Turning 2.5 in diameter on Rapid Turn

[GMcG]

I purchased a RT for my 770 primarily to turn fly reel spools. They are approx 2.5 inches in diameter and a little over 1 inch wide. The grooving operation to take the material out between both sides of the spool needs to go around 1 inch deep. I have tried all kinds of parting tools and feeds and speeds recipes and cannot get satisfactory results. Best fee and speed is 700 SFM with .0007 inches per rev. There's just too much vibration and am wondering if anyone has asked there RT to cut grooves this deep in 6061 aluminum. By the way it faces and profiles the 2.5 inch diameter bar fine. It's just the grooving op that is not working for me. What do I need to try next or is machine just not rigid enough?

regards
GMcG

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[SCzEngrgGroup]

Have you tried a slitting saw instead of a turning operation?

Regards,
Ray L.

[tmarks11]

Really seems like a good application for a manual lathe.

Rapid turn should handle it.

[GMcG]

Really seems like a good application for a manual lathe.

Rapid turn should handle it.

I have turned these spools before with a manual lathe as well as on a mill using a rotary table to rotate into cutter.

I thought the Rapid Turn would handle it as well but it doesn't seem to have the rigidity to get in the full inch of the parting tool without pretty severe vibration.

[tmarks11]

What kind of parting tool are you using?

I like the ones with the carbide insert that has a relief on both sides so you don't end up pinching the blade in the cut.

[GMcG]

What kind of parting tool are you using?

I like the ones with the carbide insert that has a relief on both sides so you don't end up pinching the blade in the cut.

I have used two different inserted parting tools and a HSS parting tool all with about the same results. Way too much squealing and vibration. I use cool lube MQL as well. I am about ready to go back to the rotary table operation but was hoping the Rapid Turn could do the job. Rapid Turn does fine with the facing and OD and ID operations (drilling and boring) but just seems to not be rigid enough for the parting/grooving operation that needs to go 1 inch deep.

[chuckorlando]

I do not know what all you have tried so this could be mute. 90% of the folks I have seen part (including me) are no where near as aggressive as the tool want to run. It's a sketchy process, but they want to eat or they rub. Rubbing creates harmonics and that is the very definition of chatter.

If you want to run slower make sure you use HSS and not carbide. But the same rules apply. Let it eat

[kstrauss]

From my experience with manual lathes chuckorlando is absolutely correct that being aggressive works better.

To be certain that I understand what you are making, do you want to end up with a pair of 2.5 inch disks separated by a small cylinder? With 1-inch deep cuts that implies that the cylinder is only 0.5-inch in diameter. If that is the plan then using a tailstock might reduce vibration.

Considering the inch or more of stickout from the tool holder you need a pretty stout parting tool blade. Also, are you certain that the tool is exactly on centre? If you are using the Tormach 0XA tool holder that is sold with the RT that is also a weak point leading to vibration. I made a much heavier spindle attachment and use a Dorian AXA QCTP.

All things considered you'd probably have less trouble making this part on a 4th axis than with the RT. That way you could cut the spool area on several reels in a single setup.

[GMcG]

Yes the spool is 2.5 inches in diameter with a 0.5 inch diameter hub in the middle. I have tried many different feeds and speeds and the one that works best is the one in the thread. I have tried with the tool a few thousands off of center in the direction of rotation but it works best right on center. I am using the Tormach oxa toolholder. Thanks for your feedback.
Regards

[tmarks11]

What about a parting tool like the Iscar DGTR? I have one of these and they are more rigid than a parting blade, plus the side relief keeps the blade from getting trapped if the part flexes.

Iscar makes a lot of similar tool, the one I have does up to a 30mm deep cut, the one I linked to below a bit less.

https://www.iscar.com/eCatalog/Famil...pp=51&GFSTYP=M

[GMcG]

I will see if they make one that would plunge to 1 inch depth. I have the Tormach parting and grooving tool that uses an insert but it does not plunge to 1 inch. Looks similR to the one you showed in your post.

[tmarks11]

Did you verify with a dial indicator that your blade is exactly perpendicular to the work?

[GMcG]

Yes

[GMcG]

I have tried inserted parting tools with a .120 wide insert as well as a HSS/cobalt parting tool that is .095 wide. In both cases the stick-out is 1.05 inches as the depth of the cut must be 1 inch.

[kstrauss]

Have you considered using normal lathe tools rather than a parting tool? You should be able to nibble away with a neutral DCGT insert holder followed by a cleanup of the sides of your reels using left/right hand insert holders. Using a wide parting tool puts large forces on even a heavy lathe and with the required stickout you can't really use a thin parting tool.

I don't recall if you are using a tailstock. One would make your setup a little more rigid.

[GMcG]

I tried using a tailstock but there is not enough clearance between tool holder and tailstock. Can't even begin the cut with tailstock in place. It is also very difficult to get any other tool into the space since the groove I am cutting is only 1 inch wide and it is 1 inch deep. In the past, before I had the 770 and RT I found the best way to cut the waste out of this spool was to place the blank on a Sherline motorized rotary table and mill the material away and then finish up on the lathe. The RT was suppose to be able to do this but so far no go. I still am feeling the RT is not rigid enough to do what I am asking it to do so I was hoping that someone on CNC zone might have tried it on their RT and had success. So far all the suggestions have either been tried or were not pertinent to the operation I am trying to do.
Thanks for your comments and suggestions. I really appreciate it.

Regards
GMcG

[MichaelHenry]

Longer term you will be better off with a high quality 2mm carb insert blade - they are worth the money.

cheers Keen

Do you have any suggestions on manufacturer and type? I'm using a Tormach 4-mm parting tool in my SBL-15 and need something better for the smaller diameter stock I usually turn.

[CadRhino]

You don't happen to have a link to the model you recommend do you?
Cheers
Nathan

Hi Michael.

I have found 2.00 mm/ 0.80" wide is the magic width. More is too wide and chatters, less is too fragile.

I use Iscar - but I am sure most of the high end brands will be on par. If possible choose a double ended, separate blade in block style, so you can set the projection per job to the minimum.

Cheers Keen.

[CadRhino]

Thanks
Just in time for Christmas

Hi Nathan

I think mine is a Iscar SGFH 26-2 blade to hold the 2mm tips. You want the 26 deep option for stiffness.

https://www.iscar.com/eCatalog/Famil...pp=51&GFSTYP=M

But there looks like there is more current versions of it available now. Which will probably be at least as good.

Cheers Keen

[MichaelHenry]

Thanks Keen!