My router has variable speed. So do I, for that matter. How do you estimate what speed to set the router, and how quickly to move along the wood?
There must be a theory to this, but my router book doesn’t provide any guidance.
Janet
Edited 9/27/2004 12:25 pm ET by jyang949
Replies
Janet,
Check this link for some good information: http://www.sawdustmaking.com/Routers/routers.htm
Here's an excerpt from the page:
Router Speeds
The larger the diameter of the cutter the faster the tips of it travel, a large bit will be travelling too fast for optium performance and safety on a router at full speed unless the RPM is slowed. If your router does not have a speed control you can use an external attachment.
0 - 1 inch in dia - 22,000 RPM
1 - 2 inch in dia. - 18,000 RPM
2 - 2.5 inch in dia. - 16,000 RPM
2.5 - 3.5 inch in dia. - 12,000 RPM
At 22,000 RPM the tips of a 3/4" bit travel at 49 MPH, on a 3 1/2" bit they would be travelling over 220 MPH.
Be safe!
Bill Arnold - Custom Woodcrafting
Food for Thought: The Ark was built by amateurs; the Titanic by professionals.
It seems to have the most to do with the bit size. Bits over 2" like panel raisers use lower speeds. I forget the speeds. Your bits usually tell you what the corect speed is. If it is a smaller bit, like a 1/4 or 1/2" round over crank it up. If you are getting burning you are either taking too much off in one pass or not moving the piece fast enough. I suspect others will have more information.
Mike
Janet,
As you suggest, in addition to taking the diameter of the router bit into account when deciding upon the operating speed of the router, there's the issue of how slowly, or quickly you move the router across the work (or the work across the router table).
Feed rate Is usually a compromise: The faster you go, the less heat build-up (and less burning), but the greater the likelihood of causing misfeed, chatter, or an accident. Moving slowly usually produces a smoother cut, but at the risk of overheating the cutter and burning the work. I usually move at a fairly brisk pace when hogging off stock in multiple passes, and slow down for a final, thin, "money" pass.
In my experience, the species matters, e.g., cherry (and other resinous woods) burn easily and benefit from a higher feed rate. Resinous woods also require vigilance to ensure against bits and their bearings becoming fouled with resins, which burn easily and can really gum up the works.
I find that focusing on the feel of the work or router to detect vibration, chatter, etc., and the sound of the bit as it cuts the wood is very helpful: When a student is routing at an inappropriate rate of speed, our instructional staff usually reacts to the "wrong" sound and comes running, while the student may not react at all, in some cases, even what smoke is bellowing forth!
"The answer," is usually found through test pieces. And, of course, a consistent feed rate is very important if you're trying to achieve a surface with a consistent texture and a minimum of burning.
Hope this is the kind of information you were looking for,
-Jazzdogg-
Whether you think you can, or you think you can't, you're right.
Thank you for the links and suggestions. Have I got the gist of it here?--(1) The bit needs to move quickly through the piece so the cut doesn't overheat and the bit is always cutting into new, cooler material.
(2) Choose rpm to accommodate the "plow speed". Too slow and the cut is poor; too high and the bit overheats.
(3) The larger the diameter of the bit, the faster the cutting edges travel, so the rpm needs to be slower.
Is the mass of the bit pretty much irrelevant compared to these other factors? I mistakenly set a slow plow speed and rpm for a 1/4" bit, figuring that such a small bit would soon overheat at higher speeds. But something (the smell of wood charring) told me that was the wrong approach.
Janet
"Is the mass of the bit pretty much irrelevant compared to these other factors?"
The diameter of the bit determines the rotational speed to set; i.e., the RPM of the router motor. The best I can explain the rate of movement across the material is as another poster noted: you learn to feel the correct feed rate. Experience will teach you how slow or how fast you can perform the operation. If you go too slow, the material will probably burn and the router motor will sound like it's not working very hard. On the other hand, if you feed too fast, the router may bog down; you can hear the motor slowing (overworking), material may begin to chip out and you may hear and feel the bit chattering (skipping on the material).
Regards,Bill Arnold - Custom Woodcrafting
Food for Thought: The Ark was built by amateurs; the Titanic by professionals.
Janet,
A previous link including manufacturer's input
http://forums.taunton.com/tp-knots/messages?msg=8157.1
Cheers,
eddie
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