More sliding fence box joint issues - Router Forums
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post #1 of 60 (permalink) Old 11-15-2016, 07:30 PM Thread Starter
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Default More sliding fence box joint issues

Other than the dust collection issues discussed in yesterday's thread, the sliding fence/box joint jig is working well.

Except that the tear-out on both entry and exit sides of the notches makes the workpiece unusable.

The jig is set up to cut 0.490" (cutter dia.) X 0.466" (thickness of nom. 1/2" ply) pegs and notches. The pegs fit the notches and everything meshes OK, except for the tear-out.

Thinking that the issue was with the quality of the shop-grade ply, I tried some high-quality ply this afternoon. Same result.

So, maybe it's the laminations and the cross ply grain. So I tried on some straight-grain hemlock. Same results or even worse. As you can see from the first two pix, the tear-out even broke one of the pegs off the work piece. (second and third photos)

So, I tried on some red oak scrap I had laying around. Success! (first photo)

But I need to make box joints for drawer boxes for my vintage trailer restoration, and I don't want to have to use hardwood for drawer boxes.

Clamping the work to the sliding fence makes no difference, putting a backer board behind the work makes no difference.

What am I doing wrong?
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<Chas>

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post #2 of 60 (permalink) Old 11-15-2016, 07:57 PM
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clean, replace or get your cutter sharpened...
use sacrificial layers of wood front and back...
stop using plywood that has dried out or is from the pacific/asian rim or south America...
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This would have been the week that I'd have finished chewing thru the restraints...
If only new layers hadn't been added....

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post #3 of 60 (permalink) Old 11-15-2016, 08:02 PM Thread Starter
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cutter is brand new

sacrificial layers don't help

the first try today used expensive 9-ply birch

third try used solid softwood

I understand the plywood quality issue, but why does this happen on hemlock?

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post #4 of 60 (permalink) Old 11-15-2016, 09:06 PM
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It would help if you showed a picture of your set up (With the router turned off) of how you are cutting them. Also are you drawing the piece back thru the bit after the cut? How about the speed of the router does it sound good when it cuts ,or is it bogging down? Another thing I question is that you are cutting side grain and not end grain, that is quite IFY.

Herb
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Last edited by Herb Stoops; 11-15-2016 at 09:08 PM.
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post #5 of 60 (permalink) Old 11-15-2016, 09:11 PM
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My SWAG (Scientific Wild Arsed Guess) 'bout the fingers breaking off, is a result of the grain direction. Plus, hemlock is s a soft wood with tendency to split and chip.

Read what Herb posted 'bout grain direction. On the scrap that you utilized, the grain runs horizontally and the resulting fingers would not be very strong, tending to break along the grain. Have a feeling that if you had the grain held vertically, then cut the joints, the resulting work would be stronger..

Also think a spiral bit would work better.
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Last edited by Ray Newman; 11-15-2016 at 09:22 PM.
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post #6 of 60 (permalink) Old 11-15-2016, 11:30 PM
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Do you have the workpiece clamped to the sacrificial piece? The only times I've ever had issues with tear out like that is when they aren't tight together.
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Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #7 of 60 (permalink) Old 11-16-2016, 12:02 AM
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cutter is brand new
who made it...

sacrificial layers don't help
if you have them clamped together tightly they don't...

the first try today used expensive 9-ply birch
expensive means little..
origin means more...


third try used solid softwood
and???

I understand the plywood quality issue, but why does this happen on hemlock?
you don't say which hemlock you are using but it's the nature of hemlock to be brittle and splinter..


Eastern Hemlock

Color/Appearance: Heartwood is light reddish brown. Sapwood may be slightly lighter in color but usually isn’t distinguished from the heartwood. The conspicuous growth rings can exhibit interesting grain patterns on flatsawn surfaces.

Grain/Texture: Grain is generally straight, but may be interlocked or spiraled. Has a coarse, uneven texture.

Endgrain: Resin canals absent; earlywood to latewood transition ranges from moderately abrupt to gradual, color contrast fairly high; tracheid diameter medium-large.

Rot Resistance: Rated as non-durable regarding decay resistance, and also susceptible to insect attack.

Workability: Working properties are intermediate. The wood tends to splinter easily when being worked, and tends to plane poorly. Also, because of the disparity between the soft earlywood and the hard latewood, sanding can create dips and uneven surfaces. Glues, stains, and finishes well.

Odor: No characteristic odor.

Allergies/Toxicity: Eastern Hemlock has been reported to cause skin irritation. See the articles Wood Allergies and Toxicity and Wood Dust Safety for more information.

Pricing/Availability: Eastern Hemlock is one of the two primary commercial species of hemlock harvested in North America—with the other being Western Hemlock (Tsuga heterophylla). Hemlock is used primarily as a construction timber, and is in good supply. Expect prices to be moderate for a domestic softwood.

Sustainability: This wood species is not listed in the CITES Appendices or on the IUCN Red List of Threatened Species.

Common Uses: Boxes, pallets, crates, plywood, framing, and other construction purposes.

Comments: In addition to its lumber, Eastern Hemlock is also known for its ornamental value, and hundreds of cultivars are known to exist. Eastern Hemlock is also the state tree of Pennsylvania. Currently, the species is threatened by the hemlock woolly adelgid, a non-native insect that kills infested trees.

When compared to Western Hemlock (Tsuga heterophylla), Eastern Hemlock generally has wider growth rings, though both species can have tightly spaced growth rings.

the other two hemlocks...
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This would have been the week that I'd have finished chewing thru the restraints...
If only new layers hadn't been added....

Stick....
Forget the primal scream, just ROAR!!!
"SNORK Mountain Congressional Library and Taxidermy”
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post #8 of 60 (permalink) Old 11-16-2016, 12:17 AM Thread Starter
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OK, thanks.

The bit is a no-name bit that came with the router.

I'll cut some pieces and try the end-grain, and will try to find decent ply to try. The problem with that is finding a small piece, I'm not interested in spending $$$ for a sheet of Swedish or Canadian birch ply only to find it didn't work because of some other reason.

I think the first step is to get a new bit and clamp the wood between sacrificial layers. Question, do they have to be the same wood as I'm cutting?

As for Hemlock, it is surely Western Hemlock, since I'm in Oregon.

There's no way I can take an adequate photo of the setup, but there's a diagram on Pg 45 of Bill Hylton's router table book. I'm confident in my setup because the notches and pins line up correctly and would fit well but for the tear out.

Thanks for the suggestions, I'll report back.

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post #9 of 60 (permalink) Old 11-16-2016, 01:02 AM
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OK, thanks.
yur welcome...

The bit is a no-name bit that came with the router.
that speaks volumes..

I'll cut some pieces and try the end-grain, and will try to find decent ply to try. The problem with that is finding a small piece, I'm not interested in spending $$$ for a sheet of Swedish or Canadian birch ply only to find it didn't work because of some other reason.
have you considered Baltic Birch or Apple Plywood??? both come in small pieces...
States Industries



I think the first step is to get a new bit
I like Freud and many here rave on Whiteside...

and clamp the wood between sacrificial layers. Question, do they have to be the same wood as I'm cutting?
no...
doesn't have to be very thick either...


As for Hemlock, it is surely Western Hemlock, since I'm in Oregon.
surely you can fin quality USA made ply there...
the data for Western is virtually the same as for Eastern


There's no way I can take an adequate photo of the setup, but there's a diagram on Pg 45 of Bill Hylton's router table book. I'm confident in my setup because the notches and pins line up correctly and would fit well but for the tear out.
the tearout isn't because of the jig...

Thanks for the suggestions, I'll report back.
I'll stay tuned...

This would have been the week that I'd have finished chewing thru the restraints...
If only new layers hadn't been added....

Stick....
Forget the primal scream, just ROAR!!!
"SNORK Mountain Congressional Library and Taxidermy”

Last edited by Stick486; 11-16-2016 at 01:06 AM.
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post #10 of 60 (permalink) Old 11-16-2016, 08:40 AM
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Unless there is some reason that you want to use a box joint, such as making it look authentic you are wasting your time. The traditional old fashion carpenter made drawer could be knocked out in the time it takes to try and sort the problem out. A box joint is not the best joint in the world to use on a drawer. Unlike a dovetail there is not the strength that you get out of the angled pins and tails. I would argue that it is weaker than the traditional carpenter drawer because if the glues weakens then there isn't anything holding it together.
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