Comp WIP - Extending Table - Completed! Animation added.

[RobertMP]

Thought it was about time I started a WIP thread. Might help get me moving a bit faster. At current speed I might just make it by the end of the allowed time.. might

I've spent a fair bit of time on the completely unproven design in this thread - https://www.ukworkshop.co.uk/forums/view ... hp?t=32615 . Whether it actually works is yet to be seen so it may yet be a fixed table project!

I went to my usual timber merchants and managed to catch them almost completely out of Beech They has some heavy stuff that was just over 4" by 3" in section and just 3 planks of 1". With the odd left over piece I still have it should be enough. It also meant the 60mm sq legs could be solid instead of glued from thinner stock.

So I cut the table legs and the breadboard ends and have left them to cook in the conservatory where the table will live.

The items this is to match all have breadboard ends. This will too but I want to fake it with an MDF core to avoid the movement problems.
Might give a bit of a strip wood effect to the finished table but as cutting the 3" side was easier i decided to use the smaller face for veneers. I planed the face then cut it off.

The resawing guide on the bandsaw fence. There is a small block of oak laying in front of the resaw thing to help me judge feeding it through straight. Don't like seeing all that blade so did all this with great respect!

Strips have one smooth face and one sawn. they are not consistent enough to use as they are plus they are 5mm odd thick and i want 3mm

As the thicknesser cannot do 3mm i made a sled with a bit of 12mm MDF. I was worried about the thin leading edge as it hit the blade so i super glued a strip across with a 45 deg cut. All the strips have a matching cut to retain the leading edge. Worked well so far.

Beech for the tops on the left. Oak that will not be seen for the underside on the right. It is taking ages to thickness this lot! One more mm to come off yet.

Need to go and get a sheet of 18mm MDF for the core soon. Then the fun will really start when I have to face up to glueing this lot on!

 

[MikeG.]

As the thicknesser cannot do 3mm i made a sled with a bit of 12mm MDF. I was worried about the thin leading edge as it hit the blade so i super glued a strip across with a 45 deg cut. All the strips have a matching cut to retain the leading edge. Worked well so far.

Now that is a clever idea!

Mike

 

[OPJ]

I agree with Mike; that is a very smart idea. :wink: Most people would make a false bed with a hook on one end, as opposed to a sled which is pulled through the machine... So, is there a back stop on your jig as well, to stop the wood from being fired back out the thicknesser towards/past you? :shock:

Pleased to see that your build is now under way and I really look forward to seeing how your mechanism design works out. Me, I'm beginning to doubt whether I'll be able to start and finish my entry in time - I'm only just finishing my workbench now and have several others jobs lined which are essential to bringing some money in.

 

[RobertMP]

Nothing apart from the glued on strip you see. The drive rollers only touch the workpiece (and the little stuck on piece) so the workpiece pushes the sled through.

I expected the angled edges to stay forced together but the gap does open as the cut progresses down the strip. When a 900 long strip comes out out of the machine there is a 25mm gap where the vibration from cutting has moved the strip on the sled.

It all went smoothly and no leading or trailing edges were shredded. Everything is just over 3mm thick now and smooth so job done. Today job is to get the edges trued up, get some 18mm MDF and then scratch my head about glueing methods. I have a large bucket of Cascamite type resin glue and no idea yet how I'm going to clamp all these strips.

 

[RobertMP]

As expected I've not put in much time on this.

I've realised I did a stupid thing by only squaring one side and edge of my thick beech before I set to with slicing off veneers. Making these strips parallel to the one true edge is a right PITA.

I really don't like hand tool operations like planing but these are too thin and flimsy to put through the thicknesser. So I has to find a way to do it by hand.

I have a saw guide made from two strips of flooring laminate. Having held a hand plane to it I could see the blade was far enough from the edge of the plane to not cut the guide. So I clamped a MDF straight edge on top and now have a parallel planing jig. Bit of wax on the sliding surfaces and start cutting.... and cutting... until it does not cut any more.

Soon reminded me why I don't like hand tools. Some might find the production of nice curly shavings satisfying but I'm struggling with keeping going it is so tedious - and this is really easy cutting!

Anyway off on holiday soon. Maybe I'll feel more inspired when I get back.

The modified circular saw guide and my rarely used old plane -

another view

 

[RobertMP]

After a holiday and a bunch garden jobs I'm back on the table.

This thick veneer lark is an awful lot more work than just making a top out of planks!

I've been puzzling over how to clamp the main table panel for gluing for a while now. Contemplated buying some kind of plastic bag so I could try sucking the air out but couldn't see me keeping things in the right place whilst doing it. In the end I just cut another table top sized piece of MDF to clamp on top.

having been left a couple of weeks my nice straight strips had a slight banana to them so when laid next to each other there were gaps near the middle. First job was taking slithers off the edge with a plane so they butt together nicely again.

Painted the back and edges liberally with extramite (cascamite) and laid them on the table top starting from a marked centre line then covered it with thin poly bags to stop the cover sheet sticking.

Put 6 clamps on lightly gripping then gave the edges a squeeze in with the long Bessey clamp and tightened the G clamps next to the Bessey to keep in place. middle then edges.

Guess more clamps will be on my Christmas list this year. Didn't really have enough for this. Added a bit of weight to the middle.

next morning....

Can't really capture it with the camera but the strips have all cupped a bit in the middle area. Plenty of thickness to get it back to flat. The draw leaves I did a couple of days ago came out better as the clamps were not so far from the middle. Too late now but I wish I had sprayed the top surface with water before putting the bags on top. might have stopped the cupping from the wet glue.

The 3 panels. Just realised the figured small panel has the veneers on upside down for the swirly grain pattern to follow correctly. doh! Doubt anyone will notice.

Need to repeat the procedure now for the Oak veneers on the underside.

 

[Night Train]

I've tried that method of gluing large surfaces, it was never very satisfactory.

The old method of doing it is to have a series of cauls across the work. Basically battens cut with a convex edge. As stiff board is place over the work, as you have done, and then the cauls across width of the top. As you cramp the ends of the cauls the pressure is applied to the centre of the work first and gradually, as the cramps tighten the pressure extends to the edges as the cauls bend.

 

[OPJ]

Yep, those tapered cauls really do work very well indeed. The taper doesn't need to be much more than 1mm at either end. Having a sheet of ply in between is still essential though - I once tried to veneer something without this (using only the cauls) and, let's just say, the finished panel wasn't as flat as it could've been...

Looks like it's coming along well.

 

[RobertMP]

I've glued the Oak onto the other side of the large panel. I could see the strips cupping as the glue soaked in. So once everything was in position I brushed the unglued top surface with water and they seemed to start straightening. Couldn't really wait to look properly and got it clamped up.

Curved battens did cross my mind for clamping but I was worried about leaving a permanent set in the panel.

There is no spring/bounce where the edges are slightly raised so it should flatten OK. Not sure what the best way to do that is either. I was expecting it to be flat enough for the DA sander but this may be a bit too uneven

 

[RobertMP]

Well I've done a lot of work with not much to show for it in terms of new parts.

Due to the lack of clamping pressure the middle area of the table was a bit 'corrugated' but solidly glued. I found a old blade for my equally old plane and ground a curve across the cutting edge then reground the bevel and sharpened it. That gave me a blade where only the middle would take a shaving. Taking very thin cuts i attacked the top with diagonal strokes. Generally I don't do hand tools if I can help it but I couldn't think of a way round this one

I could shave hairs with the blade but it still made a few small tear outs i n the surface so i stopped as soon as the worst was off and went over it lightly with a coarse disc on the random orbit sander.

For final flattening I went over the entire surface with a large MDF backing pad with sandpaper from a roll. I scribbled pencil lines over the area to be sanded so I could see the unevenness being removed. Gave me plenty of aches but it worked well. kept a small bag of sanding dust to make some filler.

Trued up one 'end' then got the opposite end cut parallel, marked the trim cuts to the sides with a framing square and used the planer to get down to the line.

Wider view. Checked the diagonals when I'd finished and they were only 1mm different - well pleased with that.

Cut some oversize edging strips, glued and clamped whilst drying. Don't have enough clamps to glue the smaller panel now.

After trimming back the edging the next stage will be making the breadboard ends and preparing the table ends to attach them.

 

[RobertMP]

So it was on to the router table. Used a bearing guided trim cutter to remove the excess edge trim. Then a 1/2" cutter to make a groove along the breadboard and a 3/4" one to make a tenon on the table panel ends.

Its difficult to hold large panels so I went for an average thickness a little oversize to the 12.7mm groove width

After checking which shoulder to attack to keep things central any excess thickness was remove using a chisel as a scraper.

Once it is 12.7 along its length I know the breadboard will fit.

Still have a junior hackasw I made in school metalwork I prefer to think of it as patina rather than rust. As the blade can flex a bit it worked great for cutting back the end of the 'tenon' without having the blade damage the shoulder.

dry fit. Rub marks from the ali router table top should sand off easily.

Trimmed the ends off after glueing. You can see the Oak on the underside here.

Looks like it will be quite a big table after all! Still think its a shame I got the short figured veneers the wrong way up. SWMBO has not noticed

Just started planing the legs. Nice to be doing something that isn't a panel!

 

[OPJ]

I must admit; at first glance, a little earlier in the build, I wasn't sure of your decision to lay the veneers out in this way... But, looking now, I think it works very well with the breadboard ends. :wink:

You've got some balls making the top before you've built the frame, though!!

I like the junior hacksaw tip. I would've suggested a small flush-trimming saw with no set but, there's an awful lot of flex in the blades. :?

 

[RobertMP]

If the mechanism is a failure then it just means I'll have made the two pull out leaves for nothing!

I will admit I was getting a bit bored with the tops - there is so much work in them! Legs, rails and internal bits should be a bit more interesting.

 

[RobertMP]

So I planed and thicknessed the legs and some rails. Made tenons on the rail ends with the router table, then drilled and chiselled out mortices on the legs.

Dry fit and table tops rested on top -

Got one of the existing dining chairs and sat at the table to check leg room. My legs went under OK but just touched the under edge of the rail. Dissapointing as I thought I'd allowed enough clearance. The chair seats for the existing table are about 20mm higher than any other dining chairs in the house so they could come down a bit. (new chairs will be a later project so reducing the legs on the old ones a little is not a problem) The mechanism was already raised above the table edge level so the 'apron' can go up 20mm. The legs could have some glides on the bottom so that would add maybe 8mm to the table height... so problem overcome.

As I've already made the leg to rail joints I can't just make the rails narrower so I've decided to do this -

Shame introducing angles to a square design but i think it will look kind of intentional

 

[OPJ]

...Well, good luck with that, then!!

Seriously, if it turns out like your drawing then I think it will be fine. At least you've kept most of the edge straight. It's still in keeping with the overall design, if you ask me.

 

[RobertMP]

Modified the rails and started on the mechanism parts.

Made some pockets to drop the cross bars into. I milled the cut outs with a 6mm router cutter in the bench drill and my cross slide vice with digital readouts.

Sounds good but the digital readouts are 2 cheap Aldi verniers cobbled in place with screws and brackets. Crude but effective

Results weren't bad

Modified rails and the start on the internals dry fitted again.

Want to be able to glue it up in stages hence the joint design for the internal parts.

 

[RobertMP]

made up the leaf mounts to try them out. Instead of directly fixing the slide to the table inner frames I've put them on some oak plates that I can clamp and adjust position easy. Once right they can be drilled and bolted to make the leaf removable.

Can't resist another look at the finished size

Been looking at my lifting idea for the table top and started not liking it. Going back the the sketchup now to think of an alternative way of doing it. Still confident it can be done - just not the way it was.

 

[RobertMP]

Well its been a while since I updated this thread. Excuses are a disruption from having a new gas boiler and larger supply pipe fitted and all the associated kitchen rebuilding and a nice 10 day break in Greece

In between things I have been doing more - just not had time to take the pictures and update here. Think an element of the not reporting was the potential for embarrassment once my mechanism was made fitted and tested as it may have been a highly original failure. I'm pleased to report the design does work and seems to work well too!

So I needed a new design for lifting and lowering the main table top. This is the carriage.

The bearing parts are 3mm polycarbonate which is unbreakable and has a little flexibility to take the knocks in use.

The other side which will be screwed to the table top underside via the access holes.

The carriage works on rollers on the table frame. The clamped blocks are a tight fit to the 6mm stainless 'axles' but are slightly counterbored larger to allow independent position adjustment so I can ensure the top rises and falls level. You can see the lowered carriage edge outline marked in pencil on the side cheek.

Bits of seamless tube act as rollers for the carriage edges.

The axles are held by the middle bar and nothing fixes to the side panels. Once I'm happy with the the axle positions I'll take the middle bar assembly off and drill and bolt the axle mounts in position.

The slides for the pull out leaves are now bolted to the subframe. As the drawer slides are detachable they can stay as they are now.

Here's the carriage in the raised position. The stick held with a screw is a temporary operating handle so I can move the carriage when the top is in position.

And lowered.

Now this carriage moving side to side as it raises and lowers is no good if the table top travels with it.... so I needed to constrain the top to only move vertically. What I really wanted was a 70mm long drawer slide. As that doesn't exist I took a hacksaw to a 500mmm one and made 3 out of it. I didn't use the outer part of the drawer slide, just the inner and middle rails.

70mmm drawer slide

As there is no operating handle to one side now I mounted one onto the outside rail. Might try and fill the notch behind it.

2 in the other axis either side of the handle shaft

Corresponding blocks on the table top underside.

You can just about see where I made some saw cuts and squeezed them shut to create a lead in for the start of the slide. The wood mounts are slightly taller than the slide so it should help prevent scratching something when fitting or removing the top.

The table top has absolutely no rotation or side to side movement when fitted yet raises and lowers easily.

Need to get on and make a proper operating handle now so I can try mounting the carriage to the table top.

It has been a great relief to find that all the effort I put it has ended up with something that works. Now the challenge is to get it finished within the comp deadline.

 

[Imperial]

What a lot of work this has been! when it's finished post a video link of the mech working please.

 

[RobertMP]

It's kept me entertained though

I was thinking a video might be the best way to show how it works... when its finished.