Router Speed Strategies

[scottacus]

I've got the really sweet feed rate calculators on my computer and phone and I was wondering what strategies folks use for choosing the RPM's that they run their machines at?  You could run at higher RPM's and finish the piece faster but perhaps this puts more stress on the gantry, router and mill. 

For example do you hog out material at lower RPMs for the roughing passes with a larger end mill and then run faster RPMs for the finer bits that have really long tool paths to get them to run the path faster?  Do you just leave the router at one speed and never touch the dial?

[ttabbal]

Spindle speed is very directly related to the feed speed. Generally speaking on spindle speed, smaller diameter tools spin faster, and working softer materials spin faster. The calculators should take both spindle RPM and feed rate into account along with the tool diameter and material type.

There are books written about this, and the reasons for it, so I don't think it's worth going into a lot of detail here. There are also other variables like machine rigidity that play critical roles. I can run an industrial mill with a significantly faster feed rate than any gantry router could ever dream of running without breaking something.

Another general rule of thumb is that faster feeds will usually cause a loss of accuracy. So a finishing pass is likely the time you want to be a bit more conservative on feeds. This is due to the steppers possibly losing steps, smaller bits used for fine details being more likely to flex slightly, and a few other things.

For now, I suggest you use the speeds and feeds from the MillRight calculator while learning the machine. If you want to know the whys, there is a lot of data on the subject. Far more than I know, I'm sure. As you learn your machine, you will start learning how it behaves when you change things and where the limits are. There's also that you don't really KNOW the speed of the router, you guess based on the dial. If you have a tachometer, you can know, at least the no-load speed. Though I think these more modern routers are pretty good at maintaining speed under load.

And don't forget, deeper and faster cuts will put more force on the work as well. So your workholding needs to be able to handle it. Everything you change affects something else.

[Hommer Woods]

I agree using the Millright calculator is a good idea. I have a carve king with a dewalt router. Most of the work I do is 1/8 deep pockets for inlays and cutting 1/8 to 1/4 woods. I usually have the router set on it's slowest speed. I find that if I run it faster I get a lot of buildup on the mills particularly in oily woods. Most of the mills I am using are 1/16 and 1/18.

[scottacus]

Thanks ttabbal and Hommer Woods for the excellent information!  I hadn't thought about machine errors like missing stepper steps, tool flex and build up on bits, this is all great stuff to take into consideration.  I'm just about to start putting the Carve King though its paces and I don't want to damage the machine while learning what not to do.

I found this on the internet for the standard Carve King Dewalt router speeds, does this look correct?

[Hommer Woods]

Dec 5, 2018 13:38:31 GMT scottacus said:

Thanks ttabbal and Hommer Woods for the excellent information!  I hadn't thought about machine errors like missing stepper steps, tool flex and build up on bits, this is all great stuff to take into consideration.  I'm just about to start putting the Carve King though its paces and I don't want to damage the machine while learning what not to do.

I found this on the internet for the standard Carve King Dewalt router speeds, does this look correct?

That matches the specs on Dewalts site for the 611.

[ttabbal]

I agree the chart looks reasonable.

If in doubt, slow the feed a bit. You are far less likely to damage the machine with slower feeds. If you get burning/melting, speed feeds up a bit. Try to only change one thing at a time, more variables make it hard to figure out what went wrong if something bad happens.

[rowiac]

Dec 5, 2018 13:38:31 GMT scottacus said:

Thanks ttabbal and Hommer Woods for the excellent information!  I hadn't thought about machine errors like missing stepper steps, tool flex and build up on bits, this is all great stuff to take into consideration.  I'm just about to start putting the Carve King though its paces and I don't want to damage the machine while learning what not to do.

I found this on the internet for the standard Carve King Dewalt router speeds, does this look correct?

That is taken directly from the DeWalt 611 Operator's Manual, so it is not specific to the Carve King.  I've been running my M3 with 1/4" endmills and a V-cutter between 3 and 4 on the DeWalt and it seems to be working well.  What is more important is the feed rate.  At first I had mine set at 100 in/min (default on Vectric software) and the X-axis lost a bunch of steps while cutting a large oval.  Since then I have dropped the feed to 30 in/min and it's working fine.  This is in soft wood by the way.

I learn something every time I run the machine.