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View Full Version : Creating a chamfer with a medium size router



PaulHenry
08-12-2007, 12:03 AM
I need to make a chamfer (preferably 30-45 degrees) on the edge of a shelf made of MDF, but the local shop told me I should not use a chamfer bit in my hand held, 1 3/4 HP router.

I think the shop gave me the right advice, since the 45 degree chamfer bit would spin much too fast in a router that has no variable speed control.

I was thinking I could work from the underside of the shelf with a straight or rabbet bit, and remove a little bit at a time, so I ended up with steps, and then sand the steps smooth with sandpaper. In other words, my first pass with the router would be 3/4'' wide but only 1/8'' deep; my second pass would be 5/8'' wide but 1/4'' deep, and so on.

Oh yes, the shelf is curved, so I will need to guide the router, using a pattern made of MDf, set on top. I don't have any bushings for my router, though I suppose I could get some. (Money is real tight now.)

The last time I did this, for my last project, I used one of those portable drill guides with drum sander attachments, and set an angle on the portable drill guide. This method is a bit imprecise and takes a while. I have 16 feet of board shelf to chamfer.

rrich
08-12-2007, 12:40 AM
Paul,
Permit me a bit of scarcasm...

And how much did you say that the shop would charge to do the routing for you?

Seriously, with a bearing guided chamfer bit, you should be able to cut a chamfer with your router.

Clamp your shelf to the bench. Place a second shelf parallel to and about 3 inches from the first shelf and clamp to the bench.

The second shelf is going to help to support your router. Set the depth of the router bit to the size of the chamfer desired. (Depth determines the size of the chamfer.) Run the router along the edge of the shelf to cut the chamfer. If you want to, you can cut the edge of the other shelf with this set up. If you feel the need to make multiple passes, make all your cuts and then lower the router bit for the next cut.

With all that said...

Why not just get an Ogee bit for the router? I think that you would like the looks of an Ogee on the shelf edge rather than the chamfer.

beamerweb
08-12-2007, 03:05 AM
I wouldn't worry about it at all, Paul. You should be able to spin a chamfer bit just fine in that router (I have, several times). While speed can be important, you can usually work around that by taking small bites. Set the depth to around 1/3 of your final depth and make one pase, set it to 2/3 and make another, then go just a HAIR less than your final depth and make one more pass. Then adjust to your final depth and take a few molecules of. This helps take out any burning you may get as well as give you a tasty smooth surface in the end. :)

cabinetman
08-12-2007, 07:12 AM
Adding to the already good advice given is that you'll notice either a sound or difference in feel in your procedure, if you are moving too fast or slow, or taking too much off at a time. Most all of todays routing procedures were done with single speed, fixed base routers, before the "variable speed" and "plunge base" routers ever came out. It's up to the operator to come up with the right combination. Think safety first. If something you are attempting doesn't seem right, evaluate your procedure.

PaulHenry
08-12-2007, 01:15 PM
When at the store, Woodcraft, we looked at roundover bits with a 3/4'' radius, quite a big bit for a hand held router. Rockler also recommends that you only use a 3/4'' roundover bit in a router table.

My intent is to create the chamfer so that the highest part is on top, so that the edge goes down and away from the front. In other words, if you took the shelf and turned it upside down and used a roundover bit, then flipped it rightside up, you would create the edge I want.

I could use a chamfer bit:

http://www.rockler.com/product.cfm?page=2124

which can definitely be used in a hand held router,

or a roundover bit

http://www.rockler.com/product.cfm?page=2127
(91342 1/2'' Radius X 3/4'' High)

which can definitely also be used in my router and my be just big enough. The roundover bit might create a more gentle edge; the chamfer bit would completely hide the edge, which might give the visual pleasing appearance of a thin ledge.

The piece will be modern, with sharp clean lines.

There are also chamfer bits with 30 degree and 15 degree angles.

At any rate, it seems that I *can* use a router bit, and certainly the camfer bit, so thanks for the help.

JBark
08-14-2007, 04:27 PM
Paul,

Just wanting to add to the help given with a word of caution when asking questions...the obvious, be careful who you ask. Is it that this shop wanted to charge you or were they just dumb? Something to think of in the future...many a professional can hang out a sign, it doesn't make them knowledgeable.

John

PaulHenry
08-14-2007, 04:47 PM
I think the shop is pretty knowledgeable. It is woodcraft, a national franchise (or maybe chain), and all the people who work there are die hard woodworkers.

To be fair, the sales rep thought I would need a 3/4'' roundover bit. If you look at the link above, rockler.com says the same exact thing as the sales rep: don't use such a big bit unless you use it in a router table and unless you use it at a slower speed.

However, I can't figure out why the sales rep didn't steer me in the direction of a smaller rounderover bit or a chamfer bit. If nothing else, one of these two bits would have removed a lot of wood and made my sanding job easier.

Even good shops can give bad advice. Porter paint has done this to me a number of times, once telling me by a paint sample that the paint on the house was latex and I didn't need to prime. I knew for a fact that the paint was oil because I had painted it last time. Can you imagine the loss of labor and the complete disaster I would have created if I had listened to them!

(Any suggestions on *which* bit I should use--small chamfer, big chamfer, roundover?)

beamerweb
08-14-2007, 05:11 PM
Woodcraft is in the business of selling you more tools, of course. And I wouldn't put a TON of stock in everyone who works there. They're subject to the same mental haze that any other retail outfit is.

I'm not tryin to disparage them, by any means. I just wouldn't put them too high on the Practical Woodworking Advice chart, in my book. Maybe I'm a cynic ... but they DO have an interest in getting more of your money.

3/4" diameter bits are absolutely FINE in hand held operation. 3/4" radius roundover bits, though, would be over 1 1/2" diameter and THAT would certainly be pushing it for handheld use. Though, grab a scrap chunk of flat stuff (ply, mdf, melamine, etc) and bolt yer router under it and you have yourself a quick router table! Clamp a 2x4 for a fence and yer good to go :)

PaulHenry
08-14-2007, 05:42 PM
Point taken. Though, they actually missed out of the opportunity to sell me a 3/4'' bit!

I have a small, tiny router table, 12'' by 16''. Am not too thrilled about trying to run a 12'' x 24'' shelf across it. Plus, I don't have a device to slow down the motor. On the other hand, I guess I just could fasten it to a bigger piece of plywood...

beamerweb
08-14-2007, 07:22 PM
You probably don't have to slow down the router.

In the 1" to 2" diameter range it's borderline. Over 2" and it's a must, but below 2" is most likely fine. I rarely slow my bits down, table or not. I never use anything over 2", though.

My chamfer bit is probably the largest diameter bit I use the most and it does perfectly fine at full boar, really.

Lemme find that chart ...

http://www.rockler.com/articles/display_article.cfm?story_id=135

Not quite the one I was thinking of, but this gives you a good bunch of info nonetheless. Near the bottom, they give speed suggestions.

That 18k-22k range is really tough to measure with most speed controllers ... without a tacheometer, you'd be hard pressed to count the RPM's with a given electrical supply. You'd basically just dial back until you start to hear the sound change a bit.

In my experience, people generally only bother to slow down the monsters over 2". It's usually a matter of "slowish" versus full tilt. Slowish sounds a little different than full tilt, but sound's not a great measure, either. The real test is how it cuts ... if it cuts bad, speed adjustment may be needed (slower OR faster).


Edit: Oh, another factor that may or may not be important: My chamfer bit is about 2 1/4 diameter at it's widest point. I've never cut way out there, i always cut way up by the bearing. I did a 1/2x1/2 chamfer (45 degree) in 3 passes on cherry at full speed using that bit. I think the diameter around the area I was cutting was probably close to 1", maybe 1 1/4" at most. Since the rest of that width wasn't doing the cutting, maybe that had something to do with my success.

I don't know if i'd ever have a call to make a chamfer quite that big using my router. I'd probably do such a thing in MANY passes, maybe even hogging off most of the stock to be removed with my tablesaw if possible. In that case, i might back the speed off just a little bit if the cut improved any.

rrich
08-15-2007, 01:54 AM
Paul,

Generally speaking, When using a round over bit for edge treatment, the round over bit size should be less than half the thickness of the material that you are rounding. This is not ALWAYS true as there are some situations where you might want a unique edge treatment.

I'm assuming that you are building shelves that are 3/4" thick. To get a nice round over a 3/8" bit would be about right. You may want to do a 1/8" or 1/4" round over on the bottom edge also.

Remember that the bearing has to have some unshaped stock to guide the cut.

PaulHenry
08-15-2007, 11:28 AM
I don't really want a conventional roundover. I want the chamfer to go under the shelf to create a ledge. The high part of the edge will be on top and the cut will go underneath.

http://www.woodworking.com/dcforum/DCForumID17/395.html

The first and last image show a type of upside down roundover with an angle of about 15 degrees. I want to use a router next time (the shelves will also be curved) with a steeper angle, maybe 20 degrees, maybe 30, maybe even as high as 45.

I can use my template to guide the bearing of the roundover (or chamfer) bit.

dbriski
08-15-2007, 11:33 AM
I would set up the plywood table and just take small passes, maybe 1/4 for the first pass and 1/8 for the following passes, so like 5 passes. Just watch your feed rate since you can't vary your bit speed you have to vary your feed rate so you don't burn.

JBark
08-16-2007, 04:11 PM
Paul,

Not to be arguementative but I have worked in a Woodcraft store and I have a fairly good idea of the expertise of the staff at the one I frequent now, they leave something to be desired. They will have a fair amount of book knowledge but not much practical, but will still try to sell you something. Then again the store you go to may be quite different???

I have done a lot with a router table not much different in size from what you are dealing with, and I think someone else has suggested this...make one. A big hole and longer screws to hold the base in place and clamp it down to your bench - anything for a fence but you will be using a bearing bit.

John