Hydraulic Punch hole size question
 

Hi Gang -

In the process of finishing the hydraulic punch and have a question on
tooling.
I have to build a railing (steel) and want to use 1/2" SQUARE bar for
the stiles (vertical) that pass through a rail (horizontal) 2" wide x
1/4" thick flat stock
Should I punch with a 1/2" square punch or go up to the 9/16" punch.
The intent is to weld around the bar when in position. Does a 1/2"
punch actually make a 1/2" hole or is it a little bigger? Also, what
are the tolerences on typical steel bars (when they say 1/2" is it
really 1/2")?
Always drilled and never used a punch before so am a little unsure.

Thanks in advance...

Tom

PS... What else can I do with a hyraulic punch? :-)

Hydraulic Punch hole size question
 

surftom wrote:
Hi Gang -

In the process of finishing the hydraulic punch and have a question on
tooling.
I have to build a railing (steel) and want to use 1/2" SQUARE bar for
the stiles (vertical) that pass through a rail (horizontal) 2" wide x
1/4" thick flat stock
Should I punch with a 1/2" square punch or go up to the 9/16" punch.
The intent is to weld around the bar when in position. Does a 1/2"
punch actually make a 1/2" hole or is it a little bigger? Also, what
are the tolerences on typical steel bars (when they say 1/2" is it
really 1/2")?

HRS (hot rolled steel) is often supplied with a
10% over to 5% under tolerance by weight.
As a rule of thumb for punching holes use a die
clearance for the bottom die of 10% of the material
thickness. In that case the resulting hole will be
very close to the punch size for the top 1/3 of the
material thickness. From there the bottom 2/3 part
of the hole is torn out and tapers to the die size.
If you want to punch holes for 1/2 square HRS bars
a 9/16 square or larger punch should work. HTH.
--
SATOR AREPO TENET OPERA ROTAS
Have 5 nice days! John
******************************
--- ILN 000.000.001 ---

Hydraulic Punch hole size question
 

surftom wrote:
Hi Gang -

In the process of finishing the hydraulic punch and have a question on
tooling.
I have to build a railing (steel) and want to use 1/2" SQUARE bar for
the stiles (vertical) that pass through a rail (horizontal) 2" wide x
1/4" thick flat stock
Should I punch with a 1/2" square punch or go up to the 9/16" punch.
The intent is to weld around the bar when in position. Does a 1/2"
punch actually make a 1/2" hole or is it a little bigger? Also, what
are the tolerences on typical steel bars (when they say 1/2" is it
really 1/2")?

HRS (hot rolled steel) is often supplied with a
10% over to 5% under tolerance by weight.
As a rule of thumb for punching holes use a die
clearance for the bottom die of 10% of the material
thickness. In that case the resulting hole will be
very close to the punch size for the top 1/3 of the
material thickness. From there the bottom 2/3 part
of the hole is torn out and tapers to the die size.
If you want to punch holes for 1/2 square HRS bars
a 9/16 square or larger punch should work. HTH.
--
SATOR AREPO TENET OPERA ROTAS
Have 5 nice days! John
******************************
--- ILN 000.000.001 ---

Hydraulic Punch hole size question
 

Hydraulic Punch hole size question
 

(surftom) wrote in message
.com...
Hi Gang -

In the process of finishing the hydraulic punch and have a question on
tooling.
I have to build a railing (steel) and want to use 1/2" SQUARE bar for
the stiles (vertical) that pass through a rail (horizontal) 2" wide x
1/4" thick flat stock
Should I punch with a 1/2" square punch or go up to the 9/16" punch.
The intent is to weld around the bar when in position. Does a 1/2"
punch actually make a 1/2" hole or is it a little bigger? Also, what
are the tolerences on typical steel bars (when they say 1/2" is it
really 1/2")?
Always drilled and never used a punch before so am a little unsure.

Thanks in advance...

Tom

PS... What else can I do with a hyraulic punch? :-)


Better going 9/16".The punch will punch the proper size.One of the
problems with punching the holes in the rails is that you will have to
straighten it after and it can be a bit time consuming.You will need
14 tons of pressure for that size.
Regards,Mark.


I would use a 17/32 punch as long as you can punch the holes square as possible
to the bar. 9/16 would give you a little more play with the vertical pieces
enabling you to make sure they are square to each other.

The rule of thumb is that when blanking out parts, the die controls the size
with the clearance on the punch.. When punching a hole, the punch controls the
size with the clearance on the die.

Personally, I feel clearances called out by some sources are a little tight. Of
course, I'm not knocking out just a few holes on a slower hydraulic machine.
For 1/4" HRFB I would run up to .050" clearance. That ensures me the cleanest
holes and longest tool life on thousands of holes done in the punch press.
You have to know on clearance callouts if they are talking a certain percent
per side or total clearance.

Good luck.
Les

Hydraulic Punch hole size question
 

"surftom" wrote in message
om...
Hi Gang -

In the process of finishing the hydraulic punch and have a question on
tooling.
I have to build a railing (steel) and want to use 1/2" SQUARE bar for
the stiles (vertical) that pass through a rail (horizontal) 2" wide x
1/4" thick flat stock


My question would be why bother to pinch any holes? Just make a jig to
position your vertical posts and weld away.

For the legs, just weld on in line with the upper posts.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.



Should I punch with a 1/2" square punch or go up to the 9/16" punch.
The intent is to weld around the bar when in position. Does a 1/2"
punch actually make a 1/2" hole or is it a little bigger? Also, what
are the tolerences on typical steel bars (when they say 1/2" is it
really 1/2")?
Always drilled and never used a punch before so am a little unsure.

Thanks in advance...

Tom

PS... What else can I do with a hyraulic punch? :-)

Hydraulic Punch hole size question
 

Thanks for the responses!

Roger: I think it would be faster to punh the holes than welding/jig
building. plus I now have a reason for building the press :-)


(surftom) wrote in message . com...
Hi Gang -

In the process of finishing the hydraulic punch and have a question on
tooling.
I have to build a railing (steel) and want to use 1/2" SQUARE bar for
the stiles (vertical) that pass through a rail (horizontal) 2" wide x
1/4" thick flat stock
Should I punch with a 1/2" square punch or go up to the 9/16" punch.
The intent is to weld around the bar when in position. Does a 1/2"
punch actually make a 1/2" hole or is it a little bigger? Also, what
are the tolerences on typical steel bars (when they say 1/2" is it
really 1/2")?
Always drilled and never used a punch before so am a little unsure.

Thanks in advance...

Tom

PS... What else can I do with a hyraulic punch? :-)