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Mahogany Kitchen Stool Project #15: Jigs for glue up

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Blog entry by sras posted 764 days ago 3536 reads 0 times favorited 8 comments Add to Favorites Watch
« Part 14: Finish is on - all 9 coats! Plus 2 buffing, wax and polish Part 15 of Mahogany Kitchen Stool Project series Part 16: Assembling 6 stools with pre-finished parts »

This last weekend was spent setting up the process for assembly and glue up. I had not expected I would spend this much time coming up with a glue up solution. Still, this was a fun puzzle to solve.

The first step was to remove the masking tape. It took a while to peel of tape from all 244 tenons!

One concern I had with clamping pre-finished parts was damaging the finish. In past times I have had the texture of any padding end up imprinting into the finish. I decided to use a smooth surface to line the inside of my clamping jigs. I used masonite hardboard to line the jigs. The assembly of the jigs took all my spring clamps!

I went through a couple iterations to arrive at my final solution and clamping sequence. I chose to assemble the entire chair in a single glue-up. I used my prototype to develop the clamping sequence.

One of the fun parts about this step is I had to go buy more clamps!

The first step is to clamp the seat back assembly. This step is optional and is only done when the assembly resists being fully compressed. The jigs look like this.

And is used like this. The trick was the top rail and the bottom rail do not line up so I needed a way to get the clamp force to pull the parts together without causing the clamp to slide off.

Next are two pads for the top of the back.

The angled wedges on each side are used to let a clamp pull the two back legs together at the top.

Then there are two sets of clamping pads to pull the back legs together at the middle and bottom rails.

Here is a view of the bottom pads in action. The middle pads serve double duty and will show up a little later…

The next set of pads are for the front legs. They have a top block so they rest on the legs and are long enough on the outside faces to cover the lower rail.

The first clamping step is to pull the two front legs together at the top and bottom.

Then the front leg assembly is clamped to the back leg assembly at the top. Here is where the middle pads for the back legs show up.

The last set of pads are for the bottom rails.

Two more clamps finish the job.

Here is the final solution.

I promise the next post will show assembled frames!

Finally a note on the hours. I only added the time to remove the masking tape. I have not included the time to build any of the jigs and I chose to stay with that precedent.

=================================================

Current time log:

Cutting rough stock: 2 hr

Legs
> Cutting to width and thickness: 4 hr 20 min
> Cut to final length: 3 hr 30 min
> Shaping: 5 hr 50 min
> Mortises: 10 hr 35 min
> Sand & radius edges: 19 hr 35 min
> Oxidize and Final sanding: 3 hr 10 min
> Prep for finish: 1 h 25 min
> Finish: 12 h 15 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hr 35 min
> Prepping laminations: 8 hr 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min
> Tenon: 5 hr 40 min
> Mortises: 5 hr 30 min
> Sand & radius edges: 6 hr 10 min
> Oxidize and Final sanding: 1 hr 20 min
> Mask & Prep for finish: 20 min
> Finish: 2 h 45 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hr
> Glue up Laminations: 6 hr 5 min
> Trim Laminated Parts: 30 min
> Tenon: 2 hr 50 min
> Sand: 7 hr 35 min
> Oxidize and Final sanding: 1 hr 30 min
> Mask & Prep for finish: 40 min
> Finish: 4 h 35 min

Lower rail parts
> Cut to width and thickness: 10 hr
> Cut to length: 1 hr 30 min
> Mortise: 4 hr 35 min
> Tenon: 28 hr 30 min
> Sand & radius edges: 15 hr 35 min
> Oxidize and Final sanding: 3 hr 40 min
> Mask & Prep for finish: 2 h 30 min
> Finish: 12 h 5 min

Corner Blocks
> Cut to size: 1 hr 50 min
> Shape: 1 hr 50 min
> Tenons: 35 min
> Holes: 1 hr

Frame assembly
> Remove Masking Tape: 1 hr 30 min

Total so far: 216 hr 45 min (~36 hrs per stool)

-- Steve - Impatience is Expensive



8 comments so far

View JL7's profile

JL7

7103 posts in 1589 days


#1 posted 764 days ago

Hey Steve – that’s a lot of engineering in the clamp blocks and strategy. Looks like you are well prepared! Good luck on the glue up!

-- Jeff - I have not failed. I've just found 10,002 ways that won't work.

View Roger's profile

Roger

14311 posts in 1428 days


#2 posted 764 days ago

Ahhh yess….... fabrication, and clamps. You can never have too much, or too many. Looks like they’re comin along nicely

-- Roger from KY. Work/Play/Travel Safe. Kentuk55@bellsouth.net

View SPalm's profile

SPalm

4783 posts in 2506 days


#3 posted 764 days ago

I love it. Just love it.
Engineer your way out of a situation. Others may do differently, but this is how I would handle it. I can’t help it either.

Steve

-- -- I'm no rocket surgeon

View stefang's profile (online now)

stefang

12860 posts in 1958 days


#4 posted 764 days ago

Amazing Steve. You certainly have my respect. This looks like an excellent and well thought out setup. It appears that you used a mockup stool to do your glue-up rehearsal, smart. This is bound to work out well. I look forward to seeing the grand finale!

-- Mike, an American living in Norway.

View sras's profile

sras

3813 posts in 1753 days


#5 posted 764 days ago

Thanks guys! I should have noted that the black clamps in the last two pics are the new ones (they still have their warning labels on them).

Even after all this prep, it took me a couple days to get up the nerve to use actual glue!

-- Steve - Impatience is Expensive

View lew's profile

lew

9990 posts in 2379 days


#6 posted 763 days ago

Seems like everyone has the same word come to mind as they see this- “Engineering”!
Wonderfully thought out. I’m glad I’m not trying to glue that all at once- I don’t think I know enough “Navy” language.

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View sras's profile

sras

3813 posts in 1753 days


#7 posted 763 days ago

Thanks Lew – I have all the jigs to make more of these, but I’m not sure I want to! Solving the problems is the fun part.

-- Steve - Impatience is Expensive

View sras's profile

sras

3813 posts in 1753 days


#8 posted 759 days ago

FYI – Stool #4 went in the clamps today. Hope to post the results soon …

-- Steve - Impatience is Expensive

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