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Trim a panel and remain centered?

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Forum topic by MrLaughingbrook posted 09-21-2016 09:18 PM 313 views 0 times favorited 5 replies Add to Favorites Watch
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MrLaughingbrook

93 posts in 1430 days


09-21-2016 09:18 PM

Topic tags/keywords: question trick tip jig milling

Hi,

Let’s say you have built a frame and panel that is slightly over sized, then want to trim (rip on table saw) the same from each side to remain centered while reducing overall width. How do you proceed?

Detail: 1/4” ply is installed in groove of stub tenon frame with outside dimension of about 12” width. The carcass on which we need to overlay is 11 3/4” wide. I could measure, mark, align and rip 1/8” cutoff on first side, then rip remainder at 11 3/4” but wish to learn about technique that produces a truly centered panel.

Thank you,
David

-- MrLaughingbrook


5 replies so far

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Rick M

7910 posts in 1843 days


#1 posted 09-22-2016 12:04 AM

The best way I’ve found is mark both sides and trim it but its been churning in the back of my mind to think of a better way that will work when I need precision.

-- http://thewoodknack.blogspot.com/

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jbay

813 posts in 362 days


#2 posted 09-22-2016 01:10 AM

There’s not much more to it! You got a 12” Frame and panel you need 11 3/4”
That’s 1/4” to big. You need an 8th inch off both sides. Set you saw for 11 7/8 cut off one side.
Set the saw for 11 3/4” cut off the other side.
I don’t see why it wouldn’t be truly centered, unless it wasn’t to start with.
Only other way I see is to mark the center of the panel then mark 5 7/8 to each side of the mark. Measure from the edge and set the saw, flip panel and frame around and do the same for the other side.

Otherwise I hear metric is easier, just convert everything to metric and be done with it.

-- My “MO” involves Judging others, playing God, acting as LJs law enforcement, and never admitting any of my ideas could possibly be wrong or anyone else's idea could possibly be correct -- (A1Jim)

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clin

510 posts in 459 days


#3 posted 09-22-2016 02:45 AM

If possible, mount panel to carcass, then trim with router. This still requires you to center the panel when you mount it, but it will result in a panel that fits the carcass perfectly.

-- Clin

View JBrow's profile

JBrow

818 posts in 383 days


#4 posted 09-22-2016 03:08 AM

MrLaughingbrook,

Your description sounds as if the table saw fence is not calibrated to the measuring tape frequently mounted on table saws. If it is not calibrated, spending some time to setting the radical to reflect an accurate rip cut could save a lot of set up time.

While I use the method described by jbay, Rick M., and you, there is a method for ripping the same amount from opposite edges of a panel with only one measurement (and no math). I will call it the Shim Pair Method. The final width needed for the panel is marked on the panel. The fence is set to the width of the oversized panel and a stop block is clamped to the fence on the side of the fence away from the blade. Sets of paired of shims, where each shim in the pair is the same width, are then inserted between the blade and the final width mark on the panel until the paired shims align with the final width mark. Once the number of paired shims is discovered, one shim from each pair of shims is removed from the shim stack and set aside for use when making the final cut. With the shim stack reduced in the overall width by half, the other half of the stack in hand is placed between the rip fence and the stop block. This sets the fence for the first cut. After the first cut, the shims that were set aside join the shims already between the rip fence and the stop block, thus repositioning the fence for the final cut.

An obvious limitation is if an odd number of shims are required. But if the rough width of the panel is cut so that an even number of shims is needed, this problem can be avoided. Using shims that are all the same width is probably best to avoid confusion, but a pair of 1/16”, 1/8”, ¼”, etc. could be used.

The only advantage to the Shim Pair Method is that only one measurement is required and no division or subtractions of fractional numbers is needed.

View Derek Cohen's profile

Derek Cohen

296 posts in 3431 days


#5 posted 09-29-2016 04:40 PM



Hi,

Let s say you have built a frame and panel that is slightly over sized, then want to trim (rip on table saw) the same from each side to remain centered while reducing overall width. How do you proceed?

Detail: 1/4” ply is installed in groove of stub tenon frame with outside dimension of about 12” width. The carcass on which we need to overlay is 11 3/4” wide. I could measure, mark, align and rip 1/8” cutoff on first side, then rip remainder at 11 3/4” but wish to learn about technique that produces a truly centered panel.

Thank you,
David

- MrLaughingbrook

David, woodworking is simply laying out lines and working to them.

So another method is to mark a line 1/8” each side, and hand plane to this (my preference), or use a thicknesser.

Regards from Perth

Derek

-- Buildiing furniture, and reviewing and building tools at http://www.inthewoodshop.com

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