routing a 1/4inch curved trench.

[Pauls321]

Hi all,

I want to router a semi circle say 5mm deep into a piece of 12mm timber. I want the width to be 1/4 inch, hence a1/4 inch bit would be perfect. But if I was to make a template out of say mdf board, I cant seem to find any pattern bits or flush trim bits that have a 1/4 inch shank with a 1/4 inch bearing with a 1/4 inch cutter. I don't think they exist.

Any thoughts,...

Paul

[NCArcher]

Use a standard 1/4 inch bit with a template guide.
http://www.ebay.com.au/itm/like/281661581430?limghlpsr=true&hlpht=true&ul_noapp=true&hlpv=2&chn=ps&lpid=107&ops=true&viphx=1 something like this

[snowyskiesau]

Try these guide bushes from McJings (https://mcjing.com.au/categorybrowser.aspx?categoryid=1252), much cheaper.

[elanjacobs]

You could run a solid carbide bit with a template, using the shank as the bearing surface. I wouldn't recommend it if you have a whole stack of parts to cut, but it's fine for a few pieces. I've done it before and it worked a treat, just don't press too hard against the template to minimize heat build-up.

[ian]

mount your router on a trammel to cut the semi-circular slot

[aldav]

If you're going to go to the expense of buying a set of template guides get a set with the biggest diameter guide you can, like these (in the black box) - https://www.carbatec.com.au/search?ProductSearch=router%20template

The larger guides make the set much more versatile when using templates you have made using a smaller guide bush. You can use much larger diameter cutters. Nothing more frustrating than having to use a 1/8" cutter because you don't have guides of a diameter big enough to allow you to use 1/4" or even a 3/8" cutter with that set.

How big is the diameter of the circle Pauls321? You could possibly use a router circle cutting jig like this - https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRSh9CfJOq8qq5qws2VU7c8Etg4sCE7-JDQGp6cHdbNfwVZxwMENw

[Lappa]

They are available
http://www.toolstoday.com/c-311-core-box-router-bits.aspx

i suggest you ring AP Workshop as they sell Carbitool router bits and have managed to get me what I have asked for.

[Chief Tiff]

They are available
http://www.toolstoday.com/c-311-core-box-router-bits.aspx

i suggest you ring AP Workshop as they sell Carbitool router bits and have managed to get me what I have asked for.

Lappa's link takes you to core box bits but here is the page for miniatures flush trim bits:

http://www.toolstoday.com/p-6238-miniature-flush-trim-plunge-template-router-bits-with-upper-ball-bearing-guide.aspx

I would never have thought such a thing existed so once again I am amazed by the wealth of knowledge held by the forum members!

[Ratbag]

A template guide, as stated above, will work nicely provided its I.D. > 6.35mm, and the offset is calculated to provide the required radius.

Another alternative is a circle guide. This can be as fancy & complicated as you desire, and provided you mount both router, pivot and board in the same plane relative to each other can produce circular (& of course semicircular) work of an almost infinite variety of radii. A perfectly serviceable guide that I occasionally use consists of nothing more than a length of stiff fencing wire with a loop @ one end passed over a nail or screw or even a thumbtack with the other fixed in the router's guide rod holes. Smaller, lighter more compact hand-held machines like my much-loved Elu 96E seem to work best in circle work: bigger ones can get a bit unruly.

Yet another alternative is to use a standard 1/4" bit with a height offset which allows the plain shank of the bit (when fully plunged) to bear directly on the template edge. A liberal wipe of dry soap on the template's edge will help eliminate friction and burning.

[elanjacobs]

Wow, only ever seen a 1/4" bearing on the end of a 1/4" bit, didn't think you could get them with a top bearing

[Pauls321]

Hi and thanks everyone for all your ideas. The plunge router I use is a pretty cheapie, I've sort of got it on permanent loan from one of my sons. Its a small Ryobi and isnt that flash. My really good Triton plunge router is permanently mounted underneath my home made router table and I dont want to disturb that. The Ryobi has a metal template follower I found in the original box, which I will try tomorrow. I tend to think this router isnt designed for those brass bush guides on your links. Unless I can maybe make another base for it.

This is what I would like to be able to make.

http://www.rockler.com/how-to/tambour-topped-box/

Paul

[John Saxton]

Wow, only ever seen a 1/4" bearing on the end of a 1/4" bit, didn't think you could get them with a top bearing

Here is a link to real cheap (not talking quality ) top bearing 1/4"router bits.

http://www.ebay.com/bhp/top-bearing-router-bit

[Pauls321]

Hi again, That 1/4" miniature router bit from America looked good, but it would have cost about $90 to get it here with postage and conversion. I just found this on ebay, and bought it for ten bucks. Worth a try.

http://www.ebay.com.au/itm/Flush-Trim-Pattern-Router-Bit-Shank-Bearing-Woodworking-/281826769515?var=&hash=item419e2f3a6b:m:mCcvvTMRIlX0dJJWG-ZdGUg

Paul

[GarciaJ]

As they say, there are many ways to skin a cat (I never understood why anyone would skin a cat). A pair of reference points somehow mounted outside the router base (eg via the guide rod holes) following the edge of a semi circular template with a straight bit will cut a semicircle with a bigger diameter. If you already have the bit then the additional cost is $0 because which ever way you go you will need a template. If the straight bit is narrower than the intended with of the trench, make a second cut after adjusting the reference points. Would only work well for large diameters, and only on circles or arcs.

Sent from my C5302 using Tapatalk

[BobL]

Yesterday I started making a large 90º rectangular junction for a dust extraction system.

I needed to cut 4 x 90º curved channels, 2 @ ~450 mm radius, and 2 @ 280 mm radius.

The router comes with a circle cutting jig but it is only good for about 200 mm radius, so I removed the centre locator from the jig and replaced it with a strip of metal ~450 mm long.
By drilling holes every 70 mm I now have a circle jig that is good for up to about 500 mm radius

Worked a treat. The channels only needed to be 2mm deep but they could just as easily have been 5mm.

[joe greiner]

This router compass can work from a few inches (~100mm) radius to several feet (~1000mm); or more with added coupler nuts.

http://www.woodworkforums.com/showthread.php?t=50372

Cheers,
Joe

[ian]

Hi Paul

from my perspective nothing to it.

If the router has a template following attachment, make a template and use the guide.

if not make a trammel, screw the router base to the trammel -- the last trammel I made was for a Makita trimmer. I used 3mm MDF to make the trammel and attached the trimmer using the screws which normally attach the trimmer to its base plate.
a trammel is just a simple jig for cutting circles.

a trammel how to http://www.woodworkingtips.com/etips/etip030201wb.html

[Pauls321]

Thanks for all these ideas fellows. I got those plans blown up today at a shop so they are now life size. I'll get a start on this shortly. I did order that bit I mentioned, will be a cheapie but. I'll also try the template following attachment that come with this small router.

Paul