How to machine inside torx at cnc lathe?

ricardo_gt · Mar 18, 2017

Hi people,
i have to machine 5000 parts with this inside torx at them. Material is X30Cr13 (420F). I do not know any tool capable of doing it as fast as it would be appreciated. In fact, i do not know how to do it...
Any advice, method, tool advice i will be very appreciated. Thanks.

WABOOM · Mar 18, 2017

So you are you creating the torx feature? You don't say what size torx. You'll have to use a carbide drill, a carbide endmill and a ball endmill. Its going to be time consuming.

72bwhite · Mar 18, 2017

rotary broach it

gregormarwick · Mar 18, 2017

Rotary broach will make light work of those.

Houndogforever · Mar 18, 2017

4 Bad Request

search there for your torx size

Zahnrad Kopf · Mar 18, 2017

We do Torx and Hexolobular pockets with rotary broaches.

ricardo_gt · Mar 18, 2017

WABOOM said:
So you are you creating the torx feature? You don't say what size torx. You'll have to use a carbide drill, a carbide endmill and a ball endmill. Its going to be time consuming. And you WILL be breaking tools.

Size 40, it is at the print: Iso 10664-40 (torx - size 40).

mikemaat · Mar 18, 2017

ricardo_gt said:
Size 40, it is at the print: Iso 10664-40 (torx - size 40).

polygonsolutions.com. I haven't used them, but this looks like the ticket.

JP Machining · Mar 18, 2017

+100 for rotary broach

Judging by your one print, there might be a splined diameter outside the torx hole. You can get a rotary broach for that too, they just cost a bit more.

ricardo_gt · Mar 19, 2017

Rotary tools are very expensive...
Is it possible, using the lathe live tool, with the torx bit, rotating at same rpm as spindle rotates, to do the same effect as using a rotary broach tool with rotary tool holder? I mean, just buying the torx bit (200 dollar),and using the front live tool, is it possible to do it? Spending 1200 dollar on a holder is very expensive... i have never done this type of job and i am feeling a bit lost in here...
Thank you for helping.

BKP · Mar 19, 2017

Rotary tools are actually very INEXPENSIVE. The holder from polygon solutions is less than $800 and most of the broaches are well under $100. More than reasonable for the time savings and quality you will achieve. And you'll have the holder for all future needs that may call for rotary broaching. $0.20 per PC over your 5000 qty run.

The NT Guy · Mar 19, 2017

ricardo_gt said:
Rotary tools are very expensive...
Is it possible, using the lathe live tool, with the torx bit, rotating at same rpm as spindle rotates, to do the same effect as using a rotary broach tool with rotary tool holder? I mean, just buying the torx bit (200 dollar),and using the front live tool, is it possible to do it? Spending 1200 dollar on a holder is very expensive... i have never done this type of job and i am feeling a bit lost in here...
Thank you for helping.

Are you asking if using a torx driver bit to CUT a torx configuration in a part is possible? While I would love to see you try and post video of it, I am going to be really nice because you must be very new to machining to even have thought of such a thing and advise you to listen to the wise gentlemen above and a buy a rotary broach. If you think the rotary broach is expensive consider that your idea could cause way more than $1200 worth of damage to your poor machine.

Nerdlinger · Mar 19, 2017

ricardo_gt said:
Rotary tools are very expensive...
Is it possible, using the lathe live tool, with the torx bit, rotating at same rpm as spindle rotates, to do the same effect as using a rotary broach tool with rotary tool holder? I mean, just buying the torx bit (200 dollar),and using the front live tool, is it possible to do it? Spending 1200 dollar on a holder is very expensive... i have never done this type of job and i am feeling a bit lost in here...
Thank you for helping.

NT is right...it won't work. The bit wouldn't be hard enough or sharp enough. The magic comes from the 1 degree offset that the expensive holder provides. But like BKP said then you'd have it forever and it is hands-down the best way to do it. I suppose you might be able to polar interpolate it with G112 if you want to provide some samples or quote off that but I'm guessing that would take....?10 times?longer than rotary broaching.

New techniques can always be scary but it's always fun and rewarding once you figure them out for future use! Then the next time someone needs, say, a round part with a square hole in it you can say, "square hole? No problem! I'll just rotary broach that $hit!""

Bobw · Mar 19, 2017

ricardo_gt said:
Rotary tools are very expensive...
Is it possible, using the lathe live tool, with the torx bit, rotating at same rpm as spindle rotates, to do the same effect as using a rotary broach tool with rotary tool holder? I mean, just buying the torx bit (200 dollar),and using the front live tool, is it possible to do it? Spending 1200 dollar on a holder is very expensive... i have never done this type of job and i am feeling a bit lost in here...
Thank you for helping.

Rotary broaches are also called WOBBLE broaches for a reason..
The axis of rotation of the broach is about 2 degrees off of the axis
of spindle rotation, and the broaches are relieved kind of like a shallow
dovetail.

Someone on here a while ago was using rotary broaches in a live tool holder, the fancy kind that
you can set up off angle(2 degrees).. If I remember correctly he was getting far better tool life by syncing
the broach to the spindle than letting the spindle grab the broach and bring it up to speed.

If you dig around on the internet, there are some home brew plans for making your own rotary broach
holders.. They really aren't particuarly complicated. Factory made one are spendy, but you only ever
have to buy it ONCE..

You will need to buy the broach (or multiples) either way.. Using a wrench isn't going to work, or
at least work well, and certainly won't last very long.

gregormarwick · Mar 19, 2017

Bobw said:
Someone on here a while ago was using rotary broaches in a live tool holder, the fancy kind that
you can set up off angle(2 degrees).. If I remember correctly he was getting far better tool life by syncing
the broach to the spindle than letting the spindle grab the broach and bring it up to speed. .

I must have missed that. Can you link it?

JP Machining · Mar 19, 2017

NEW Rotary Broach / Wobble Broach Tool Holder 3/4" shank for 1/2" shank broaches | eBay
If that is expensive to you, you're in the wrong game.

Bobw · Mar 19, 2017

gregormarwick said:
I must have missed that. Can you link it?

I've already lost a 3/8" allen wrench 5 times today, and I must have 10 of them in the shop..
I've also forgot where I left my coffee at least 3 times... SO... I don't have a clue
what thread it was in, though I don't think it was all that long ago..

It was for broaching small stuff, socket head on a 4-40 or something.

cameraman · Mar 19, 2017

gregormarwick said:
I must have missed that. Can you link it?

@BobW Are you thinking of this?

http://www.practicalmachinist.com/vb/cnc-machining/rotary-broaching-212329/

post#4 used machine 's post ?

I still can't quite 100% get my head around polygon machining/Swiss stuff... So this is a little mysterious to me but the link seems to match what you are talking about.

Ta

Rotary Broaching a 36 Tooth Spline into a Custom Socket - YouTube

This graphically shows the "wobble" not so easy to see on other more industrial / faster machines.

Bobw · Mar 19, 2017

cameraman said:
@BobW Are you thinking of this?

No, that wasn't it, but that is a cool idea...

It was definitely a live tool holder, the kind you can adjust the angle on,
synced to the spindle.

BKP · Mar 19, 2017

JP Machining said:
NEW Rotary Broach / Wobble Broach Tool Holder 3/4" shank for 1/2" shank broaches | eBay
If that is expensive to you, you're in the wrong game.

Those are the "economy" offerings from Polygon. I sprung for the GT line and it was a no brainer. PS markets those solely to the eBay/home machinist crowd. The bearings are not up to snuff for production runs, especially not if your first run is 5000 pcs. And if memory serves me, the op mentioned a Y axis or live tooling, or both, so I'm missing how $1000 investment is exorbitant.

How to machine inside torx at cnc lathe?

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