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View RichardDePetris's profile

Repeated router kickback, Why?

by RichardDePetris
posted 01-27-2017 04:12 AM


26 replies so far

View TungOil's profile

TungOil

841 posts in 399 days


#1 posted 01-27-2017 05:01 AM

I think the 1/4” deep cut in end grain on such a small part probably added up to your kick back. roughing your oak blank much closer to the finished size before you clean it up with the pattern bit will help. If you use your pattern to draw the outline on the oak you can cut pretty much right up to the pencil line on the bandsaw and still have material to clean up with the router. I try to leave 1/32” to 1/16” max to cleanup with the router.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View Loren's profile

Loren

9941 posts in 3552 days


#2 posted 01-27-2017 05:23 AM

That oak has real tough endgrain. Try it on something
like poplar and you’ll probably have a much easier
time.

This issue comes up here often. The best way to
go about theses sorts of cuts is with a template
guide ring because it allows incremental depth of
cut. The pattern bits make you take a whole cut
all at once, which works okay on friendly grain
and plywood, but as you discovered, end grain
is unforgiving.

There’s a way to cut to a pattern on the band saw.

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RichardDePetris

61 posts in 1589 days


#3 posted 01-27-2017 03:44 PM

Thanks. Initially I left too much material, but I went back on the bandsaw and tried again. Same thing. I did no

View a1Jim's profile

a1Jim

116902 posts in 3481 days


#4 posted 01-27-2017 03:57 PM

Can this piece be made on a longer piece of wood routered and then be cut free? you will get better results if you take very small cuts raising the bit a little at a time. This the kind of operation an oscillating spindle sander work really well on if you have one.

-- http://artisticwoodstudio.com Custom furniture

View pintodeluxe's profile

pintodeluxe

5566 posts in 2717 days


#5 posted 01-27-2017 04:57 PM

While I generally agree with all the good advise that has been given here, I think routing that small of a curved part is an uphill battle. I would spend a few minutes sanding it back to the line and skip the router on this one.

I use an oscillating spindle sander for such things, but I realize not everyone has access to one. Do you have a drill press that you could mount a spindle sanding attachment to?

In your original post you called it a “flesh trim” bit (typo). That gave me chills!

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View HorizontalMike's profile

HorizontalMike

7747 posts in 2818 days


#6 posted 01-27-2017 05:18 PM

I agree with all of the above. Having made several totes myself, I would recommend the following after you have drawn the pattern on your chosen lumber:

  • In the tight corner/curve, I would use your DP to drill a 3/4in. to 1-1/4” (or other choice) hole using a forstner bit. That will give you a very clean inside corner.
  • With your bandsaw, cut out the remaining pattern. THAT will finish the pattern completely.
  • Choose and appropriate size “round over” bit. NO straight bit here. Work the round-over slowly against the grain. BTW, good choice of clamp for holding the tote.
  • After that, a half round rasp comes in handy to fine tune the round over curves and corners. Sand paper comes last. A spindle sander would have come in handy here.

-- HorizontalMike -- "Woodpeckers understand..."

View ClammyBallz's profile

ClammyBallz

424 posts in 1040 days


#7 posted 01-27-2017 06:33 PM

I’m surprised no one suggested buying a better quality router bit.

View splintergroup's profile

splintergroup

1872 posts in 1126 days


#8 posted 01-27-2017 06:35 PM

I do this often.

You have the correct bit. Place (DS tape) the template on the workpiece then head to the bandsaw and remove the excess to within 1/16” inch or so of the template.
Make sure your router speed is high enough for the bit diameter!. I then run the workpiece/template against the bearing such that all cuts are “downhill” with respect to the grain. I then raise the bit and flip the workpiece/template over to finish the remaining cuts (should also all be downhill now).

The only times I have had things launched from the table are when either the RPMs were too low or there was a defect in the wood.

View TheFridge's profile

TheFridge

8862 posts in 1390 days


#9 posted 01-27-2017 06:36 PM

Stick the template to ithe piece and bandsaw it close.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View dbray45's profile

dbray45

3310 posts in 2681 days


#10 posted 01-27-2017 07:24 PM

I would check that bit to see if it is bent. When you kick out a piece of wood like that, I have found that I bent the bit.

If possible, I would use a 1/2” bit. Create a 1/4” MDF template and glue it to the piece (with a piece of paper between them). Run the bit at its rated speed and the MDF against the bearing. Go slow and steady.

-- David in Damascus, MD

View RichardDePetris's profile

RichardDePetris

61 posts in 1589 days


#11 posted 01-27-2017 07:33 PM

Thanks for the suggestions. I greatly appreciate them.

I just put in an order for 1/4” a top bearing spiral cutting bit from Yonico. At the possibility of unleashing wrath from the “I uh tole yuh so manys”, the flush trim was a $4 cheapo from China off eBay. Yeah I know, like a .99 cent burger, it was hard to say no until the reflux sets in.

In the meantime, I am determined to find a reason. I would at least like to use a round over bit at some point. So I pulled out my dial indicator and measured the runout. At the base of the bit, I read very close to 0. At the top of the bearing screw, I read .005. which is more than the suggested 3 thousands. As I was unchucking the bit to chuck in the trash, I noticed the nut bareky finger tight! Somehow the collet loosened itself. I retightened the collet and the top of the bearing read near zero. Perhaps, the heavy hogging made the nut loose.

I might try the operation again with the cheapo bit after building up my courage. Can such a run out or loose bit cause such a kickback?

View OSU55's profile

OSU55

1519 posts in 1893 days


#12 posted 01-27-2017 08:04 PM

Ive made many totes with the same type bit. I made a combination pattern/clamp to hold them because a wood screw clamp didnt seem reliable enough, but I do use one with round over bits on the totes. I suspect you had the bit bearing riding the pattern and put it into a heavy cut. As mentioned, cut as close as possible with the bandsaw, and drill out the tight corners to remove excess material, but I still have areas that extend too far out of the pattern for one pass. I can feed the part into the bit and guide it through a light cut w/o being on the bearing. I just keep working the excess material down until the bearing rests on the pattern. I do several passes with the roundover bit, raising it some each pass. Gluing sandpaper to one or both faces of the screw clamp with hold the work more securely. Here is a blog entry, with modified drawings, you might make use of.

If you cut an end grain surface all the way through against bit rotation, i.e. in your pic the lower front of the tote toe, the wood will blow out. I leave that as clean up, and feed with bit rotation so the wood is removed ahead of the next cut. Its only an 1/8” or so in length, not enough for the bit to grab the piece and throw it. One of the reasons I made the pattern/clamp jig – to control the operation well.

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RichardDePetris

61 posts in 1589 days


#13 posted 01-27-2017 11:50 PM

You have all been very helpful. I’ve determine that the cheap router bit is at fault. With the runout issue solved by tightening the collet nut, I did a cleanup pass and it went smoothly. When I started from the apex of the curve for a last pass, it kicked back even though there was hardly any material to trim. I checked the runout afterwards and noticed that it worsened with a slight bend to the bit. I believe the small diameter makes the cutting edge attack the fibers on the flat under edge part of the blade. The kickback has a perceptible blunt hammer feel to it.

This bit will be chucked and not in any router. It will be chucked in the trash! No more bargain basement bits for me, Again thanks for all the help!

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waho6o9

8099 posts in 2481 days


#14 posted 01-28-2017 01:17 AM

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RichardDePetris

61 posts in 1589 days


#15 posted 02-02-2017 01:23 AM

Thanks for the help. Unfortunately, I cannot blame the router bit.

Yesterday, I successfully rounded over part of the profile using a round over bit with a 1/2 shank, The cut was burnt and there was lots of tear out, but suspected it wasn’t sharp or my feed was too slow. Today, I just tried out my new spiral top bearing router bit and had the piece kickback at me as soon as I entered the cut. There was only a tiny bit of material to trim. I don’t think this kind of kickback from a router bit is normal.

I noticed since the first time I tried this operation that there was quite a bit of vibration on the router table, Enough to cause a piece of wood to walk off the router table top. Also, when the router powers down it makes some squealing noises. The shaft turns, but not smooth and easy. Could a bad bearing or collet cause the issues I’ve ben experiencing? I could try the operation on my newer 1617, but at 2 1/4 HP it could turn into more than a kickback. Any suggestions.

View jbay's profile

jbay

2041 posts in 803 days


#16 posted 02-02-2017 02:13 AM

Are you moving the material as you enter the bit or are you stopped and pushing the material into the bit pivoting off the pin?
I say loose the pin and enter the bit slowly while moving.

-- If anyone would like to see my Portfolio, PM me and I would be glad to send you the link.

View a1Jim's profile

a1Jim

116902 posts in 3481 days


#17 posted 02-02-2017 02:18 AM

Hi again Richard
I own 40 routers and 500 router bits but even with all of that router/routerbit hardware ,my 30 years in woodworking tells me routing is not the best approach for shaping rounded end grain, my best approach as I suggested before is standing end grain.If you don’t have an oscillating spindle sander to perform this operation may I suggest a set of drum sanders that fit in a drill press or even in a cordless drill all for the price of an inexpensive router bit.

https://www.amazon.com/Long-Sanding-Drum-Sleeves-Set/dp/B01BUSM7YW/ref=sr_1_5?ie=UTF8&qid=1486001658&sr=8-5&keywords=drill+press+sanding+drum

-- http://artisticwoodstudio.com Custom furniture

View TungOil's profile

TungOil

841 posts in 399 days


#18 posted 02-02-2017 02:19 AM

sounds like a bad router bearing or bent armature. the question is- was it bad before all this, or did the kick back damage the router?

Perhaps try the 1617 (carefully!)

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View RichardDePetris's profile

RichardDePetris

61 posts in 1589 days


#19 posted 02-02-2017 05:37 AM

Thanks for all the great suggestions.

The router was vibrating before I even started the project. The only reason I am trying this is because it should work and I want to know why. I can understand tearout or even a tiny kickback, but throwing the piece doesn’t seem OK. Also, I don’t understand how the size of the piece would make a difference, especially when it is effectively a larger piece when held tightly in a clamp. Also, the operation went relatively OK with a round over bit, but not with a flush trim bit, The round over took off more material, whereas the trim barely touched the surface, Currently, I am leaning towards a bad router.

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RichardDePetris

61 posts in 1589 days


#20 posted 02-02-2017 05:40 AM



Thanks for all the great suggestions.

The router was vibrating before I even started the project. The only reason I am trying this is because it should work and I want to know why. My searches have allc lead to dead ends or no cause given. I can understand tearout or even a tiny kickback, but throwing the piece doesn t seem OK. Also, I don t understand how the size of the piece would make a difference, especially when it is effectively a larger piece when held tightly in a clamp. Also, the operation went relatively OK with a round over bit, but not with a flush trim bit, The round over took off more material, whereas the trim barely touched the surface, Currently, I am leaning towards a bad router.

- RichardDePetris


View Tony_S's profile

Tony_S

818 posts in 2987 days


#21 posted 02-02-2017 11:14 AM

This is strange….
To start…No, the router shouldn’t vibrate to that degree. Vibration should be barely noticeable.
It shouldn’t make any whining or squealing noises either.
With that said, a bad bearing or Collet(or both) won’t ‘necessarily’ cause a kickback, but more often just a chattery, torn out shitty cut. Probably why the cheap bearing blew apart as well.
Repeated kickback time after time makes me wonder if your feeding in the proper direction. Climb cutting, or feeding in the wrong direction will result in what you’re experiencing (especially when you don’t realize your doing it).
see the pic’s below for proper feed direction, and start point.

-- It is the mark of an educated mind to be able to entertain a thought without accepting it. Aristotle

View pvwoodcrafts's profile

pvwoodcrafts

243 posts in 3826 days


#22 posted 02-02-2017 01:45 PM

Get off the router table and climbcut with a hand held router.
I retired my router table 20 years ago and climbcut only, Can’t climbcut with a router table

-- mike & judy western md. www. pvwoodcrafts.com pvwccf1@verizon.net

View RichardDePetris's profile

RichardDePetris

61 posts in 1589 days


#23 posted 02-02-2017 02:30 PM

We’re getting somewhere. For the record, I wish I was climb cutting, but the moment the bit touched the bit, it kicks back. I suspect it may be the collet or the shaft bearing or all of the above. I got a bit of tearout with a 1/2” bit and burning with a 1/2” round over, From what I’ve read, red oak doesn’t burn as easily as other woods. I did measure a .005 runout previously with the collet fiully tightened. I guess I have to try the operation again on a different router when my whiskers grow back. I might try it out my new trim router as it is only 1 1/2 hp.

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RichardDePetris

61 posts in 1589 days


#24 posted 02-03-2017 06:14 PM

OK. With all the great help here, I may have discovered the source of the problem. I was measuring the runout indicating off of the router shaft and discovered .005 runout. Significant, but can’t determine if it is unusual. I’ve read anything more than .003” is not optimal. What surprised me was when I pushed the shaft with my thumb and the indicator needle moved by more over .010 depending on how hard I pressed it. That is definitely bad and could be the source of the problem.

View MrRon's profile

MrRon

4628 posts in 3147 days


#25 posted 02-03-2017 08:22 PM

Use an “up cut or down cut” bit after fixing the router, or getting a new one. Kick back as you call it is similar to what is called “chatter” in metal working; caused by excessive run out. Routers operate with a lot of radial load; therefore bearings are most important with these tools. The difference between a cheap and an expensive router is the bearings. When routing a groove, the radial load is equally spread out, but when edge routing, the load is directed against one side of the bit/router spindle. Shallow cuts should be taken, especially on end grains.

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RichardDePetris

61 posts in 1589 days


#26 posted 02-21-2017 06:18 AM

OK. Latest news. I’ve given up on the template routing for now. I was successful using my 1hp Makita compact router knock off to freehand. I had to abandon it because I didn’t have enough clearance. I mounted the compact router upside down and tried routing. Again, as soon as the bit touched the surface it kicked it back. It turns out that there is one crucial detail that I never learned. Entering the router bit directly on the end grain will cause it to kick back. Instead, you have to ride into it from straighter grain. Unfortunately, the piece I was routing had no straight grain to ride off.

It’s amazing how tiny but important details are often missed.

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