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Back Boring / Threading Tools?

Ox

Diamond
Joined
Aug 27, 2002
Location
Northwest Ohio
I plan to run a part from one side as opposed to flipping it around. I need to back bore and thread.

Kenna has a back boring bar that will work, but it is a 55* insert, and I would really like a 35* insert so that I can leave the 45* thread relief that they call for, but in all honesty, it is a thread relief, so I doubt that it will be the end of the world as we know it if it ends up a 35* chamfer, but still, would be nice to have a 35* insert.

Also, I would like to have a 1.250 bar, and the biggest Kenna goes on this is 1".


Then I need to thread this bore. I could get away with a std bar with a std 60* insert, but I REALLY would like to have cresting abilities if at all possible. So - that means that I want to be able to use a RH insert on a RH boring bar. Or to say another way - on a TOP NOTCH the clamp would need to be further out on the end of the bar, not closer to the turret.

Or more likely - maybe someone might make a lay-down style holder that just has the pocket milled into it the other way.


Can anyone think of such tools off the shelf?


My hole may be big enough that I might be able to make a slotted end shank and clamp in a small external holder. But would like to explore any possible OEM holders.


???


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Think Snow Eh!
Ox
 
Ox, can't help on the threading, but Seco has a good selection of back turn bars in the style you're after. Hit their website and check out EDP 02284. I think that's close to what you're looking for. We actually just purchased one.
 
Ox, can't help on the threading, but Seco has a good selection of back turn bars in the style you're after. Hit their website and check out EDP 02284. I think that's close to what you're looking for. We actually just purchased one.


Talked with Tech Support there and found that this is a 32mm unit, and the smallest inch version is 1.500, which is just too big. We can put this 32mm unit on Jenny Craig and make work, so we can git around that. The worst is that it is very expensive and not stocked in the US.

Not sure how bad I want to get in bed with a holder that will take a week to replace - and is $alty to boot...
Maybe... but not leaning that way right now...

Too bad - it looked like a slam dunk. (almost)

Thanks tho!


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Think Snow Eh!
Ox
 
I've got an old Valenite back turning tool with a 35 degree insert. It's a 1.5" shank, but about 3" has been turned down to make clearance.

It's been sitting in a drawer for at least 5 years and no prospects on future use.

If you want to give it a try, it's yours. I'll send it over.

IMG_1233[2].jpg
 
so I doubt that it will be the end of the world as we know it if it ends up a 35* chamfer

hello OX :) i can not visualize exactly what you wish to say, but if by 35* chamfer you will get a thicker thread end spiral, than is all ok; in many cases is better to change the classical 45* to another value

Then I need to thread this bore

recently i needed to prepare a lathe for a back boring + back threading operation

it may be possible, that a simple modification to a standard tool, will perform well on your setup :
... grinding all along the tool shank, or
... cutting the actual head of the tool, and milling another one, a bit excentric

for exact sugestions i would need a technical drawing :)
 
Ultradex actually makes the right tool in 35*, but only up to 1", but I may be able to make that work, just not as big as I'd like.

[h=1]S16X SVXBR3[/h]
S-SVX.jpg




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Think Snow Eh!
Ox
 
Wesly's solution is a good possibility as well.

Seco does have a 1.500" version of what I want, and it's a lot of Jenny, but could be made to work. But it's also a lot more $ too... And if I was to go that route, I'd buy your tool first. Thank you.


But I think that I am leaning towards just going with a small stick tool on the end of a shank. I'm gunna hafta go that route to get the threading layout that I want anyway, and this will be 1/4 the cost and very basic tool - so stock will be good anywhere. But what's better, is that I believe that if I go that route that I will actually have enough reach to face off the back of the part in the same chucking yet, which is more than expected, but Shirley a bonus.


I'll post pics when done.



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Think Snow Eh!
Ox
 
Ox, why not just take Tores' suggestion? You could send him a CAD file of what you need, and he could make it, right Tores? I think Tores is great about helping with really complicated stuff. Tores seems to know a lot about stuff AND things.
 
Obviously the lay-down threading inserts wouldn't work. (at least I've never seen a left hand insert in a right handed bar).

You might want to look into top-notch style inserts for the threading, or perhaps a stand-up type triangular insert because both of those options have a narrow insert in the Z-axis dimension.

You could probably purchase a regular top-notch style threading bar and do just a little grinding if the radial-step from your "front-bore" to your back-bore requires it.

Top-Notch.jpg
 
Ox, why not just take Tores' suggestion? You could send him a CAD file of what you need, and he could make it, right Tores? I think Tores is great about helping with really complicated stuff. Tores seems to know a lot about stuff AND things.

you change moods faster than she does
 
you change moods faster than she does


OK, now you have me laughing so hard that I'm coughing!
roflmao.gif



Toyota, I was planning on going with an NT2R18E Top Notch, but the voice at Kenna said that they don't doo cresting inserts in NT2 size. So I am going with an LT-16 Lay Down insert/holder.

By going this route I will need to drop down one pitch size insert to get the crest to come out at the right place.
(internal thread depth v/s external)

This should work.


BTW Toyota, this will not be a boring bar holder, but an external stick tool. Just held via an internal means...




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Think Snow Eh!
Ox
 
OK, now you have me laughing so hard that I'm coughing!
roflmao.gif



Toyota, I was planning on going with an NT2R18E Top Notch, but the voice at Kenna said that they don't doo cresting inserts in NT2 size. So I am going with an LT-16 Lay Down insert/holder.

By going this route I will need to drop down one pitch size insert to get the crest to come out at the right place.
(internal thread depth v/s external)

This should work.


BTW Toyota, this will not be a boring bar holder, but an external stick tool. Just held via an internal means...




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Think Snow Eh!
Ox

Understood, that makes perfect sense if you can fit that combo in the bore.
Topping inserts weren't on my mind there, but I do prefer them.

I'm curious to see how you program that operation.

Will your topping cut be in front of your threading cut (on the insert)?
I don't think I've ever seen that happen, but but I suppose it will work.

Will you have a thread clearance at the back-bored "near" inside-shoulder?
That would allow your threading insert to start on diameter and allow the small acceleration distance.
 
Understood, that makes perfect sense if you can fit that combo in the bore.
Topping inserts weren't on my mind there, but I do prefer them.

I'm curious to see how you program that operation.

Will your topping cut be in front of your threading cut (on the insert)?
I don't think I've ever seen that happen, but but I suppose it will work.

Will you have a thread clearance at the back-bored "near" inside-shoulder?
That would allow your threading insert to start on diameter and allow the small acceleration distance.


You are overthinking it. Same as the tech @ Kenna.

RH tool starting at the back of the part, spinning M3 and feeding to an inside shoulder, no diff than normal external apps. The cresting surface will trail.


I was trying to find a LH boring bar that would work like you're thinking, but I couldn't get my cresting surface where I wanted it for moving in Z+, so I'm rolling my own.



Wes, thanks. I understood that as your intention, but I would have given a fair price for it none-the-less.



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Think Snow Eh!
Ox
 
Will you have a thread clearance at the back-bored "near" inside-shoulder?
That would allow your threading insert to start on diameter and allow the small acceleration distance.

I was wondering the same thing? I don't think I've ever started threading at the end of the thread either.

Brent

Edit, I didn't see you post before I posted this Ox.
 
You are overthinking it. Same as the tech @ Kenna.

RH tool starting at the back of the part, spinning M3 and feeding to an inside shoulder, no diff than normal external apps. The cresting surface will trail.


I was trying to find a LH boring bar that would work like you're thinking, but I couldn't get my cresting surface where I wanted it for moving in Z+, so I'm rolling my own.



Wes, thanks. I understood that as your intention, but I would have given a fair price for it none-the-less.



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Think Snow Eh!
Ox


Guilty as charged Ox, I tend to overthink things sometimes... Haha. :crazy:

Did you mean M4?
I may put my foot in my mouth later, but my brain is telling me that M3 would give you a reversed thread cutting in the away from the chuck direction.
 








 
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