Tambour cabinet

[recipio]

Nice work. For the one and only tambour I ever made I used 'Leatherette' to glue the tambours on with the faux leather exposed. I simply couldn't find canvas at the time and I must say after 20 years it is faultless. No splits or cracks. I used PVA glue but I see our American cousins advocate hide glue. How is the project going ?

 

[gasman]

Thanks for asking
I am still trying to solve my two problems I talked about in my last post. Yesterday I made a trial mitred corner out of 18 x 60mm walnut and tried using my brand new 6mm spiral router cutter to cut round the corner as it were - using a 2-point fence - and unfortunately it is too hard to control going round the corner to ensure I won't take a divot out and cock the whole thing up. The problem is that the two points need to be close together - only 20mm or less apart - or the thickness of the surface 'outside' the rebate increases significantly as you go round the corner. Having the points close together makes it less stable and harder to control. I also think I would need more than one pass as I want the groove to be 5mm deep and I don't think they are 100% reproducible like that. So I think for that problem I am going to do the straights and the rounded corners of the top and bottom separately. The straights I will do with a router fence. For the corners I think I will use an old ellipse jig I have to mount the router, put a reference pivot point in and then cut the corners as a quadrant referenced from a 60mm radius. Not sure if that makes sense but it does in my head. It would all be so much easier with a CNC router but I like problem-solving and it doesn't matter how long this takes
Also need to decide whether to do the internal cabinet in solid maple, or I am increasingly thinking, in maple-faced 12mm ply/mdf as it will make lots of bits of it easier - but I also am struggling to find some decent maple near me.
Ho hum. Thanks for enquiring

 

[Inspector]

When I did mine I used a guide bushing in the router, one with a reasonable diameter. I made a template with a piece of plywood to go from the entry point in the back and the final stopping point at the front. The template fitting the inside area of the groove. Tack it down with some brads or screws where you have the inner structure and will be covered. Make the cuts keeping the bushing tight to the template. Once done flip the template over and cut the opposite piece. You only have one contact point for the router bushing so the orientation of the router doesn't matter. You just need to concentrate on holding the guide bushing tight. I had no pucker moments that I recall. It would never occur to me to try to follow the outside lines of the piece with a couple pins in the baseplate

Pete

 

[gasman]

OK thanks Pete yes I quite like that idea

 

[Sgian Dubh]

OK thanks Pete yes I quite like that idea

Pete's technical suggestion essentially matches a method I've used many times for a range of similar shaping tasks. Crucially, in the absence of using the impressive capabilities of CNC kit for working the groove in this case, it works very well as long as you take care and don't let the router drift. I prefer to make the template out of 12 mm MDF than plywood; it's easier to tweak and shape the edge of MDF with hand tools if that's what's needed. There's also the benefit of being able, after making the groove, to just nudge the template across a bit to widen it at the turns with a second pass. Check the corner widening is satisfactory with three of four sample staves or slats taped together to run around the groove. Slainte.

 

[gasman]

Some more progress over the weekend. Thanks Pete and Richard for your helpful suggestion about using a guide bush. I feel a little stoopid as I did know about using a router with one but I hadn't done it for ages and kind of forgot. Senior moment!
Anyhow, I made a template in 9mm MDF

Then set the router up with an 11mm guide bush and the 1/4" spiral cutter. I used the guide rail attachment as it made the router much more stable

It came out really quite well on both top and bottom

I have ordered a sheet of 12mm maple faced MDF to do most of the internal cabinet which will take a week to arrive. The trial tambour I made earlier - slid so easily in my grooves which has given me some confidence this will pan out OK

 

[gasman]

A month has gone by.... so much other stuff etc going on so apologies for the delays. Progress slow but I think all remaining major problems are (almost) solvable.
Last time I wrote I had finished the top and bottom of the cabinet and routed a 6mm slot which the tambour will run in
I had to do a tiny repair on the groove in the base when my router slipped very slightly but all turned out OK with a small piece glued in and then cleaned up

I used some dark fairly straight grained unidentifiable hardwood which I had in the workshop to make 130 staves 525 x 16 x 12mm. When this is stained and has the Spanish walnut veneer glued on top it will look fine I think...

For the internal cabinet, I bought a sheet of 12.7mm maple-faced MDF which took forever to arrive but was exactly what I wanted. The grain matches the maple I have to make the corner pieces very closely
The corner pieces of the cabinet were a bit fiddly to make. They are curved internally and externally to match the curves of the corners of the base so it will look like there is a continuous 12.7mm wide 'wall' going round the rear corners
I bought a beast of a router cutter - a 2-Inch Diameter 2-Flute Carbide Cove Core Box Router Bit - to do the internal corners

For the rear corners, I started with 2 pieces of maple 22 x 44 x 520mm and took corners off two adjacent sides with a 45 degree chamfer bit. By this means I could run the piece along the router table at 45 degrees as below. Taking it very slowly - 1 mm at a time it was fine with the coving bit.

Once this process was complete for both pieces, I removed waste on the outside of both pieces on the planer table with a 45 degree chamfer bit...

.... and then used the new reference face to put 5mm dominoes in the edges to create joints between the curved corner pieces and the maple faced MDF.

Once this was all complete, I finished the outside curves with planes and card scrapers

I dry-assembled the sides and the corners of the cabinet for the first time...

It will sit so there is a 4mm gap between the outside of the cabinet and the groove in the cabinet top and bottom
I've run out of space for photos for this instalment
Cheers Mark

 

[gasman]

I also started on the front corners of the cabinet which were the same as the rear but only half as wide so they will be in line with the diagonal line on each corner
Again it was a little fiddly but easier than the rear corners - I glued up those front corners onto the side pieces again using dominoes and with TB1 glue. Clamping was a small issue but came out OK with some improvisation...

At the end of the day I was able to dry fit the whole thing together - here the central pieces have not yet been joined to the rear - they are just sitting supported by the top and bottom

I will try not to let another month go by before the next instalment!
Cheers Mark

 

[Inspector]

One thing I don't see is a way to get the tambour into the grooves. Are you going to cut in a lead in slot later or somehow assemble the cabinet around the tambour? I used a lead in slot in the back so I could glue the cabinet together and finish it, then slip the finished tambour in last. Should you ever need to fix the tambour or want to touch up/refinish it, removal is easy.

Being thrifty, okay cheap, I would have coved the insides of the corners on the table saw. Only disadvantage is there is it's little more work to sand smooth.

Pete

 

[Fitzroy]

Loving the explanation on the rear corner construction, very educational. Interesting comment on how to get the tambour into the grooves, it’s the sort of thing I’d realise after gluing the whole thing together!

 

[Sgian Dubh]

One thing I don't see is a way to get the tambour into the grooves. Are you going to cut in a lead in slot later or somehow assemble the cabinet around the tambour? I used a lead in slot in the back so I could glue the cabinet together and finish it, then slip the finished tambour in last. Should you ever need to fix the tambour or want to touch up/refinish it, removal is easy. Pete

I must admit I was wondering about that issue of getting the tambour in place. The image below illustrates what you're talking about. In this about half of the base to a tamboured cabinet shows where, at the very bottom right corner, the groove for the tambour staves or slats has a lead in and out into a rebate. The image, by the way, was taken whilst the panel was still sat on CNC machine but had just completed cutting the dovetails, tambour groove and rebate.

The rebate is there, of course, for the later installation of a back panel to protect the tambour and hide all the other gubbins at the back of the cabinet. I'm also wondering what gasman has in mind for a similar back panel for his cabinet because I don't see a rebate or groove to carry such a panel. Slainte.

 

[gasman]

Thanks guys but I had always planned to remove a small part of the “lip” on the back edge of the top and bottom to allow the tambours to be inserted or removed. Then I will make a small replacement piece which will have screws to hold it in place so I will always be able to remove it

 

[Sgian Dubh]

Thanks guys but I had always planned to remove a small part of the “lip” on the back edge of the top and bottom to allow the tambours to be inserted or removed. Then I will make a small replacement piece which will have screws to hold it in place so I will always be able to remove it.

That makes sense and solves that little mystery.

Are you incorporating a back panel as well to cover the rear ends of the tambours, or will that be left open? I realise the back won't normally be seen if the cabinet is up against a wall, but if this was my piece I'd incorporate a panel all the same to prevent stuff getting trapped at the back, and for neatness or tidiness when moving the cabinet around after construction and its installation somewhere, and maybe more than one move and installation exercise depending on how often you rearrange the house, or actually move house, etc. Slainte.

 

[gasman]

The internal maple cabinet has a wide rear surface which is about 1080 x 510 and if all goes to plan there should only be a gap of 4 or 5mm with the tambour outside that. So I don't think anything else is needed. The tambour is completely on the outside of the piece - so if the doors are slid shut, then the back will be visible. When the doors are open, the tambour will cover the back

 

[Sgian Dubh]

The internal maple cabinet has a wide rear surface which is about 1080 x 510 and if all goes to plan there should only be a gap of 4 or 5mm with the tambour outside that. So I don't think anything else is needed. The tambour is completely on the outside of the piece - so if the doors are slid shut, then the back will be visible. When the doors are open, the tambour will cover the back.

Okay. Fair enough. I'll be interested to see how it looks when finished. Slainte.

 

[MARK.B.]

What a great post,clearly explaining the good and bad bits with pictures to help those of us that struggle to picture things clearly in our heads. Will look forward to the next installment .
That super slidey stuff that Droogs mentioned also comes in black if that helps any

 

[recipio]

Correct me if I'm wrong but have you decided to go with the 'single skinned' design - simply attaching the maple to the base and top with no 'inner skin' for the drawers. ? Are you joining this with Dominoes as it will have to be absolutely free from racking ? The Poritz design has an inner carcass which would be more rigid but heavier and bulky of course.
Is that MDF that you have mitred with the solid walnut ? Doing it with solid wood would be a no no due to expansion and contraction. I thought I might have a go myself and have ordered the 'beast of a bit ' !

 

[gasman]

Thanks. The top and bottom are veneered 18mm MDF with a 60mm wide mitred walnut frame
The maple internal cabinet is 12mm maple faced MDF
Yes I am planning to do this without a top or bottom to the internal maple cabinet and to use dominoes to join it - and agree about the racking issue you highlighted. I am confident to get this within 1mm which I think will be enough but I do still have the option to add the top and bottom to the internal cabinet if required. It will as you say make it alot heavier. I am just trying to get a wedding gift desk finished before I carry on with this. Thanks for your comments
Regards Mark

 

[gasman]

I finally finished making another desk for a nephew's wedding present so the workshop is much clearer and I can get on with the tambour cabinet - now officially designated as a whisky cabinet
First thing I did when I had space was to look in much closer detail at the accuracy, dimensions and symmetry of the maple internal cabinet - as this will be absolutely crucial to the tambour running smoothly.
The accuracy was reasonable - within 0.5mm but I went over and above to try to get the heights of all the components of the cabinet exactly the same - 510mm, and then worked on the corner components to get them much closer to a perfect curve
I spent a couple of hours doing this and feel I am now ready to cut dominos to join the internal maple cabinet to the walnut top and bottom. I will start with the back and then work out how to do the sides in order to get left and right sides exactly the same - it will need some trial and error I imagine. I think that's another advantage of using dominos here - because, if I am 1mm out in one of the domino slots, I can easily fill this with half a domino and then recut it in the right position
I am planning to glue dominos in to the internal cabinet components but then will leave the other half of the joints dry for now until I have cut all the tambour slats in order to enable me to make slight alterations if needed
Back soon
Mark

 

[gasman]

I finished the internal cabinet over the weekend and started making the slats for the tambour.
The internal cabinet was close to being finished but I needed to work on the four corners to make sure the curves were exactly right so as to allow a 4mm gap between the outside edge of the cabinet and the slot for the tambour slats. This was time-consuming but fine if one proceeded slowly. I actually did this on the surface planer and then used cabinet scrapers to smooth out the curves.
Then I started on attaching the cabinet to the top and bottom. I had been stressing about this a little as there was so little room for error. I started with the back as this was less critical than the sides in terms of the fore and aft movement because there isn't a front as it were.
I did it with 5mm dominoes at regular intervals and put elongated slots into the top and bottom to allow for some lateral movement...

So this was the cabinet dry-assembled before I had dominoed the sides

Once I was happy with the rear of the cabinet, I started on the sides. The slots for the sides of the top and bottom had to be exact - within 0.2mm I estimated - as those of you with dominoes will know, you can only alter the position of the joint side to side as it were - and the sides therefore will be relatively fixed because I now had dominoes going perpendicularly to each other. The domino slots in the top and bottom are offset by 16.5mm from those of the cabinet (12.5mm for the tambour and 4mm for the gap between tambour and cabinet.
After endless measuring and re-measuring I bit the bullet and it actually turned out fine

I assembled the cabinet for the first time and a shave or two off the rear corner pieces made it fit well. I left it dry for the moment as I want to fit the tambour before the final glue up

Once that was done I glued up the corner pieces onto the sides

The I could start thinking about my huge pile of tambour slats again...