1/4" shank x 25mm+ cutting length straight bearing bits?

[d.m.s]

looking for a top bearing pattern bit with a 1/4" shank that will allow me to route deeper than 25mm in a pass?

[Template Tom]

looking for a top bearing pattern bit with a 1/4" shank that will allow me to route deeper than 25mm in a pass?

If you are considering doing it in ONE pass then it is not a good idea.
Have you ever considered using template guides and a straight cutter without a bearing? This may give the extra depth you require
Tom

[ian]

looking for a top bearing pattern bit with a 1/4" shank that will allow me to route deeper than 25mm in a pass?

after looking through the CMT catalogue, I don't think they exist.

if you need more than 25.4mm of cutting length, you need a 1/2" shank bit

[elanjacobs]

Nothing from Carbitool either.
Could you do it in multiple passes? Run the bearing off the template, then plunge and run the bearing off the shape you just cut.

[Ratbag]

An inch deep in a single pass with a 1/4" shank is just too much at once! It isn't safe, and will seriously overload the router's bearings, the collet fastening and the bit's shank, and something's bound to give.

Apart from anything else, at an inch deep there's nowhere for the swarf to go other than behind the bit's passage through the groove. This means compaction, friction and heat, all enemies of a good clean job.

Although you haven't mentioned the actual width of the trench, I'm assuming that it's just one pass, so the same rules apply irrespective of width, except that the broader the groove, the greater the overall strain on the system.

You've had some excellent advice from others already and should take heed.

To effectively groove 1' deep you would ideally need to:
(a) take at least 3 passes to provide adequate "chip" clearance and minimise undue loads.

(b) use a spiral upcut solid carbide bit for "chip" clearance.

(c) use double fences, a template follower guide or some alternative means of guidance other than a top bearing which would hinder swarf clearance.

(d) where possible use a 1/2" shank bit to provide stability and security.

[d.m.s]

for the others with helpful advice there's no trench I'm not plunging down to full depth right off the bat on a solid lump it's for cleaning up cavities after roughing in with a forester bit to remove the bulk of material with a drill press so I'm left with 1-2mm around the perimeter and 1 or 2mm on the base of the cavities.Sorry for the confusion I assumed it was just common sense not to route something that deep without removing a bulk of material first.
this is the end product anyway
stra5413.jpg

Nothing from Carbitool either.
Could you do it in multiple passes? Run the bearing off the template, then plunge and run the bearing off the shape you just cut.

that's what I've been doing for years.sometimes leaves a ring though and was looking to do it in just one pass and avoid the ring + less time.

I've not gone down the templates and a guide due to the offsets I'd really REALLY rather not go ahead and make all my templates over again (100+) besides when I do repair work I'm often setting up a fence on the piece and not using a template at all

[Ratbag]

Ok I sort of get it now. Please ignore my rather terse lecture. It was meant with the best of intentions.

I still think you'll need 2 passes though: one to clean up the sides to the desired width, and another to depth with the bearing against the sides at the correct width.

I doubt anybody makes 1/4' shank cutters longer than 1" for the reasons already stated.

Maybe it's time to look at a deep plunging 1/2" router and long shank cutters. The DW625 is one of the better ones in this regard (80mm from memory I think).

[ian]

for the others with helpful advice there's no trench I'm not plunging down to full depth right off the bat on a solid lump it's for cleaning up cavities after roughing in with a forester bit to remove the bulk of material with a drill press so I'm left with 1-2mm around the perimeter and 1 or 2mm on the base of the cavities.

that was what I thought you were doing -- cleaning up the last mm or so after roughing out the shape.

I've not gone down the templates and a guide due to the offsets I'd really REALLY rather not go ahead and make all my templates over again (100+) besides when I do repair work I'm often setting up a fence on the piece and not using a template at all

Maybe it's time to look at a deep plunging 1/2" router and long shank cutters.

factoring in your existing investment in templates a mid range (power and weight wise) 1/2" router would appear to be your best option. Some are available with 1/4", 8mm and 1/2" collets.