Shop Floor Talk  

Go Back   Shop Floor Talk > Welding and Metalworking Forums > Fabrication

SFT Search:   
Reply
 
Thread Tools Display Modes
  #1  
Old 02-09-2013, 03:28 AM
clive's Avatar
clive clive is offline
 
Join Date: May 2007
Location: Western Australia
Posts: 1,843
Default hope this is of use to someone

I am in the process of making a shop press and have poached ideas and blatantly copied presses that others have made. In looking at them a couple of questions were asked about pins and welds so this may help.
To calculate the shear strength of a pin take cross sectional area x3.142(pi) x shear strength of material = shear strength of pin.
eg. my pins are 19.5 mm dia. I always calculate in inches so 19.5 /25.4 = 0.767" dia
so rad is 0.3835
0.3835 x 0.3835 x 3.142 x 35 ( I used 35 ton steel) = 16.17 tons.
my pins are in double shear so to shear each side takes 32.34 tons and both sides together 64 tons.
As I'm using a 20 ton jack the pins are well able to handle the tonnage.

Now on to weld strength. If you use a 60XX rod the 60 denotes 60,000 lbs tensile, a 70XX rod or wire 70,000lbs and so on.
If you have done a fillet weld and want to know the strength it is leg lengthx0.707(sin45) x weld length inches x tensile strength weldment.
Using a 1/4 inch fillet as an example and 5 inches long using 60XX rods =
0.250 x 0.707 x 5 x 60,000 = 53,025 lbs shear strength thru the length. divide this by 2240 (pounds per English ton) and you get 23 tons shear.
Welds are deceptively strong.
If anyone wants to rewrite this to make it clearer please do.
Clive
__________________
It's So Easy

Last edited by clive; 02-09-2013 at 04:18 AM. Reason: grammer
Reply With Quote
  #2  
Old 02-09-2013, 07:49 AM
Wolfram's Avatar
Wolfram Wolfram is offline
Senior Member
 
Join Date: Sep 2010
Location: Virginia, USA
Posts: 545
Default

Quote:
Originally Posted by clive View Post
0.3835 x 0.3835 x 3.142 x 35 ( I used 35 ton steel) = 16.17 tons.
I think you might need to throw in a factor of .75 there since the shear strength is about 75% of the tensile strength.

(So shear strength of your pins is probably about 12 tons.)

See table at:

http://www.engineersedge.com/manufac...s_strength.htm
Reply With Quote
  #3  
Old 02-09-2013, 07:55 AM
clive's Avatar
clive clive is offline
 
Join Date: May 2007
Location: Western Australia
Posts: 1,843
Default

Yep, but still a good degree of safety at 12 tons. Thanks for pointing that out.
__________________
It's So Easy
Reply With Quote
  #4  
Old 02-09-2013, 08:30 AM
cramd's Avatar
cramd cramd is offline
Drivin' Fool
 
Join Date: Nov 2008
Location: Yorkton, Saskatchewan,Canada
Posts: 4,273
Default

Quote:
Originally Posted by clive View Post
I am in the process of making a shop press and have poached ideas and blatantly copied presses that others have made. In looking at them a couple of questions were asked about pins and welds so this may help.
To calculate the shear strength of a pin take cross sectional area x3.142(pi) x shear strength of material = shear strength of pin.
eg. my pins are 19.5 mm dia. I always calculate in inches so 19.5 /25.4 = 0.767" dia
so rad is 0.3835
0.3835 x 0.3835 x 3.142 x 35 ( I used 35 ton steel) = 16.17 tons.
my pins are in double shear so to shear each side takes 32.34 tons and both sides together 64 tons.
As I'm using a 20 ton jack the pins are well able to handle the tonnage.

Now on to weld strength. If you use a 60XX rod the 60 denotes 60,000 lbs tensile, a 70XX rod or wire 70,000lbs and so on.
If you have done a fillet weld and want to know the strength it is leg lengthx0.707(sin45) x weld length inches x tensile strength weldment.
Using a 1/4 inch fillet as an example and 5 inches long using 60XX rods =
0.250 x 0.707 x 5 x 60,000 = 53,025 lbs shear strength thru the length. divide this by 2240 (pounds per English ton) and you get 23 tons shear.
Welds are deceptively strong.
If anyone wants to rewrite this to make it clearer please do.
Clive
That may be a bit confusing, as North America generally used 2000 pounds as a ton (short ton), versus the long ton of 2240 pounds you are referring to. See reference here: http://en.wikipedia.org/wiki/Long_ton
__________________
Miller Thunderbolt XL AC/DC
Hobart Handler 190
Angle grinders,14" chop saw,Hobart medium duty O/A set
Some air tools,fair selection of hand tools,and other "stuff"
____________________________________________

The difference between genius and stupidity, is that genius has limits. Albert Einstein
Reply With Quote
  #5  
Old 02-09-2013, 10:30 AM
toprecycler's Avatar
toprecycler toprecycler is offline
Elite Member
 
Join Date: Jan 2009
Location: Petoskey, Michigan
Posts: 3,515
Default

Thank you for posting. That info helped clear some things up in my mind. It is always nice to learn something everytime I come to this forum from the great people posting. This is what makes this the best forum!
__________________
Brian

You don't know what you don't know.

"It's what you learn after you know it all that counts." John Wooden
Reply With Quote
  #6  
Old 02-09-2013, 01:01 PM
DrBob's Avatar
DrBob DrBob is offline
I fear I'll do some damage one fine day
 
Join Date: Jan 2009
Location: New York
Posts: 1,423
Default Kudos

Quote:
Originally Posted by toprecycler View Post
This is what makes this the best forum!
Well, we like to think so!

DrBob

So THAT'S what a "long ton" is!
Reply With Quote
  #7  
Old 02-09-2013, 04:00 PM
willy willy is offline
Member
 
Join Date: Sep 2007
Location: Traer, Iowa
Posts: 70
Default

Cool - thanks for posting that! Learn something new every day! Long Ton, Short Ton, now I just need to figure out what a $h!t Ton is...

Last edited by willy; 02-09-2013 at 05:36 PM.
Reply With Quote
  #8  
Old 02-09-2013, 06:00 PM
clive's Avatar
clive clive is offline
 
Join Date: May 2007
Location: Western Australia
Posts: 1,843
Default

Quote:
Originally Posted by willy View Post
Cool - thanks for posting that! Learn something new every day! Long Ton, Short Ton, now I just need to figure out what a $h!t Ton is...
Lets add to that - the metric ton is 2200lbs. But metric, long or short they are all in a ballpark figure.
__________________
It's So Easy
Reply With Quote
  #9  
Old 02-09-2013, 06:05 PM
jb-mck's Avatar
jb-mck jb-mck is offline
Member
 
Join Date: Jun 2012
Location: NW Louisiana
Posts: 72
Default

Anyone looking for a good units converter, try this one. http://joshmadison.com/convert-for-windows/

Sent from my iPad using SFT
Reply With Quote
  #10  
Old 02-09-2013, 06:21 PM
GAS's Avatar
GAS GAS is offline
Member
 
Join Date: Mar 2007
Location: Pleasant Grove,Utah
Posts: 50
Default

Quote:
Originally Posted by willy View Post
Cool - thanks for posting that! Learn something new every day! Long Ton, Short Ton, now I just need to figure out what a $h!t Ton is...
That would be a crap load more than either the long, short or metric tons
__________________
Jack A** of many trades
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Web Search:

All times are GMT -5. The time now is 08:22 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.