Housing Joint Width

[drillbit]

Sorry if this is a daft question.

If I want to rout a housing joint to take a piece of 9mm MDF, how wide should I cut the housing? 9mm, or a little bigger?

The reason I ask is that I have been looking for a 9mm router bit, but they are not actually that standard. Axminster do a 9.57mm cutter, screwfix do 9.5mm....

So I started out thinking surely 9mm is a standard MDF thickness, why don't people do a 9mm cutter...and then I thought maybe it's because it needs a half millimetre clearance and that's why people want 9.5 not 9?

So should I search online abnd find a 9mm router cutter, or will a 9mm housing be too tight, and a 9.5mm cutter provide a better fit for a 9mm MDF board?

 

[marcros]

first job, i would measure your mdf- 9mm is nominal and you will find that it is not exactly 9mm itself.

 

[Phil Pascoe]

9.5mm is the commonest equivalent of 3/8" it's not specifically made to give clearance on 9mm board, although it would probably be ok.

 

[marcros]

you can always use a smaller bit and take a second pass.

 

[drillbit]

you can always use a smaller bit and take a second pass.

That's exactly what I have been doing, but it's quite a pain having to mark out the housing, then measure and mark two guide lines for the first and second pass, unclamp and reclamp the guide rail etc. When you have 20 or 30 rebates to cut, it makes you want a bit which exactly matches the housing required!

It sounds like you are saying the housing for a 9mm board should be 9mm, so I guess a 9.5mm bit isn't going to make a snug fit?

 

[WoodMangler]

Trend do one - http://www.google.co.uk/products/ca...a=X&ei=yjp9UIyMF8TJ0QWJqIDgAg&ved=0CF0Q8wIwAw

Is it OK to post links here ? Apologies if not.

 

[Phil Pascoe]

If you used 9.5mm, you'd have to be sure your construction didn't go out of square when you glued it, but other than that what's the problem? You could always use an 8mm cutter for the housing and rebate the other board to as tight a fit as you want - tedious, but quicker and more accurate than taking two passes on the housing.

 

[siggy_7]

Make yourself a fractionating base plate for your router. It looks like a square base, but each side has a slightly different offset to the spindle centreline - by using different sides with 2 passes, you can widen a groove/dado without having to buy lots of odd-sized bits or move your guide. Trend also sell one as a "trenching base", which is hexagonal with the capability of going +1-5mm by using different sides, although I prefer a finer stepping than that - and you don't need regular intervals in the sizing, an arithmetic progression would give you more range.

 

[WellsWood]

Here's your answer, make yourself one of these. Mailee's version is a little more refined but the principal's the same.

 

[The Bear]

Charlie recently uploaded a vid showing how to make a variable width housing jig.

Lots of other versions on the web

Agree with wells wood, this is the best method


Mark

 

[Steve Maskery]

Yes, the best way to make a housing is with a two-pass jig. I feature it on my last DVD, but it is no different to the many that are published for free, so I can hardly claim it as a USP!
The advantage of such a jig, apart from the much better safety c.f. a tablesaw dado (which is what I am comparing it with) is that it is EXACTLY the same as the workpiece, not just nominally so. Also, each side of the housing is cut in in a conventional manner, rather than one side being conventional and the other climb-cutting, which is what happens in a normal routed slot. Clean edges on both sides.
S

 

[adzeman]

I do like that idea ziggy7 I will give that a go next time I make dado's I have a set of ply templates to which I cope OK but the off set base is sheer genius.

 

[Steve Maskery]

The offset base does work very well, except that is does rely on the workpiece being an exact size. OK, if your increments are 1/4 mm (ten thou) then you can probably get it, for all practical purposes, spot on.

But the beauty of the two-pass jig is that you can see, before you cut anything, exactly where it is going to cut, and know that it will be exactly right.

S

 

[adzeman]

Good point, will still give it a try and play around a bit. Incidently I had a look at your ultimate tenon jig after the post on making tenons and some others on utube. I ike it and it was the best on view.

 

[Steve Maskery]

I ike it and it was the best on view.

Of course, what else did you expect? It wouldn't be Ultimate otherwise would it?
You know, sometimes I wonder how the world developed as much as it did before I came along.

Arrogant, moi?
S