Well you thread a 3/8 bolt through the .350 hole. The first inch is a bitch
but onces its through it turns easier. LOL


"Bob Engelhardt" wrote in message
...
I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
confused. There are 3/8 UNC tapped holes in the blocks, but the other
holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
through the hole in one block into the tapped hole in the other. But
how do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16
bolt through the .350 hole, how do you thread it into the 3/8 threads?

The only way I can see to bolt these together is with 5/16 bolts and
nuts through .350 holes in both blocks. But then what are the 3/8
tapped holes for?

Am I missing something, or is this a Chinese gotcha?

Bob

Question about 1-2-3 blocks
 

I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
confused. There are 3/8 UNC tapped holes in the blocks, but the other
holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
through the hole in one block into the tapped hole in the other. But
how do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16
bolt through the .350 hole, how do you thread it into the 3/8 threads?

The only way I can see to bolt these together is with 5/16 bolts and
nuts through .350 holes in both blocks. But then what are the 3/8
tapped holes for?

Am I missing something, or is this a Chinese gotcha?

Bob

"Bob Engelhardt" wrote in message
...
I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
confused. There are 3/8 UNC tapped holes in the blocks, but the other
holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
through the hole in one block into the tapped hole in the other. But how
do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16 bolt
through the .350 hole, how do you thread it into the 3/8 threads?

The only way I can see to bolt these together is with 5/16 bolts and nuts
through .350 holes in both blocks. But then what are the 3/8 tapped holes
for?

Am I missing something, or is this a Chinese gotcha?

Are these made by Browne & Sharpe? I have a B&S 1-2-3 block sets with that
problem and think that there was an error in the specs or the manufacturing.

Mike

I don't remember who made my 2 sets of 1-2-3 blocks but they suffer
from that hole syndrome as well........

On Fri, 1 Jul 2005 20:48:32 -0500, "Mike Henry"
wrote:

===
==="Bob Engelhardt" wrote in message
...
===I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
===which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
===confused. There are 3/8 UNC tapped holes in the blocks, but the other
===holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
===through the hole in one block into the tapped hole in the other. But how
===do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16 bolt
===through the .350 hole, how do you thread it into the 3/8 threads?
===
=== The only way I can see to bolt these together is with 5/16 bolts and nuts
=== through .350 holes in both blocks. But then what are the 3/8 tapped holes
=== for?
===
=== Am I missing something, or is this a Chinese gotcha?
===
===Are these made by Browne & Sharpe? I have a B&S 1-2-3 block sets with that
===problem and think that there was an error in the specs or the manufacturing.
===
===Mike
===


==============================================
Put some color in your cheeks...garden naked!
"The original frugal ponder"
~~~~ }((((o ~~~~~~ }{{{{o ~~~~~~~ }(((((o

Bob Engelhardt wrote:

I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
confused. There are 3/8 UNC tapped holes in the blocks, but the other
holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
through the hole in one block into the tapped hole in the other. But
how do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16
bolt through the .350 hole, how do you thread it into the 3/8 threads?

The only way I can see to bolt these together is with 5/16 bolts and
nuts through .350 holes in both blocks. But then what are the 3/8
tapped holes for?

Am I missing something, or is this a Chinese gotcha?

Bob

Mine work fine. Send yours back and buy some better ones. GWE

In article ,
Bob Engelhardt wrote:

I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
confused. There are 3/8 UNC tapped holes in the blocks, but the other
holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
through the hole in one block into the tapped hole in the other. But
how do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16
bolt through the .350 hole, how do you thread it into the 3/8 threads?

The only way I can see to bolt these together is with 5/16 bolts and
nuts through .350 holes in both blocks. But then what are the 3/8
tapped holes for?

Am I missing something, or is this a Chinese gotcha?

I've got a Chinese set (MSC # 06378012), and it has exactly the same
problem. No, it cannot be fixed unless you are equipped to drill holes
in hardened steel.

I complained to MSC because the catalog description gave no clue that
the untapped holes were too small to pass the 3/8-16 studs the other
holes were tapped for, and the catalog picture showed the unthreaded
holes as larger than the threaded holes, thus implying that they were
drilled for clearance, which was not true.

MSC's first response was deeply annoying, saying that the blocks met
MSC's spec, which called out 5/16 holes. I wrote back saying that they
had failed to address the complaint, which was that the item was
misdescribed and misleading in the catalog, and suggesting that they run
this issue a bit farther up the food chain, with catalog photo and
description in hand.

After a long delay, MSC replied that they would be correcting the
catalog, and apologized. I thanked them, and suggested that the
long-term solution was to change the MSC spec to require clearance
holes, as the current spec defeats the purpose of tapping the holes in
the first place. So far, no response.

Joe Gwinn

I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
confused. There are 3/8 UNC tapped holes in the blocks, but the other
holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
through the hole in one block into the tapped hole in the other. But how
do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16 bolt
through the .350 hole, how do you thread it into the 3/8 threads?

The only way I can see to bolt these together is with 5/16 bolts and nuts
through .350 holes in both blocks. But then what are the 3/8 tapped holes
for?

Am I missing something, or is this a Chinese gotcha?

Bob

Don't know exactly whose "gotcha" it is, but my B&S 1-2-3 blocks had the
same problem...so I fixed it by burning the "clearance" holes out to be
actually clearance for the 3/8 bolts. Actual size after going thru the wire
EDM was .3751"...which made them large enough to use pins for alignment.

I"m pretty sure that it was NOT a design feature of the blocks, but it
worked for me.

Mike

"Bob Engelhardt" wrote in message
...
I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
confused. There are 3/8 UNC tapped holes in the blocks, but the other
holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
through the hole in one block into the tapped hole in the other. But
how do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16
bolt through the .350 hole, how do you thread it into the 3/8 threads?

The only way I can see to bolt these together is with 5/16 bolts and
nuts through .350 holes in both blocks. But then what are the 3/8
tapped holes for?

Am I missing something, or is this a Chinese gotcha?



Bob,
As far as I know the holes you are referring to are used primarily to
lighten the block.
They have the added advantage of being able to stick things through them to
aid in set ups but this is coincidental.


--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com

I wrote an article for HSM (which I have no idea when they'll publish,
it could be a year or more) where I showed my solution.
Telegraphically:
In a nutshell, make some rods that are less than .350 dia (I used
5/16"), in lengths 1,2 and 3 inches, make cross holes in half that are
clearance for a #10 screw, and teh other half that are tapped #10-32,
all spaced out by the holes in the blocks( different spacing for rows
and columns across the blocks, which is another peeve). Basically just
cylindrical nuts and washers. Then bolt the things together. The heads
of the #10 SHCS end up below the surface of the block.
Makes it easy to put together custom angle plates, etc.

In article ,
Bob Engelhardt wrote:

I rented a video on the use of the horizontal mill, by Rudy Kouhoupt, in
which he used 1-2-3 blocks in a set-up. So, I bought a set and I'm
confused. There are 3/8 UNC tapped holes in the blocks, but the other
holes are .350. Now, Rudy bolted 2 blocks together by passing a bolt
through the hole in one block into the tapped hole in the other. But
how do you get a 3/8 bolt through a .350 hole? Or, if you pass a 5/16
bolt through the .350 hole, how do you thread it into the 3/8 threads?

The only way I can see to bolt these together is with 5/16 bolts and
nuts through .350 holes in both blocks. But then what are the 3/8
tapped holes for?

Am I missing something, or is this a Chinese gotcha?

And the point of lightening the blocks is so that someone who
can normally handle a 40 pound lathe chuck can...er ...Hum??

I must be missing something here.

OK. Why don't we go back to the pencil holder idea?

:-)oooo

DOC


"J. R. Carroll" wrote in message
...




Bob,
As far as I know the holes you are referring to are used primarily to
lighten the block.
They have the added advantage of being able to stick things through them
to
aid in set ups but this is coincidental.


--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com

Doc,
That was what I said too but then had it explained to me. The manufacturers
of these things have to heat treat and then ship the things. The shipping
and energy costs involved exceed the profit margin on this sort of commodity
product and its nearly free money if you can poke holes cheaply. Drilling is
the cheapest method of metal removal you know.

I have an entire collection of blocks and parallels I made as an apprentice.
MY stuff was going to be rock solid, and it all is. I pantographed my name
into the things and they are solid but for that. They weigh more than I do
as a group and were the reason I ended up buying my first versa cart.

I do like the pencil holder thing though.

--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com



"DOC" wrote in message
...
And the point of lightening the blocks is so that someone who
can normally handle a 40 pound lathe chuck can...er ...Hum??

I must be missing something here.

OK. Why don't we go back to the pencil holder idea?

:-)oooo

DOC


"J. R. Carroll" wrote in message
...




Bob,
As far as I know the holes you are referring to are used primarily to
lighten the block.
They have the added advantage of being able to stick things through them
to
aid in set ups but this is coincidental.


--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com

Joseph Gwinn wrote in
:

Guys,
Why not make a set of reduced-shank studs that are short by a 0.03 from the
length of two blocks together, drill and thread the end for a SHCS.


--
Anthony

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

Remove sp to reply via email

http://www.machines-cnc.net:81/

Anthony wrote in
:

Joseph Gwinn wrote in
:

Guys,
Why not make a set of reduced-shank studs that are short by a 0.03
from the length of two blocks together, drill and thread the end for a
SHCS.



That's along the lines of what I was thinking. Why not use thread repair
inserts? A 3/8-16 external thread has a 1/4-20 internal thread.

http://www.jergensinc.com/infodir/ca...?GroupNum=3017


--

Dan

Simple...take a 3/8 bolt, and turn down the shank above the threads to
..3495. That way you have a bolt that where the threads match the
threaded hole and the turned down part fits the smaller unthreaded
hole...for a nice snug fit...

Al in colorado (tongue planted firmly in cheek)

While I like your argument, I am still not sure I am convinced.

How about this idea? The holes are there because the guys in the
shop just wanted to see if the new hire could drill and tap square
holes?

Then along came the like of B&S, Starrett... and figured they shouldn't
mess with a good thing! :-)ooo

BTW, I think Surburban makes solid 1-2-3 blocks. They seem to charge by
weight though. ;-)


Regards,
DOC

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




"J. R. Carroll" wrote in message
...
Doc,
That was what I said too but then had it explained to me. The
manufacturers
of these things have to heat treat and then ship the things. The shipping
and energy costs involved exceed the profit margin on this sort of
commodity
product and its nearly free money if you can poke holes cheaply. Drilling
is
the cheapest method of metal removal you know.

I have an entire collection of blocks and parallels I made as an
apprentice.
MY stuff was going to be rock solid, and it all is. I pantographed my name
into the things and they are solid but for that. They weigh more than I do
as a group and were the reason I ended up buying my first versa cart.

I do like the pencil holder thing though.

--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com



"DOC" wrote in message
...
And the point of lightening the blocks is so that someone who
can normally handle a 40 pound lathe chuck can...er ...Hum??

I must be missing something here.

OK. Why don't we go back to the pencil holder idea?

:-)oooo

DOC


"J. R. Carroll" wrote in message
...

wrote:
Simple...take a 3/8 bolt, and turn down the shank above the threads to
.3495. That way you have a bolt that where the threads match the
threaded hole and the turned down part fits the smaller unthreaded
hole...for a nice snug fit...

Al in colorado (tongue planted firmly in cheek)


Before I got to the "tongue planted firmly in cheek" part, I was trying
to understand what you were suggesting and it gave me an idea! The
*minor* diameter of a 3/8 tapped hole is less than .350! You could turn
down a 3/8 bolt to .350 and still have some thread left. Would you have
enough? Well, I tried it and it seems like enough to me. Here's a pic:

http://home.comcast.net/~bobengelhardt/threads.jpg

Bob

I read somewhere that the holes were to make the heat treating
better/easier/more uniform somehow.
Don Young
"DOC" wrote in message
...
While I like your argument, I am still not sure I am convinced.

How about this idea? The holes are there because the guys in the
shop just wanted to see if the new hire could drill and tap square
holes?

Then along came the like of B&S, Starrett... and figured they shouldn't
mess with a good thing! :-)ooo

BTW, I think Surburban makes solid 1-2-3 blocks. They seem to charge by
weight though. ;-)


Regards,
DOC

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




"J. R. Carroll" wrote in message
...
Doc,
That was what I said too but then had it explained to me. The
manufacturers
of these things have to heat treat and then ship the things. The shipping
and energy costs involved exceed the profit margin on this sort of
commodity
product and its nearly free money if you can poke holes cheaply. Drilling
is
the cheapest method of metal removal you know.

I have an entire collection of blocks and parallels I made as an
apprentice.
MY stuff was going to be rock solid, and it all is. I pantographed my
name
into the things and they are solid but for that. They weigh more than I
do
as a group and were the reason I ended up buying my first versa cart.

I do like the pencil holder thing though.

--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com



"DOC" wrote in message
...
And the point of lightening the blocks is so that someone who
can normally handle a 40 pound lathe chuck can...er ...Hum??

I must be missing something here.

OK. Why don't we go back to the pencil holder idea?

:-)oooo

DOC


"J. R. Carroll" wrote in message
...

Very good....
I was wondering how long it would take some to figure out I was
kidding....

al in colorado

Bob Engelhardt wrote:

... You could turn
down a 3/8 bolt to .350 and still have some thread left. ...

OK, if I were to do this, *how* would I do it?

1. Center drill the threaded end, hold the head in a chuck and the
threaded end with a center and turn in 1 set up.

2. Use chuck only and do 1 end at a time. Concentricity of the 2 ends
wouldn't need to be too precise. I guess that I'd need a fixture (?) to
hold the head end. Something to allow chucking on the shaft & not the
head. For the short bolts - the heads of the longer ones would reach
behind the chuck jaws.

3. All thread. Ewww!

4. ??

Bob

The head could also be center-drilled, then the bolt turned between centers.
The bolts would be easily recognizeable as special-purpose .

If ya want to add complexity, chuck the bolt in a collet for C-D'n the bolt
head (but the unthreaded shank probably isn't really round anyway).

Another option would be eliminate the bolt head, which I think may have
already been suggested, their use would just be to hold stacked blocks.

WB
..............

"Bob Engelhardt" wrote in message
...
Bob Engelhardt wrote:

... You could turn
down a 3/8 bolt to .350 and still have some thread left. ...

OK, if I were to do this, *how* would I do it?

1. Center drill the threaded end, hold the head in a chuck and the
threaded end with a center and turn in 1 set up.

2. Use chuck only and do 1 end at a time. Concentricity of the 2 ends
wouldn't need to be too precise. I guess that I'd need a fixture (?) to
hold the head end. Something to allow chucking on the shaft & not the
head. For the short bolts - the heads of the longer ones would reach
behind the chuck jaws.

3. All thread. Ewww!

4. ??

Bob




----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

I think the holes in 1-2-3 blocks are for utility.

When I worked at a mold shop, the mold maker had solid 1-2-3 blocks as he
used them on the mag chick on the EDM and the solid blocks work better than
the ones with the holes.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.
"DOC" wrote in message
...
And the point of lightening the blocks is so that someone who
can normally handle a 40 pound lathe chuck can...er ...Hum??

I must be missing something here.

OK. Why don't we go back to the pencil holder idea?

:-)oooo

DOC


"J. R. Carroll" wrote in message
...




Bob,
As far as I know the holes you are referring to are used primarily to
lighten the block.
They have the added advantage of being able to stick things through them
to
aid in set ups but this is coincidental.


--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com

Bob Engelhardt wrote:
wrote:
Simple...take a 3/8 bolt, and turn down the shank above the threads to
.3495. That way you have a bolt that where the threads match the
threaded hole and the turned down part fits the smaller unthreaded
hole...for a nice snug fit...

Al in colorado (tongue planted firmly in cheek)
Before I got to the "tongue planted firmly in cheek" part, I was trying
to understand what you were suggesting and it gave me an idea! The
*minor* diameter of a 3/8 tapped hole is less than .350! You could turn
down a 3/8 bolt to .350 and still have some thread left. Would you have
enough? Well, I tried it and it seems like enough to me. Here's a pic:

http://home.comcast.net/~bobengelhardt/threads.jpg

That idea might have been useful to me a few years ago, when I
tried tapping 3/8-16 in 3/8" HRS edgeon. The 5/16" tap drill
left plenty of meat, but after tapping it didn't look strong
enough to be useful. See http://pat7.com/jp/tap-3-8-3-8.jpg
-jiw

"Anthony" wrote in message
...
Joseph Gwinn wrote in
:

Guys,
Why not make a set of reduced-shank studs that are short by a 0.03 from
the
length of two blocks together, drill and thread the end for a SHCS.
--
Anthony

On real good reason I could offer is that doesn't solve the problem. How
do you get the major diameter of the threaded portion through the reduced
hole?

Harold

"Harold and Susan Vordos" wrote in message
...

"Anthony" wrote in message
...
Joseph Gwinn wrote in
:

Guys,
Why not make a set of reduced-shank studs that are short by a 0.03 from
the
length of two blocks together, drill and thread the end for a SHCS.
--
Anthony

On real good reason I could offer is that doesn't solve the problem.
How
do you get the major diameter of the threaded portion through the reduced
hole?

Harold


Blush!

Ooops. Sorry----I get it now.

Harold

Not a Chinese gotcha. My 1-2-3 blocks are made by Changda and have
five holes tapped for 3/8 UNC. The rest of the holes are a tight fit
for a 3/8 UNC thread to go thru them. I am sure they were a sliding
fit before the heat treat, now the scale makes it a tight fit.

Unfortunately I don't remember where I bought them. It could have
been J & L, Harbor Freight, or Enco.

I am sure the holes are not for saving weight in shipping. When I took
a machine shop class back in about 1973, one of the people in the class
was making some 1-2-3 blocks. The drawing he had included lots of
holes.

Dan

In article ,
Wild Bill wrote:
The head could also be center-drilled, then the bolt turned between centers.
The bolts would be easily recognizeable as special-purpose .

If ya want to add complexity, chuck the bolt in a collet for C-D'n the bolt
head (but the unthreaded shank probably isn't really round anyway).

Hmm ... if you really care about the thread concentricity, set
up some spacers with some soft jaws for the 3-jaw chuck, bore to thread
minor diameter, and single-point a female thread. Then, the modified
jaws would hold it centered on the pitch diameter, not on the OD.

The same could be done with a soft collet.

Of course, if you are using a stud with two threaded areas
separated by a blank shaft, they are probably rolled threads, and may
well not be concentric with each other.

Another option would be eliminate the bolt head, which I think may have
already been suggested, their use would just be to hold stacked blocks.

Take the bolt head, drill it through and tap to fit threads cut
on the reduced part of the studs. That way, you can fit it after
passing the reduced shank through. Use Allen Cap screw heads, and it
might even look normal at first glance, until you unscrew the head from
the stud. :-)

Enjoy,
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 ---

If you have occasion to make a lathe setup on a faceplate and need to use
clamping blocks,
then the holes in a 1-2-3 block are a BIG advantage in terms of weight, and
whether counter
weights are required.

Ace


"DOC" wrote in message
...
While I like your argument, I am still not sure I am convinced.

How about this idea? The holes are there because the guys in the
shop just wanted to see if the new hire could drill and tap square
holes?

Then along came the like of B&S, Starrett... and figured they shouldn't
mess with a good thing! :-)ooo

BTW, I think Surburban makes solid 1-2-3 blocks. They seem to charge by
weight though. ;-)


Regards,
DOC

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




"J. R. Carroll" wrote in message
...
Doc,
That was what I said too but then had it explained to me. The
manufacturers
of these things have to heat treat and then ship the things. The shipping
and energy costs involved exceed the profit margin on this sort of
commodity
product and its nearly free money if you can poke holes cheaply. Drilling
is
the cheapest method of metal removal you know.

I have an entire collection of blocks and parallels I made as an
apprentice.
MY stuff was going to be rock solid, and it all is. I pantographed my
name
into the things and they are solid but for that. They weigh more than I
do
as a group and were the reason I ended up buying my first versa cart.

I do like the pencil holder thing though.

--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com



"DOC" wrote in message
...
And the point of lightening the blocks is so that someone who
can normally handle a 40 pound lathe chuck can...er ...Hum??

I must be missing something here.

OK. Why don't we go back to the pencil holder idea?

:-)oooo

DOC


"J. R. Carroll" wrote in message
...

On Sun, 03 Jul 2005 11:18:33 -0400, Bob Engelhardt
wrote:

Bob Engelhardt wrote:

... You could turn
down a 3/8 bolt to .350 and still have some thread left. ...

OK, if I were to do this, *how* would I do it?

1. Center drill the threaded end, hold the head in a chuck and the
threaded end with a center and turn in 1 set up.

If it's a hex-headed bolt, clamp a 6-pt socket in the chuck and use a
steady rest to hold the threaded end while you center drill it. If
you are working with a SHCS, cut off a length of allen wrench and
clamp that in your 3-jaw chuck to hold the head.

Ed

2. Use chuck only and do 1 end at a time. Concentricity of the 2 ends
wouldn't need to be too precise. I guess that I'd need a fixture (?) to
hold the head end. Something to allow chucking on the shaft & not the
head. For the short bolts - the heads of the longer ones would reach
behind the chuck jaws.

3. All thread. Ewww!

4. ??

Bob

"Ed Bailen" wrote in message
...
On Sun, 03 Jul 2005 11:18:33 -0400, Bob Engelhardt
wrote:

Bob Engelhardt wrote:

... You could turn
down a 3/8 bolt to .350 and still have some thread left. ...

OK, if I were to do this, *how* would I do it?

1. Center drill the threaded end, hold the head in a chuck and the
threaded end with a center and turn in 1 set up.

If it's a hex-headed bolt, clamp a 6-pt socket in the chuck and use a
steady rest to hold the threaded end while you center drill it. If
you are working with a SHCS, cut off a length of allen wrench and
clamp that in your 3-jaw chuck to hold the head.

Ed

Ed,

If you haven't noticed, heads are rarely concentric with the threaded or
grip portion of bolts. Driving them that way would yield a real wonky end
result. Best method would be to grip the threaded portion with a split
bushing, then hold the bolt in a collet or good running chuck, perhaps
fitted with soft jaws. Even that doesn't guarantee the center drill will
be concentric with the pitch diameter, but it should be closer that when
driving the head. I've seen heads eccentric by a huge margin.

Harold

"Jeff Wisnia" wrote in message
...
wrote:

I also own a set of those blocks.

I'm thinking maybe the threads aren't made with a cutting tap but with a
thread forming tap and those "undersize" holes are actually the tap drill
size for doing that?

Actually, thread forming taps require a *larger* hole than cutting taps.
That's because form taps displace metal upwards to "grow" the crests of the
internal threads (whereas the crests of the internal threads are determined
by the size of the pre-tapped hole).

- Michael

The holes on my blocks that are not tapped are way too big to tap to
3/8 unc. A 3/8 unc thread will slip thru some of the holes and can be
forced thru any of them. If the scale from heat treating were not
there, they would all slip through easily. They are noticeably bigger
than the tapped holes.

Dan

Jeff Wisnia wrote:


I also own a set of those blocks.

I'm thinking maybe the threads aren't made with a cutting tap but with a
thread forming tap and those "undersize" holes are actually the tap
drill size for doing that?

Any takers?

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

Maybe a possible solution is to have two grub screws connected end to
end by something like a ball and socket joint that would pull in
tension but not transmit (much) torque. That way you could use the two
tapped holes to connect the two blocks together. I just bought a set
of Brown and Sharpe blocks with the same feature, and was thinking of
trying something of the sort.

-Justin


Jeff Wisnia wrote:
wrote:
Not a Chinese gotcha. My 1-2-3 blocks are made by Changda and have
five holes tapped for 3/8 UNC. The rest of the holes are a tight fit
for a 3/8 UNC thread to go thru them. I am sure they were a sliding
fit before the heat treat, now the scale makes it a tight fit.

Unfortunately I don't remember where I bought them. It could have
been J & L, Harbor Freight, or Enco.

I am sure the holes are not for saving weight in shipping. When I took
a machine shop class back in about 1973, one of the people in the class
was making some 1-2-3 blocks. The drawing he had included lots of
holes.

Dan


I also own a set of those blocks.

I'm thinking maybe the threads aren't made with a cutting tap but with a
thread forming tap and those "undersize" holes are actually the tap
drill size for doing that?

Any takers?

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

DeepDiver wrote:
"Jeff Wisnia" wrote in message
...

wrote:

I also own a set of those blocks.

I'm thinking maybe the threads aren't made with a cutting tap but with a
thread forming tap and those "undersize" holes are actually the tap drill
size for doing that?


Actually, thread forming taps require a *larger* hole than cutting taps.
That's because form taps displace metal upwards to "grow" the crests of the
internal threads (whereas the crests of the internal threads are determined
by the size of the pre-tapped hole).

- Michael



Yes, I understand that, but I was thinking that maybe the tap drill size
for as 3/8"-16 thread forming tap,while larger than for a thread cutting
tap might be slightly under 3/8", which is what those untapped holes in
my 1-2-3 blocks appear to be.

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."