[[email protected]]

I've run into several situations where set screws were used to tighten
against threads.

It's usually been on some type of spring loaded clutch where
the threads were part of an adjustment mechanism to vary the
main spring pressure on the clutch and the set screws are used
to lock everything in place.

Of course this quickly ruins the threads and, with it, the ability to
adjust
clutch pressure.

I've seen this on Tapmatic tapping heads and the problem
I have right now on the lead screw for my Harrison L6.

Normally I handle this problem by inserting a small bit of brass
in the set screw hole. When the set screw is tightened the brass
deforms to the shape of the threads that it is pushing against.

The brass can tend to get stuck in the hole, but generally this
solves the problem.


But what to do if the set screw hole isn't deep enough?

The clutch on the lead screw has a wall thickness of about 1/8" max.
And it uses two 6-32 set screws.

I'm thinking about putting a collar around the clutch to build up the
wall thickness. The clutch is about 2" OD so it seems doable.

But I can't figure out how I would be able to accurately drill a hole
in the
collar and thread it so as to keep the thread alignment of the set
screws.
(So that the set screw would have continuous thread through the collar
and the clutch wall.)

I've thought of putting another two holes through the collar and
clutch
but the clutch case is hardened and I would rather not have to anneal
and re-harden.

Any ideas? Alternate solutions?


Tanks,
DOC

Buy my junk! http://www3.sympatico.ca/doc/robotone/for-sale.html

[Anthony]

wrote in news:e25411c6-4bf0-4361-985a-81579ca9cfc3
@b15g2000hsa.googlegroups.com:

Use a flat-tipped dog set screw. These have a reduced diameter on the
business end for some distance (different distances are available). All the
threads would be in your collar, with only the reduced diameter dog acting
on the bit of brass in the original collar hole.



--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

[Leo Lichtman]

"Anthony" wrote: Use a flat-tipped dog set screw. (clip)
Or make the collar thick enough so the threads are sufficient to hold the
set screw. Then make the brass insert long enough to occupy the present
threads, plus a little.

Or, take your Dremel and grind out the present threads, so the set screw can
enter the hole without meshing.

[Don Young]

wrote in message
...
I've run into several situations where set screws were used to tighten
against threads.

It's usually been on some type of spring loaded clutch where
the threads were part of an adjustment mechanism to vary the
main spring pressure on the clutch and the set screws are used
to lock everything in place.

Of course this quickly ruins the threads and, with it, the ability to
adjust
clutch pressure.

I've seen this on Tapmatic tapping heads and the problem
I have right now on the lead screw for my Harrison L6.

Normally I handle this problem by inserting a small bit of brass
in the set screw hole. When the set screw is tightened the brass
deforms to the shape of the threads that it is pushing against.

The brass can tend to get stuck in the hole, but generally this
solves the problem.


But what to do if the set screw hole isn't deep enough?

The clutch on the lead screw has a wall thickness of about 1/8" max.
And it uses two 6-32 set screws.

I'm thinking about putting a collar around the clutch to build up the
wall thickness. The clutch is about 2" OD so it seems doable.

But I can't figure out how I would be able to accurately drill a hole
in the
collar and thread it so as to keep the thread alignment of the set
screws.
(So that the set screw would have continuous thread through the collar
and the clutch wall.)

I've thought of putting another two holes through the collar and
clutch
but the clutch case is hardened and I would rather not have to anneal
and re-harden.

Any ideas? Alternate solutions?


Tanks,
DOC

Buy my junk! http://www3.sympatico.ca/doc/robotone/for-sale.html


Others have posted some good ideas but if you had to thread a collar to
match you could build a jig to do it. You could arrange a tap holder on the
end of a same pitch rod with the rod screwed into an adjustable nut, align
everything with the existing thread, back out the tap, install the collar
and run the tap back in. I think there are tapping devices which basically
do this, feed the tap independently of the tap itself. You could probably do
it on a screwcutting lathe with the tap in the spindle and your work
attached to the carriage if you could manage everything without breaking the
tap.

Don Young

[Tom Gardner]

wrote in message
...
I've run into several situations where set screws were used to tighten
against threads.

It's usually been on some type of spring loaded clutch where
the threads were part of an adjustment mechanism to vary the
main spring pressure on the clutch and the set screws are used
to lock everything in place.

Of course this quickly ruins the threads and, with it, the ability to
adjust
clutch pressure.

I've seen this on Tapmatic tapping heads and the problem
I have right now on the lead screw for my Harrison L6.

Normally I handle this problem by inserting a small bit of brass
in the set screw hole. When the set screw is tightened the brass
deforms to the shape of the threads that it is pushing against.

The brass can tend to get stuck in the hole, but generally this
solves the problem.


But what to do if the set screw hole isn't deep enough?

The clutch on the lead screw has a wall thickness of about 1/8" max.
And it uses two 6-32 set screws.

I'm thinking about putting a collar around the clutch to build up the
wall thickness. The clutch is about 2" OD so it seems doable.

But I can't figure out how I would be able to accurately drill a hole
in the
collar and thread it so as to keep the thread alignment of the set
screws.
(So that the set screw would have continuous thread through the collar
and the clutch wall.)

I've thought of putting another two holes through the collar and
clutch
but the clutch case is hardened and I would rather not have to anneal
and re-harden.

Any ideas? Alternate solutions?


Tanks,
DOC

Buy my junk! http://www3.sympatico.ca/doc/robotone/for-sale.html



I've run into this a few times, usually due to my poor design. I've ground
off the threads on the bolt where the set screw hits it, all the way around.
Now you don't need a brass insert and the bolt can be in any position. We
call these "Bob-Bolts" in honor of my uncle that first started using them to
fix his ****-ups.

[Dan]

McMaster Carr, and I'm sure others, sell soft tip allen head set
screws. They offer three tip materials, Brass, Nylon, and Silver.
Have a look at 2039 online or there abouts or search for soft point
set screws.

Depending on how offten you need to adjust this, You could mark the
spot and drill a little counterbore for the set screw to sit in so it
don't smash the threads.

[Lew Hartswick]

wrote:

But what to do if the set screw hole isn't deep enough?

The clutch on the lead screw has a wall thickness of about 1/8" max.
And it uses two 6-32 set screws.

Any ideas? Alternate solutions?

Tanks,
DOC
If the setscrew dare stick out from the surface a bit, take a
longer setscrew and make a brass tiped one by drilling a hole
in the end and pressing in a bit of brazing rod. I've done this
for a fixture I was making and couldn't get brass point dog
setscrews.
...lew...

[Leo Lichtman]

Wouldn't a soft point set screw get torn up being tightened against screw
threads? It seems to me you need a soft insert that seats and doesn't turn.

[Sevenhundred Elves]

wrote:

Any ideas? Alternate solutions?

Take a file and remove those threads that may otherwise come in contact
with the set screw.

S.

[Jim Wilkins]

On Dec 1, 7:36 pm, wrote:
...
But what to do if the set screw hole isn't deep enough?

The clutch on the lead screw has a wall thickness of about 1/8" max.
And it uses two 6-32 set screws.
...
DOC

Grind the end of the setscrews flat and drop a piece of solder or
birdshot in the hole to pad the threads. You might have to knock it
down with a punch before installing the setscrew.

Put the brass insert in the socket end of a long setscrew and grind
two flats on the other end to tighten it.

[[email protected]]

Thanks for all the suggestions.

I ended up putting a collar on it. Then drilled and tapped new holes
for 10-32
set screws.

Little bits of brass with bosses that fit into holes in the set
screws.
Drill the set screws. Grind down to just the right size. Mostly
vairations
on ideas suggested here.

One problem I ran into...

Before I put the collar on I used a torch on the case figuring I would
put a
enough heat into it do soften it up a bit.

But the case warped and I had a not quite cylindrical cylinder! (

Anyway, a little grinding got everything going again and I now have
a lathe with an adjustable clutch on the lead screw.

Tanks,
DOC

[Bob Engelhardt]

wrote:
... I now have
a lathe with an adjustable clutch on the lead screw.

Is this something that you added to your lathe? If so, would you care
to elaborate? Pictures, maybe?

Bob

[[email protected]]

On Dec 1, 5:36 pm, wrote:
I've run into several situations where set screws were used to tighten
against threads.

It's usually been on some type of spring loaded clutch where
the threads were part of an adjustment mechanism to vary the
main spring pressure on the clutch and the set screws are used
to lock everything in place.

Of course this quickly ruins the threads and, with it, the ability to
adjust
clutch pressure.

I've seen this on Tapmatic tapping heads and the problem
I have right now on the lead screw for my Harrison L6.

Normally I handle this problem by inserting a small bit of brass
in the set screw hole. When the set screw is tightened the brass
deforms to the shape of the threads that it is pushing against.

The brass can tend to get stuck in the hole, but generally this
solves the problem.

But what to do if the set screw hole isn't deep enough?

The clutch on the lead screw has a wall thickness of about 1/8" max.
And it uses two 6-32 set screws.

I'm thinking about putting a collar around the clutch to build up the
wall thickness. The clutch is about 2" OD so it seems doable.

But I can't figure out how I would be able to accurately drill a hole
in the
collar and thread it so as to keep the thread alignment of the set
screws.
(So that the set screw would have continuous thread through the collar
and the clutch wall.)

I've thought of putting another two holes through the collar and
clutch
but the clutch case is hardened and I would rather not have to anneal
and re-harden.

Any ideas? Alternate solutions?

Tanks,
DOC

Buy my junk!http://www3.sympatico.ca/doc/robotone/for-sale.html

I would have made a threaded split clamping collar rather than relying
on set screws to hold something like that. Sounds like poor design to
me, small set screws bearing against adjustment threads, particularly
if there's any reasonable amount of torque involved. A split clamping
collar could still be added, after making it, just pin it to the
clutch body axially. Much better clamping around and in the threads
than bearing up against them at one point. If it's a standard thread,
these collars are standard parts from the likes of MSC.

Stan