How to Construct This Clock ?

[John Buzzurro]

I decided to make a skeleton mantle clock, and finally found a design that I like. I'd like to take a stab at making this one (http://us.st12.yimg.com/us.st.yimg.com/I/clock-watch_2010_38109062).

I can get the same clock movement from Klockit, so the clock movement is no problem. The key thing I'm struggling with is how to make the arch. Would it require bent lamination, or is there another way to do it? I'm assuming for the sake of simplicity that the arch will be a separate component from the posts.

Any and all ideas are appreciated.

John

[Dewey Torres]

If you wanted to make it separate from the posts, one way would be to make an mdf template for the router and make a series of arcs (say 1/4 inch thick each) to be laminated together as needed to make up the depth for the clock. The outside pieces would be best faces for show or veneered.

Does that make sense?

Dewey

[Eric DeSilva]

If you don't want to go the bent lamination route, why not cut it out of a solid piece of wood on a bandsaw?

[Carroll Courtney]

Use bending plywood(1/8 baltic birch)stacking till the thickness you need ,then apply curly maple veneer.O-ya there better be some pics posted of your progress.Or the "Pic Police"will come during the nite:eek:

[mike holden]

There is an awful lot of veneer work on this clock.
The good news is its all veneer so you can make the base for the veneer by cutting and stacking wood. I would cut the first piece and make it smooth along the curve, then cut subsequent pieces a bit over size, and glue one at a time using a pattern bit to match to the previous piece.
This piece just cries out for hammer veneering. Have you ever used hide glue?
Mike

[Matt Hutchinson]

If you're veneering it anyway, and there is only one of these arched parts, I would just make it out of MDF. If you don't planning on making another one then don't worry about making a template. Otherwise, make a template and use a pattern bit in a router for repeatability. It doesn't appear to be a very difficult part to make.

I would be more concerned with the one piece arched and bent housing. With that you had better have a bending form that has perfectly square sides supporting the entire piece being bent. If there is any twist (non-squareness to the 'face frame') in this bending, it could ruin the outcome. As far as materials, the one pictured uses plywood for the carcas, and some type of bending plywood is probably the easiest way to tackle it.

Hutch

P.S. You might want to clarify which part you are calling the arch. I, of course, was initially responding to the face piece, then at the end I was referring to the carcas.

[Frank Drew]

If you don't want to go the bent lamination route, why not cut it out of a solid piece of wood on a bandsaw?

With that amount of curve there would be some short grained areas that would be very weak.

I think I'd either laminate over a form using thick veneers or bending ply, then face veneer, or maybe better yet bricklay, then apply the face veneer (as with a curved table apron). The latter method would perhaps give you the most predictable results, i.e. no springback.

[John Buzzurro]

Thanks for all the responses. Now for some dumb questsions:


If you wanted to make it separate from the posts, one way would be to make an mdf template for the router and make a series of arcs (say 1/4 inch thick each) to be laminated together as needed to make up the depth for the clock. The outside pieces would be best faces for show or veneered.

Does that make sense?

Dewey

Yes, makes sense. In fact, this was my 1st thought. However, why not make the individual arcs thicker than 1/4"? Also, wouldn't I still need to veneer over this to hide the glue lines?



If you don't want to go the bent lamination route, why not cut it out of a solid piece of wood on a bandsaw?

Thought of this too, but don't have a bandsaw.


Use bending plywood(1/8 baltic birch)stacking till the thickness you need ,then apply curly maple veneer.O-ya there better be some pics posted of your progress.Or the "Pic Police"will come during the nite:eek:

Is bending plywood a special plywood designed for bending, or are we just talking about thin plywood?


With that amount of curve there would be some short grained areas that would be very weak.

I think I'd either laminate over a form using thick veneers or bending ply, then face veneer, or maybe better yet bricklay, then apply the face veneer (as with a curved table apron). The latter method would perhaps give you the most predictable results, i.e. no springback.

I'm not familiar with bricklay, can you explain?

---
thanks again
John

[Peter Quinn]

Thanks for all the responses. Now for some dumb questions:

JB: Yes, makes sense. In fact, this was my 1st thought. However, why not make the individual arcs thicker than 1/4"? Also, wouldn't I still need to veneer over this to hide the glue lines?


MPQ: Not dumb questions sir. That's a very complicated piece of woodworking and I applaud you for tackling it. Great chance to learn and grow. I would make the arcs 3/4"-1 1/4" thick. For strength I would brick lay segments in a 2/3/2 pattern or 3/4/3, as full arcs glued up will suffer the same short grain weakness as a solid blank would.


JB: Thought of this too, but don't have a bandsaw.

MPQ: You could cut these arcs with a good jig saw and patience or a router and trammel, but what a great opportunity to buy a new tool! I would not attempt to make an arc that severe from a solid blank for several reasons mentioned above (short grain weakness at the stress points) plus it is an awful waste of fine wood, and you would need one heck of a band saw to attempt it.


JB: Is bending plywood a special plywood designed for bending, or are we just talking about thin plywood?

MPQ: Bending plywood has all the laminations running the same direction, unlike regular plywood which runs each layer perpendicular. This allows you to form very tight curves with minimal spring back. Even regular 1/8" plywood won't perform like bending (often called Italian bending poplar) plywood. You create strength by orienting each layer of your lamination perpendicular to the next and balance by using an odd number of layers.



JB: I'm not familiar with brick-lay, can you explain?


MPQ: Think of a wall of bricks. The joints are always off set as the bricks are stacked so that a full brick resides over the joint below. Same Idea, except with wood and moving sideways in this case. You build up the arch using shorter segments of the total curve glued together edge to edge with the but ends of one layer over lapped by a full segment in the next layer. Creates considerable strength. I just made some round storm screens for a client this way, very very sturdy. I wish I had a picture for clarity. FWW has an excellent primer on curved work in the current issue with good pictures for reference. Much easier to do than explain.

[Frank Drew]

http://www.taunton.com/finewoodworking/SkillsAndTechniques/SkillsAndTechniquesPDF.aspx?id=2345

If this link works, it might require a trial membership if you're not already a suscriber.

[John Buzzurro]

Wow - you folks are awesome. Lots of useful info. I've learned a bunch just by reading your responses. I still am not sure what approach I wish to take, but I've got plenty to think about.

It sounds like whichever approach I take, I'm going to end up needing to do some veneering, except possibly if I go with bending plywood?

Just 1 more question (and I'm not sure I'll take this approach), but are there any online sources for bending plywood? I'll Google it and check locally, but I'm not sure whether I'll have any luck.

Thanks again
John

[Frank Drew]

John,

Bending plywood won't come in a face veneer suitable for finish work, as far as I know, so you'll have to veneer over it. With bricklaid construction, you might have to veneer twice if your face veneer isn't on the thick side (hard to find these days), otherwise the joints can telegraph through. The counterveneer underneath doesn't have to be anything special, though; it's just adding thickness.

I've only bought bending ply from local suppliers so can't help with online sources. Sorry.