Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old June 9th 04, 05:06 AM
Vincent Coppola
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

Hello,

I am rehousing a webcam for use in astronomy and I turned down on my
minilathe a simple adapter tube out of aluminum to fit the standard
1.25" diam eyepiece holder.
I now have to turn an inside thread to hold
a standard filter. The filter requires a 1.125" x 40tpi thread. I am
trying to grind my own highspeed steel tool and having some difficulty
getting the threads to look right. They are there but look flattened.
Does someone have a dimension or procedure for grinding such a
tool to work with aluminum? Would the same tool work for delrin? I
have searched the web many times and I can turn up very little on this
subject.

Please advise,

Vince Coppola

  #2   Report Post  
Old June 9th 04, 06:07 AM
DoN. Nichols
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

In article ,
Vincent Coppola wrote:
Hello,

I am rehousing a webcam for use in astronomy and I turned down on my
minilathe a simple adapter tube out of aluminum to fit the standard
1.25" diam eyepiece holder.
I now have to turn an inside thread to hold
a standard filter. The filter requires a 1.125" x 40tpi thread. I am
trying to grind my own highspeed steel tool and having some difficulty
getting the threads to look right. They are there but look flattened.


Hmm ... at a first guess, you don't have enough relief below the
point. Remember that your workpiece is curving towards the tool, so you
need to grind away enough (a curve) below the point so it stays clear of
the workpiece. The smaller the ID, the more the curve needed to clear.

Personally, I would use laydown insert tooling for this. I find
tooling for that made in Israel (ISCAR is the brand, IIRC) for very
small inside threads. I think almost small enough to handle
single-pointing a 1/4-20 thread, and at least small enough for a 5/16"
thread.

Does someone have a dimension or procedure for grinding such a
tool to work with aluminum? Would the same tool work for delrin? I


What lube are you using for aluminum? The easiest to use is a
spray can of WD-40 -- it makes a nice aluminum cutting lube.

For the Delrin, you should not need any lube (or coolant) unless
you are turning *way* too fast.

have searched the web many times and I can turn up very little on this
subject.

Please advise,


You have my thoughts above.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
  #3   Report Post  
Old June 9th 04, 06:30 AM
Harold & Susan Vordos
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project


"Vincent Coppola" wrote in message
om...
Hello,

I am rehousing a webcam for use in astronomy and I turned down on my
minilathe a simple adapter tube out of aluminum to fit the standard
1.25" diam eyepiece holder.
I now have to turn an inside thread to hold
a standard filter. The filter requires a 1.125" x 40tpi thread. I am
trying to grind my own highspeed steel tool and having some difficulty
getting the threads to look right. They are there but look flattened.


DoN has mentioned the necessary amount of clearance on the threading tool,
but there's one thing that you may be missing, and it's easy to do. The way
you describe your thread leads me to believe that you have your compound set
improperly. The markings on compounds are not all the same. What is 30
degrees on one is 60 degrees on another. To set your compound properly,
assuming you are threading a right hand internal thread, cutting from the
outside towards the headstock, you should start with your compound parallel
to the cross slide, with the handle towards you. At that point, you should
turn the handle TOWARDS the headstock until you've gone almost 30 degrees.
I like to use 29, which makes sure you keep cleaning up the back side of the
thread. It may not read 29 degrees, but 61 instead. Don't let that worry
you, it's the way the machine is marked. Setting the compound as I've
suggested is important to a good end result. Don't set the compound the
same way you do for an external right hand thread.

If you're not comfortable with your compound set as I've suggested, the next
best way is to set it exactly 180 degrees opposite, with the handle on the
far side of the bed, and pointed towards the tailstock. That way you always
feed such that you keep the leadscrew loaded by the cut. I tend to harp
on this subject endlessly, but it's a good lesson to learn and remember, and
it ALWAYS applies when threading, regardless of the type of thread.

Hope this helps. If you're still having trouble, feel free to contact me
on the side and I'll try to carry you through the proper threading tool
configuration. There's no real reason to NOT hand grind this tool, it's
quite simple to do.

Harold





Does someone have a dimension or procedure for grinding such a
tool to work with aluminum? Would the same tool work for delrin? I
have searched the web many times and I can turn up very little on this
subject.

Please advise,

Vince Coppola



  #4   Report Post  
Old June 9th 04, 10:30 AM
Richard J Kinch
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

Vincent Coppola writes:

Does someone have a dimension or procedure for grinding such a
tool to work with aluminum?


I use a band saw (or hack saw) to cut a 1/8" notch across the end of some
1/2" mild steel rod, braze in a length of 1/8" square HSS crosswise, and
grind that to a 60 degree tip with 10 degrees relief. This yields
essentially a boring bar, but with a threading profile. Then I hold that in
a boring bar holder on the toolpost.
  #5   Report Post  
Old June 9th 04, 11:51 AM
gerry
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

"Harold & Susan Vordos" wrote in message ...
"Vincent Coppola" wrote in message
om...
Hello,

I am rehousing a webcam for use in astronomy and I turned down on my
minilathe a simple adapter tube out of aluminum to fit the standard
1.25" diam eyepiece holder.
I now have to turn an inside thread to hold
a standard filter. The filter requires a 1.125" x 40tpi thread. I am
trying to grind my own highspeed steel tool and having some difficulty
getting the threads to look right. They are there but look flattened.


DoN has mentioned the necessary amount of clearance on the threading tool,
but there's one thing that you may be missing, and it's easy to do. The way
you describe your thread leads me to believe that you have your compound set
improperly. The markings on compounds are not all the same. What is 30
degrees on one is 60 degrees on another. To set your compound properly,
assuming you are threading a right hand internal thread, cutting from the
outside towards the headstock, you should start with your compound parallel
to the cross slide, with the handle towards you. At that point, you should
turn the handle TOWARDS the headstock until you've gone almost 30 degrees.
I like to use 29, which makes sure you keep cleaning up the back side of the
thread. It may not read 29 degrees, but 61 instead. Don't let that worry
you, it's the way the machine is marked. Setting the compound as I've
suggested is important to a good end result. Don't set the compound the
same way you do for an external right hand thread.

If you're not comfortable with your compound set as I've suggested, the next
best way is to set it exactly 180 degrees opposite, with the handle on the
far side of the bed, and pointed towards the tailstock. That way you always
feed such that you keep the leadscrew loaded by the cut. I tend to harp
on this subject endlessly, but it's a good lesson to learn and remember, and
it ALWAYS applies when threading, regardless of the type of thread.

Hope this helps. If you're still having trouble, feel free to contact me
on the side and I'll try to carry you through the proper threading tool
configuration. There's no real reason to NOT hand grind this tool, it's
quite simple to do.

Harold





Does someone have a dimension or procedure for grinding such a
tool to work with aluminum? Would the same tool work for delrin? I
have searched the web many times and I can turn up very little on this
subject.

Please advise,

Vince Coppola


When stuck for an internal threading tool, I've used a ground down
cutting tap.
Grind everthing away except for one full tooth on the tap. It's saved
my butt before.

Gerry


  #6   Report Post  
Old June 9th 04, 01:38 PM
jim rozen
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

In article , Harold & Susan Vordos says...

DoN has mentioned the necessary amount of clearance on the threading tool,
but there's one thing that you may be missing, and it's easy to do. The way
you describe your thread leads me to believe that you have your compound set
improperly. The markings on compounds are not all the same. What is 30
degrees on one is 60 degrees on another. To set your compound properly,
assuming you are threading a right hand internal thread, cutting from the
outside towards the headstock, you should start with your compound parallel
to the cross slide, with the handle towards you. At that point, you should
turn the handle TOWARDS the headstock until you've gone almost 30 degrees.
I like to use 29, which makes sure you keep cleaning up the back side of the
thread. It may not read 29 degrees, but 61 instead. Don't let that worry
you, it's the way the machine is marked. Setting the compound as I've
suggested is important to a good end result. Don't set the compound the
same way you do for an external right hand thread.

If you're not comfortable with your compound set as I've suggested, the next
best way is to set it exactly 180 degrees opposite, with the handle on the
far side of the bed, and pointed towards the tailstock. That way you always
feed such that you keep the leadscrew loaded by the cut. I tend to harp
on this subject endlessly, but it's a good lesson to learn and remember, and
it ALWAYS applies when threading, regardless of the type of thread.


I much prefer the second setup, becuause otherwise the compound
dial and handle tend to interfere with the work on smaller machines.

Has anyone suggested that he double check his thread form with a
simple thread gage to be sure it is correct? I suspect at 40 tpi
his problem is not thread relief on the tool.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

  #7   Report Post  
Old June 9th 04, 06:45 PM
Stan Schaefer
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

(Vincent Coppola) wrote in message . com...
Hello,

I am rehousing a webcam for use in astronomy and I turned down on my
minilathe a simple adapter tube out of aluminum to fit the standard
1.25" diam eyepiece holder.
I now have to turn an inside thread to hold
a standard filter. The filter requires a 1.125" x 40tpi thread. I am
trying to grind my own highspeed steel tool and having some difficulty
getting the threads to look right. They are there but look flattened.
Does someone have a dimension or procedure for grinding such a
tool to work with aluminum? Would the same tool work for delrin? I
have searched the web many times and I can turn up very little on this
subject.

Please advise,

Vince Coppola



For threading holes over an inch, I use a boring bar and make a
threading tip for it. When I say boring bar, I'm not talking about
one of those one-piece jobbies, it's a chunk of round bar with a
square hole in the end at 90 degrees and has a set screw to hold the
bit. I've made one up in about 20 minutes with some spirited filing
to square the hole out. I like to use the Tantung G I've got for
those threading tools, once you get them shaped and stoned, they hold
an edge for a long time. I like to use a bar with just enough
clearance for chips, stiff is good when it comes to threading. For
internal threading you have to watch the top-to-bottom clearance, if
you don't grind enough of an angle, the heel is going to be dragging
in your fresh cut and will mess things up. As another poster
mentioned, the compound has to be kicked opposite the direction it
would be used in when external threading. It also take a little
practice to get to thinking in reverse. Threading stops help a lot,
too. On aluminum, make sure you use some decent cutting fluid made
for the job. Tap-Magic works, Alumi-Cut is good, too. For 40 TPI,
you're going to want to use a thread gauge for both bit grinding and
setup, a magnifying glass will help with stoning to final contour.
You'll have to have a pretty good finish on the tool flanks to get a
good result on your threads. I usually use a black Arkansas stone for
final polish on something that fine. I didn't use to do that when I
first started out, it really does make a difference in final finish on
the threads.

Stan
  #8   Report Post  
Old June 9th 04, 08:59 PM
Bob May
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

The tool holder for a small bit is probably the best way to go as you don't
need a large tool tip to do 40tpi threads. You DO need a fair bit of relief
of the tip in order to stay away from the cut surface. If you can't fit
your tip into a properly finished thread at the proper angles, you need to
do more relief of the tip.

--
Bob May
Losing weight is easy! If you ever want to lose weight, eat and drink less.
Works every time it is tried!


  #9   Report Post  
Old June 10th 04, 04:45 AM
Vincent Coppola
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

jim rozen wrote in message ...
In article , Harold & Susan Vordos says...

DoN has mentioned the necessary amount of clearance on the threading tool,
but there's one thing that you may be missing, and it's easy to do. The way
you describe your thread leads me to believe that you have your compound set
improperly. The markings on compounds are not all the same. What is 30
degrees on one is 60 degrees on another. To set your compound properly,
assuming you are threading a right hand internal thread, cutting from the
outside towards the headstock, you should start with your compound parallel
to the cross slide, with the handle towards you. At that point, you should
turn the handle TOWARDS the headstock until you've gone almost 30 degrees.
I like to use 29, which makes sure you keep cleaning up the back side of the
thread. It may not read 29 degrees, but 61 instead. Don't let that worry
you, it's the way the machine is marked. Setting the compound as I've
suggested is important to a good end result. Don't set the compound the
same way you do for an external right hand thread.

If you're not comfortable with your compound set as I've suggested, the next
best way is to set it exactly 180 degrees opposite, with the handle on the
far side of the bed, and pointed towards the tailstock. That way you always
feed such that you keep the leadscrew loaded by the cut. I tend to harp
on this subject endlessly, but it's a good lesson to learn and remember, and
it ALWAYS applies when threading, regardless of the type of thread.


I much prefer the second setup, becuause otherwise the compound
dial and handle tend to interfere with the work on smaller machines.

Has anyone suggested that he double check his thread form with a
simple thread gage to be sure it is correct? I suspect at 40 tpi
his problem is not thread relief on the tool.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================


Actually I think I had the compound set wrong. To start with, my
threading tool is made from drill rod. I got the idea from the 7x10
minilathe post on yahoo some time ago. Anyway the suggestion was to
get the same size rod as my boring tool holder, in my case 3/8" and
then turn a disk on one end. Make it a 60 degree angle on each
shoulder. Then grind off the top and bottom of the disk to form two
cutting tools. This is what I have been using. Now as far as the
compound angle goes I don't have a handle like you say. Picture it
this way....I shrink myself and stand on the tailstock. I then peer
straight into the headstock. Let's call this 0 degrees. I point the
boring bar in this direction. Now I turn it 30 degrees
counterclockwise. I then feed toward the headstock. I just tried this
and the thread looks much better. Must have done something right. How
does this sound? Of course now I have to bore it to the correct i.d.,
thread it, and finally screw the filter into it. The proof is in the
pudding.

Vince
  #10   Report Post  
Old June 10th 04, 04:51 AM
Vincent Coppola
 
Posts: n/a
Default Inner threading turning tool out of HSS...Need for astronomy project

Richard J Kinch wrote in message ...
Vincent Coppola writes:

Does someone have a dimension or procedure for grinding such a
tool to work with aluminum?


I use a band saw (or hack saw) to cut a 1/8" notch across the end of some
1/2" mild steel rod, braze in a length of 1/8" square HSS crosswise, and
grind that to a 60 degree tip with 10 degrees relief. This yields
essentially a boring bar, but with a threading profile. Then I hold that in
a boring bar holder on the toolpost.


This is a cool idea. One suggestion I heard was to file a square hole
in a rod, grind an HSS tool, insert it and hold it with a set screw.
Your way sounds easier only I don't have any welding equipment. I do
have a propane torch but I don't think that gets hot enough to braze.
What would you suggest I purchase to do a small job like this
repeatably?

Vince


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Reversing leadscrew on small lathe Lewis Campbell Metalworking 22 December 24th 03 07:45 AM
How do you adjust the cutter bit on Aloris Tool Holders Steve Metalworking 28 October 20th 03 03:12 AM
Project time management Philosophy Tom Gardner Metalworking 11 October 5th 03 05:40 PM
Basics on Depth of Cuts Chris S Metalworking 10 September 2nd 03 03:15 AM


All times are GMT +1. The time now is 05:18 AM.

Powered by vBulletin® Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Copyright 2004-2021 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"

 

Copyright © 2017