Top or Bottom bearing router bit?.

[Mreagleeyes]

Just a quick one.
The girlfriend wants a small side table made similar to this,

I have cut and jointed the top and cut four rough sized legs and also the template in 1/4" MDF and was wondering what the best cutter would be to create equal shaped legs.
Would it be the Top bearing

Or Bottom bearing

I have allowed for the excess on the legs so I can screw the template down so it dose not matter to me if the template is on the bottom or top when I come to route the pieces.
Does it have something to do with the way in which I use the router, ie hand held or in a Router table?.
I'm hand holding the router.

 

[Smudger]

In my experience (limited) using a top-bearing cutter handheld means that you may strike the bench or, if using, the anti-slip mat. So if hand-holding and using a reasonably thick template it may be preferable to put the template below and use a bottom-bearing.
I have no idea how that would affect tear-out, and would love to know from someone who understands it better.

 

[Mreagleeyes]

That's one of the things that I thought may affect it, the tear out factor, but surely it dose not make any difference.
Someone will come along shortly and give us the definitive answer, or maybe they won't and I'll order the wrong one!!.

 

[jasonB]

You will get tearout when moving the router into the grain, two options to avoid this

1. Reposition the template on teh other side so you are always cutting down the grain, obviously can lead to misalignment.

2. Use what I prefere, a double bearing cutter with replacable tips, that way you just flip the work/template over without having to reposition the template.
I have the Wealden one which works out quite cheap as the blades are double sided so you get a sharp bit for a few quid.

Jason

 

[OPJ]

In my experience (limited) using a top-bearing cutter handheld means that you may strike the bench or, if using, the anti-slip mat.

Yes, but that's where the Bench Cookies come in! :wink:

 

[mailee]

I only have a bottom bearing cutter so use that. I place the template on a piece of MDF scrap with the wood taped with double sided tape on top of this. Try to work with the grain as much as possible and trim the wood to a rough size first. HTH. :wink:

 

[Mreagleeyes]

The template I have made has 100mm over hang at the top and bottom of the legs so I can either screw or bolt this to the work piece.
I can therefore rotate the piece so the template is above or below the work and in turn this can be attached to a piece that I can clamp down to my bench if I need a little more security.
Never had a problem with working out where the bench is and cutting into it, had a router bite down onto a steel work top that I was using as a rest and as a result have ever since checked the cutting clearance for obvious reasons.

 

[Smudger]

In my experience (limited) using a top-bearing cutter handheld means that you may strike the bench or, if using, the anti-slip mat.

Yes, but that's where the Bench Cookies come in! :wink:

Looks good. The traditional answer was to drive a few nails into the workbench, apparently...

 

[Smudger]

The template I have made has 100mm over hang at the top and bottom of the legs so I can either screw or bolt this to the work piece.
I can therefore rotate the piece so the template is above or below the work and in turn this can be attached to a piece that I can clamp down to my bench if I need a little more security.
Never had a problem with working out where the bench is and cutting into it, had a router bite down onto a steel work top that I was using as a rest and as a result have ever since checked the cutting clearance for obvious reasons.

Trouble is, if you have a longish cutter it may end up quite tight, and if using a rubber mat it can squash down. And then get caught on the cutter...
DAMHIKT.

 

[jhwbigley]

At the points where you cant go with the grain, you could do a climb cut.. 8)

thats what i've been doing for a few bits for some rails.

Just make sure you rough it on as close to the line as you can, dont want to be taking 5 mm off when climb cutting.

JHB

 

[chingerspy]

The bench cookies look really handy. There was an article in one of the mags giving ideas on how to make your own with circles of wood and router matting for the tops/bottoms.

For £11 the manufactured ones look the danglies, why make your own at that price

 

[Mreagleeyes]

Just make sure you rough it on as close to the line as you can, dont want to be taking 5 mm off when climb cutting.

JHB

I've got roughly 3mm-5mm to remove and will do this with as many runs as it takes.
Thinking I may make a second template to go above the work and bolt through the two templates and the work piece to try and prevent as much tare out as possible.

 

[wizer]

I used the double spiral bearing that Jason mentioned. It's great if you remember to change direction. It depends on the wood, but I'd only want 1mm max of excess to trim. With that little, the danger is greatly reduced.

Please be careful with this operation. I nearly lost a finger doing this on the RT. Make sure you have plenty of guarding and your fingers are well away from the cutting action.

 

[Smudger]

The bench cookies look really handy. There was an article in one of the mags giving ideas on how to make your own with circles of wood and router matting for the tops/bottoms.

For £11 the manufactured ones look the danglies, why make your own at that price

I tried to use router matting as a base for push guides on the router table. A nightmare to stick! Might be easier to staple it.

 

[jhwbigley]

You should get a good result from a brand new cutter, and bigger the diameter the better.

Just thought i'd explain what a climb cut is, and about grain direction

above shows a bad drawing of the rail from my last post. i've shown the router direction.

(working form the left)At first you feed the router the normal left to right, till you get to the middle. then change to feed the router from the right to the left.

This way you are working with the grain. like stroking a dogs fir the right way, one way its smooth, the other way you ruffle it up.

Its all just like hand planing.

JHB

 

[Doug B]

Did Jase colour that in for you JH. #-o #-o

 

[wizer]

and take it from me. Don't go anywhere near the end grain :shock:

 

[jhwbigley]

and take it from me. Don't go anywhere near the end grain :shock:

or climb cut on a router table or one of these

:shock:

JHB

 

[Mreagleeyes]

Did you do that for me Mr jhwbigley?. If so your a true asset to this forum.
I sort of understood your method in your first post, thanks for clearing it up.
I've trimmed with a router before so fairly confident of taking it easy and the right direction for the grain.
Was just unsure of whether I should be getting the Top or Bottom router bit, and the difference in the two processes and if one is more suited to a hand held method as the other for a 'Table' method.

The timber I am using is Oak at 28mm thickness so I could get the Wealden double bearing with a cutting depth of 30mm.

 

[Chems]

Thats great to put up a picture of it. Someone should sticky it up as it keeps been asked on here. People seem to think climb is the devils work but its better than going with the grain and getting it dig in and shoot off.