Guided straight cutter - bearing on top

[PerranOak]

So! I realised that I can us the router to size a piece of ply for a drawer bottom! I know, bit slow(!)

Now. I used the straight bit that came with my dovetail jig (for finger joints, I guess). It has a bearing on top of the cutting edge. I marked out the size I wanted, clamped a straight board on top of the ply, right on the line.

Then I routed with the bearing on the board, cutter on the ply.

TOTAL SUCCESS! I can't believe how good this routing lark is!

So, problem. Every guided straight bit I see has the bearing UNDERNEATH the cutting edge! How mental is that!!

I can see that this is useful to trim a top on a project, sure. Why though, aren't the "bearing on top" ones very common?

Do they have a special name? Where can I get one or two?

Cheers.

 

[Big John]

Try Wealden's they stock them.

 

[Argee]

Look here for top bearing and here for their brilliant down-shear trim bit (bearings top and bottom).

Ray.

 

[jasonB]

Better still get one with a bearing on both ends, replaceable tip makes it cheap in the lonng run.

Jason

 

[BradNaylor]

If you need one in a hurry B&Q stock the ones with the bearing at the top.

Dan

 

[Derek Willis.]

If you have bearings, you can put a 1/4 bore on a 1/4 shank cutter of your choice, why buy special ones. In any case bottom bearings are the most useful cutters when used ina table, as most people would do.
derek.

 

[John. B]

Even better,
Make up another base from polycarb or phenol. If you have a lathe as well, making a base is a doddle.
Get a set of bushes from Axminster, a cheapy set of 12 for under £20.00.
you'll be able to use your excisting cutters then. Then for special jobs follow Ray's (Argee) link to Wealden and have a look at their Spiral fluted cutters.
They are magic :tool:


John.B

 

[PerranOak]

Ah bushes.

I'm only part-way through my router book and don't really get the idea of bushes.

 

[Derek Willis.]

Once you get used to using guide bushes there are a vast number of jigs you can make to make life much simpler, one of my favourite jigs, and one I was using only last week a great deal, is my Slotted Tee square, this takes a guide bush and is used for making repeat housings, slots, which recently made life easier in the making up of a very large box shelf unit all in moisture resistant m.d.f.
Derek.

 

[wizer]

I was using my Wealden Pattern bit today (bearing top an bottom). Love it. Best bit i've ever bought.

 

[Chris Knight]

Like Derek says, bushes are extremely useful - much more versatile than bearing bits (although not as convenient for some jobs). It really is worth the effort of experimenting with them and making a few simple jigs. One I use over and over with a guide bush, is a jig for making mortices in a line to receive eg upright dividers in a bookcase or cabinet.

 

[wizer]

I bought this jig a few years ago to cut in the hinges on my old workshop doors.

It came with a bearing guided cutter. The bearing slipped no matter how much I tightened it. In the end we did all 12 hinges by hand. A couple of months ago I was going to bin it, then I realised I could use a guide bush with it! So it's been saved.

 

[Derek Willis.]

When cutting housings for butts, it is much easier if you make your own jig from m.d.f. to the exact size of the butt and then use a c.m.t. milling cutter which is 12mm with a bearing of the same diameter and it is only 12mm long, therefore making the cutting of housings very simple and always accurate.
derek.

 

[chippy1970]

At a guess I would say the bottom bearings are more common because they are used for trimming Formica etc.

If you have a decent tool shop near you you should be able to get both really easy anyway. I must admit I have had and used routers for over 20 years and have never bought the top bearing type where as I have had loads of the bottom bearing trimmers.

Wizer,

How do you get on with that jig is it good quality ? I think Axminster advise you to use a guide bush with it anyway and not the cutter it comes with. I prefer using single hinge jigs I hate that Trend 3 hinge jig its rubbish in my opinion.

 

[PerranOak]

I must admit I have had and used routers for over 20 years and have never bought the top bearing type where as I have had loads of the bottom bearing trimmers.

Interesting. Maybe I'm doing something wrong?

What I do is to use the router to trim very near to a line (then hand plane the last little bit). I clamp a straight edge over the piece to be trimmed then use the top bearing on the straight edge to trim the piece below it.

If I used a cutter with a bearing on the bottom then the straight edge would have to be underneath the work-piece and I couldn't align it properly.

Am I bonkers?

 

[wizer]

Wizer,

How do you get on with that jig is it good quality ? I think Axminster advise you to use a guide bush with it anyway and not the cutter it comes with. I prefer using single hinge jigs I hate that Trend 3 hinge jig its rubbish in my opinion.

Sorry, missed this.

I have not yet used it with template collet. But in terms of build quality: It's ok. IIRC It clamps well and it has rulers but I assume you ignore them as they are slidey.

I have heard other people talk highly of them since I bought it (used with template collars).

I wonder if Rutlands are still selling it with the bearing bit? I guess that's easier to sell than something that needs a template collar.

 

[Derek Willis.]

Perranoak,
Most people would use cutters with the bearing at the bottom, as I do, but for use in a table to do the same job as when using a router freehand and with a top bearing, they all have their own uses, as they say,'horses for courses'.
Derek

 

[chippy1970]

I must admit I have had and used routers for over 20 years and have never bought the top bearing type where as I have had loads of the bottom bearing trimmers.

Interesting. Maybe I'm doing something wrong?

What I do is to use the router to trim very near to a line (then hand plane the last little bit). I clamp a straight edge over the piece to be trimmed then use the top bearing on the straight edge to trim the piece below it.

If I used a cutter with a bearing on the bottom then the straight edge would have to be underneath the work-piece and I couldn't align it properly.

Am I bonkers?

No just do it how you find works, both types of cutter have different uses. I suppose I never use the top bearing cutters because I just use a template guide bush instead but then you have to allow for the difference between the cutter and the bush when making your template.

I just thought of another reason for using the bottom bearing trimmers, if you accidentally tilt the router while trimming it wont damage the work but if you are using the top bearing cutters it will damage the work if the router tilts over while cutting.

 

[PerranOak]

Derek, thanks that is true. I'm learning with th router and don't want to go too far off on a limb.

chippy, that's a good point, didn't think of that: I've been lucky so far!!!