For routing circles, ideal bit diameter and pass depth?

[Aaron Connor]

For routing circles with a jig, what's an ideal cutter diameter/length in an spiral upcut bit?

For a cutter size, what's the max depth of a pass should you make in softwood, hardwood, MDF?

Thanks!

[Richard Coers]

The ideal combination is the one that works. Length of bit depends on the thickness of material cut. Lots of straight cut bits won't plunge cut, but some do. Number of passes depends on material hardness and thickness of material.

[Jim Becker]

I will add to Richard's comments that you may find it's better relative to the end result to partially cut through the circle with a router and circle fixture, cut the remainder off with a jig saw (or the bandsaw for small projects) and then finish the rest of the edge with a quality flush trim tool, using your routed circle as your guide.

[Bruce Wrenn]

Toughest bit I have ever used cutting circles is a Woodcraft $5, 1/4" straight bit. (Anybody remember those?) It cut half the head off a drywall screw with no loss of sharpness, or carbide. With solid carbide bits (usually 1/4",) I limit cuts to about 1/8" per pass. A good hint for using circle cutter is arrange for cord to come down from overhead.

[Mike Henderson]

I do as Jim suggested - I rough out the circle on my bandsaw. I have a MicroFence Jig, which is a very good jig, but expensive. I drill a pivot hole on the backside and then use maybe a 1/2 inch spiral bit and take only a small cut each time. I do the cut with the work clamped on the corner of my bench, so I have to stop and rotate the work a couple of times for each circle pass. Eventually, I get it down to where I want it.

Mike

[Mike Cutler]

1/2" diameter, 1/4" depth per pass.
Make sure your spiral bit has bottom cutters. Some look like they do, but do not.

[George Yetka]

I would go 1/4" on a 1/4 shank or 1/2 on 1/2. 1/4" per pass. Bits are strongest when there is no diameter reduction or so I read.

[Aaron Connor]

The ideal combination is the one that works. Length of bit depends on the thickness of material cut. Lots of straight cut bits won't plunge cut, but some do. Number of passes depends on material hardness and thickness of material.

That's what I'm trying to figure out... what combinations generally work. I'm looking to buy a single router bit or that purpose, as I don't have many.


I will add to Richard's comments that you may find it's better relative to the end result to partially cut through the circle with a router and circle fixture, cut the remainder off with a jig saw (or the bandsaw for small projects) and then finish the rest of the edge with a quality flush trim tool, using your routed circle as your guide.

Thanks for the tip


Toughest bit I have ever used cutting circles is a Woodcraft $5, 1/4" straight bit. (Anybody remember those?) It cut half the head off a drywall screw with no loss of sharpness, or carbide. With solid carbide bits (usually 1/4",) I limit cuts to about 1/8" per pass. A good hint for using circle cutter is arrange for cord to come down from overhead.

1/4" is starting to sound good


I do as Jim suggested - I rough out the circle on my bandsaw. I have a MicroFence Jig, which is a very good jig, but expensive. I drill a pivot hole on the backside and then use maybe a 1/2 inch spiral bit and take only a small cut each time. I do the cut with the work clamped on the corner of my bench, so I have to stop and rotate the work a couple of times for each circle pass. Eventually, I get it down to where I want it.

Mike

Thanks


1/2" diameter, 1/4" depth per pass.
Make sure your spiral bit has bottom cutters. Some look like they do, but do not.

I will keep out for that. Thank you.


I would go 1/4" on a 1/4 shank or 1/2 on 1/2. 1/4" per pass. Bits are strongest when there is no diameter reduction or so I read.

Ok, that is good to know. I see that both the Milescraft and Jasper jigs offer or include a 1/4" shank 1/4" cutting diameter bit, 1 to 1-1/4" long. So, that size must work fine, and sounds like I can't go wrong with it.

Any opinions here on the Milescraft circle kit versus Jasper, for cutting holes and discs?

It looks like Milescraft offers a tape-on jig that allows you to cut the circle without drilling the surface. However, the milescraft may be better value.

Also, I'm noting that the Jasper carbide bit is 1-1/4" cutting length, whereas Whiteside is 1". Anyone find a longer bit is more useful, or is it safe to go slightly deeper (say 1/4" than the cutter length) on a spiral uncut? I would think that could be problematic.

[Rich Engelhardt]

I sprung for one of Tamar's 6 in one router jigs.
https://www.3x3custom.com/store?category=6-in-1+Universal+Trim+Router+Jig

One of its functions is a trammel.

Like everything Tamar does - it's well thought out and executed.

[Richard Coers]

That's what I'm trying to figure out... what combinations generally work. I'm looking to buy a single router bit or that purpose, as I don't have many.




And what I am saying is one universal router bit won't work for every situation. I don't know anyone that just uses one bit. A 1/4" diameter cutter will screech like crazy cutting hard maple, but work great on plywood

[Mel Fulks]

A single- flute 1/2 inch diameter bit cuts FAST .

[Aaron Connor]

I sprung for one of Tamar's 6 in one router jigs.
https://www.3x3custom.com/store?category=6-in-1+Universal+Trim+Router+Jig

One of its functions is a trammel.

Like everything Tamar does - it's well thought out and executed.

That looks like a nice jig. It looks like it just fits the smaller routers, is that right? Ideally I'd get something that accommodates both the full size Bosch and the smaller makita routers.


And what I am saying is one universal router bit won't work for every situation. I don't know anyone that just uses one bit. A 1/4" diameter cutter will screech like crazy cutting hard maple, but work great on plywood

Okay. But, I have to start somewhere. Unless the jig mfg's are entirely off, that seems like a good place to start.


A single- flute 1/2 inch diameter bit cuts FAST .

How rough is the edge on that cut?

[Mel Fulks]

Cut is not rough ! How could you say that ?? ! But , with with something gnarly a spiral bit might be good.

[Dan Barber]

What size circles are you wanting to cut and in what material? That info could change recommendations on jigs or bits by quite a bit.

[Aaron Connor]

Cut is not rough ! How could you say that ?? ! But , with with something gnarly a spiral bit might be good.

Pretty easily. My fingers just typed it, not painful at all :) Seriously, though - I was under the impression that the more cutting edges the smoother, and figured one cutting edge would go the other way. I guess I'm wrong on that.



What size circles are you wanting to cut and in what material? That info could change recommendations on jigs or bits by quite a bit.

I'm not an advanced woodworker, and wood working isn't a main hobby, but more like one of many interests. I've found from time to time a need to cut something circular, but don't have a project planned at the exact moment.... however, can envision a variety of little projects with my daughter. I'm sure literally some will be wheels for something; I'm sure I will cut some speaker holes. Initially more softwood, MDF, and plywood than hardwoods.

I like the design of the jasper jigs, and the repeatable accuracy they offer, not to mention the tape-down pivot option. However, I have a large Bosch router, and 2 smaller trim makita routers, and it seems that I'd need to buy 4 of the jasper jigs to cover the same range as the Milescraft circle kit. That is, except or for the metric jig that handles both compact and full sized routers (seems odd to me that they only offer that for the metric jig).

Technically, I can probably buy only a jig for the large router, but it seems a little silly to buy jigs that work with only some of my routers.

While the milescraft kit may have a few shortcomings, probably better value for my interests. I'm thinking that with that one, I should be able to tape down the center pivot in situations where it's needed without damage to the center piece, but curious what you all think?

[Rich Engelhardt]

Aaron,
Yes - that jig is only for trim routers. I'm ok with that though.

Something else you might want to look into is a Daisy Pin Router. (https://www.hvalleytools.com/product/v9061-mlcs-daisy-pin-router-attachments/router-accessories)

CNC has pretty much made pin routers obsolete, but, for a lot of people (myself included) the Daisy opens up a whole world of solutions.

[Michael Burnside]

Pretty easily. My fingers just typed it, not painful at all :) Seriously, though - I was under the impression that the more cutting edges the smoother, and figured one cutting edge would go the other way. I guess I'm wrong on that.


You're not entirely wrong but that said, the number of flutes is a lot less important to the quality of cut than the angle and orientation of said flute/flutes. Take a single-flute spiral down-cut bit compared to 2 or 3 flute straight bit and you'll find the single flute bit is vastly superior to cut quality. All things being equal, including chip-load (often not relevant in hand-held routers), then yes multiple flutes will yield a finer cut simply because each flute is taking a smaller chip

[Curt Harms]

While the milescraft kit may have a few shortcomings, probably better value for my interests. I'm thinking that with that one, I should be able to tape down the center pivot in situations where it's needed without damage to the center piece, but curious what you all think?

Something to be aware of when using tape to hold jigs. Make sure the wood you're taping to is smooth. I was routing something using a taped down jig where the work piece was pretty smooth but not perfect. The jig came loose and moved:mad:. If I'm in a similar situation again I'll think about hot melt glue. I have not tried alcohol to break the bond of hot melt glue on wood to wood but it works quite well with wood to solid surface temporary bonds (clamping blocks).

[Brian Gumpper]

Also, I'm noting that the Jasper carbide bit is 1-1/4" cutting length, whereas Whiteside is 1". Anyone find a longer bit is more useful, or is it safe to go slightly deeper (say 1/4" than the cutter length) on a spiral uncut? I would think that could be problematic.

As the solid carbide spirals get smaller in diameter you will see cut length options reduce. Carbide wears very well but is also brittle. Steel will bend, carbide will break. So if your 1/4" solid carbide spiral bit has too long of a cut length then it could break easier and if they start to chatter will snap as well.

Not sure the finish quality you are looking for but many ways to do what you want depending and you have received many good suggestions.

[Dan Barber]

For large circles, I tend to make tramel boards out of scrap 1/4 MDF or Plywood. I would typically drill a center hole in the project piece and pivot on that. The nice thing is you can use these over and over by just drilling new holes. For smaller circles, I tend to cut templates on my laser and use a pattern bit with bearing. Bit choice varies by wood type, circle size and router at hand. I tend to use the largest spiral bit I have that will fit the router.

[Jim Becker]

I sprung for one of Tamar's 6 in one router jigs.
https://www.3x3custom.com/store?category=6-in-1+Universal+Trim+Router+Jig

One of its functions is a trammel.

Like everything Tamar does - it's well thought out and executed.

Yea, that's a really nicely designed fixture and super versatile. Between her design and Katz-Moses' production, it's quality for sure. If I owned a small router that it's aimed at, I'm pretty sure I'd have that fixture in my shop already.

[Michael Burnside]

Yea, that's a really nicely designed fixture and super versatile. Between her design and Katz-Moses' production, it's quality for sure. If I owned a small router that it's aimed at, I'm pretty sure I'd have that fixture in my shop already.

I bought one to support her, and while I do have and use my trim router constantly, the jig use/application is not really my thing either.

[Ron Selzer]

A single- flute 1/2 inch diameter bit cuts FAST .

Sure enough true statement, been way too many years ago that I cut 3/4 MDF into 5' round table tops, one time around and done. x12