# bit rpms



## delroy33 (Sep 10, 2004)

hi:

where can i find a chart that shows what rpm. different dia. router bits should be safely run at.
does the bit configuration make a difference in the rpm to be used? i know that different wood requires rpm change. i have 1 3/4 hp. table mounted router.
thanks roy


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## BobandRick (Aug 4, 2004)

delroy33 said:


> hi:
> 
> where can i find a chart that shows what rpm. different dia. router bits should be safely run at.
> does the bit configuration make a difference in the rpm to be used? i know that different wood requires rpm change. i have 1 3/4 hp. table mounted router.
> thanks roy


Roy: Nice to hear from you. There are more to your question than is there a chart. All router bits should be designed to be run at the router's full speed. Having said that, not all router bits are created equal: some have the proper rake and sheer angle others don't, some have the proper carbide and others don't, some are balanced properly others are not. etc. 

Cutting action is controled by two things feed speed and spindle speed. It is more important to understand the relationship between the spindle speed of router bit X, your feed speed and the cut. 

Try cutting with your 1/4" round over bit at different feed rates then look at the cut. Faster feed rate will give you mill marks and slower will give you a cleaner cut. What is happening is the router bit at the faster feed rate has an increased chip load which produces the mill marks. 

Slower spindle speed increases operator conidence (this is good) but will also increases the chip load on the cutter, which increases chatter and mill marks. This means that you need to slow down on the feed rate. Faster the cutter moves faster the feed rate. Practice with a variety of different router bits to get the feel of the relationship between feed and spindle speed.


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## delroy33 (Sep 10, 2004)

bob and rick:
thankyou for the information, it has made things alot clearer. 
roy


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## reible (Sep 10, 2004)

Hi,

Do I get in trouble if I add some importain information to a "bob and rick" answer? This relates to safety so here goes......

Just to be clear here.... Large dia. bits like horizontal panel bits should not be run at the full speed of most routers, in fact the bits often tell you details like "requires a 2 H.P. variable speed router" and "Do not exceed 12,000 RPM" This sets the maximum speed that you would want to use but a lower speed might work better depending on details like outlined above.

This also might be a good item for a show or "router tips" detailing some of the factors that effect chip removal, I personal can thinking of at least a dozen.

ed


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## Julie (Sep 11, 2004)

This is an interesting thread. I, too, was wondering about bit speed. I have a Hitachi 3 1/2 H.P. and am not sure what speed to use. It has 5 speeds. Ed's comment was interesting that the size of the bit matters. What about the wood type? If I'm using pine would I use a different speed than oak, for instance?
~Julie~


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## Glenmore (Sep 10, 2004)

What about routers that have no varible speeds such as my 690 porter cable and my craftsman 1 3/4 horsepower.


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## reible (Sep 10, 2004)

Hi again,

First keep in mind I am not the expert that Bob and Rick are, I’m just a router user with a few years under my belt. When I first got a router I also ordered a book on routers, and made a copy of the chart (bit dia vs speed) to keep with the router. I have long ago lost that chart and don’t miss it. If you really want a chart try your local library. Or the manual that came with your router…

When you are routing wood you should be making “chips” not “sawdust”. You want to slice very thin shavings of the wood; if you are then the feed rate is good (I love the times when the chips fall like snowflakes). Most users tend to move to slow, if you ever get a chance to see a CNC router (power feed, programmed set up) they move very fast to increase bit life and make clean edges. (Of course if you are routing MDF/particle board you get dust no mater what you do.)

Since some of you might be interested in some of the variables related to this subject I have divided them into (what makes sense to me) categories. Feel free to add more to my list.......

Routers:
Horsepower
Fixed or Variable speed
Variable speed with electronic speed control
Hand held or Table mounted
Condition of the router (worn bearing/collets/)
Quality of router

Bits:
Size of shank
Diameter of cutter
Number of cutting surfaces
How sharp
Carbide/HHS
Quality

Material:
Hardness
Density
Wood/Plastic/Aluminum
Dry/Green

Operation:
Type of cuts – plunge/edge/plough 
Depth of cut
Quality of cut desired
Feed rate
RPM of router

If this was too much I’m sorry, Ed


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## reible (Sep 10, 2004)

Glenmore said:


> What about routers that have no varible speeds such as my 690 porter cable and my craftsman 1 3/4 horsepower.


I have two 690 routers, an old craftsman commercial router and a trim router that are not varible speed. ( I also have a 3 1/2 HP varible speed plunge that is table mounted) 

For those few times when I feel I really need a speed control on the ones that don't have it I have an add on speed control made for routers (sold by several online stores). You plug the speed control into the wall and the router into the small box that you can clip on to your belt. A dial sets the speed up to full speed. 

I personal only use it with the old craftsman because of the 15 AMP rating on the contoller. I got mine a number of years ago so maybe the newer ones can handle more current. For the number of times it is used I'm not sure it was worth the $25......

Ed


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## Vern1938 (Sep 24, 2004)

Hi Roy

I just did a quick google search and seen a few sites that have a bit of information on router speeds.

Judging from most, practice and experience to observe the results.

Large panel bits I would suggest starting a lower speeds. As mentioned before, the large bits usually have information on how fast they should turn.


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## Glenmore (Sep 10, 2004)

reible said:


> I have two 690 routers, an old craftsman commercial router and a trim router that are not varible speed. ( I also have a 3 1/2 HP varible speed plunge that is table mounted)
> 
> For those few times when I feel I really need a speed control on the ones that don't have it I have an add on speed control made for routers (sold by several online stores). You plug the speed control into the wall and the router into the small box that you can clip on to your belt. A dial sets the speed up to full speed.
> 
> ...


Thanks that was my next question I've seen the varible speed boxes and did'nt really know if they worked I'm going out and getting one for my table.


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