Dovetailing MDF

[Benchwayze]

Hi Folks.

I want to make a dovetailed cupboard with MDF, veneered with resawn cherry. ('Real-veneer' of about 3mm thickness.)

Before I go for it, I thought I'd start with a small box; something for my granddaughter maybe. However, even that would waste time and material, if it didn't work. So I am asking the forum for any pointers.

I think a router would work MDF best, and as the dovetails will be obscured by the veneer, the hand-tooled look wouldn't be necessary.

Has anyone had any experience with dovetailing MDF?

I am aware of the health and safety issues with dust; one of the reasons I never considered MDF to be fit for anything but standing on in the winter, as an insulator! Oh yes! The 6mm stuff makes nice boards for painting landscapes, but I get the sawmill to cut those for me! 8)

Maybe someone can prove MDF is a way of making good timber go further.


Any observations folks?
Cheers

John (Birmingham)

 

[SketchUp Guru]

John, I think the dovetails in MDF would be a waste of time. There'd be no strength advantage and perhaps there'd be less strength. You would be better off cutting a locking rebate or even a simple rebate and gluing it. There would be less fiddling around with those joints so they'd be much simpler to fit.

Besides, even if dovetails were a good idea, what's the point if you are going to veneer over them. With today's adhesives there's little point in cutting a joint like a dovetail if it is going to be hidden.

 

[Scrit]

Well John

Dovetails were supposedly devised as a method of making a strong joint with maximum glueing area in a time when glues weren't that good so extra glueing surfaces were therefore a boon. These days there's much less need for them as modern glues and jointing techniques are pretty reliable. MDF, unlike wood, has no grain and is very weak when you machine it down to very small sizes, such as a fine-pitch dovetail, and it will consequently produce a weak structure. More appropriate jointing techniques include dowels, biscuits and pinned housings or rebated butt joints - all of which are also much less work. If you want a material to practice on have you considered clear redwood or poplar?

As a way to make good wood go further I'll say this: for carcass contruction where the joints are not for show, MDF has no peers as a stable, flat substrate for veneers. As a material for making flat panels for Shaker-style frame and panel doors it also excels, especially if you want to make a showy timber such as zebrano or flame mahogany go further. The material itself uses a huge percentage of the tree, not just the 20% or less we actually end up getting into a finished piece of furniture, and the pulp comes from sustainable resources, so there is potentially an environmental cachet in using it. and as a material to make painted furniture it is cheaper and more stable with better finishing properties than any piece of knotty pine will ever be

But as a material for dovetailing or comb jointing - it's useless.....

Scrit

 

[Benchwayze]

Thanks for the replies, Scrit and DaveR.

Most helpful. I have used MDF for door panels, (3mm veneered both sides with the 'show' side in Flame mahogany as coincidence happens!) The idea of using it to make exotics go further isn't new of course, and the reason I thought about dovetailing, was purely for cabinet strength. However, if it has no strength when dovetailed, then I have found a sensible use for some of that poplar I have in stick, in the back yard!

As for clear redwood Scrit, any kind of clear, stable softwood is like gold-dust where I live. My local merchant has plenty of Scandinavian 'deal', but some I bought yesterday split while I was working with it, outside in the spring sunshine. And picking over the pile to find planks that were close to 'quarter-sawn' took almost 3/4 of an hour and my hands were covered in sticky resin. All I wanted was to knock-up two trestles! :roll:

But thanks again my friends, for the advice re. MDF. I will proceed as suggested.

Scrit, your 'ticky-boxes' ? # 1.

Cheers
John ccasion5:

 

[lurker]

Benchwayze,

Regarding wood supply.

I've not bought wood, except for a few small turning bits and sheet materials, for 5 years.

I found a local double glazing outfit and asked them if I could go through their skip. They welcomed me with open arms!
I go down every other Saturday morning and help myself. Usually I take "mahogany" window & door frames that have been ripped out of someones house to be replaced. Althought there are some new offcuts too. I have boxes full of door furniture & brass hinges too. They often have complete doors that break down very nicely.

Using a table saw I rip to size and cut away the rubbish, there is up to 50% waste (goes on the fire) but I get some great stuff - useable planks up to 8ft long.

I reckon I save the company about 5 skip empties a year. They even put the best stuff to one side for me, so its just a matter of knocking out protruding screws & nails and bunging it in the car.

Main disadvantage is I can't get in my garage for wood!

 

[Benchwayze]

Hi lurker,

I know the feeling of a shop stuffed with timber. With me it's parana pine, and those 'Kentucky' house-doors. I used those for back-garden gates, and they are standing up well to the weather. That still leaves a couple to use, when I build my additional shop.

Most of the window frames I reclaimed turned out to be Utile, as opposed to Mahogany. A nice timber in its own right, but it gets 'up your nose', as the dust is the finest particle size I have ever come across.

It just occurred to me, those doors are often made from Luan, (Phillipine Mahogany) Am I right? I had loads of that too, as I salvaged some strip-glued boards from the tip a few years ago. Now I have offcuts, that I have to take back to the tip. No woodburning allowed in Birmingham.

Cheers for the skip idea though. There are a good few D/G firms in Aston!

John :wink:

 

[lurker]

Benchwayze,

I put mahogany in commas as I have't a clue what it really is.

Other than brown, :shock: I was aware it was different wood because some is very hard & close grain whereas other works almost like good quality pine.

Will make a note of the names you suggest - thanks for information.

Fact remains, bowing & cupping and warping are not something I ever see and that alone is worth the effort of cleaning and sizing the stuff I get.

And the recycle gives me a warm feeling.

 

[Benchwayze]

Hi Lurker,

If the timber is pretty soft (like parana pine and deal, it's probably Luan. A pinky-brown colour, much like Meranti, with a mahogany grain that can be prone to tearing out.

Utile is usually darker brown, is definitely hard and the end grain often shows marked, 'zebra-stripes'. (Makes good end-grain chequer-board table tops.) After planing, the 'arrises' are especially wicked for cutting fingers btw!

Nothing much wrong with utile. I never had any that was unstable, and it does make a good Mahogany substitute. As does iroko for teak.

I have one board of Cuban Mahogany that I gloat over. It was from a Victorian dropleaf table I rescued from a Guy-Fawkes bonfire in the late sixties. I used some of it, until I relised exactly what it was. Now I just keep it. One day I might make something, but it will probably be worth more to my son and place my estate into the 'Inheritance-tax' bracket!

Happy Wooding and have a good Easter

John

 

[manso]

If it's going to be veneered, and if the MDF is at least 12mm, I would go with pocket holes - very strong and squares up nicely.
Regards

 

[Benchwayze]

Obliged Manso.
Will bear that in mind. I shall make a jig though I think!
Have a good Easter
John

 

[woodbloke]

Benchwayze wrote:

good Mahogany substitute. As does iroko for teak.

Sorry, rubbish. Iroko is nasty, horrid, stuff, difficult to work with, horrible interlocked grain, awful colour, peppery sawdust, no grain pattern to speak off. Teak, if you've never tried it, is fabulous stuff (apart from blunting your tools ) planes beautifully, finishes well, beautiful grain, tricky to glue granted, but ticks all the boxes....at least mine anyway and incidently, it's the most expensive commercial hardwood - Rob

 

[Benchwayze]

Hi Rob,

Agreed, iroko isn't an ideal furniture wood, and yes, teak works like a dream. However, it wasn't looked on as a cabinet wood until the Scandinavian makers turned it into a fashinable wood, around the 50's-60's. (G plan and Nathans made nice furniture popularising teak, using construction methods that were reminiscent of the old 'Utility Furniture'). You must be famliar with the utility mark, that looks like two 'pacman' characters'? Inexpensive, mass produced furniture but still well-made.

Prior to the Scandinavian fashion taking off, teak was used primarily for boat building, (especially decking) and for making jetties, piers and berthing catermarans. This was because of its resistance to insect attack; the very property which makes it difficult to glue. (I used CTC at one time to degrease it, but I don't know if you can buy CTC these days. ) It quickly got to the point where afrormosia was used as a teak substitute. (There's fashion for you). And afrormosia really can have wild grain. But it's a nice furniture wood all the same.

Like you, I always found iroko to be 'sneeze-wood', and not easy to work, but then Mahogany can have some wild-grain, as can English Walnut. (Another expensive timber). But pay for an iroko 'centre-board', and things are easier straight way. There are ways around the dust problem as with any other wood, and if you have more than one plane, you can avoid the need to sharpen every half hour! So whilst iroko isn't the finest of cabinet timbers, I have used it in furniture with good results.

I don't think I was talking rubbish, Rob. I was making an observation from my own experience. The fact remains, if you don't want to use iroko for furniture (I find the grain a bit 'gaudy') it does make a good substitute for teak, due to its weathering properties. I have a garden seat that is planked with iroko. It's been weathering for five years now, and is still sound. So, not as good as teak, but better than some of the rubbish we get that is classed as tannalised deal. Agreed?

Yes, teak is THE expensive hardwood, but I believe it's illegal to import in log form and can only be brought into the UK as ready made furniture. For the garden it is ideal, using pegged joinery. No need to worry about glueing there. Although even teak benefits from a good oiling when used outside, to prevent moss growth. And for sheds? Nothing beats Western Red Cedar... Not in my book.

Okay Rob, thanks for the debate, and have a good Easter my friend. Enjoy the woodwork.
John (Birmingham)

 

[woodbloke]

Hi John - sorry for the rant last night, SWIMBO forced me to have a second bottle of the red vino last night. Agree with your sentiments on the 'debate' of iroko vs teak.
I've done a fair bit in each timber (much of my iroko was scrounged as old lab bench tops) and I found it (iroko) horrible to use as I was using a P/T in a school at the time with no extraction on it....hence the workshop was filled with this ghastly, peppery dust for hours and it left me with eyes streaming and sneezing for hours afterwards, so I'm very wary of it now.
Teak on the other hand is one of my all time favourite timbers. It does have its problems, for sure, particularly the way it will strip the edge off a plane iron in a few strokes but that not withstanding I think that it's great stuff, shame it's not used more often as it seems to have fallen out of favour (not surprising when you see the price of it). I'm a great fan of the Scandinavian furniture produced earlier, pieces by Wegner I find wonderful especially his teak chair (206 I think) with the cane seat, a classic, wish I could afford a couple but at about £3k each, I think not - Rob

 

[Benchwayze]

Hi Rob,

Where did you get the Vino? I was full of Bass myself, although to be fair, I do my drinking once a week at lunchtime on a Thursday, . (Pension Day!)

I know exactly what you mean about iroko without dust extraction. It filled my workshop with the dust too.

I used some to replace the legs of a drop-leaf table. I made the table 40 years ago, but I love the patina on the top, so I just re-made the undercarriage.

I might have used teak, but it was going to be hidden mostly. The iroko I got was surprisingly 'brown', and very teak-like to look at. So it was a 'centre-board' I believe. Still filthy to work with though! I can't post a pic yet, because I don't know how. I am working on that.

I am due to replace most of my furniture after 45 years of marriage, but I am loathe to break up my first side-board.

I made it with a panel saw, tenon saw, a smoothing plane and a 4-set of Marples chisels. I built it around an idigbo frame, so I found a lot of use for a Yankee-pump screwdriver! Those were the days. But the sideboard still functions although the softwood drawers sag a bit now). It really was a primitive bit of woodwork, but it's seen us through all that time!

That's lotsa money for a chair Rob, so make your own Wegner eh? I know I would.


Have a good Easter and enjoy the Vino too!
I am going to enjoy some chocolate and to heck with the diet!

John

 

[woodbloke]

Wegner chair is the PP 501 in teak, can't find an image to post tho' - Rob

 

[Benchwayze]

Thanks Rob.
I will keep an eye out, but I think I knowthe design...
I am due for some new dining chairs too!

Cheers
John