Routing - Why use Guide Bushes instead of bit + bearing

[Prizen]

Hi all

Just a general query - out of curiosity, why do some route with guide bushes / copyrings instead of just using a bit with a bearing?

 

[Setch]

Cost of cutter, and ability to adapt depth of pass to the material being cut, rather than having to take a deep pass to engage the bearing.

 

[Bingy man]

I find guide bushes give a smoother cut edge as if you are routing any type of particle board the bearing will bounce on any miner dents and dings and this of course is transferred to the workpiece.

 

[Spectric]

With a bush you can use any router cutter, I find cutters with bearings are better suited to flush triming task.

rather than having to take a deep pass to engage the bearing

Not always, with some cutters you can change the bearing. I have the Wealdon flush trim cutter that uses a 19mm bearing as standard to give a flush trim, but on some jobs using a template where the amount of material to be removed varies a lot then I use bearings that are over sized so it takes a smaller cut.

So you start with the larger bearing and work down until you use the 19mm for final flush trim, the largest bearing I have is 5.5mm oversize so you can bring an irregular cut down to template in smaller passes.

 

[mikej460]

Also, when plunge cutting, guide bushes enable you to increase the depth gradually relative to the template. I use both dependent on the type of cut and the depth of the template/guide. For trimming and shallow plunge cuts I tend to use bearing cutters, for deep plunge cuts using a shallower template/guide I use bushes.

 

[johna.clements]

 

[johna.clements]

I have only done a few cuts as only have had a router for a few months. But I would say bearing for one off and a bush for repeats.
But as i said a may be wrong, I have only used a bearing..

 

[bp122]

One guide bush can serve a multitude of cutters, so a small number of guide bushes can give you plenty of options, and will be still far side cheaper than having the same number of options with bearing cutters.

 

[LancsRick]

Having taken a nice big gouge out of wood before, bearings on cutters can fail. Rare, but definitely rage inducing if it happens (it's not the bearing that fails per se, but if it sticks it can undo the screw).

Still use them though!

I also have many bottom trim cutters but none with bearings at the top, so that's another reason why guide bushes cam be useful.

 

[ColinDeVelen]

Guide bushes are also useful in positioning the router. Think large tramelling jig, shelf pin jig.
Also, assuming you mark the center of the cut, you can switch bits, keep the same guide bush, and the cut with the second bit will follow the cut with the first (clearing a sliding dovetail and then actually cutting the dovetail is an example).

 

[Sideways]

When working with a bearing guided cutter that needs to be set full depth from the start, you can always freehand a few light passes to work upto a final pass where you engage the bearing. Light freehand passes are sometimes more easily controlled routing "the wrong way" ie climb cutting, because the bit is less likely to dig in to the edge. Of course you have to be handling the router expecting it to pull away from you.

If you happen to be edge routing a straight edge using a bearing guided cutter, you can fit the normal fence and use that to control the incremental passes if you want. Remove the fence for the final pass on the bearing.

 

[rogxwhit]

In the real world, what you use could be determined by what you have to hand.

Routing isn't all about profiling edges, though, and there are circumstances where only a guide bush will do the job. An example could be a plunge cut defined by a template located on the work.

 

[Spectric]

They are essential with jigs, a circle jig or anything else because they allow the router to be precisely located and can allow you to do things that a cutter with a bearing will not. Think of a jig for cutting a circle or large curve. These guides written by Ron are a good read.

https://www.wealdentool.com/kb/rons-tips/guide-bushes/guide-bushes-part-one-basics/
https://www.wealdentool.com/kb/rons...t-two-commercial-jigs-templates-introduction/
https://www.wealdentool.com/kb/rons-tips/guide-bushes/guide-bushes-part-three-commercial-jigs/
https://www.wealdentool.com/kb/rons-tips/guide-bushes/guide-bushes-part-four-commercial-templates/

 

[Ollie78]

For me it's just because you are not limited in depth by the cutter and bearing.
You can do cuts in stages rather than in one giant cut. It's safer and as others have said you can use different cutters.

Ollie

 

[Fergie 307]

Not common to have the bearing go, but if it does then all to often the result is that you make a right mess of the job. Has happened to me a couple of times. I always try to avoid them.

 

[Sgian Dubh]

Routing isn't all about profiling edges, though, and there are circumstances where only a guide bush will do the job. An example could be a plunge cut defined by a template located on the work.

Agreed. An excellent example for using a guide bush plus template rather than a bearing guided bit is making cash till cut-outs in pay station tops. e.g., for bank and building societies. A template, plus guide bush, plus a 12 -16 mm diameter cutter, plus powerful plunge router will do the job very cleanly and efficiently. It's pretty much an identical process to that required for many other applications, e.g., making a sink cut-out in kitchen worktops, cut-outs for letter plates, and so on. True, the job could be done with either a top or bottom bearing edge trimming bit, but that method still requires a template to run the bearing against and a means to cut the cut-out close to the finished size, typically involving drilling a hole or holes with a drill and bit plus a jigsaw, and sometimes a means to minimise chip-out of HPL, veneer or some other form of decorative top surface. Slainte.

 

[peter-harrison]

As noted above, there's no right answer. However, flush trim cutters make template design and making an awful lot easier, especially if your template has internal and external elements.

 

[bp122]

Not common to have the bearing go, but if it does then all to often the result is that you make a right mess of the job. Has happened to me a couple of times. I always try to avoid them.

This reminded me of the mess I made on a photo frame recess. It was a cheap Router bit when I didn't know any better, flung the bearing out and the bit just ran riot!

You are right, it is rare but when it goes you had better be awake. Shouldn't happen with good quality cutters though.

 

[HamsterJam]

With right combination of bushes it it possible to route a piece that is an exact fit for a hole. (Think inspection hatch in a floor or a router table inset for example).
As others have said plunge cutting doesn’t really work well with a bearing, although a fence or guide rail often works here.
Cutting kitchen worktops using a jig.