Cam and Dowell Joints

[Anonymous]

Hi

I am hoping that someone can help me with some cam and dowel joints that I want to use.

I am looking for a dowel jig that can be used for the dowels(!!). The problem is that most dowel jigs that I have found come with 6mm, 8mm or 10mm drill bits. The dowelfittingg requires a 7mm hole for locating into the cam and a 5mm pilot for fixing the dowel.

I figure that if i have two jigs set up I can use them in conjunction with a router to create the joint. Are there any alternatives to this method (other than doing it all by hand, I have 8 radiator cabinets that I have to make)? Or are there any more suitable knock down fixings?

Thanks


Saint

 

[tim]

Saint

You can get jigs - Hafele do one (search under minifix jig) but they are pricey - c £170. I think Roger Sinden has made one though, so may be worth asking him.

Cheers

Tim

 

[RogerS]

Hi Saint...yes, Tim's right. I built an awkward shaped kitchen carcass using these joints.

OK - as you've probably gathered you have three holes to drill. Two in the panel where the metal cam is inserted and one in the other panel to take the metal pin.

For the cam panel, I used a circular template, suitable guide bush and router bit. I screwed a fence to the underside of the template and that gave me the correct distance from the edge of the panel. I lay the two panels end-on and mark pencil lines across both ...so that gives me the register for the hole spacings the same in both panels. Then using the Mk 1 eyeball, I line up the template and rout to the required depth. Set the router depth first using a piece of scrap !!

For the hole in the edge that will take the metal dowel from the other panel, the biggest problem you'll find (if not already :wink: ) is getting the holes vertical. I've got one of those Triton battery drills that has a built-in vertical stand. I then knocked up (using spare thick MDF) a saddle that fitted exactly over the edge of the board and had a cut-out that matched the triton base. Just carry your pencil line over to the edge using a square and then drill down into the previously cut routed hole. You could use a similar approach with a router.

The final hole in the second panel is again measured up, dot punched and using the Triton drill simply drilled out to the right depth. Guess you could make a jig for using a router although I think lining up the jig might not be quite as easy as using a drill and centre-pop but do-able.

That's it. If anythings not clear PM me.

When you screw in the cam and dowel and tighten up your joints it IS a great sense of satisfaction seeing them cramp up nice and tight!

Maybe I'll put together a How to Do It picture set if enough interest is out there.

 

[Steve Maskery]

Hi Saint,
Roger's outline is very sound. I finished a wardrobe recently, and whilest I didn't use these fixings, I had a similar marking situation for the cup-hinges - getting one part on one piece accurately lined up with another part on the other piece.

I made a couple of template-style jigs to mark the hole positions and them drilled them by eye. Sounds like you have a perfect excuse to go shopping. Many reatilers sell sets of twist-drills in 1-13mm sets (in 0.5mm increments). However, these are not ideal for wood and sheet materials, but Axminster do a twin-lip-and-spur set, and they are very good.

I made a Mackintosh wardrobe a few years ago and used the big brother fixings of these - the Rondolex, I think they are called. I tried routing and drilling, and drilling was definitely more successful.

HTH
Steve

 

[Scrit]

Hi Saint

This is a job I do on a point-to-point router and the vertical (face) holes are drilled-out using a carbide-tipped flat-bottom bit like these hinge boring bits. I can get these in 1mm increments from about 12mm up to about 26mm then various sizes above that.

There are a couple of alternatives which lend themselves to the router such as the Rafix fitting which requires a 20mm router bit and a dowel bit, alternatively there is the Blum cam fitting which just requires a 25mm router cutter or hinge boring drill and dothing else.

Apart from that the obvious question is why do you need a KD fitting? Dowels or biscuits are ideal ways to assemble rad covers and cheaper than KD fittings, and as for the front cover, it can be hooked-over the front bottom brace on a French cleat if the top face of the brace is angled and the top held in place using a couple of magnetic catches.

Scrit

 

[jasonB]

If you are not bothered by seeing the cams on the inside of the casing then why not use pocket screws. I have made quite a few rad casings all held together with a combination of biscuits, glue blocks and carcase screws, not made one since I got the pocket hole jig but will use it next time.

Jason

 

[Anonymous]

Thanks for the replies.

I have volunteered to make quite a few rad covers in the near future which is why I am going down the KD route (easier to store and transport). As much as that i have tried to use these fittings and I have only had limited success which is why i thought that a dowel jig would help. (It is now that male ego has taken over and doesn't want me to try anything else until I can use damn these fittings!!!) I have got the hole for the cams sorted using the same method that Roger describes. Its is the accurate and repeatable alignment of the 5mm and 7mm holes that has got me stumped. I did try enlarging the hole that receives the dowel to 8mm, but this isn't really satisfactory. I am finding that without a pillar drill i am not able to drill accurate enough holes to create my own jig.

Pocket Hole Joinery works well and I did resort to this for the first batch, but I find that occasionally I get a split between the layers of the MDF which is a bit unsightly. Having said that those experiences were based on B&Q 18mm MDF and based on advice from this forum I have started using MR MDF (Medite or Caber from memory) which certainly machines well, and takes a screw better.

Tim, that jig that Hafele supply is certainly the business, but I am not going to be able to justify that price.

I suppose that I could get knock up a couple of centering jigs with 5mm and 7mm holes but I find that they wear after a while and aren't really the solution.

Anyhow, any more suggestions gratefully received!


Thanks

Saint

 

[Scrit]

I suppose that I could get knock up a couple of centering jigs with 5mm and 7mm holes but I find that they wear after a while and aren't really the solution.

That's the problrm in any batch production work as opposed to one-offs - producing a jig which will last the course. Know anyone with an engineer's lathe who can turn you up some guide bushes? That's the only way to go unless you change your fastening style or invest in some machinery

Scrit

 

[jasonB]

Why not make the jig to suit a guide bush then instead of using a drill to cut the holes plunge cut with the router. Best to use TCT dowel bit in the router as it will clear the waste better than a straight cutter. I do shelf pin holes this way with a 10mm bush and 5mm dowel drill, the router depth stop will also control the depth of hole for the dowel so you don't come out the other side.

If you made the jig L shaped you could have the hole for the cam on one side and the dowel clearance on the other so the two would always line up, would mean a lot of dot changing if you didn't have two routers though.

Unless you have a 10mm collet the 7mm hole may have to be 8mm as I don't know of a 7mm dowel drill that will fit standard imperial collets.

Jason

 

[Scrit]

Unless you have a 10mm collet the 7mm hole may have to be 8mm as I don't know of a 7mm dowel drill that will fit standard imperial collets.

Which set me thinking. Elu used to list a collet for the MOF177 which accommodated a 10mm shank (not 9.5mm, 3/8in, but the full 10mm) as this is/was a size used in Germany (as 12mm still is - they use metric size shanks in the main). As the collets for the MOF177 also fit Elus MOF11/31/77/98/131/177, deWalts DW624/625/626, Festool OF2000, the 2000watt Mafell and Trend T10/T11 if you own one of those you have a way round the problem. The downside is that Elu/DW collets are about the £20 to £25 mark. You might be able to get a 12.7mm o/d x 10mm i/d reducer bushing from an engineering supplies company, but I'd be VERY careful using that with a 10mm shank tool like these from Titman as the shank has a flat which loses something like 30% of the gripping area in a bushing, and then putting that in a collet may result in overtightening as you try to stop the drill bit from "punching up" into the chuck under drilling pressure. If this is gradual you will lose any effective depth control.

KWO has made 8mm shank tooling like this in the past as there are a few older borers which use 8mm shanks. It may be worth giving them a call.

The thing I'm concerned about is that by the time you buy a collet and a couple of specialised dowel drills (5mm +7mm) you'll be be somewhere between £40 and £50 out of pocket - and I've seen cheap drill presses on our local market for a lot less than that....... either way with MDF you'll need TCT tooling as tool steel brad point bits don't last too long on that stuff.

The last thing to consider is that there a number of KD fastening systems around which are used in conjunction with the biscuit jointer such as Lamello's own system. although there are others in the market like this:

and there is even a teflon-coated spring steel dowel available:

which hammers in and will turn a dowelled carcase into a KD carcase when used in place of conventional glued dowels. I use Ø8 x 32mm ones in place of Ø8 x 30 dowels on some jobs where we'll be assembling on site but glueing is called for. Used in conjunction with conventional dowels they will hold a carcass together whilst the glue sets without the need for cramps (except for the initial tighten-up) - good for batch production if you are short of sash cramps.

Of course the ultimate in KD simplicity is the humble mod block combined with a plywood marking template and an awl.

Scrit

 

[jasonB]

Two problems as I see it

1, If you are drilling the 7mm holes in to the end of the board the length of your rad casing will be limited by the capacity of the drill, even a floor mounted one won't go that big.

2, is there a risk of the plastic KD fittings splitting the MDF as it's likely to be quite narrow frame sections.

Jason

 

[Scrit]

1. If you are drilling the 7mm holes in to the end of the board the length of your rad casing will be limited by the capacity of the drill, even a floor mounted one won't go that big.

Swing the drilling head round and hang it over the side/back of the bench to get 4-1/2 to 5ft, or clamp a portable drill press into a Workmate and use horizontally..... like this one from Machine Mart a la Alf Martensen ("Woodworkers Bible"). It might even be worth building a horizontal drill press and getting the platform to slide towards/away from the drill on a couple of pairs of drawer runners.

However, I've just looked up the spec for the fittings from both Woodfit (Klix BA518) as well as the Hafele version and they actually call for a 7 OR 8mm clearance hole, a 5mm hole for the threaded end and a 14mm diameter pocket for the cam (in the 18mm think versions). So why are we looking at 7mm, a non-standard size? This means that a standard 8mm drill would be useable with a few simple of dowelling jigs like these:

My sketches are rubbish but I think they convey the point. the drilling blocks are 18mm birch plywood or hardwood or Tufnol, the flat parts are 4mm MDF or thin plywood and they should last 6 to 10 covers with reasonable care. Any more than that and you'll need to make more jigs or go to using 2 or 3mm steel plate instead of plywood and learn to drill straight :wink:

2. Is there a risk of the plastic KD fittings splitting the MDF as it's likely to be quite narrow frame sections?

Yes, the rails would need to be wide enough to accommodate two fasteners, or one fastener and a standard dowel to locate/prevent twisting

Scrit

 

[Anonymous]

Thanks again everyone.

Like I said, I decided to use pocket hole joinery for the first batch.

I like the idea of using a router with a 7mm bit. Could I use a 2 flute bottom cutting bit instead of a dowel drilling bit? I would of thought that if I plunged in several stages i would be able to get away with it???

Maybe I will have a pillar drill before I get the next batch under way which should enable me to make up some reilable drilling jigs.

Thanks again


Saint