Another (Yuck) Shear Hog Thread With a Side of Pull Out

[Bob La Londe]

I discovered that I can't really run a 1/2 end mills in my 1100 for what I hoped to which was bulk material removal, well not without a lot of tweaking and adjusting. I want to stay with factory setup atleast until the warranty is expired. After that I may go with a servo or air hydraulic tightened draw bar., and move the Tormach PDB over to a smaller machine. I may be wrong but I have jobs to cut so I'm leaving out the 1/2 end mills for now. Atleast those with the 40+ degree helixes for aluminum. The 3/8 does a fair job and so far has not resulted in any measurable pull out even under decent cutting loads. It just doesn't remove material as fast as I would like.

Tormach offers the AB Tool Shear Hog (or a variant of it) and some of sponsored or long time fan video channels really promote it. I just wonder if it might also experience pull out under near maximum cutting loads and maximum material removal strategies.

Who has a) experienced tool pullout with other tool & b) tried to push a Shear Hog? How did it work out.

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[Bob La Londe]

Speaking of pullout...

I managed to pull a tool holder out with just a 1/4 inch end mill in it the other day. I was doing a cleanup spring pass, and somehow I placed the tool path on the wrong side of the profile line. OOPS! Tool holder walked out until it was screaming at more than half inch depth of cut with 100% engagement and then it broke off. The part was ruined, but the machine just stopped when it failed to make the next tool change.

I think I'll stop at this point and just accept the limited cubic inch per minute rate and design jobs around that. I don't see any reason to invest hundreds in a tool if I have to baby it anyway.

All that being said I ran two jobs yesterday basically unattended. 2.5 hrs each. I was in the building, but in my office watching the cameras and doing CAD and CAM for the next jobs to go. I've got three more jobs (6 parts) to go on the Tormach and a couple dozen to go on the Speedmasters. Literal weeks of machine time.

[mactec54]

Speaking of pullout...

I managed to pull a tool holder out with just a 1/4 inch end mill in it the other day. I was doing a cleanup spring pass, and somehow I placed the tool path on the wrong side of the profile line. OOPS! Tool holder walked out until it was screaming at more than half inch depth of cut with 100% engagement and then it broke off. The part was ruined, but the machine just stopped when it failed to make the next tool change.

I think I'll stop at this point and just accept the limited cubic inch per minute rate and design jobs around that. I don't see any reason to invest hundreds in a tool if I have to baby it anyway.

All that being said I ran two jobs yesterday basically unattended. 2.5 hrs each. I was in the building, but in my office watching the cameras and doing CAD and CAM for the next jobs to go. I've got three more jobs (6 parts) to go on the Tormach and a couple dozen to go on the Speedmasters. Literal weeks of machine time.

There obvious is something wrong with the draw bar setup I don't have this machine, but can't you add more draw bar pressure using an R8 is not that greatest for CNC but works well for thousands of machines, I have one machine with R8 and even with a 3/4" end mill cutting steel I have never seen any pullout of the cutter 1/4" and 1/2" this should not happen no matter what kind of cut you are doing, you can only use the Hp you have and that it not very much

You can buy direct from AB Tools I have there whole range of shear hogs up to 6" and have never had any problems with them, I never take more than .100" cuts with them even though they can cut more than that I use these in the R8 machine as well without any problems up to 3" diameter Shear Hog

[jwatte]

R8 is not that greatest

We are talking about TTS, where there's a R8 collet with a flat bottom that mates to a 3/4" straight shank tool holder that in turn holds the tools.
It's this 3/4" straight shank that pulls out of the R8 collet that's held in the spindle.

I managed to pull a tool holder out with just a 1/4 inch end mill in it the other day.

That doesn't sound right. Check:
- is there grease or oil in the wrong spots? some could have migrated from the collet surfaces or threads to the actual holding part in the 3/4" bore
- do you have sufficient pressure? make sure it's adjusted so it just barely releases when the power drawbar activates. Or, if you don't use PDB, crank more on the drawbar.
- is your R8 TTS holder marred on the inside, or skewed somehow, or is the TTS holder marred or non-round?

Allegedly, you can sandblast or otherwise put a surface roughness on the TTS shank, and it will hold better. I've never tried it.

[SCzEngrgGroup]

I managed to pull a tool holder out with just a 1/4 inch end mill in it the other day. I was doing a cleanup spring pass, and somehow I placed the tool path on the wrong side of the profile line. OOPS! Tool holder walked out until it was screaming at more than half inch depth of cut with 100% engagement and then it broke off. The part was ruined, but the machine just stopped when it failed to make the next tool change.

Bob,

I would suggest:

1) Clean collet (inside and outside), spindle taper, and TTS shanks thoroughly with solvent (brake cleaner works well), then dry
2) Put a coat of Dykem on the spindle taper, collet taper, collet bore, and TTS shank
3) Do a heavy cut for a few minutes
4) Disassemble, and look at all the surfaces to see where they were making contact

In an ideal world, you'd see nearly all the Dykem removed. In the real world, you'll find it untouched in some areas, which means there is NO contact there. There have been reports of bad TTS collets that end up with a slight internal taper when tightened, so only make contact with the TTS shank at the very bottom edge of the collet. The R8 taper, or your spindle taper may also be off.

In actual use, it is VERY important to have a light coat of anti-seize on the R8 taper ONLY. Without that there will be more friction, which will greatly reduce the clamping force on the TTS shank. ANY of the above will cause greatly reduced retention of the tool holder, and give you pull-out.

Regards,
Ray L.

[mactec54]

We are talking about TTS, where there's a R8 collet with a flat bottom that mates to a 3/4" straight shank tool holder that in turn holds the tools.
It's this 3/4" straight shank that pulls out of the R8 collet that's held in the spindle.



That doesn't sound right. Check:
- is there grease or oil in the wrong spots? some could have migrated from the collet surfaces or threads to the actual holding part in the 3/4" bore
- do you have sufficient pressure? make sure it's adjusted so it just barely releases when the power drawbar activates. Or, if you don't use PDB, crank more on the drawbar.
- is your R8 TTS holder marred on the inside, or skewed somehow, or is the TTS holder marred or non-round?

Allegedly, you can sandblast or otherwise put a surface roughness on the TTS shank, and it will hold better. I've never tried it.

I'm well aware of what was being talked about I had one of these machines for a short while

I guess anyone would try anything in desperation ( sandblasting ) is instead of fixing the real problem

It does not have very much to do with the TTS holder you are relying on the R8 to grip the TTS Holder just like if you where to use an Endmill direct in the R8 collet, if they designed the TTS Holder correct this would never be able to pullout of the R8 the R8 master would have to be changed in design also to achieve this

[Bob La Londe]

The collet inside is clean. The tool holders are clean. I think I might actually have gotten a weak set of belleville washers. When tightened down enough so the tool just barely falls out the bellevilles have very little travel left. Enough, but just barely. A stronger spring stack is really what is required for this system.

[wildwhl]

The collet inside is clean. The tool holders are clean. I think I might actually have gotten a weak set of belleville washers. When tightened down enough so the tool just barely falls out the bellevilles have very little travel left. Enough, but just barely. A stronger spring stack is really what is required for this system.

Stronger spring stack is not hard to achieve. My machine arrived with 6 springs, I originally bumped it up to 8. That works well if all is clean and happy, PDB coated correctly with anti-seize etc. I've recently bumped it up to 12 springs and am having great success/results so far (~2 weeks of heavy running). My best material removal rate, by the way, is achieved with 1/2" end mill running around 3800 RPM (forget DOC/WOC off hand but nets about 3.5 cu.in MRR) or .375" running flat out with about .65 DOC and .09-.12 DOC - 80-100 IPM depending on goals.

WW

(no idea why photos are rotated - note I shortened the drawbar to accommodate the extra springs, and need to keep about 105-110 psi in the compressor for everything to release groovy)

[Steve Seebold]

I used to have pull out problems but then I spoke with someone at Tormach and he suggested that I tighten the collet to where I could step on the pedal and just barely get the TTS holder out of the collet.

I tried that and guess what! It works. I don’t have the ATC on my machine. It wasn’t available yet. The ATC came along in October 2011 after I bought my machine in July.

I seldom use larger than a 1/2 inch end mill in and it works just fine.

If I have a lot of material to remove, whether inside or out, I don’t side cut, I will plunge ruff and only side cut to finish.

[mountaindew]

WOW!
(no idea why photos are rotated - note I shortened the drawbar to accommodate the extra springs, and need to keep about 105-110 psi in the compressor for everything to release groovy)

I replaced my air compressor to a 2 stage 155 psi unit recently. Adjusted my PDB to release tool at 120 psi. "Adjust tight and atc would not work I bet" I seen one comment someone runs theirs at even higher psi. I was going to do some research to see what the cylinders are actually rated for. Then determine if I wanted to go above what Tormach recommends as max.


Anyway outside of that I keep everything clean and anti-seize at proper locations. Tool stick-out is what catches me all the time. I tend to run long cutters and chatter is easy to find and both precision and pullout is often compromised not long after. If I take the time to setup or use short cutters for performance cutting work I get much better results. HSMAdvisor feeds, speeds, doc, woc are much more realistic with my setups when I input actual tool stickout or overhang


As for MMR of 6 ci a minute they show in Tormach video is crazy! 2 minutes of that video made more chips by volume then the last dozen parts I turned out finished including the parts.