[spv123]

I have been working my RF45 (Zay variety) mill fairly hard over the last few weeks. I am finding it is coming up a bit short on fly cutting capabilities. I have been trying to face some mild steel. Mainly removing the scale from it and squaring it up. I am running one of these little Tormach SuperFly fly cutters with a 45degree carbide insert held by an ER20 collet. The issue is when I run a cut of any depth the gears chatter like hell and the mill head vibrates. It is a 1.5hp, 1600rpm gear drive with 0.01mm run-out on the spindle. Trammed level to 0.005mm across 4 inches+. The vise is also squared to less than 0.01mm. If I run a cut of say 0.2mm deep (diameter is about 8cm or 3 inches) at 1,000rpm (copying the Tormach youtube demo speed) with the fly cutter in steel it really carries on a treat.

I am wondering if my issue is the gear drive and if switching to a ~3hp 4,000rpm belt drive system with a VFD and a couple of pulleys (low and high range) would make the machine more steel capable? The Tormach machine seems to blast through steel with the fly cutter at a much greater depth of cut (I was under the impression the Tormach machine was less rigid than the RF45?). I would not even bother trying their feat as I am sure something would let go given the noise the machine makes. It tends to be mostly at low to 1,000 RPM where the noise is most pronounced. I even spotted the fly cutter momentarily stop (only once!). As a side note I have tried fly cutting steel from 500rpm through to 1,600 rpm without much success. I tend to get streaks and grooves along the axis of travel.

I have not been able to produce any straw colored chips, but many are literally smoking hot. But when cool are either shiny silver color or a darker silver.

Ideas?

[jid2]

So you are not mounting the fly cutter straight into the spindle with a TTS 3/4" collet, but using an ER20 holder in between? Perhaps post a picture. If using an ER20 in between, this is likely making things less rigid.

I would start trying different tools before jumping to fixing the machine. Unless you just want a belt drive because it kicks butt to have some real spindle speed. Then, by all means go for it. But it won't solve your current issue.

[gd.marsh]

Couple of thoughts ..

Rate of feed can make a big difference in performance ..
Proper gib adjustment makes a difference ..
The correct insert makes a difference ..

Is your machine CNC or Manual?
I also would question gear train backlash as the problem .. as long as you're providing a steady rate of feed, backlash should be taken up at the beginning of the cut & the gears should remain solidly engaged until exiting.

[SCzEngrgGroup]

Couple of thoughts ..

Rate of feed can make a big difference in performance ..
Proper gib adjustment makes a difference ..
The correct insert makes a difference ..

Is your machine CNC or Manual?
I also would question gear train backlash as the problem .. as long as you're providing a steady rate of feed, backlash should be taken up at the beginning of the cut & the gears should remain solidly engaged until exiting.

Yes, but.... What happens with a fly-cutter is the gears are loaded when the tool is actually cutting. Once the tool exits the cut, which it does on every rotation, the load suddenly disappears, and the tool will lead the spindle, opening up any backlash in the gears. When it again re-enters the cut, the backlash is very suddenly taken up.

Why someone would choose a fly-cutter over a face mill is a mystery to me. I've always found the finish with a face mill to be as good, if not better, than a fly-cutter, and it will do it almost silently, and at a MUCH higher feedrate, spindle power permitting. A Tormach should EASILY be able to handle even a 4" face mill, and leave almost a mirror finish. I use my 4" Glacern all the time, and wouldn't go back to fly-cutting for anything.

Regards,
Ray L.

[BAMCNC.COM]

Flycutter uses less power, you can always use less inserts in a facemill aswell.

[SCzEngrgGroup]

Flycutter uses less power, you can always use less inserts in a facemill aswell.

Yeah, but why limit yourself based on power when running on a Tormach, which has PLENTY of power to handle even a fairly large face mill? My machine has only a true 1.5HP spindle (never mind the label that claims 3HP....), and it handles a 4" 6-insert face mill with no problem at all, in steel or aluminum.

Regards,
Ray L.

[BAMCNC.COM]

He doesn't have a tormach.

[gd.marsh]

[QUOTE=HimyKabibble;1236051]Yes, but.... What happens with a fly-cutter is the gears are loaded when the tool is actually cutting. Once the tool exits the cut, which it does on every rotation, the load suddenly disappears, and the tool will lead the spindle, opening up any backlash in the gears. When it again re-enters the cut, the backlash is very suddenly taken up.

Agreed Ray .. I didn't consider the tool exiting the cut at either or both sides .. come to think of it .. it does every time the tip swings around to the surface already cut. MY BAD!

[TiagoSantos]

He doesn't have a tormach.

No, but he's got an RF-45 with a 1.5HP motor, running through gears - so in all likelyhood, the same or more HP at these speeds than the tormach.

[SCzEngrgGroup]

I have found a cheap source of polyethylene (HDPE as well LDPE) and POLYCARBONATE SHEET. I tried them as an oil painting support and like the feel of oil painted directly on them.

I was wondering how durable this would be? I am mostly looking at 1/8th inch thick material of around 10-12 inches max width or height. I am sure polyethylene (is this same as mylar?) seems impervious to OMS or turpentine but I am unsure if polycarbonate is.. In any case, I do not use any mediums or diluents so I am probably not going to face issues with this.

WTF does this have to do with the topic of this thread????

[MichaelHenry]

WTF does this have to do with the topic of this thread????

He's a foreign member (assuming this site originates in the US) and that was his first post - it would be more civil to either ignore his post, or gently point him to the correct forum.

Mike

[loply]

That message was automated spam.

Back to the OP - I think something is wrong if you're getting chatter and a poor finish with a light cut.

I have the same mill and I can take a reasonable cut (say 0.25mm to 0.5mm) with a 5" carbide face mill or a 2" carbide fly cutter and it is virtually silent.

I wonder if there's something wrong with the head - gears not meshing properly, a bearing out of alignment, etc?

You presumably have the quill locked and the Z-axis gib locked? The nuts that allow the head to rotate aren't loose? Drawbar definitely tensioned sufficiently with lubed threads?

In any case I don't think it's the fundamental gear head design which is your problem, as my machine is the same and cuts steel like butter under similar circumstances.

Cheers,
Rich

[fretsman]

Just thought I'd add my 2 cents here, but I don't believe it was said how wide and thick the material is that you're cutting?

If it's thin, wide, and unsupported, you'll always get chatter. It must be fully supported from underneath when using a fly cutter or it will chatter even at a couple of thousandths depth.

Dave

[spv123]

Just to clarify a few things:

jid2: Sorry my mistake. I am actually using the TTS collet not an ER20 holder. The SuperFly has a 3/4 shank and would not fit in an ER20. I am not sure why I posted that.

gd.marsh: I am feeding by hand. The machine is manual. I have tried a few different hand speeds and they all seem to have the same result of increased vibration through the head and chatter. I have not adjusted the gibs as it all felt reasonably tight and play free. The insert is the standard SEHT1204AFSN-X45 Cemented Carbide insert that sells with the fly cutter.

RayL: Thanks for the input. I see the suggestion is to get a face mill. I have been eying off the Glacern 45 for some time. That said, I really want to get to the bottom of this issue before I throw more money at tooling.

Loply: I agree that it seems like there is some sort of issue with the gears or drive system. I may well have to pull down the gearbox and have a look. The quill and gibs are locked down. Bolts are tight for the head. Drawbar with sufficient tension.

fretsman: The material is varying. I have mild steel square stock that is 45x45mm (EDIT: that is meant to be 25x25mm) (about 1"). I also have flat bar that is about 2 inches wide. I notice the issues and the gearbox complaints even when the work piece is fully supported in the vise (on parallels - no longer than the vise jaws).

At times I can see a few (not a lot) small bubbles through the gearbox hourglass. I am running ISO 68 hydraulic oil in the gearbox.

I have noticed that the drawbar (as seen out the top of the head) tends to oscillate when running. It is a wonder there is no round V shaped bushing to keep it all nice and square.

The issue really rears its head when the machine is under load. I have a vague recollection that I have seen this issue when drilling 13mm (1/2") holes (already piloted).

Any other ideas? I guess I may well have to tear down the head and see if I can spot anything amiss.

[SCzEngrgGroup]

45mm = 1.77inch

One inch is 25.4mm.

Regards,
Ray L.

[spv123]

45mm = 1.77inch

One inch is 25.4mm.

Regards,
Ray L.

Thanks for the correction Ray. I am working with 25mm. Interesting that you corrected this as I went and did the conversion on Google for 25mm, but then for some reason wrote 45mm. How about we resolve this and have the USA move to Metric?

For completeness, I am working with 25mm sq, and ~50mm flat bar.

[fretsman]

How about we resolve this and have the USA move to Metric?

I was all for it in 4th grade when we starting learning about it. Then it just died.....should have stay with it here, agreed.

Yes, that is a good amount of material for sure, not the issue here at all

Dave

[SCzEngrgGroup]

How about we resolve this and have the USA move to Metric?

Believe it or not, we tried that in the '70s. Even road signs were changed to show miles and kilometers. Apparently the average American found metric too complicated - all that multiplying and dividing by 10 just confused the bejeezus out of them. So, in short order, the signs were changed back, and we returned to our oh-so-logical system of 8 ounces to a cup, four cups to a quart, 16 ounces to a pound, 12 inches to a foot, 3 feet to a yard, 5280 feet to a mile.....

Regards,
Ray L.

[TiagoSantos]

Really the only thing that makes sense in the imperial system is working in thousandths of an inch.. And I guess that's mostly because it's sorta like.. The metric system

[handlewanker]

Hi, until the customer orders their jobs in Metric dimensions nothing will change.

Back in UK in the 70's we changed from Imperial to Metric overnight...by Royal decree no doubt.....LOL
Ian.