is 11/16" OD and the one on the right is the stock 3/4" OD one off the router bit. Both at 1/4" ID to fit the shaft on the bit.



Route a step using the undersized bearing the step is half the difference in dia.; the step is 1/32nd. the Hole diameter is enlarged 1/16th. or 0.06125





I then routed off the step using the template bit with the full 3/4" stock bearing. For both the template and the top section.
I then flipped the template over and secured it to the top section. THis gave me overlapping holes by 0.2 inches since I drilled 1/10th inch off center.
I used Xfasten doublesided WW tape to attach the template piece to the top piece. an placed it carefully over the table mounted bottom bearing pattern bit. I also carefully wrapped two layers of masking tape around the perimeter of the stack.

I was able to rout this easily. I then took off all the tape and now I had
template with offset 1.56" hole
Top piece with 1.56" x 1.76" oval hole.
Bottom piece with the 1.5" hole 3/8" deep.

At this point my plan was to use the top piece with the oval hole as a template over the bottom piece. It would have exposed a 1/32 ledge to the right,, bottom and top of the circle and a .2" cut on the left.
THis is the route I am looking at:
red is the existing recess or .375", black is the oval template and blue is the size of the 3/4" pattern bit. Gray woudl be where material is removed.


Pictured as I was looking at it
Since there was a closed bottom to the shape, I used a top bearing 3/4" dia. x 3/4" length which would ride on the template and cut 3/8" deep. I set the height so it was just lower than touching the bottom of the inverted assembly.
Here's what I actually did. Because I had such an easy time on the last step, I just wrapped tape around the 3x3 perimeter and did not use the double sided tape. I figured I was only cutting 3/8" deep. And the double tape was a bear to work with because I needed 1/2" wide and cutting that stuff sticks to both blade of the scissors.

Having the closed top I was also doing it blind. But I figured out I started the router with the bit centered and not touching anything, I would push it slowly forward until I heard it contact the edge at the bottom of my figure, and then rotate it around clockwise as I had done before.

Well this is where it grabbed when I pushed it forward. What happened was very fast, I don't really know, but judging from the damage to the Bottom piece, the bit took the assembly for a very rapid spin touching multiple sides of the inside of the 1.5" hole, then it climbed and took gouges out of the face and then the four outside sides as it spun it around. It broke the perimeter tape I was using to hold the two pieces together. The template piece was broken in two along the grain which is more than 1 inch wide at the ends of the oval. Somewhere the piece on top must have gouged my hand causing the injury as it spun out of control and out of my hand.


So having cleaned up the mess, I figured I learned some things. I also salvaged some things.

First what I salvaged:
I glued the two halves of the top piece that is the template in this step - it was a clean grain break and glued well. There were a handful of gouges in the inside circumference that the bit had made while tossing this thing around. I leveled the gouges with the oscilating spindle sander in the center. I could still see the gouges but they didn't protrude. I then decided from the nice slip fit of the screwdriver that 3/4" deep was plenty and I did not need the 1-1/4" I planned for with the recess in the bottom piece. So I took another scrap (no more maple) and fastened it to the bottom, giving the item as pictured:




So what went wrong?

1. I was in a rush. I had spent about 5 days thinking about how to do this, spend another day looking for the bearings (I got 3 for $6 from Amazon) and another 2 days waiting for them to arrive So I was ginger at first but the first two cuts went really well I was speeding along (note I didn't even take the picture of the setup).
2. I didn't use the double sided tape I used for the first template guided cut. More about cutting tape later (that is a story in itself now) but It was such a pain. I decided to do without it. In complete retrospect, I should have drilled the top piece and the bottom piece and attached them with 2 screws or a dowel pins (one of my early design thoughts). I think the template or bottom was spun by the router bit and ripped the perimeter tape. In retrospect, even using masking tape (paper, easily torn) and probably reusing the tape from the previous operation were all very bad ideas. Once the two pieces came apart I lost control and had 2 missiles flying around. I got way overconfident that the perimeter tape was sufficient and didn't spend the time on cutting some adequate pieces of Double tape.
3. I could have not tried to cut the full 3/8" depth in one pass, In retrospect, cutting a 1/8th or even 1/16th pass to get started and minimize the grab would have been very good idea. With the router lift, its 1/16th rise for a full turn on the lift crank, wouldn't even have to lift the workpiece off.
4. As a result of this, I learned how to cut the double sticky tape correctly (I'll make a separate post on that).