[Steve303]

I am having a problem with the TTS Holder being pulled out when using a 1/4" endmill pocketing 6061 aluminum. I am pocketing 1" diameter circular pockets 0.260" deep using a Lakeshore Carbide ZRN 1/4" variable endmill with a DOC of 0.075". When I reduced the DOC to 0.070" I still had pull out but only on the second pocket. I am running 4500 RPM at 25 IPM with 0.075" DOC.

I am using the stock Pulsar with the Lever Draw Bar. I have less than 5 hours on this machine. I've cleaned both the collet and tool holder with acetone. What DOC should I be able to pocket in 6061 Aluminum with a 1/4" endmill? Any recommendations to minimize tool pull out.

Steve

[brianbonedoc]

Steve - I'm the king of took pullout. I've been wrestling with this and adjusting the lever drawbar. Basically do this tighten the drawbar to 20 ft lbs. but before u do, clean the R8 collet inside. Put anti seize on the outside contact areas.

[SCzEngrgGroup]

I'd suggest you talk to John at Novakon about the LDB. It's a tricky thing to get adjusted properly, and he can also make sure you have all the latest parts for it. You should be able to do FAR better than you are.

Regards,
Ray L.

[upnorth]

I would consider pullout with a cut that conservative to be 100% unacceptable. I just went through some problems with a tool pulling out but my cut was heavier. I can't remember the exact details but it was a bit over a .5 horsepower cut. I was also cutting steel. The tool pulled out a few times. I trashed some end mills and it dug into the vise jaws. when the pullout happens it would drop about 1/4 inch by the time I could hit the Estop.

I have a modified coolant system so it does put out a lot of coolant. It appeared to me that the anti seize was washing off the taper and onto the shank of the tool holder. I did not test this further I went with a different system to finish the parts. I recommend trying something other than anti seize on the taper. I'm trying bicycle grease and will let you know after I get a chance to test it. I do recommend cleaning the tool shank with acetone every time it comes out of the spindle.

Tom

[Steve303]

I appreciate everyone's help! I'll email John and see what he recommends. I am on the road today so I can't do much until tomorrow evening.

Steve

[handlewanker]

Hi, I've heard this problem a dozen times before, then something is wrong with the system.....no system that has a problem as simple to cure as this is reliable.

This is in reality just an R8 collet holding a parallel shank tool, but the difference is the way the drawbar applies the force to close the collet and hold the tool shank not the cutter.

On a Bridgeport mill I once had, the collet was held in by a nut and screw drawbar.........using a spring force will not come anywhere near the dead force a nut and screw can exert due to the fact that the spring needs to constantly exert upwards of 500 Kg to make it close the collet to hold the plain shank tool.

I doubt that the actual cutting force from the cutter itself is pulling the tool holder out of the collet.

I suspect that if you have a resonant frequency from the cutter that causes the spring stack on the drawbar to vibrate you will get a loosening of the collet force right when you need it most.

The poster did say that it was the TTS HOLDER that pulled out of the collet......with a 3/4" diam shank......., not the cutter out of the tool holder........and he was using a 1/4" carbide cutter.....LOL.

Somewhere I've seen a need to have a collet force gauge to determine the holding force of a TTS collet, but haven't seen a solution to the problem.

BTW.....if you have to clean the shank of the tool holder and the cutter every time before you mount them, you may as well just use a nut and screw draw bar with it's inherent implacable force and sleep soundly.

One thing's for sure, I doubt anybody with the TTS system walks away and leaves the machine to it's own devices.
Ian.

[SCzEngrgGroup]

One thing's for sure, I doubt anybody with the TTS system walks away and leaves the machine to it's own devices.
Ian.

That is not even remotely "for sure". I leave my machine running for hours on end when doing production runs of my PDB and ATC, and have never once experienced pull-out with a TTS holder, even when running at the spindle power limit on my Torus Pro. All it takes is adequate drawbar tension, which mine DOES provide.

Regards,
Ray L.

[handlewanker]

Hi, I quite agree with what you say......provided you have adequate draw bar pull the tool will stay in the collet........point is who know how much "adequate" pull is present on other people's draw bars........that is a worry......mostly you get away with just cranking the pressure up until the tool doesn't fall out.

The makers will have set the drawbar pressure with the spring pack as they have done the R&D to determine it, but it doesn't stay that way forever.

I still say, with spring loaded pressure, if the system can fail it will fail as has been noted on a number of occasions here due to the need to have a Gorilla like friction grip to ensure the collet holding onto the tool shank.

I would agree that if you cranked the draw bar tension to humungeous pressures nothing apart from a bearing failure would cause a problem in a spindle.

If all else fails to cure the problem like degreasing and scrupulous cleaning of the tool shank, it would mean a strip down to determine if the Bellville washers had failed, and that is not an everyday DIY approach to tool holder integrity.

We are talking about a 1/4" carbide cutter pulling the tool shank out of the collet.........I hate to even contemplate what would be the drawbar pressure to hold a 20mm cutter in.....maybe a dab of super glue.....LOL.

BTW.....on a demo I saw on UTUBE, a guy called ROG ....I think, working on a Tormach 1100.....used a spanner on a nut to tension the drawbar, no power drawbar.......just a light pull was sufficient.......there are no Bellville washers present in that mode.

It would appear the poster on this thread has Bellville washer "under tension" problems, or so it would seem, if they cannot hold a 1/4" cutter in the TTS collet under mild cutting forces.
Ian.

[LeeWay]

That is not even remotely "for sure". I leave my machine running for hours on end when doing production runs of my PDB and ATC, and have never once experienced pull-out with a TTS holder, even when running at the spindle power limit on my Torus Pro. All it takes is adequate drawbar tension, which mine DOES provide.

Regards,
Ray L.

We do the same, but we are usually in the shop while it is running. Certainly not babysitting though. You can hear when something is not right. Now do we leave new Gcode to itself? Depends on the time between tool changes, but once I see it is working as intended, I leave it.
We usually had good luck with the LDB as long as things were clean and using smaller end mills. We had trouble with long 3/8" end mills doing deep slots. Could not use any 1/2" EM's reliably. I eventually just removed everything LDB related and switched to a medium quality butterfly impact.
Now the only reason a tool ever pulls out is due to cleanliness. It is usually a larger tool that shows this first. If I could get my Son to clean it every week, then we would not have that issue ever. However, he treats my tools the same way he did his room when he was young.
Just glad he puts them back in the correct hole when done.

[handlewanker]

Hi...cleanliness!!.......that means you always insert a clean tool in the collet.....that means there should be no grease, oil or coolant on the cutter shank when it's mounted......the same applies to the TTS tooling if you manually insert it.....if you don't see the crud on the tool shank you must be blind or just plain lazy.

I don't think this thread is about cleanliness on tool shanks........but I may be wrong.......I've seen people mount a Camlock chuck with swarf in the register and are happy to work that way.

I would have thought a cutter would pull down from an ER chuck before the tool pulled down from the TTS collet especially if the cutter was an Imperial size in a metric collet that had to be squeezed down from 7mm to get the 6.25 or 1/4 size to clamp.

With ER collets I always go for the top size rather than squeeze down to the next level as ER collets are known to be able to do......this means Imperial sizes for all Imperial cutters and Metric as per.

We may yet find out the real cause of the problem, but I don't think the Acetone cleaning will be top of the list.
Ian.

[LeeWay]

While I never actually said it, I was hinting that his LDB is not setup correctly. Then explained our experience and routine, why we switched to what we use now.
I also think with regular cleaning, that cleanliness is not an issue. Especially since the OP ruled that out.

[jpniewski]

When we first got the Pulsar, the drawbar was not adjusted properly as received from Novakon, so if you're using it as delivered, that could be your problem. I had to take the LDB unit off to adjust the drawbar that's threaded into the collet so that the TTS toolholder just releases when the bar is fully pulled down. Took a few attempts to dial it in properly. Have not done too many heavy cuts in metal with it (that's what our Torus Pro is for) but have not had any pullout problems.

Joe

[LeeWay]

I basically think we just wore ours out. Replaced the springs once and that helped for awhile. I have to say that we change a lot of tools per day. I just don't think it was designed for production use like that. That said, if you can do routine maintenance and adjustments on it, it should stay reliable.

[handlewanker]

Hi, I doubt the LDB is a problem as it only works with force when pushing down on the drawbar.......it's more of a retention problem which makes me think the Bellville washers need to be compressed more or sorted out if they are "coil bound".....maybe even in the wrong configuration. .

I'd not rule out the ER collet scenario I mentioned as a 1/4" shank is 6.2 mm and to get it to work in an ER collet you need Imperial collets........a 7 mm collet has to squeezed down a wack and that means the diam of the collet bore is no longer in full contact with the cutter diam......just a theory.

Another wild guess.....if the draw bar is restricted in it's upper travel and cannot be raised any more no matter how much tonnage you apply and so prevents the lower taper from seating either, it might not be applying enough force to the collet......this could occur if the collet is making contact with the top of the bore it fits in......easily cured by grinding a bit off the top of the collet where the draw bar screws in.

I suspect there is a problem with the B washer stack..
Ian.

[LeeWay]

I haven't had anything slip out of an er collet. Ever. Set screw holder either. And this is without Weldon flats sometimes. I have had to use higher quality set screws sometimes, but I don't think that is the problem. We don't do anything special about it. Use the right collet size and torque everything the proper amount and you should be good to go.
We do use some high quality collets as well as low cost ones. Results are the same for both. The key is using the proper size collet.

There is a drawing around somewhere of the LDB. It does help to study how it works.

[Steve303]

Interesting discussion.

Here is a little more info about the lever draw bar on my Pulsar. I've not adjusted it at all, it's factory stock. I've only cleaned the collet and TTS holders with acetone as I've read should be done here on CNCZONE. The tool is not moving in the collet, the TTS actually being pulled out. There was no coolant on the TTS holder as I had just cleaned the holders and inside the collet with acetone to remove any contaminants. I'll have to adjust the draw bar, as some of you have mentioned, as they seem to be shipped from the factory without being fully adjusted. I'll remove the collet at the same time. Also waiting to hear back from John and Novakon.

Here is the breakdown of the lever draw bar from the Novakon website.
Attachment 335658

[Steve303]

Steve - I'm the king of took pullout. I've been wrestling with this and adjusting the lever drawbar. Basically do this tighten the drawbar to 20 ft lbs. but before u do, clean the R8 collet inside. Put anti seize on the outside contact areas.

Brian, can you give me a quick step by step on how to tighten the drawbar.

[SCzEngrgGroup]

Hi, I doubt the LDB is a problem as it only works with force when pushing down on the drawbar.......it's more of a retention problem which makes me think the Bellville washers need to be compressed more or sorted out if they are "coil bound".....maybe even in the wrong configuration. .

I'd not rule out the ER collet scenario I mentioned as a 1/4" shank is 6.2 mm and to get it to work in an ER collet you need Imperial collets........a 7 mm collet has to squeezed down a wack and that means the diam of the collet bore is no longer in full contact with the cutter diam......just a theory.

Another wild guess.....if the draw bar is restricted in it's upper travel and cannot be raised any more no matter how much tonnage you apply and so prevents the lower taper from seating either, it might not be applying enough force to the collet......this could occur if the collet is making contact with the top of the bore it fits in......easily cured by grinding a bit off the top of the collet where the draw bar screws in.

I suspect there is a problem with the B washer stack..
Ian.

You seem to like speculating on things with which you have no experience....

A 6mm collet will hold a 1/4" tool with no problems whatsoever. Metric ER collets have a usable range of +/-0.5mm. I use ER collets almost exclusively, most of the ones I own are metric, and I have NEVER had a tool come loose from an ER holder.

Also, with adequate drawbar tension, coolant on the TTS shank is a total non-issue. Mine very often come off the machine with the shanks dripping coolant, and it has never caused a problem.

As for the LDB - there have been several design revisions during its production life. I would expect current production LDBs to be better than earlier ones due to these improvements. Personally, I'm not convinced any practical Belleville-based drawbar will provide fool-proof tool retention.

Sometime, hopefully early next year, my PDB will be available for the Pulsar, and will provide the same tool retention as it does on the Torus Pro.

Regards,
Ray L.

[handlewanker]

Hi, I found this one somewhere and saved it for future reference......the title appears to be for the Tormach.
Ian.

[handlewanker]

You seem to like speculating on things with which you have no experience....

A 6mm collet will hold a 1/4" tool with no problems whatsoever. Metric ER collets have a usable range of +/-0.5mm. I use ER collets almost exclusively, most of the ones I own are metric, and I have NEVER had a tool come loose from an ER holder.

Also, with adequate drawbar tension, coolant on the TTS shank is a total non-issue. Mine very often come off the machine with the shanks dripping coolant, and it has never caused a problem.

As for the LDB - there have been several design revisions during its production life. I would expect current production LDBs to be better than earlier ones due to these improvements. Personally, I'm not convinced any practical Belleville-based drawbar will provide fool-proof tool retention.

Sometime, hopefully early next year, my PDB will be available for the Pulsar, and will provide the same tool retention as it does on the Torus Pro.

Regards,
Ray L.

Ray....speculating perhaps but with an educated guess which is better than pure guesswork.

BTW.......I don't know where you get the +/- 0.5mm from.....an ER collet is nominal size and down 1 mm.....it would be very difficult to press a larger size cutter into a smaller size collet, even at - 0 .5mm......even the nominal size cutter diam is a tight fit in the collet........well, mine are......are you saying that an ER collet can be forced open + 0.5mm and squeezed down 1mm........that's a 1.5mm range......the manufacturers don't advise this....down 1mm yes, but not up.

This comes about due to the fact that you can't fit a 25mm plug into a 25mm hole....that's a press fit.....the collet has to expand slightly to get the cutter diam into the same size hole........a half mm bigger and you'll be forcing it.............maybe your collets have gone a bit slack from constant use.
Ian.