Thread: More gear head mill problems - SM-MD45

Hi Variant22,

I don't want to tell you to eat eggs or insult your intellegence but since you will no doubt want to leave no stone unturned, I will ask the question: Are you sure the spindle is travelling Forward and not in Reverse?


I'm almost embarrised to mention this but what the hell! I recently converted my 45 mill to VFD. The night that I finally mounted the newmotor to the head and wired up the VFD I gave it a run. It was late at night and I was tired and had tunnel vision of how my adapter plate would work and how the new bearings would sound and how the VFD parrameters were set. When I finally got to making chips I was most devistated and disappointed at the amount of vibration and chatter, even for very very modest DOC and feedrates. No amount of adjustment on my U beaut POT speed control would fix it............. You can imagine the simultaneous relief and embarissment when it dawned on me that the motor was running in reverse!

The poor endmill. It never stood a chance

Cheers,

Simon

Originally Posted by simonl

Hi Variant22,

I don't want to tell you to eat eggs or insult your intellegence but since you will no doubt want to leave no stone unturned, I will ask the question: Are you sure the spindle is travelling Forward and not in Reverse?

Cheers,

Simon

Ha Ha, who hasn't ever run their gear in reverse

You are not alone.

Rob

Originally Posted by variant22

This fly cutter is specifically engineered for small machines. Tormach have a great article on the development (TTS SuperFly Cutters: A Modern Update to an Old Shop Standard « Milling Around). Tormach reported far better performance on their small mills with the fly cutter than their indexable face mill. The article goes into some detail on why this works better than a face mill on a 1.5hp machine.

Yes, but apparently they take significantly more horsepower.

That's because the Tormach *has* no power. Their fly cutter must have a cutting edge geometry to do what it can to compensate for this. You must pay for this in either shorter life of the cutting edge or increased machining time - shallower DOC or slower feed. There's no free lunch.

TCT tooling is used because it works, provided you have the HP to drive it. A Tormach doesn't so they have to do what they can. Trying to extrapolate the workaround for a toy machine to a bigger one is simply wrong. Given the results you're getting, either using the fly cutter is not correct or something is wrong elsewhere. I do know that using a fly cutter is going to hammer your bearings. I can run a 50mm 3 tooth TCT face mill on my 3/4HP B/port motor, at 0.100 DOC, fast enough to have blue chips and a shiny surface. R8 taper. As soon as the cutting edges get blunt, power needed goes way up and the cutter starts hammering. I can run a single point fly cutter on my horizontal mill at around 40 rpm, 6" sweep, .040" DOC and slow feed to get nicely finished surfaces on hot rolled angle iron. The baby horizontal mill has a very rigid spindle ad I use a hand-ground & honed HSS toolbit in the cutter body not carbide. Fly cutters need a rigid setup, to run fairly slowly and to enter the work at as shallow an angle as possible to minimise the shock loads.

I'm not going to engage in an endless debate over it. Believe what you wish. How I do it works.

PDW