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[machinist] Roller box turning tool | Best Insert For Smaller Parts
- From: Lawrence London <lfljvenaura@gmail.com>
- To: machinist@lists.ibiblio.org
- Subject: [machinist] Roller box turning tool | Best Insert For Smaller Parts
- Date: Wed, 11 Dec 2013 21:09:15 -0500
http://www.practicalmachinist.com/vb/general/best-insert-smaller-parts-276734/
Thread: Best Insert For Smaller Parts
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12-11-2013, 06:50 PM #1
- Join Date
- Jan 2008
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- spokane
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- 734
Best Insert For Smaller Parts
I need to turn a number of pieces 1/4 dia. with a couple steps down to 3/16 - 4140. WNMG, TNMG, TPG321 aren't getting me there. Both finish & size. 6" oal with the steps on 4" one end. I also cut a little long to work my way in there & later remove the center.
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What hardness if it at? Use a aluminum insert with a small nose radius and a light feed. cut a part and then program your taper in if you have any. Or get someone with a swiss to run it.
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No insert ? Id go the HSS route.
1/4 by 6" is ugly. 6" by 3/16 is even worse.
I remember turning something in the order of 1/4 by 8" with the finest HSS tool and still got more taper than i would have liked. That was a total exercise in futility. Without a follower rest that is, we had none for that machine.
With steps etc. you may be able to use a steady....
I have had some good results using sharp VCMT inserts for this sort of thing. Was a sharp steel finishing grade actually, you can get even sharper ones if there is need. A lot of model engineers use CCGT etc. style ground and polished non coated carbide for almost everything. It will even work on small bench lathes and can turn small parts that CNMG et al could never do. -
Use a roller box for the long skinny bit and ordinary tool for the steps.
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12-11-2013, 07:21 PM #6
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- Feb 2005
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- Hatch, NM Chile capital of the WORLD
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- 4,677
4140... If it needs to be heat treated, do that first. The stuff is gummy and likes to tear in the annealed condition, especially at a low surface speed,
and at 1/4" you are at a low surface speed.
Sharp insert, small nose radius. Something ground, most likely meant from aluminum. But that's already been said. -
Limy Samy hit the nail on the head. Forget insert choice for a bit, look at the approach for now...you're gonna try to turn 32xD(!) with an approach that has problems at 3xD without a center, and MAYBE 3 or 4 times that with a center holding things still. Add to that a sub 1" diameter...box tool wins hands-down, short of aforementioned Swiss.
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12-11-2013, 07:43 PM #8
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- Jan 2008
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- spokane
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- 734
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12-11-2013, 07:51 PM #9
- Join Date
- Mar 2001
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- Switzerland
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- 1,725
Google box turning tool. Basically a tool with two rollers that are adjustable and a cutting tool that is also adjustable, the rollers support the work just ahead of the turned portion. Can turn small diameters just about as long as you please with one.
Originally Posted by blake in spokane
Whats a roller box? My lathes are a an older but tight LeBlond & a Turnmaster/Clausing. -
Google 'box turning tool'. Turns up results here and around the web that explain the layout and use of these tools. They've mostly been replaced by the use of sliding headstock Swiss autos, so box turners are available cheap on Craigslist and epay and the like.
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Is this a manual or cnc machine?
I have to make a tool every so often from 4140 it is about .062 X .5 on one surface the one behind it is .125 X 1.25 on second surface. I have had good success with a fine point cemented carbide I have used carbide inserts but not as much luck with them.
Kick the rpm way up. 2K or more if your machine has it.
Slow the feed way down.
Get your center line perfect otherwise the material will get pushed around like a fat kid on the playground. -
12-11-2013, 08:03 PM #12
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- Jul 2004
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- N. GA- 33.992N , -83.72W usa
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- 2,143
go to ebay, get cermet inserts of the tnmp ,wnmp,dnmp...whatever holder ,,run those fuckers wide assed - open - as fast as you can . doc, .020 max,
finish about .005.-.001, feed about .002
/rev (it should be fast at the top rpm) your finish should be mirror.
Teledyne DNMP 432 8cc Cermet Carbide Inserts 10 Pcs | eBay
i forgot the orange-glowing ribbons part.... -
Originally Posted by blake in spokane
Whats a roller box? My lathes are a an older but tight LeBlond & a Turnmaster/Clausing.
This is a 5/8" straight shank Boyar-Schultz 00RT roller box tool. It
is made for use in a turret, like a Hardinge DSM59. But it can be
mounted to a toolpost holder on the carriage or held in a Morse taper
end mill holder in a conventional tailstock. They are very accurate and
do not produce a taper. You can get a similar model that uses TPG221
inserts. The second picture shows the best way to grind a HS tool bit
for this tool.
Larry -
12-11-2013, 08:21 PM #14
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- Jul 2006
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- rochester, ny
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- 884
Larry, on that grind is there relief after the very front edge of the tool? All the cutting right on that edge, no shaving behind it?
Reply
- [machinist] Roller box turning tool | Best Insert For Smaller Parts, Lawrence London, 12/11/2013
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