Internal thread relief tool

[morrisman]

Is there a special tool to do this cut ? To cut the relief clearance for the threading tool . I would imagine its shape would be somewhat like a parting off tool but wider and short . MIKE

[Stustoys]

Hi Mike,
I'm not sure I undersatnd the question, are you asking about a runout groove for thread in a blind hole?
If so I just use a boring bar. You can get internal grooving tools but I dont have one.

Stuart

[morrisman]

Hi Mike,
I'm not sure I undersatnd the question, are you asking about a runout groove for thread in a blind hole?

Stuart

Yes Stuart. It's tricky doing it with a boring tool as you won't get a clean 90 degree relief because of the way the boring tool is shaped. MIKE. BTW I am cutting a 7 tpi internal thread . I am making a spindle nose protector for the PREMO lathe ..it is 1 and 3/4" BSF thread . I have to change the stud gear around on the Sheraton to 40 tooth ... it never ends ..fiddly stuff :D

[Bryan]

You mean like this? MGIVR/L INTERNAL GROOVING TOOL #L88 (http://www.ctctools.biz/servlet/the-722/MGIVR-MGIVL-Indexable-Lathe/Detail)

[morrisman]

You mean like this? MGIVR/L INTERNAL GROOVING TOOL #L88 (http://www.ctctools.biz/servlet/the-722/MGIVR-MGIVL-Indexable-Lathe/Detail)

Yes Bryan, that is a rather fancy example, but that's what I was asking about . MIKE

[Stustoys]

Hi Mike,
7 tpi doesnt need a run out groove, it needs a ruddy great trench lol
You're right, with a thread that size a normal boring bar isnt going to get it done. But 1 3/4" should get you plenty of room to make a bar with a HSS tip on the end.
Are you looking for plans for one?

Stuart

[pipeclay]

Not sure if I have missed something in your job description,but why would you require a runout groove in a through hole,or is this a spindle nose protector with a solid outer face.

[morrisman]

Yes pipeclay it has a solid outer face .Stuart ..yes it's a big thread . You are correct , a normal little threading tool will just scratch it :rolleyes: If you do have a plan for a HSS threading tool I can grind up :2tsup:. I have a chunk of HSS that would suffice. MIKE

[Stustoys]

Hi Mike,
I'm confused, you want a plans for a threading tool or a internal boring tool or both?

Shouldnt be hard to find a tool holder that does both with a different tip. I'll have a look around in the morning. As the thread isnt that deep it should make things pretty easy(famous last words)

Stuart

[RayG]

Hi Stuart, Mike
I'll save you the trouble, I got some from Threading Tools : Mesa Tool (http://www.mesatool.com/index.php?main_page=index&cPath=4)

That does internal external left and right handed, threading and grooving with one holder and different inserts..

I've not used it much for internal grooving, except once to cut some internal circlip grooves

Regards
Ray

[Stustoys]

First question, is your HSS square or round?
Stuart

[pipeclay]

Is there a reason why it has to be a blind hole,most spindle protectors are hollow.
Have you considered just using the Threading tool to cut the undercut,saves the hassle of having to grind something else.
Theres no reason why the blind end would need to be square cornered,and the inner end of the thread would have a chamfer.

[Michael G]

This may sound a dumb question, but why would a spindle protector be needed? Unless the lathe is a combo machine, it is only ever going to be used with something on the spindle - whether that be a chuck, face plate, or drive plate for a dog. Perhaps some collet types only use the internals, but anything put on to protect threads would then need a through hole.
I keep my lathe under a drop sheet for dust control mainly but have never bothered with a metal spindle protector, and the bed needs just as much protection as the spindle nose does. If I felt that it needed some temporary while I was making repairs I might fit the collet chuck, it being the smallest and most compact that I have, but a purpose made nut seems overkill.
Enlightenment please

Michael

[Pete F]

I think the idea of them is precisely as you say Michael, when using collets directly in the spindle bore. I have a spindle nose protector, and until I fitted my new chuck used to use a collet chuck quite regularly, but don't ever use the protector, it just sits in a drawer gathering dust.

If I were using my MT3 collets directly in the bore of the 9", given that I have the protector I would throw it on, but I don't think I will bother with one for the 260.

Pete

[Stustoys]

Hi Micheal,
If you were turning between centers or collet chucks that use a draw bar Mikes nut would protect the spindle.

Hi PC,
If the runout groove (at least the face the will be against the spindle) isnt square, wouldn't make a place for swarf/coolant to collet, some of which will end works its way into the spindle thread?
I don't think my little boring bar would be able to cut a groove deep enough that wasnt 10mm wide.


Something like this wouldnt take long to make if you didnt have something already.
Making a Boring Bar for the Lathe (http://www.truetex.com/boring.htm)

Stuart

[Pete F]

Stuart if you're turning between centres wouldn't you normally have a drive plate or similar on the spindle to drive the work?

I can photograph my nose protector when I get home if it's of any benefit. However I won't be back home until the weekend.

Pete

[Stustoys]

Stuart if you're turning between centres wouldn't you normally have a drive plate or similar on the spindle to drive the work?

Me personally? normally, yes.
Others maybe not so much.

Stuart

[morrisman]

First question, is your HSS square or round?
Stuart

Stuart, it is odd in that it is rectangular ..it came with a box of HSS odds and ends . It is 3/8" X 1/2" , about 3" long . Ok on the comments re: the spindle protector being bored right though , that makes sense . I was thinking more of a protector for when the lathe is being moved etc. But I will make it bored through as it does mean its easier to make . The first attempt at internal threading failed ..the tool was flexing and just scratched the surface . As Stuart said, it is a large thread and I need a rigid lump of HSS in order to do this job ..you live and learn , another lesson for me . MIKE

[Pete F]

Me personally? normally, yes.
Others maybe not so much.

Stuart

Oh. If there's a centre in the spindle but nothing on the spindle threads (well except the protector), how are they driving the work? I typically need to reverse the work as the drive dog gets in the way, so it sure would be handy to be able to turn a full length.

The only other way I've personally seen to drive the work between centres without some form of dog is a centre I saw a picture of, it looked like the wood turning centres with teeth machined that bit into the end of the piece. I don't think they're commercially available though and doubt anything other than the lightest of cuts could be taken. Very keen to get some other ideas for driving the work though.

Pete

[Stustoys]

HI Mike,
One thing I forgot to add, you could likely make your life a lot easier if you make it out of Alum or some sort of plastic. But then its not always abot making life easier :)

Stuart

[morrisman]

Some pics ..the HSS lump for the threading tool I hope to grind ..I will have to make another piece as i stuffed the first attempt

[morrisman]

HI Mike,
One thing I forgot to add, you could likely make your life a lot easier if you make it out of Alum or some sort of plastic. But then its not always abot making life easier :)

Stuart

That is true , but I need the practice at internal large size threading for I am planning on making new adapter plates out of cast iron for the chucks on the PREMO .. they came with rust damaged threads after years of being in a shed .

[Stustoys]

Hi Mike,
I'd forget the groove and thread in reverse. I guess with a screw on chuck thats not an option(?).
That piece of HSS is a little on the large size, nothing smaller in the shed?

Stuart

[Machtool]

The only other way I've personally seen to drive the work between centres without some form of dog is a centre I saw a picture of, it looked like the wood turning centres with teeth machined that bit into the end of the piece. I don't think they're commercially available though and doubt anything other than the lightest of cuts could be taken. Very keen to get some other ideas for driving the work though.

Pete
Here you go Pete.

Drive Center Spring Loaded for #2MT Lathes (5/8" CROWN) | eBay (http://www.ebay.com.au/itm/Drive-Center-Spring-Loaded-2MT-Lathes-5-8-CROWN-/110785334601?pt=LH_DefaultDomain_0&hash=item19cb520d49)

Phil.

That wasn't what I was looking for, I see these out in industry, on decent sized CNC lathes. I'll B.B

(On Edit) “Face drivers” was the word I was looking for. I see them about, and you often see work that’s been produced on them. If you look at the face of a lot of electric motor shafts. You have the centre, but there will be 6 small indents, arrayed around the centre.

http://www.riten.com/products/face-drivers.html


http://lmcworkholding.com/pdfs/NeidleinBrochure.pdf (http://lmcworkholding.com/pdfs/NeidleinBrochure.pdf)

http://www.rohm-products.com/produktdetails00.html?&user_products_pi1%5BshowUid%5D=247&MP=&cHash=0273082758461dde7722f6a6a6f8f5ed (http://www.rohm-products.com/produktdetails00.html?&user_products_pi1%5BshowUid%5D=247&MP=&cHash=0273082758461dde7722f6a6a6f8f5ed)

[Bryan]

Here's Frank Ford's: HomeShopTech (http://www.frets.com/homeshoptech/Projects/DriveCenter/drivecenter.html). Seems to me you would sacrifice some accuracy/rigidity if your plunger fit was less that perfect/worn/dirty/etc. Damned handy though. I could have used one only yesterday.

[Pete F]

Thanks guys, appreciate that. I think that ebay one is actually for a wood lathe, very common on them, and hence why in the description they talk about the work splitting. Bryan, yes it was Frank Ford's that I was thinking about. I go through his site from time to time when I'm away and bored. The guy has so many great ideas it's amazing. I don't recall seeing the commercial face drives though, they look expensive :oo:

Pete

[morrisman]

Ok

I ground up the big HSS threading tool and it does work. The problem is, the Sheraton has limitations as I found out .. Cutting a deep thread like I am doing requires everything to be rigid . The Sheraton 9 and Hercus have a saddle/carriage that you can lift up at the front side :doh:......I turned the saddle lock til the saddle just slides without any upwards play ... this helps but other problem is > The main problem is the tool post I am using rotates under load ... I need to make a solid tool post for the threading tool . Then I will be cooking with gas MIKE Anybody got a good tool post design ?

[pipeclay]

Is the one you have at the moment an original post designed for the lathe or an after market one?

[morrisman]

it is a home made tool post see pics .. the thread isnt as good as it looks ..it isnt deep enough . I have the compound rest set over 27.5 degrees , and use the compound feed to feed in the tool. The tool has a few degrees of side rake as you can see in the pic . MIKE

[RayG]

Hi Mike,

What's moving? the tool post itself, the tool deflecting or rotating or something else?

The body of the tool holder looks solid enough. Maybe the feed sequence needs to be looked at, to reduce the amount of cut.

Regards
Ray

[morrisman]

Hi Mike,

What's moving? the tool post itself, the tool deflecting or rotating or something else?

The body of the tool holder looks solid enough. Maybe the feed sequence needs to be looked at, to reduce the amount of cut.

Regards
Ray

hi Ray , the centre column is rotating on the T nut when it has side force on it . In order to fix this, I have milled a slot or step into the column base , this step fits into the T nut groove, in the compund , if you follow me . I milled down the T nut height about half way so the column can sit in where the T nut was. I hope it works . MIKE

[RayG]

Hi Mike,

Worth a try, and I can't see why it wouldn't help stop the tool rotating..

At least its going to want to rotate away from the work rather than dig in and grab :)

At some point the tool will start to deflect anyway, and the solution is of course to take light cuts, just advancing the compound into the thread, means the cut gets heavier as you progress, it might be worth while seeing if you can plan the cuts so that it doesn't deflect too much.

Big threads can chew up a lot of horsepower to cut..

Regards
Ray

[pipeclay]

There is a general rule when thread cutting that depth of cut starts large and lessens with each sucsesive cut.
If you machine the base of the tool block will it effect tool positioning if you wish to turn with the compound set in the usual position.
Which of the bolts/set screw are doing the majority of the clamping .
Is the large centre pin and Tee nut made in one piece,or are they seperate items.