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Greene & Greene Gamble House Side Chair #13: CNC Templates and Begin Back Leg Fabrication

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Blog entry by TungOil posted 12-19-2017 03:52 AM 2441 reads 0 times favorited 9 comments Add to Favorites Watch
« Part 12: Roughing It Part 13 of Greene & Greene Gamble House Side Chair series Part 14: Back Leg Mortises and Back Seat Rail »

My routing templates arrived Friday from the millwork shop so I headed out to pick them up. A few of the corners were damaged in transport, so I unwrapped everything to take a closer look.

After inspecting the templates closely I was relieved to find that the damaged corners were all in non critical areas. It’s a good thing I made my routing templates a bit long on the ends to have a little lead in.

Time to get to work. For this project, I plan to fabricate the back assembly first, then cut the angled side rails and finish up with the front assembly. By working in this order, I can adjust the length of the front rail to account for any errors that might accumulate during fabrication and be assured of tight fitting joints.

I start by laying out the back legs. I trace the full size template onto the leg blanks. For darker woods like walnut and sapele, I use a white fabric pencil for my layout lines for visibility. I cut enough parts for fourteen chairs leaving four extras in case of mistakes.

I head to the bandsaw to rough out the back legs.

While cutting out the blanks, I came across hidden checking on four of the parts. There goes all of my spares! Any mistakes going forward will require me to make more parts.

After hardening the edge of the routing template with some thin CA Glue, I affix the template to the poplar set up piece and make a test cut at the router table.

With my test blank completed, I moved on to pattern routing the legs. This is a large piece at 43 inches long and each part takes quite a while to pattern route.

This is a tricky cut, even with a spiral carbide cutter, due to the end grain and tight radius at the top of the leg. Not surprisingly I lost several parts while routing the top of the leg. Cutting against the grain, even with a spiral cutter, is always iffy.

Since I have no spares left, I head back to the lumber rack and rough out several more blanks and pattern route replacements. After all the dust settled I end up with eight damaged leg blanks- four with checking and four damaged while routing. I’m down to a single spare leg at this point.

In preparation for laying out and cutting the mortises I arrange the legs on my shop cart, flipping then into pairs of right and left legs. Most of the leg pairs are matched from the same board, but due to the damaged pieces unfortunately not all of the legs could be matching pairs.

Next steps- lay out and cut the mortises, then move on to the back seat rail.

-- 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"



9 comments so far

View pottz's profile

pottz

2415 posts in 855 days


#1 posted 12-19-2017 02:08 PM

nice progress,have fun buddy.

-- sawdust the bigger the pile the bigger my smile-larry,so cal.

View Siv's profile

Siv

52 posts in 440 days


#2 posted 12-19-2017 03:45 PM

Just want to say that I love following your progress on these builds; it’s nice to see the attention to detail and your learning process. It’s clear you are very thoughtful and plan extremely well – the total opposite of me!

As someone who makes plenty of mistakes when building, I have gotten into the habit of making the largest parts first. Then, when I screw them up, they have the potential to be re-purposed for some of the smaller pieces.

View pintodeluxe's profile

pintodeluxe

5544 posts in 2684 days


#3 posted 12-19-2017 04:05 PM

What did I miss here, I thought you were going to pattern sand the parts? Change of heart?

I know the feeling of proceeding without many extra chair parts. Spooky.

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

View Mean_Dean's profile

Mean_Dean

5802 posts in 3018 days


#4 posted 12-19-2017 10:38 PM

I know what you mean about pattern-routing endgrain…..... I tried that once (and learned my lesson—never agin!) and in the process had the workpiece flung across the shop. Scared the hell out of me….......

From then on, endgrain is always shaped on the spindle sander. Which is what I thought you were going to do.

By the way, don’t get timid now that you have little margin for error—I’ve found, if I’m too concerned about screwing up, I usually screw up. Just work as you normally do,

-- Dean -- "Don't give up the ship -- fight her 'till she sinks!" Capt James Lawrence USN

View TungOil's profile

TungOil

799 posts in 366 days


#5 posted 12-19-2017 11:54 PM



What did I miss here, I thought you were going to pattern sand the parts? Change of heart?

I know the feeling of proceeding without many extra chair parts. Spooky.

- pintodeluxe

Pinto- I plan to pattern sand only the parts that are too wide for the router/shaper (crest rails, lower seat rails and back slats). The narrow parts can be pattern routed so that is the faster way to go.

-- 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 TungOil's profile

TungOil

799 posts in 366 days


#6 posted 12-20-2017 12:05 AM



I know what you mean about pattern-routing endgrain…..... I tried that once (and learned my lesson—never agin!) and in the process had the workpiece flung across the shop. Scared the hell out of me….......

- Mean_Dean

I’ve had that happen as well, it’s sobering to know how much force these tools can generate. Good reminder to keep body parts well clear of things that spin!

in this case I realized as I was taking the router bit out after I was done, that I had grabbed the down spiral bit by mistake instead of the up spiral. The down spiral, when table mounted, has a tendency to lift the workpiece, making it difficult to control around the end grain. Wish I had noticed it sooner!

-- 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 EarlS's profile

EarlS

685 posts in 2219 days


#7 posted 12-20-2017 12:47 PM

That has to be frustrating to lose so many planks this soon. At least you have plenty of test pieces for the mortises…

Are you using double sided tape only when pattern routering? I’ve never been able to get the tape to stick well enough so I use a clamp sled to hold the pattern and the piece. How tall are the legs?

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View TungOil's profile

TungOil

799 posts in 366 days


#8 posted 12-20-2017 01:15 PM



Are you using double sided tape only when pattern routering? I ve never been able to get the tape to stick well enough so I use a clamp sled to hold the pattern and the piece. How tall are the legs?

- EarlS

Earl, I’m using both double sided tape and my clamping sled, which has four De-Sta-Co clamps on it. I started using the double sided tape from MLCS about a year ago, I find it has really good holding power but I can still get it off the part fairly easily- much better than carpet tape. Legs are 43” long, which is longer than my 36” sled, so I need to reposition the leg several times to make the full cut. I’m using the tape to be sure the pattern doesn’t move when I reposition.

-- 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 CaptainSkully's profile

CaptainSkully

1538 posts in 3429 days


#9 posted 12-20-2017 04:37 PM

I can’t believe how much you’re getting done between blog posts! These chairs are turning out great! The blog posts are very informative and make my mornings.

-- You can't control the wind, but you can trim your sails

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