[nolage]

Interesting project a machinist friend of mine brought up.
On these smaller mills and lathes, he complained about how even at tiny depths of cut, they lack real power or spindle stability.

We began discussing a powered fly wheel.

Effectively it could be added easily to anyone running a belt conversion on their mill, simply requires using a pulley with another tract running to a balanced weight.

It would increase spin up times as well as apply some load during speed changes, but would in practice apply a decent amount of dampering.

Any thoughts? Hoss?

[SCzEngrgGroup]

No offense, but I bet your friend has no engineering training, does he? A flywheel will do nothing at all to help with a deficiency of power, and I very much doubt whatever "instability" there is in spindle speed would have any measurable effect, when compared to the many other FAR greater sources of error in these machines (like runout, backlash, flex, sticktion, etc.). It would also lead to increased current during spin-up, and increased back-driving when spinning down, both of which could lead to a blown motor controller.

Regards,
Ray L.

[nolage]

None taken, he is not an engineer.
I believe the idea was more that there would be a more gradual slowing or unload-to-load change as the bit encountered material on large cuts.

[SCzEngrgGroup]

None taken, he is not an engineer.
I believe the idea was more that there would be a more gradual slowing or unload-to-load change as the bit encountered material on large cuts.

Which would matter...... why? The motor speed controller should, and in my experience does, do a reasonable job of regulating speed with changing load. And a momentary dip in RPM, as long as it's not really huge, will be of no consequence. RPM is not a critical parameter.

Regards,
Ray L.

[nolage]

I'm not experienced enough to comment I'd say;
He came over to inspect the X2 I received, he's used to working on much larger Bridgeports at his work and home, and that was just his general comment.

He felt it was underpowered, but usable for my application. Figured I'd ask here is all.

I'm finding it oddly hard to find enough reference material and such in selecting decent tooling though.

[SCzEngrgGroup]

Compared to a Bridgeport, and X2 is under-powered, but a flywheel won't help one bit. And it's under-powered because it's a small, light-weight, flexible machine. It has as much power as it can reasonably use.

With an X2, you'll do most of your work with small cutters, generally no more than 3/8". HSS will be just fine - you don't have enough spindle speed, or rigidity to get any real benefit from carbide. If you're cutting aluminum, use 2-flutes. If steel, 4-flutes. Buy good, American-made tooling, not the cheap Chinese crap. They'll cost more but last MUCH longer, and give a better result. Go to Enco, or MSC, get on their e-mail lists, and wait for a 30-40% off sale. Putnam, Greenfield, Accupro, Hertel are all good brands.

Regards,
Ray L.

[nolage]

And how many flutes would you recommend for copper?
90% of my cutting work will be in copper.
10% in delrin/acetal and plastics.

[SCzEngrgGroup]

I've never cut copper, but I know it's very gummy, which would suggest a 2-flute.

Regards,
Ray L.

[nolage]

By my understanding...

A 2 flute has two cutters, so effectively per spin each blade has to do a bit more work at the same pass speed. Why would that be better with something gummy?

[Geof]

Being gummy copper tends to form a long chip that does not curl up into a tight coil. A two flute cutter has more space between the two cutting edges so the chip has a better chance to curl out of the flute. With a four flute cutter the chip can hit the back side of the preceding tooth because the flute is smaller, and then the chip just wedges into the flute.

If possible use work hardened copper for machining; it will give a better chip than annealed copper. Also use a lubricant, tapping fluid brushed along the line of the cut can help considerably. Keep the rpm up, probably the maximum your machine can run, and experiment with the feed to try and obtain a chip that comes off in a thin wafer.

[Andre' B]

Pure copper is not fun to machine but there are alloys that are much more machinable.

I made some parts out of some Tellurium Copper one time, very nice to machine even had it on the surface grinder.

[MrWild]

MORE POWER! If you want more power in a X2, get a KBLC-19PM motor driver. Can be found cheap or expensive on eBay, and really make a large improvement. Far more than a flywheel ever would. As far as flywheels go, they smooth out intermittent power pulses. Maybe if you were using a fly cutter, but definitely not an endmill.