[Spinnetti]

Spinnetti, I beginning to think there is something wrong here. You just shouldn't be seeing this much pullout.
My suggestion at this point is to contact Tormach with the specifics of what you are seeing, pictures and video always help. I am sure they would be happy to help resolve this, before it becomes too big of a deal.

Before I do, I'll "Take it from the top" and check everything. I have a spare TTS collect, so maybe I'll swap to that too. Its not "too big of a deal" - I don't mean to imply I'm unhappy with the machine or anything, its just that I've never seen a tool pull in nearly 20 years of being around or doing machining and was a bit surprise by it. Whenever it occurs, I back down the feed a bit and it goes away, but its a bit disconcerting. I am cutting at the maximum DOC in a radial cut with a long cutter, so that's a contributing factor. I should get my new coated carbide in shortly and I'll check how that affects it too.

[tbaker2500]

Sounds like good ideas.
How long of a cutter, and what DOC are you using? Are you getting chatter?

[nicad]

Has anyone checked for rotational slipping or mechanical precession between the holder and spindle when experiencing pullout? IE- mark the holder and spindle nose for orientation and then after some pullout has occurred, check if the marks are still aligned or if they have rotated any.

[Spinnetti]

Has anyone checked for rotational slipping or mechanical precession between the holder and spindle when experiencing pullout? IE- mark the holder and spindle nose for orientation and then after some pullout has occurred, check if the marks are still aligned or if they have rotated any.

Good idea, but I can tell you with 99.999999% sureity there is... I even roughed up the TTS finish, and after running a part and pulling the tool, its polished back up again. The obvious scenario is that the side load of the tool is canting the holder in the collet a tiny bit, which drops the mechanical grip to practically nothing since the slightest deflection between tool holder and collet cuts the gripping surface area probably by 1/2, then the intermittant cutting forces (as each 'tooth' engages) provides enough of a vibratory shock to walk the holder both around radially and let gravity pull it out vertcally. In my mind, the TTS holder should be longer for more resistance to this as the lever arm of a long cutter is greater than 1:1 due to how short the TTS insert (into the collet) length is. Could a dull tool do that? The cut quality is fine, so how do I tell?

[Spinnetti]

Sounds like good ideas.
How long of a cutter, and what DOC are you using? Are you getting chatter?

Very little chatter, and only on cut entry. None in the depth of the cut where its pulling out. Details (maybe too much cut for this machine?):

PDB, set tighter than recommended - keep going tighter with each try. Radial cut. 3/8 HSS cutter, ~.400 max DOC (constant depth), Max .200 radial engagement (ramps in from zero, max cut time at depth is only a few seconds), grey iron, using S&F from GWhiz (can't remember, but I wanna say 845rpm, 3.12ipm), 1.250 stickout. Finish is fine, sounds fine (especially at the deepest part of the cut), TTS walks out of the collet. Sounds like a bit of chatter at the intro of the cut (might need to speed up my feed there, but haven't because the tail end of that starts into the meat of the cut), but sounds great in the max depth of cut. since the machine and fixture don't have any problem with this cut, its just the TTS walking out, it seems to me its the TTS and not other components that need attention.

[Steve Seebold]

Very little chatter, and only on cut entry. None in the depth of the cut where its pulling out. Details (maybe too much cut for this machine?):

PDB, set tighter than recommended - keep going tighter with each try. Radial cut. 3/8 HSS cutter, ~.400 max DOC (constant depth), Max .200 radial engagement (ramps in from zero, max cut time at depth is only a few seconds), grey iron, using S&F from GWhiz (can't remember, but I wanna say 845rpm, 3.12ipm), 1.250 stickout. Finish is fine, sounds fine (especially at the deepest part of the cut), TTS walks out of the collet. Sounds like a bit of chatter at the intro of the cut (might need to speed up my feed there, but haven't because the tail end of that starts into the meat of the cut), but sounds great in the max depth of cut. since the machine and fixture don't have any problem with this cut, its just the TTS walking out, it seems to me its the TTS and not other components that need attention.

I think you guys don't understand something with your Gwizzard F&S calculator. I'll bet money that those calculations are made assuming you have a real machining center with 40 OR 50 taper tool holders on a machining center weighing 10,000 pounds or more with a 20 or 30 HP spindle.

Well guess what guys, if that's what you want to do, then you probably bought the wrong machine.

I have all but eliminated tool holder pull out by being a little conservative on my feeds and speeds.

I know this because I used to own a real CNC machine shop.

I'd like to again, but my wife keeps telling me I'm getting too frigging old to work like that. I tell her, hey, I'm only 68 years old and I still do it because it's fun, and as long as it's fun I'm going to keep doing it. But that's a subject for another time.

I have had my PCNC 1100 for about 14 months now, and I have said before, it will do "ANYTHING" I could do on a Haas or a FADAL. It's just gonna to take a little longer.

I'm working on a part right now that takes about an hour and 20 minutes to run the first operation. I know that on a real machining center, I could do the same part in 30 minutes or less. BUT, my PCNC didn't cost $75.000.00.

If you want to use Gwizzard, then take whatever it says for your feed rate and divide it by 3. I'm not saying that's the right answer, but it's a place to start. And for crying out loud, stop using those cheap HSS cutters. I don't use anything but GOOD carbide end mills in my machine.

I learned a long time ago, "GOOD TOOLS MAKE CHEAP PARTS".

[t300]

Isn't gwizard fairly 'accurate' (or ballpark at least) on S&F **assuming that you have put in the proper HP of your machine?**

[Steve Seebold]

Gwizzard is probably pretty accurate for your feeds and speeds, when you plug in all the correct data, but does it ask you how you are holding the tools?

Does it ask if you're holding your tool in a TTS holder, or a R8 collet, or a CAT 40 or 50 tool holder?

I would bet not.

[tbaker2500]

It does have 4 settings for how aggressive it recommends. 1 being conservative, and 4 being "break the bit". Default is 3. I use 2 for my 1/2" cutters, and 1 for my 1/8" cutters, and been happy.
So yes, a setting of 3 or 4 is better for hefty machines.

[Spinnetti]

Gwizzard id probably pretty accurate for your feeds and speeds, when you plug in all the correct data, but does it ask you how you are holding the tools?

Does it ask if you're holding your tool in a TTS holder, or a R8 collet, or a CAT 40 or 50 tool holder?

I would bet not.

Well, we can ask Bob.. it is a hobby market after all. Seems /3 is mighty slow. On my last try, I only needed to take it down half a point or so from 3.5ipm to 3 or so (can't remember exactly)... he's got a "aggressiveness slider" to tune that, but the range of recommendations is pretty huge... I found it to be close, but just a bit much for TTS... directly held in the collet, I bet it would have worked fine, but I bought the PDB and TTS for a reason - now just need to get them to work; after all the spindle load is practically nothing. I would think TTS should hold up to the limit of the spindle HP....

[MichaelHenry]

Steve,

G-Wizard can be customised for spindle HP and there are options for machine/setup rigidity and cut agressiveness. If you have am hour to kill, why not download the free trial and give it a spin?

GWizard: A CNC Machinist's Calculator for Feeds and Speeds

You probably don't need G-Wizard, but even a cursory look at the trial would let you comment more from knowledge than from guesses and that would be of value to many of us.

Mike

[skray775]

Not a Tormach owner but I do use the TTS and a power draw bar setup I made myself along with Gwizard. My machine is Machine Tool Warehouse MD001.

I have never experienced tool pullout. I usually run my machine with the Gwizard calculator setting at the #3 position but need to drop the feed rate on certain types of cuts like a slot so I don't get chip welding.

I would defiantly try a new collet, something has to be out of spec.

[rowbare]

Anyone else using the Curve Compensation feature in GWizard? I have separate profiles set up for the low ratio and one for the high ratio. I use the following adjustment values:

Low Ratio High Ratio HP
Low Range 100 250 .2
Peak Range 870 2200 1.5
High Range 2000 5140 1.5

I might de-rate the High Range HP at some point but otherwise it seems to do the job nicely. It is handy to figure out which range works best for a particular cut.

bob

[SCzEngrgGroup]

Anyone else using the Curve Compensation feature in GWizard? I have separate profiles set up for the low ratio and one for the high ratio. I use the following adjustment values:

Low Ratio High Ratio HP
Low Range 100 250 .2
Peak Range 870 2200 1.5
High Range 2000 5140 1.5

I might de-rate the High Range HP at some point but otherwise it seems to do the job nicely. It is handy to figure out which range works best for a particular cut.

bob

I wonder if those settings are correct (keeping in mind I don't have a Tormach....). The spindle is a 3-phase AC motor with VFD, right? As such, the motor will have constant torque up to base speed (60 Hz), and constant HP above base speed. This means that below base speed, HP decreases linearly down to 0 at 0 RPM (although, in the real world, it will fall off quite non-linearly, dropping off faster at lower RPM). It appears to me those settings are saying you have a constant 1.5HP available from 870 RPM all the way up to 5140 RPM, which I doubt is correct.

Regards,
Ray L.

[rowbare]

Ray,

I guess my chart wasn't clear enough. The Low Ratio column and HP are the settings for one profile while the High Ratio column and HP are the settings for the other. At the low ratio settings, the mill is in constant torque range from 100-870 and constant HP range from 870-2000. At the high ratio settings, the mill is in constant torque range from 250-2200 and in constant power range from 2200 to 5140. That corresponds to a frequency range of 7-140 hz on the VFD with the 60hz crossover occurring at 870 and 2200 rpm in low and high range respectively. In fact the .2HP is a bit high, it calculates to .175 but GWizard rounds to a single decimal place.

bob