# How do I choose the right speed for my router?



## Renfield (Jun 13, 2009)

I am making curtain hangers for all of the windows in the house. I believe the best way to do this is to make one and use the router and a flush-cutting bit with a bearing to follow the original and make copies.

Each piece is 1 1/2" thick pine. I bought a 2" 3-flute cutter from MLCS. Currently I am finding that the cut is really slow, and seems to also burn the wood. I am running my Makita varible speed router at it's lowest setting (mostly because it kind of scares me).

I am wondering, what is the right speed to be running my router at for various tasks (and this one in particular)? Are there any hard (or semi-hard) rules like "For this application, and this type of wood, run it at XXX speed"? Or is there some observation I can make to determine the best speed? Also, what are the safety considerations I should be aware of when choosing a speed?

Thanks.


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## CharlieM1958 (Nov 7, 2006)

In general, slower speeds are for large-diameter bits like panel-raising bits. (I'm sure someone will bring up some other scenarios where slower speeds are called for.)

For the job you describe, I believe you should be running at full speed. Slow speed is what is causing your problems.


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## a1Jim (Aug 9, 2008)

I agree with 50/50


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## lwllms (Jun 1, 2009)

I'm not a fan of big router bits in a router. If I were to do it, I'd follow the recommendation of the router bit manufacturer. It's not that hard to do, digital non-contact tachometers are pretty cheap these days. I'm a little amazed they're not standard equipment for variable speed routers and other tools. I sure like the one we have.

Amazon's digital tachs: http://tinyurl.com/m2uerj


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## Renfield (Jun 13, 2009)

This bit didn't come with speed recommendations from the manufacturer. I bought the 2" flush trim bit here:

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/triplewing.html


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## cabinetmaster (Aug 28, 2008)

I'll try to find my speed chart. But the rule of thumb is the smaller the bit, the higher the rpm on the router. 2" or larger bits should only be used at the slowest rpm and take no more than 1/16 to 3/32" off the wood at one time. MY QUESTION TO YOU: how much wood are you trying to take out at one time? Are you cutting these patterns out with a bandsaw or jigsaw close to the line and then using the flush trim to bring it down to the pattern? Or are you trying to hog it all out at one time? Really makes a difference and makes the router bit last longer if you do cut it down to size before using the flush trim bit.


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## Kjuly (May 28, 2009)

Hi Renfield,
As Charlie said you are running too slow for the bit that you are using. Most router bit manufacturers publish a guide for router speeds. 
As a rule of thumb…you do not need to reduce the router RPMS until the bit diameter exceeds 1". 
I found the chart below from a quick internet search. This illustrates the rule except the last line which should be no more than 10,000 rpms for a bit that size.

*Maximum Speed (RPM)
Up to 1" 24,000
1 1/4" to 2" 18,000
2 1/4" to 2 1/2" 16,000
3" to 3 1/2" 12,000

Bit Speed chart courtesy
Infinity Cutting Tools

Visit www.infinitytools.com *

The more flutes the slower the cutting speed but the better the finish. 
I suggest you make a patten and go from there. 
By using a pattern you can rough cut your parts about an 1/8" oversize with a bandsaw or scroll saw and then finish cutting the part with the router.
This method will be easier on you and your router.
I hope this helps.
Keith


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## TopamaxSurvivor (May 2, 2008)

My guess is taking too much material and / or trying to go too fast along with possible speed problems. Wood doesn't disipate heat like metal does; therefore, smaller bits and less pressure.


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## patron (Apr 2, 2009)

i think you are saying that the bit cutting length is 2 inches ?
i imagine the diamiter is 1/2 or 3/4 ?
so as stated above high speed !
also are you routing by hand ( in which case the work must be solid and no obsructions around edges ) .
or are you using a router table ?
as stated cut all pieces close first , but try and make your pattern of some hard and smooth material ,
as it will have a tendency to crush and burn or splinter over long use .
remember that as the grain direction changes you have to be in control and not let the work bounce around or you can have it chatter and break .


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## BigJimAK (May 22, 2009)

Rockler's recommendations for *MAXIMUM* speed are:

Router Bit Diameter Maximum Speed 
Up to 1" 22,000 - 24,000 rpm 
1" to 2" 18,000 - 22,000 rpm 
2" to 2-1/2" 12,000 - 16,000 rpm 
2-1/2" to 3-1/2" 8,000 - 12,000 rpm

You can see the post yourself at:
http://www.rockler.com/articles/display_article.cfm?story_id=135

Please note that they indicate these as guidelines, to be used only if manufactuer information is not available. From this chart, i'd say a MAX of 16,000-18,000 rpms.

If it were me with that large of a bit, I'd check to ensure the bit was clean and sharp and then slow it way down. Burning comes from moving the bit too slowly through the wood or a dull/dirty bit. If you are nervous about running that large of a bit (and it is a big one), you may be feeding the router too slowly or taking to deep of a cut in each pass.

Consider these things but don't do anything you're uncomfortable with. If it feels dangerous, it probably is.

With a bit that large, you'd be better off in a router table, if possible. I try to limit myself to a 1" bit for hand routing.

Jim


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## Renfield (Jun 13, 2009)

Thanks for all of the responses. First some clarifications. The bit's diameter is 1/2". The bit is 2" tall. This is so that I can cut the shape out of 1 1/2" thick pine. Also I am cutting close to my pattern line using my bandsaw. I would say that I have 1/8" to 3/16" of wood left that needs to be removed to match the pattern. I have my router mounted in a table, and I am moving the wood across the bit freehand (right to left against the direction of cut of course).

I like the other idea that the pattern should be made of hard material. My pattern is just another block of pine that I made by hand in the bandsaw and sanded to the final shape. This was the prototype piece.

I am using some carpet tape to keep the pattern connected to the piece to route. I had some other double-sided tape but it just didn't hold.


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## doyoulikegumwood (Jun 21, 2007)

doing this free hand i sure hope you have a starting pin if your geting burning i hate to say it but your bit mite be eather dull or dirty i would try cleaning it sharpaning a pattern bit i have found is not cost effective because after sharping the bit the baring and the carbid no longer match but i digress a little burning is to be expected. a little sanding takes care of this. also burning is a little more noticeable if your useing a 1/4 in shank bit. dont know if i was any help but good luck to you


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## CharlieM1958 (Nov 7, 2006)

Again, after reading all the clarification, it sounds like you are doing everyting right except bit speed. Turn it up to full and I'll bet your problems disappear.


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## cabinetmaster (Aug 28, 2008)

50/50 is right.


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## Renfield (Jun 13, 2009)

Ok, I have increased the router speed from 8,000 RPM to 24,000 RPM. The wood still burns, unfortunately. I am able to cut much faster though. This is a brand new bit that I just bought from MLCS, so I can't believe it is dull. I am guessing that the problem might be that I am trying to cut through too much wood. Realize that the piece I am trying to make is 1 1/2" thick. This seems to be much thicker than any examples I have seen.

My next attempt will be to cut much closer to the pattern line on the band saw first. Also I will make the pattern out of some plywood instead of using the pine prototype. I will have to create a zero clearance throat plate for my band saw, since I will want to go slow and take off small amounts of wood in each pass, and I do not want the wood to fall into the machine.

Further, I do not have a router starting/safety guide pin. I understand now the usefulness of this, and will attempt to fashion one.


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## CharlieM1958 (Nov 7, 2006)

Is the burning consistent, or just in spots?

Burning is usually caused by too slow of a feed rate. If you are just getting marks at certain points, those are probably the points where you are stopping or slowing the feed of material to adjust your grip, etc.

It can be very tricky to maintain a constant feed rate, but leaving the bit in one place will almost always leave a burn mark.


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## Renfield (Jun 13, 2009)

I was burning most of the cut, not just spots. I have done some more work and I believe the problem was that I was just trying to remove too much wood. 1 1/2" by 1/8" to 3/16" is too much to be able to go fast enough to not burn the wood.

For my second attempt, I first created a plywood template. I smoothed out some of the small bumps in the shape. I did not realize how easy it is for the flush cutter to copy every little bump. Next, I traced the template onto my work piece. I cut out the piece on the band saw (which now has a zero clearance throat plate), and made some additional small cuts to get close to the line. I tried to get close to 1/16" of material left to route.

On the router, I made sure that I was feeding the piece through faster than before. I was able to do this because there was less wood to remove. I still ended up with some burn marks, but they are much less than before.

I also found out that carpet tape does not keep the template attached to the work piece very well. The two pieces would slowly slide around and that is not good. I also bought some exterior grade double-sided tape, and this stuff appears to be doing the job I need.


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## Renfield (Jun 13, 2009)

MLCS does have some information about the recommended maximum RPMs for a given bit size in their FAQ.

http://www.mlcswoodworking.com/shopsitesc/store/html/smarthtml/pages/techfaq.htm#rpmanchor

An interesting additional piece of information listed there is that if the carbide height is greater than 1 1/2" then you should run the bit no faster than 16,000 RPM. This is the first mention I have seen of speed restrictions due to height, as all other recommendations key off of bit diameter.


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## CharlieM1958 (Nov 7, 2006)

In all the explanation, I still managed to miss the fact that you were flush-trimming material 1 1/2" thick. I can see where that would provide some interesting challenges because that's definitely a lot of stock removal, even if you do precut pretty close to the template.


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## Renfield (Jun 13, 2009)

I thought that for this application a spiral cut flush trim bit might be a better choice. It seems to me that this action might be smoother. Instead of three cutter heads going *wham*, *wham*, *wham*, as they carve into the wood, a spiral bit would present a continuous cutting action up and down the edge of the wood.

Unfortunately, MLCS does not have a spiral flush trim bit with at least a 1 1/2" cutting height.


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## NorthGaMan (Mar 12, 2009)

Best bet is to do most of your work with a saw, then do the finish work with the pattern attached and your router set at top speed. Also watch your feed rate, try to stay the same all the way threw the router operation.


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