router bit linear speed question

iclark · Post by **iclark** » Thu Oct 08, 2009 11:21 pm

it seems like I have seen mention that speed limits for larger router bits should/could be computed by the linear speed of the cutting edge. did I just dream this or can someone point me toward a good reference?

I just did the math on one bit and it came out at over 12,000 ft/min if I set the router to full speed. I'm not sure if that should worry me or not.

colday · Post by **colday** » Fri Oct 09, 2009 3:18 am

I found THIS after a quick search.

I'm still looking for the calculations...

I'm actually glad you asked, as I've been thinking of this a lot since I got a new variable speed router.

And to add to your question...

Does the speed make much of a difference when routing grooves/rabbits with a < 3/4" straight bit?

charlese · Post by **charlese** » Fri Oct 09, 2009 1:00 pm

iclark wrote:it seems like I have seen mention that speed limits for larger router bits should/could be computed by the linear speed of the cutting edge. did I just dream this or can someone point me toward a good reference?

I just did the math on one bit and it came out at over 12,000 ft/min if I set the router to full speed. I'm not sure if that should worry me or not.

Howdy, iclark! Yes, I've seen a chart referencing linear speed of router bits, but never have figured out why someone would want to know those figures. Just too many numbers to remember accurately. (Unless, of course you are a researcher into the manufacturing of router bits.)

The chart Steve showed in the last post is a very good reference. Another good rule of thumb that I used prior to getting an adjustable speed router is: NEVER USE A ROUTER BIT LARGER THAN 1½" DIAMETER IN A SINGLE SPEED ROUTER.

As to Steve's later question re: speed and the ¾" straight bit - - My answer is - Speed doesn't matter as much as depth of cut and speed of movement the wood past the bit.

reible · Post by **reible** » Fri Oct 09, 2009 5:34 pm

Hi,

I don't think I want to get to much in depth on this subject but the linear speed tables are most often associated with CNC routers and are much faster then a normal person can perform. If you see a table make sure you know what you are looking at before you spend to much time trying to understand it.

Ed

iclark · Post by **iclark** » Sat Oct 10, 2009 12:19 am

thanks, all for the replies.

Steve, that link and the discussion that is linked from it are the sort of thing I was looking for.

Chuck and Ed, points well taken. I'll try to remember them as I learn this tool.

iclark · Post by **iclark** » Sat Oct 10, 2009 12:43 am

charlese wrote:(Unless, of course you are a researcher into the manufacturing of router bits.)

I am a researcher and that does occasionally take me out to Dryden, but router bit manufacturing has not been one of my duties.

I have some router bits that did not come with a speed chart. I was thinking that the tangential/linear speed stuff might help me make a good/safe guess on what speed to try first for the different size bits. the speed chart at the link above is better for what I need.

one of the really nice things here is that one often gets answers to the questions that one has not learned to ask yet.

thanks again,
Ivan