A Frame and Panel Lid for the Workbench Base – Part 7

With the frame and panel lid that I made for the bottom of my workbench done, I need to install the hinges.  This posed a small problem.  What type of hinges to use?

The lid sits in a ¾” x ¾” rabbet that runs along the inside edge of the front and back stretchers.  If the hinge were installed as it should be, where all that is visible is the barrel, then the screws can only be installed with the lid wide open.  This can be accomplished now, without the benchtop yet installed, but once the top is attached the lid will only open to 47º.  At that point, the front edge of the lid will make contact with the underside of the benchtop.  It would be irreversible, as you would never again be able to open the lid far enough to access the screws should you ever need to remove the lid hinges.

This is a very crude drawing of stretcher, leg, and frame and panel lid. Not to scale.

I felt that some other type  hinges were needed.  I Googled the term “Double L Hinges” and looked under images.  I found some pictures of exactly what I was looking for, but unfortunately they were all for manufacturers in India.  None of the images linked to a site where I could purchase two of these.

I didn’t know if these hinges went by a different name here in the US or what terms I should have been searching for.  I went on to Woodnet.net to ask some of the fine folks there what they thought.  I was given loads of good advice and information, but one woodnet-er even had a set of hinges that would work for my purposes.  He even went so far as to make a mock-up of the hinge layout and photograph it for me so that I could see how they would work.  He wasn’t using the hinges so I bought them from him and two days later they arrived.  Thanks Dan!!!

The hinges are like this (only mine are brass plated):

The first thing that I needed to determine was the spacing of the hinges.  I experimented with ratios and decided that I liked 1:6.  I divided the length of the lid by six and made marks at points one and five.  I centered the hinges on these marks.

I experimented with the hinge spacing and clamped the hinges where I wanted them.

With the hinge clamped in place, I traced the sides with a marking knife.

While making the hinge position, I only marked the sides at this point.  I can’t determine the bottom line until the hinge is mortised into the rabbet.

Marking the hinge location.

I made a series of chisel cuts to breakup the wood and make it simple to pare away.

I chopped across the grain.

I repeated this on the back of the rabbet.  I set the hinge in this mortise and marked the bottom.

With the hinge mortises in the rabbet cut, I marked the bottom of the hinge.

I cut these mortises so that the hinge would be mounted flush with the bottom of the rabbet.

A test fit.

However, you will notice that the bottom plate of the hinge does not sit flush with the inside of the stretcher.  Is is mortised considerably deeper into the stretcher.  This is due to the design of the hinge.  When the hinge is closed, the two plates on either side of the barrel do not touch, there is a small gap between the plates.  I mortised the hinge in deep enough that the back surface of the hinge plate that attaches to the lid will sit flush with the rabbet.  I will mortise that plate into the edge of the lid, so that when then lid closes, the edge of the lid will touch the surface of the rabbet.  I hope I have described this well. It is very easy to visualize but rather hard to write.  The picture below should show what I mean.

Here you can see why the hinge is mortised deeper than the surface.

I repeated this process and mortised in the second hinge.

I repeated the process for the other hinge.

I put both of the hinges in their mortises and put the lid onto the stretchers in the location that it will be installed.  I used a knife to transfer the location of the hinges onto the edge of the lid.  I took my time doing this and made sure that nothing moved while marking the hinge position on the lid.  Any misalignment of the stretcher and lid mortises will be hard to correct later.

I clamped the lid to the edge of my benchtop and started the installation of the lid side of the hinge.

Setting up to install the hinges on the lid.

The first step in this part is to cut a stopped rabbet that the barrel of the hinge will fit into.  These overlay hinges are designed to work with a door that is one inch thick.  Since my lid is about 1-1/8″ thick, I need to create this relief space for the hinge barrel.

I mortised out this section for the barrel of the hinge.

I put the barrel into the mortise. This fixed the location of the hinge for the remainder of the layout.

I held the hinge in place with its barrel in the corresponding mortise.

I marked the sides of the narrow part.

I can’t just mark all the way around the hinge plate at this point because when I mortise the hinge into the edge of the lid, this piece will move.  I need to account for both measurements.

I made a small mark for the wider part of the hinge. This will be lower down when Installed.

To lay out the lines for the top and bottom of the wide part of the hinge plate, I used a marking gauge that I set directly off the hinge.  Once those lines were marked, I held the hinge plate in place and marked the curves.  You can just barely see the top and bottom lines in the picture below.

I used a marking gauge to mark the top and bottom of the wide part of the hinge.

I struck the lines with a chisel to deepen them and prevent the router plane from splitting out the wood.  I took progressively deeper cuts with the router plane until I had mortised in half the thickness of the hinge plate.

I used a small router to remove the wood inside the marking lines.

I think that this came out nicely.  My only screw-up here was a stray chisel strike that left a mark to the left of the narrow part of the mortise.

The waste is removed. I had an opps stray chisel strike.

I reversed the hinge plate and pushed it into the mortise for a test fit.  You can see that it does not sit flush with the wood.  This is again due to the design of the hinge.  When the hinge closes, this part slightly overlaps with the corresponding part on the other hinge plate.  If I fully mortised both sides, then it would bind and the lid would not fully close.

The hinge here is shown backwards. You can see that it is not fully mortised into the lid only about half depth. If I went any deeper the lid would not close.

The last part to be mortised is the edge of the lid.  The small router plane was too small to span the gap, so I switched to the large router.

The large router was needed to span the wider gap.

In the center of the hinge plate (where the narrow part is) the hinge fully wraps around the lid.  However, there are two strips of wood on either side of that would look odd if fully mortised.  I marked these out with a marking gauge and defined them with a chisel. I made progressively deeper cuts with the router plane until I reached a depth equal the full thickness of the hinge plate.

The cut goes all the way through in the center, but little wings are left on either side.

And this was the result:

Here’s the finished hinge mortise.

The hinge has to be sprung onto the lid to install it.  I had to gently tap it on with a hammer to get it wrapped around the lid edge.  Even with out screws, the hinge is now on fairly securely.

The hinge clipped into place.

The hinge is flush with the edge, but slightly proud of the face.

I used my center finding drill bit to make pilot holes.

Pilot holes are drilled with a center finding bit.

And installed the brass screws.

The brass screws are installed.

I put the lid into the base and lined up the hinges with their mortises.  I carefully propped the lid in place and installed the screws in the other hinge plate.  I was relived to find that everything lined up perfectly.

The last thing that remains to be installed are my “Historically Accurate” Roubo gas springs.

Here’s what I received from McMaster-Carr:

The gas springs and mounting brackets that I ordered from McMaster-Carr.

I laid out the position of all four brackets, drilled pilot holes, and installed them.

Installing the mounting brackets.

Both brackets installed.

I clipped the gas springs on to their mounting brackets and tried them out.

The installed gas spring.

Well, it appears that all of my internet research and carefully done math did not work out.  My drawings were good, the throw length of the springs are perfect.  But the force pound calculation was way off.  I thought that these 20 lb springs were going to be too strong, but they’re not strong enough.  As it is, the lid is very easy to open and close, but the springs are not strong enough to hold the lid in the open position.  With gas springs, it appears to be a tricky proposition finding the correct pounds of force.  Too weak, and the lid won’t stay open. Too strong, and the lid opens by itself and won’t stay shut.

Well, this was a $40 mistake.  I went back onto the McMaster-Carr website and ordered the same length springs but this time with 30 pounds of force.  I hope these aren’t too strong.  I don’t want to keep spending $40 a pop trying out various spring strengths.  When I install them, I’ll let you know.

I’m going to start work on the vises next. I still don’t have a really clear plan in my head of how I’m going to proceed.  Usually, a day or two of tinkering in the shop allows me to come up with a plan.  I’m going to take my grizzly vises apart, fettle them, and repaint them before I do anything else.

I think that I will also flip the base upside down and apply a few coats of finish to the underside now, while it’s still easy to do so.

– Jonathan White