Speeds n Feeds

[jessbussert]

Hi Folks,

Does anyone know of a good reference for speeds and feeds associated with routing wood? I've just finished a new build and I'm already charring up bits and throwing sparks! Am I cutting too deep or too fast? Am I using the wrong bit?

Here is my setup in a nutshell:
1) I've got a cheap trim router from Menards as my spindle.
2) I've got a speed controller I bought off the net somewhere.
3) I've been using high speed bits, but I could switch to carbide or something else if needed.
4) I'm cutting plywood at the moment. I'll be cutting oak, plastic, and foam in the future.
5) I've been making 1/4" wide cuts at about 1/8" deep.
6) My machine is only running at 8ipm.

It would be nice to find a table similar to a machinist's handbook that listed different kinds of wood then told the best bits, speeds, cut dimensions, and such.

Does anyone know of such a thing?

Thanks,
Jessica

[ger21]

https://www.onsrud.com/xdoc/FeedSpeeds

It's specific to their tools, but should still give you a reference. High speed steel has an extremely short life when cutting wood.

Burning is from going to slow and spinning too fast. 8 ipm is much too slow to prevent burning.

[jessbussert]

Unfortunately I can only do 8ipm. Would dropping the spindle speed compensate for this? What would be the result of switching to carbide bits?

-Jessica

[ger21]

Would dropping the spindle speed compensate for this?

Yes, but I don't think you can drop it enough. Carbide will stay sharp longer, but may still dull quickly at those slow speeds.

[jessbussert]

Ok, so lets say for plywood and oak, what spindle speed and feed rate would be best for carbide bits?

Will lighter cuts help keep the heat down?

[ger21]

Go back to the charts I posted, which will tel you about 180ipm at 18000 rpm. You asked what would be best, and that's it. At 8ipm, there's not much you can do. Doing the math, you should be spinning the cutter at 800rpm. But at that speed, the bit will probably break and the cut quality would be very poor.

As for light cuts, that's probably your best bet. Start at 1/32" per pass and increase to find what works best for your machine.

[jessbussert]

Eeek! How does one get 180 ipm on a home built machine? I'm using steppers, not servos, so that slows me down. I'm also only using 1/4"-20 threaded rod for my drive screws. I chose those because I wanted high resolution for small, fine pieces in wax but I'm now somewhat regretting that decision. 5/8"-10 acme screws would have been a better choice, but even that would only give me 16 ipm.

I'm going slow because at faster speeds I seem to get chatter on my steppers. At 8 ipm they run nice and smooth with a bunch of torque.

Any tips or suggestions?

Thanks,
Jessica

[ger21]

You can get ~200-300ipm with a HobbyCNC board, 300 oz steppers, and 1/2-10 5 start acme.

[artwood_decor]

Jessica,

I have the same issue using 1/4-20, and can't go any faster than 10-12 in/min.
See these videos and read the original thread they were posted.

I haven't implemented this change yet but I'm working on it.

"
My take on a stepper damper

20 ipm the resonance was bad. No MACH 3 settings were ever changed!
"http://www.youtube.com/watch?v=9RoOZs9LrYo"]YouTube - 20 inches per minute resonce in stepper

50 IPM missed steps
"http://www.youtube.com/watch?v=ivDQTeGuduk"]YouTube - 50 ipm test

65 IPM motor gets really unhappy in this one!!!!!!
"http://www.youtube.com/watch?v=8Am69_F93yA"]YouTube - 65 ipm

"

regards,
Lucian

[jessbussert]

Thanks Lucian,

Do you have any plans for building dampers? I'd love to see them!

Jessica

[artwood_decor]

Try the first post on this page,

My take on a stepper damper

"twice2" posted some DXFs

Lucian

[jessbussert]

Hmmm...

I can't open those DXFs. That doesn't surprise me since my ACAD is an old v14! Is it possible to repost those as an older format of DWG/DXF? Or perhaps just send a JPG export? I don't really need a mechanical drawing. I'm more interested in the theory of how they work and the thread doesn't go into that much. Is it just kind of like balancing a tire or is there something else to this?

Thanks,
Jessica