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Matched T&G cutter problem

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tim

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I think I may well have taken stupid pills so bear with me please!

I am trying to make a bunch of long (1.7m) sided wardrobe doors - shaker style frame and panel in oak with oak veneer panels.

I have a set of Wealden bearing guided T&G cutters which will cut a 7mm wide and 12mm deep groove/ tongue ie 12mm is the bearing radius.

My problem is this:

If the fence on the router table is set for the cutters to cut slightly less than the 12mm or exactly 12mm then there is no problem. But if the bearing is slightly proud of the fence line then the cutter nips a bit off the end as the timber is unguided and the fence to cutting edge is greater than 12mm. This is a real problem when cutting the rails since they will have a very visible notch!



Obviously I can set the fence to exactly 12mm but given the width of these cutters its easy to see the issue of rails being narrower than the total diameter of the cutter and being unsupported by the fence. Plus if sacrificial fences/ exact fence alignment have to be used whats the b***dy bearing for!

I am very convinced that I am at fault here!

Cheers

Tim
 

JFC

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Clamp the work to the mitre fence. If its a slot mitre fence rather than a sliding table then a trend toggle clamp may give you the small clamping point you need for downward pressure and a quick clamp on the back of the fence should stop the timber slipping .
Its not just you so dont worry , the only way to really stop it is get the fence spot on :D
 

DaveL

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Tim,

I normally set the fence inline with the bearing by using a steel rule across the face of the fence.
What you are seeing is the bearing following around the end of the stock, which is how you would use a bearing guided round over bit to good effect but for what your trying to do is not desirable.
 

Woody Alan

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Tim

If I undertand correctly,Is it not possible to leave the rails a little long and cut to length after grooving. Other than that, the bearing is doing what it's supposed to I guess, following the work. So an offset fence or as you say sacrificial fence is needed. Just a random thought at the end of a random day. :)

Alan
 

tim

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Thanks chaps. So I wan't losing the plot then BUT whats the point of the bearing then?

Cheers

Tim
 

Woody Alan

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To put a groove in something that's not straight or to use in a handheld router to put a groove in a straight thing but being extra careful at the ends. :)

Alan
 

DaveL

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tim":2h6rcej4 said:
BUT whats the point of the bearing then?
It gives you a reference for how deep the cut should be and unlike a solid pin should not burn the work if you are cutting using just the bearing on free hand stuff.
 

Argee

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It's a question of technique as much as owt else, Tim. The bearing sets the depth, as it rides against the workpiece edge, whether in a table or not. Used in a table, a lead pin can replace the fence if the technique is good - but this is not as safe for the less experienced.

If the bearing is exactly aligned with the fence, no problems should be encountered. This is shown in the upper portion of the following diagram:



However, in the lower portion of the diagram, the bearing protrudes ahead of the fence. In this situation, the stock will ride the bearing as it is fed in from "A" to "B", although the leading corner will be slightly less than perfect. As the workpiece passes through the cutter, the leading edge will form a shallow angle along the fence, which will get shallower as the piece passes further along. This assumes that pressure is kept against the fence on the outfeed side of the fence once past halfway. As the stock clears the bearing, it will travel inwards towards the fence and receive the "notch" referred to.

If the fence is set as in the upper portion (and the steel rule method is as good as any), then provided that pressure is kept against the outfeed fence at the end of the pass, all will be well. If the bearing protrudes, then the leading edge of the workpiece should be fed in at right-angles to the bearing, then passed to the left as normal. As the end is reached, it will be necessary to ease the piece off the bearing perpendicular to the direction of the cutter. This is really difficult to do safely, but not impossible.

It really is worth the effort to get the fence spot on, even if it means a few passes using scrap.

Ray.
 

tim

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Given what this kind of cutter is for ie rails and stiles - the long side is not the problem really, its the short end grain which has no real bearing surface - thus making a lead in pin impossible to use.

As I said, I can get the fence spot on (I have an Incra one which makes it a doddle) but I am rapidly coming to the conclusion that the bearing serves no purpose in this type of cutter.

Cheers

Tim
 

Argee

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Sorry, Tim - I misread the problem entirely (senior moment!). I've got a mitre track which helps with the ends, but I still tend to feed into the bearing instead of riding along it at the start of the cut. As soon as the cut is stable, I grip the stock to the mitre gauge fence and ease it through, taking care not to relax the grip at all. Clamping, as JFC suggests, might be a good idea if you've got a very accurate mitre gauge in the track (and if you've got Incra gear, you're probably there already). Test with scrap and set an end stop, perhaps?

Ray.
 

JFC

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Well if you all incred up then clamping has to be the solution , i have the record with sliding bed and added my own fence to the one supplied and still get this problem until i clamp the work to the sliding bed . Remember you are trying to hold 20 000 rpm or summit like that with you hands it can be done but you need to be really good like i am :lol: :lol: :lol: :lol: :lol: :lol: :lol: ok i lie i clamp down :lol:
 
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