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Beads Box #10: Get Up on your Feet! Routing Safety and Avoiding Tearout

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Blog entry by PurpLev posted 01-10-2011 01:35 AM 3712 reads 0 times favorited 11 comments Add to Favorites Watch
« Part 9: Stringee Part 10 of Beads Box series no next part

I was able to get to the garage today as a request for a new shelf for the kitchen was in. While there I saw some cutoff pieces of mahogany that I had piled up from the past 2 projects, and saw 4 legs hidden in those waiting to come out to life.

I had wanted to put legs on this box from the get go but wasn’t set on a design that I liked and was mentally blocked with it.

I decided to make 3 1.5” x 1.5” x 1” legs and just chamfer the bottoms – just to have something workable to lift the box off the table and give it a 4 point on the table rather than the entire bottom surface.

After looking at the pieces, I decided against chamfering them with a hand plane and just route it out. after all I was out in the garage to make a shelf, not play with my projects and I wanted to get back in the house as I wasn’t in the zone to woodwork at all.

I looked at my router – it had a rounover bit installed that I last used for the box pulls. I was lazy and wasn’t in the mood to invest 5 seconds changing bits… I remembered my shaper (that I’ve never used so far) had some bit installed… After unveiling to cover off of the shaper (to protect from moisture mostly) I saw that it had a ogee bit installed, not a chamfer bit… hmm… oh well, I guess that might work well as well – lets go for it.

Since the parts are small, I used the same technique I used bandsawing my drawer pulls for the machinist box – using a wooden hand screw clamp as a holder and ‘sled’ to keep my hands away from any sharp metal objects that are moving really really fast and have a tendency to be aggressive on things it comes in contact with.

Although I used a shaper – working with a router table would have the same implications.

The first couple of feet I made, I routed one edge, turned it 90, routed 2nd edge, turned 90…3rd edge, turn, route 4th edge.

This seemed to have caused some tearouts. nothing severe, but not pleasing and not something I would put on a piece that is being sold.

I decided to route the 2 long grain edges, and then do the 2 end grain edges (bit mistake, but I wasn’t thinking straight as I was trying to just wrap it up). the problem with this (that I wasn’t thinking about) is that when you reach the end of the end-grain edge, the bit grabs the last fibers as they do not have a backing support, and pushes them out of the piece being routed – and tears them out.

My immediate thought to avoid this is to touch up the torn out corner with a reverse feed – climb routing, and then go back and properly route that edge from the proper feed direction. In theory the climb cut on the corner should help as the part is being routed while having backing support as it is fed in reverse. Mind you – this is only touching up the corner – not climb cutting the entire part. I have done this with success on some occasions, and less on others.

Please be safe! climb cutting while in some cases can help avoiding tear out is never ever a safe procedure. if you are not familiar with it – get familiar with it on the web before you start feeding anything with the bit rotation direction – it can do some serious damage to the workpieces, and more importantly to the operator – be aware! I am by no means suggesting anyone running such operation – do so at your own risk.

Back to the story – in this case, especially since I was using a shaper, I took all the precaution I could and fed the piece real real real real slow into the bit, while maintaining downward pressure on the clamp against the table so resist any pulling action that is about to happen from the shaper (it’s a tremendous pulling force!) it didn’t work too well, and the first piece I was using this with got caught by the bit, and it completely shattered it (see following pic). while the clamp and my hands stayed put, the part was basically pulled apart from itself and tore in half so to speak. oh well, I guess it was time to reassess what was going on physically with the cut and address it properly (and safely)!

So. the tearout actually happens while routing the end grain edge. as it reaches the end of the edge, the part does not have any more backing to support the cutter, and the cutter pulls the last fibers away from the piece tearing them up. the solution – route the 2 end grain edges FIRST. what this does is it provides for more backing support for the bit until it reaches the end of the part, also even if it will tear some fibers off, that edge is still going to be routed to shape, so any tear out should theoretically be trimmed off of the edge anyways.

the results this time were astonishing! a clean shaped leg on all edges! success.

conclusions :
  1. Route end grain edges first, route long grain edges last.
  2. Be super safe with the shaper/router
  3. Be super safe when attempting climb cut
  4. Climb cut is not always the best/proper solution, and even it if is – it’s never a safe procedure. rethink your approach and your case at hand – there may be a safer way to do it.

Picture (Left part completely torn apart by climb cut, middle parts slightly torn up with clockwise feed, right part clean! end grain edges first, long grain edges last, righmost piece held by handscrew clamp as used on the shaper table):

While referring to the handscrew clamp, I seem to be using it quite a bit for various operations powerwise and not. Here I am using it in the kitchen as a workbench to plane/trim down small parts easily:

Be safe, and thanks for reading.
Peace!

-- ㊍ When in doubt - There is no doubt - Go the safer route.



11 comments so far

View mafe's profile

mafe

9550 posts in 1756 days


#1 posted 01-10-2011 02:13 AM

Thank you for your time.
Good lecture, have to try them all… Learning by doing!
Best thoughts,
Mads

-- Mad F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View spunwood's profile

spunwood

1194 posts in 1503 days


#2 posted 01-10-2011 02:31 AM

Thanks for the post. Very good reminder/information.

Brandon

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν

View Lee A. Jesberger's profile

Lee A. Jesberger

6651 posts in 2647 days


#3 posted 01-10-2011 03:09 AM

Hi Sharon;

I think what I would go a different way entirely… I would cut the center square, the wrap them with a molding, made using that same bit.

Lee

-- by Lee A. Jesberger http://www.prowoodworkingtips.com http://www.ezee-feed.com

View Moby's profile

Moby

64 posts in 1426 days


#4 posted 01-10-2011 03:21 AM

This reminds me of the latest box I just built out of maple and purpleheart. I had to template route the purpleheart legs of the box and tear out was a big problem with the purpleheart.

View PurpLev's profile

PurpLev

8476 posts in 2315 days


#5 posted 01-10-2011 03:58 AM

hmm.. molding made and glued to a square center – definitely sounds much safer than working with smaller parts – thanks Lee and benltyJ. Also that sled looks much safer and with a much better grip of the part than the clamp I was using. In fact, as an after thought I was thinking about using a sled that rides in the miter slot with a zero clearance bottom as well.

All that said, to build a sled, or to start fiddling with mitered corners and sneaking up on cuts, and fitting parts together would have taken me a considerable amount of extra time which I did not and usually speaking don’t have unless I plan ahead for such a procedure. Using the clamp was an easy to fabricate solution using existing and at hand parts that seem to produce a reasonable amount of holding power and stability to the extent that on the part that blew apart- the clamp and the remainder of the part were still holding secured under my hand on the table (I hold the clamp much like a jointer push block in the sense that my fingers are not grabbing inside, so if the clamp decides to fly away – so be it, and my hands are not dragged away with it).

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Karson's profile

Karson

34878 posts in 3067 days


#6 posted 01-10-2011 04:47 AM

Work safe. Keep the finger parts attached at the knuckles

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View AaronK's profile

AaronK

1397 posts in 2131 days


#7 posted 01-10-2011 03:22 PM

yowza those legs look like a piece of work, and even with the handscrew clamp as a holder still makes me nervous for some reason. they just seems small enough to be able to be ripped out of the jaws of the clamp and hurled around wherever!

i really like benltyJ’s idea for this – easy enough to knock out in minimal time while nearly guaranteeing good (& safe!) results.

View spunwood's profile

spunwood

1194 posts in 1503 days


#8 posted 01-10-2011 03:51 PM

I was thinking more about those feet this morning. I really liked them. They had a lot of character. Why not attach a sacrificial block of equal or greater thickness on both side of a foot in the hand screw, so as to extend its edges? Or is your tear out in the middle?

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν

View PurpLev's profile

PurpLev

8476 posts in 2315 days


#9 posted 01-10-2011 04:36 PM

thanks!

I agree than bentlyj idea is much safer, and will prevent the tear out. I should probably have gone that route and made a similar looking sled with one of the cutoff pieces I have laying around. If I am to do it again, I’ll probably use that method now that It’s in my head.

that said, the tearout is on the edge between the end grain and the long grain. My post here was mostly intended to cover the concept of routing end grain edge before routing the long grain edge which will clean off, and basically eliminate any tear out issues so that a sacrificial backer board is not necessary although in some cases I agree that it would be necessary which makes me think of benlyj idea once again which has that covered as well.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Jon3's profile

Jon3

494 posts in 2772 days


#10 posted 01-10-2011 05:11 PM

There’s always moulding planes. No risk of kickback there!

View HokieMojo's profile

HokieMojo

2103 posts in 2395 days


#11 posted 01-10-2011 06:36 PM

sounds like you got some good ideas. I learned a bunch from this post and the responses too.

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