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QT15 / Mazatrol T2: Backwards threading tool holder ... now cutting left hand threads

kb0thn

Stainless
Joined
May 15, 2008
Location
Winona, MN, USA
Hi Guys,

So I crashed my faithful BT25 mounted threading tool. Destroyed it badly. My lathe is a weird bugger with a 16 position turret that doesn't take stick tooling. But I made one tooling block that takes 3/4" stick tooling. That block is orientated so the spindle is running in reverse and the insert is facing up. So long story short, I bought a new SECO threading tool ... and I can only seem to cut left hand threads. I've tried setting the "R/L" in *** TOOL DATA *** to both RGT and LFT and it doesn't seem to make a difference.

Does Mazatrol T2 only do left hand threads when the spindle is running in reverse? IE do I need to make another tool block that holds the tool upside down (matching the rest of the tools in the lathe) so I can do right hand threads?

It took me an embarrassingly long time to figure out why I couldn't get the ring gauge to start on the threads... :willy_nilly:
 

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The only way you could get a RH thread from the tool orientation is to start at the chuck and feed towards tailstock.
 
Oh, that's easy. Just switch my SPT and FPT and I'm good to go? Is there any downside to this?

Thanks!
Yes..you will probably need to cut a relief so the tip doesn't break when it plunges on X. Also it will have an acceleration distance that will be added, when running in auto mode, to your stating point, so will will want to check that Z number either with graphics or machine lock. The faster you run the more acceleration distance it will use.
 
I have an early QT10 with a horizontal turret on the back. Uses right side up tools and spindle runs in reverse, similar to your new threading tool. What others have said is correct, you need to start at chuck and feed out to tail stock, just adjust start and end points in Z. It seems like this would be very hard on the tool, just plunging in, but I do it all the time and it seems to work just fine. A normal setup threading towards the chuck looks a little nicer at the end of the thread, but this works just fine. I dont do really high production runs and tend to use more passes then normal. Perhaps if you were really pushing it you might want to relieve it instead of plunging.

A little bonus of doing it this way is your slightly less likely to crash. I always found it stressful to see threading tool speeding towards a shoulder or the chuck with no way to stop it, and not knowing exactly when it was going to stop for sure. At least this way its moving away from the chuck/shoulder so if you make a mistake programming or with an offset it will be obvious right away that start point is wrong, and you should have much more time to hit e-stop if end point is wrong.
 
Hi Guys,

So I crashed my faithful BT25 mounted threading tool. Destroyed it badly.

Yes, you need a RH hand holder to cut RH threads when starting from the face of the work going toward the chuck. Kennametal makes special Top Notch holders that go in a left hand station that will cut proper RH threads.

Did a search for NSR-DH on ebay and found a lot of hits. You will have to shave the thickness down to fit a 3/4" station though.

Here's one on ebay:

KENNAMETAL INDEXABLE TOP NOTCH TOOL HOLDER 1" SHANK NSR-DH-163C + 2 NEW INSERTS | eBay


Found a BT25 threading holder on ebay as well:

SANDVIK BT25-R166-OFG-2532-16 (Used, Cleaned, Tested 2 year warranty) | eBay
 

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Yes, you need a RH hand holder to cut RH threads when starting from the face of the work going toward the chuck. Kennametal makes special Top Notch holders that go in a left hand station that will cut proper RH threads. Here's one on ebay:

KENNAMETAL INDEXABLE TOP NOTCH TOOL HOLDER 1" SHANK NSR-DH-163C + 2 NEW INSERTS | eBay

Found a BT25 threading holder on ebay as well:

SANDVIK BT25-R166-OFG-2532-16 (Used, Cleaned, Tested 2 year warranty) | eBay

Those tools should work well. I considered buying one of these, but I cant re run a finish pass on my darn T1 with reverse rotation.
 
Wow, great advice.

I tried flipping the SPT and FPT and threading from chuck to tailstock. It more or less worked but the threads weren't great looking and I wasn't getting a warm fuzzy feeling about it.

So I came in to the shop on Sunday and machined a new tool holder block for my turret. So I can use normal upside down tools. When I designed and machined the last one and didn't even think that orientation would matter. Just figured it was easier to change inserts right side up. Lesson learned. Most of a Sunday and a block of 1018 and a 1/2" EM was all that lesson cost.

With the new tool holder and new SECO threading tool and I'm also back to good. I was using a generic sharp point threading tool. Program was working well prior to crash. But with new SECO 14 TPI NPT special threading insert, I had to reduce my thread depth about 0.015" to get the parts to ring gauge correctly. I know that the NPT lay down tool has the flat on it, but it doesn't seem like it would make that big of difference on thread height. Perhaps I am missing some bigger picture on what is going on?

Phil - thanks so much for finding that tool holder on e-bay! I wish I had found that before I spent $250 and two days messing around with what I'm doing now. I guess I need to brush up on my ebay searching skills. It definitely wasn't showing up in my results. I've bought that holder. Thanks!

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Is your insert a partial profile, or full profile tool? Full profile tools not only cut the flanks and root of the threads, but also the crest (major diameter). Those inserts require different inserts for different handedness (?), Full profile inserts will give you a wonderful thread, no burrs, no caca.
 
Is your insert a partial profile, or full profile tool?

I am not sure I understand the terminology enough. Here is the SECO insert my tooling supplier "gave" me:
Seco Tools

16ER 14NPT CP5

What would that be called? So it make sense that I would have to back off the thread depth in the program? I only have a ring gauge to check the parts. When I ran the new threading tool / insert with my old program, the ring gauge went on way too far. I decreased thread depth until the ring gauge sits flush with the end of the threads. In this configuration I get about 3 turns of a mating fitting by hand. I'm concerned because I usually get about 3.5 turns by hand. I did just get some thread wires, but I'm not really sure how to use them for NPT yet.

Fortunately for me the application is pretty forgiving. Just using them for mechanical connection. But would like to get everything right. That was the point on moving these off of the Rigid threader and on to the Mazak. Trying to make everything smooth and fit together nicely for a better experience for the customer.

Thanks thanks thanks!
 
Your 16ER 14NPT insert is full profile 14 pitch external insert to cut tapered pipe threads.
Are you using your tooleye to set Z and X offsets?
 
Your 16ER 14NPT insert is full profile 14 pitch external insert to cut tapered pipe threads.
Are you using your tooleye to set Z and X offsets?

Tool eye is inoperative. I set the X by using the threading tool to turn an OD on a bar, measure it with a micrometer, then do "TEACH" soft key on the offset page. I've been pretty much eyeballing the Z. Probably getting with 0.010" on Z.
 
Tool eye is inoperative. I set the X by using the threading tool to turn an OD on a bar, measure it with a micrometer, then do "TEACH" soft key on the offset page. I've been pretty much eyeballing the Z. Probably getting with 0.010" on Z.
You can also use your "teach" function for setting your tool offset in Z.
 








 
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