Mechanism for a drop lid buruau?

[billbeee]

Hi All,
I am toying with the idea of making a drop lid bureau, (secretaire). Can anyone explain (or point me to a link ) the actual mechanism that brings out the support pieces as the lid is lowered.
Cheers
Bill.

 

[MikeG.]

Bill,

I have made a few of these, and whilst I don't know if this is the classic way, mine worked well.

The support arms run on runners like a drawer, on the underside of the "work-surface". Sticking through the worksurface at the back end of the support arm, in a long slot, is a short vertical member, protruding an inch or two. Hinged off the inside of the lid is a connecting piece, ideally slim and elegant, (you could make this of brass if you wanted) which has a pin connection to the vertical member on the support arm.

The geometry works best the further up the lid the connecting arm is attached.

Hope this helps

Mike

 

[oddsocks]

Hi All,
I am toying with the idea of making a drop lid bureau, (secretaire). Can anyone explain (or point me to a link ) the actual mechanism that brings out the support pieces as the lid is lowered.
Cheers
Bill.

Bill,
I made one of these some years ago and it featured in good woodworking mag last year (jan-march 2007 from memory). I made the linkages from brass...
This image is the loper open (i.e flap down)

this is with the flap up, loper withdrawn

Both the above show the semi built stage, the top of the loper ran against the underside of the desk main surface (which was sliding dovetailed into the sides) - the loper was captive between that and the loper runner - and this one shows the loper runner (not the loper itself) from the front of the desk- I put an ebony strip on the top and a recessed screw so that I could fine tune the friction of the loper in the guide (and eventually adjust for wear) and then screwed the retainer that can be seen in the other photos.

If you have turbocad (turbo 8 or later) I can email you the orginal drawing that includes the loper mechansim. The file is a .tcw format. Send me a PM.

I spent some time with stripos of wood and nails as pivot points to get the balance and amount of throw correct.

 

[billbeee]

Thanks Mike and Dave, that’s just the stuff I need.
I reckon you’ve given me enough info to make a couple of mock ups to test out the system.

We have neither antique shops or decent quality furniture places that I can go to and see one, or buy one for that matter. It is a sad fact, here in Aus that It will probably cost me more for the timber, than to get a custom unit built in say Thailand.

Thanks for the offer of the cad file Dave, I should be OK for now. If I get in strife I’ll ask again.

Cheers
Bill.