Biscuit jointer cutter for routers

[ByronBlack]

Basically, i'll be needing to cut some biscuits for when I glue-up my worktop, however I don't want/can't afford to buy a decent dedicated machine, so wondered what the forum's opinion on a router cutter is?

Do they give as good a performance as a dedicated machine? Do I buy seperate cutters for each biscuit size, or is there a way of making a jig to make this easier?

Any thoughts, opinions gratefully received!

 

[George_N]

Biscuit cutters for the router usually come with three different sizes of bearing to adjust the depth of cut. The router solution only works for edges or near edges. The won't do biscuit joints mid-board for shelves in a tall unit for example. Having bought such a cutter for my router, I quickly discovered its limitations and bought a dedicated machine.

 

[Paul Chapman]

Byron, why not just cut some slots with a straight cutter and make up some oblong tongues from plywood (or you could do full length loose tongues). Similar to biscuits - just a slightly different shape, and far easier than fiddling about with a biscuit cutter in the router.

Cheers :wink:

Paul

 

[ByronBlack]

As usual Paul, you present a voice of reason and a simple solution! Thx.

Sometimes, I get so stuck on an idea (biscuits in this case) that it's hard to see an alternative/easier approach.

Thanks!.

 

[chippy1970]

Biscuits are better as they are designed for the job they swell when glue is applied to them.

I bought a cheap biscuit jointer as its not the sort of thing I use all the time, its the axminster one. Then a couple of months later I bought a worktop jig and found it was easier to cut the biscuit slots with a router biscuit cutter rather than the biscuit jointer as its better for running slots length ways.

If its a one off then you could try using a 4mm straight cutter on the edge of the worktop but that would be fiddly and I wouldn't. If you use the proper biscuit cutter it takes seconds to do both worktops.

Another tip is buy a 1/4" shank biscuit cutter I have a 1/2" shank cutter and I have to swap cutters from worktop cutter to biscuit cutter when fitting worktops. If I had bought a 1/4" one I could have my small router set up to do the biscuits its sounds a small thing but it will save a lot of time.

 

[Scrit]

Do they give as good a performance as a dedicated machine?

No

Do I buy seperate cutters for each biscuit size, or is there a way of making a jig to make this easier?

Generally the come with some form of collar or bearing to control depth on each size (they are all 4mm thick), but the length of the slot varies - and that's down to hand marking

If its a one off then you could try using a 4mm straight cutter on the edge of the worktop but that would be fiddly and I wouldn't.

I agree. I've tried 4mm cutters (which for starters rarely are - 4mm that is) and they require multiple 4 to 6mm deep passes to get the necessary depth of cut, snap easily and clog the cut and thus need constant stops for cleaning out. Not recommended!

Mind you I won't use biscuits on worktops - they often have a slight bow and biscuits make it more difficult to get a perfect joint - but that's a different discussion

Scrit

 

[j]

Generally the come with some form of collar or bearing to control depth on each size (they are all 4mm thick), but the length of the slot varies - and that's down to hand marking

How do the dedicated biscuit jointers work? Does the blade move side to side to give wider slots? I thought it was all done by the depth of cut - The deeper you go, the wider the cut.

I actually have a biscuit cutter for the router, and have only used it once. I did have to move the piece sideways to get a cut wide enough to get the biscuit in, but just assumed I had some cheap non standard cutter set.

 

[Scrit]

How do the dedicated biscuit jointers work? Does the blade move side to side to give wider slots? I thought it was all done by the depth of cut - The deeper you go, the wider the cut.

I actually have a biscuit cutter for the router, and have only used it once. I did have to move the piece sideways to get a cut wide enough to get the biscuit in, but just assumed I had some cheap non standard cutter set.

It's in the detail - a dedicated biscuit jointer uses a blade of 100mm (4in) diameter, so by controlling the depth of cut you automatically control the width. Slotting cutters on a router are much smaller, so you nead to move them along to generate a slot capable of accommodating the biscuit

Scrit

 

[Paul Chapman]

Biscuits are better as they are designed for the job they swell when glue is applied to them.

I wouldn't agree that biscuits are necessarily better. In most situations I don't think there is much to choose between biscuits and loose plywood tongues. Biscuits are quicker if you have a good quality biscuit jointer but in terms of the quality of the joint I would rate them about equal. In fact, in certain situations the loose plywood tongue might be better - for example on thin material where you need to finish the job quickly, the telegraphing effect can be a problem if it causes the surface of the material to swell slightly and you don't wait for the moisture to equalise before sanding or planing the surface. That's not an issue with most worktops but can be with some jobs. In Byron's case I think that the extra cost of a biscuit cutter and the general fiddling about would simply not be worth it.

Cheers :wink:

Paul

 

[chippy1970]

Every situation is different and like you say you can use ply tongues sometimes and sometimes with thin material the biscuits can bulge the surface.

If you need something to hold together quickly then biscuits are better as ply tongues will not swell as biscuits are designed to do to lock the joint together.

Oh and then theres DOMINOES......... :lol:

 

[Pecker]

I tend to always buy god brand machines, mainly Bosch and makita, however, a couple of months back had a job that needed a biscuit jointer. Didn't want to spend a lot as it wouldn't get much use. Bought a Draper one for about £30. Not bad at all. It also gets a bit more use then I thought it would.

Paul, don't think I am trying to disagree with you here as I'm not, but isn't the point of using proper biscuits, the fact they are made of compressed Beech (sometimes ply) that when you apply PVA, the moisture from the glue goes into the biscuit causing a swelling, which helps tighten the whole joint?

I'm not a joiner, and rarely personally use the Biscuit jointer, but that was the impression i was under :?

Regards
Woody

 

[Paul Chapman]

when you apply PVA, the moisture from the glue goes into the biscuit causing a swelling, which helps tighten the whole joint?

Absolutely right. I'm a great fan of biscuits and have been using them for years with an Elu DS140 biscuit jointer. Going back to the original post from Byron, I was simply expressing the view that if you don't have a biscuit jointer, using loose plywood tongues and grooves cut with a straight cutter in a router was probably a better option than using a biscuit cutter in a router. Also, I think that sometimes a loose tongue can a better option than biscuits and I sometimes use them in preference - it just depends on the particular job in hand.

In the past I've done a few tests (totally unscientific) by deliberately smashing a few test joints, and these have convinced me that both methods produce equally strong joints. The wood or man-made board has always broken somewhere other than at the joint.

Cheers :wink:

Paul

 

[ByronBlack]

I tend to always buy god brand machines

So thats what the old guy with the beard has been doing while everyone has been fighting over which religion is the right one - been making power-tools! It stands to reason I guess as his son was a carpenter afterall.

Paul: With the loose ply tongues - should these be glued in along their length, or just at certain points, i'm assuming it shoudn't effect wood movement etc??

 

[Pecker]

I tend to always buy god brand machines

So thats what the old guy with the beard has been doing while everyone has been fighting over which religion is the right one - been making power-tools! It stands to reason I guess as his son was a carpenter afterall.

??

Sorry! :lol: I think I'll just leave that there now, or others will wonder what the heck we're on about! :lol:

woody

 

[Paul Chapman]

With the loose ply tongues - should these be glued in along their length, or just at certain points, i'm assuming it shoudn't effect wood movement etc??

If the wood you are jointing has the grain going in the same direction (like the pieces for your bench top), then yes, glue them in along the whole of their length. It's only when you have grain going in different directions (like the recent threads on breadboard ends) where you would have problems if they were glued. Hope that's clear.

Cheers :wink:

Paul

PS One other point to note, Byron. Plywood isn't always the thickness stated. For example, 6mm might not be exactly 6mm - it might be just over or under. So you might have to faff around a bit to ensure that you have a cutter that matches the thickness of the plywood you are using. Aim for a good fit - not too tight, not too loose and cut the grooves slightly deeper than the size of the tongue so there is somewhere for the excess glue when you cramp it all up - just like you would with dowels.

 

[woodbloke]

BB - I've used plywood wafers quite a lot as well as biscuits and the ply wafers have always worked well. As Paul has said the thickness of ply is not constant so the ply wafer needs to sanded to a snug fit (I hold a half sheet of 100g paper on the bench and rub the wafer over the top) and should be a fraction shallower than the combined depth of both grooves. I've used this technique to join the corners of the plinth on my comp casket, you can see it on the Projects forum - Rob

 

[Paul Chapman]

Byron,

I've been giving this some more thought in terms of when I would use plywood tongues, biscuits or dowels.

Where time is not an issue, I reckon that in many ways plywood tongues are the best option for most jobs. They give a fantastically strong joint, can be used in most situations where you would otherwise use biscuits or dowels and have almost no disadvantages in terms of the quality of the joint. If you use a good router to cut the slots, they are very accurate. They are equally good in solid wood or man-made boards. The only snag is that the tongues take time to cut and you might find that you have a bit of additional work because the plywood is not the same thickness as the cutter.

Biscuits offer most of the advantages of plywood tongues. The big plus is that they are very fast and accurate to cut. In most cases you just have to mark the material freehand with a pencil and off you go. Where you can get a snag with them is when using material that is thin or not very dense. For example, if you use Contiboard or Contiplas or other material that uses a chipboard core and is quite thin (15mm), you can get what is known as "telegraphing". What happens is that as the moisture causes the biscuit to swell, this causes localised swelling on the surface of the material. This is only slight, but if you sand or plane the surface before the moisture has equalised (which could take a few days) you will then have a depression where you previously had a swelling. This is not a problem in many situations but could be if you finished the piece with a high gloss finish. With more dense materials like MDF, with solid wood or with thick material, you can more or less discount the problem.

If you don't have a good biscuit jointer, then most of the advantages of biscuits are lost and I would stick with plywood tongues. An inaccurate biscuit jointer would drive me nuts and a biscuit cutter in a router has only limited use.

Dowels, in my opinion, come a very poor third. I would use them only for location purposes. I think they offer very little in terms of strength. I still use them and my dowelling jig, but mainly when repairing something or using the jig to drill holes for knock down fittings.

Hope this is of some help.

Cheers :wink:

Paul

 

[ByronBlack]

Paul, Rob - thanks a lot for the tips!

I think I will go the plywood route as I don't want to sink more money into another tool, especially a power-tool!

As it happens, I have a compensated router-bit designed for 12mm ply, so i'll most probably use that bearing in mind my worktop is a shade over 2" thick so the 12mm tongues should give a good strong joint. The last thing I want is for a year or so down the line, the staves start working loose.

Also, with the festool setup with the mft now it's quite an easy process to repeat-cut the tongues.

I was thinking of making the tongues about 80% of the width of the staves.

 

[Paul Chapman]

I was thinking of making the tongues about 80% of the width of the staves.

Not quite sure what you mean, Byron :? To give you an idea of sizes, Ernest Joyce says in his book: "....allowing 5mm thick tongues entering about 6mm for 19mm boards, and 6mm thick for 25mm boards. Thicker boards require double tongues."

Sizes are not really critical and whether you use a single or double row of tongues is up to you, but the above will give you a rough idea. 12mm would probably be OK for a 2"+ thick top - it's the 80% I'm confused about. Do you mean making the grooves that deep?

Cheers :wink:

Paul

 

[MooreToolsPlease]

I think he means that if each side is 25mm deep, the combined depth of both would be 50mm.
The plywood tongue would be 80% of this size, in this case 40mm
If I am reading it correctly that is :wink: