Schedule 40 frame question - Mountain Buzz
 



Reply
 
Thread Tools Display Modes
 
Old 03-15-2010   #1
 
Join Date: Apr 2006
Posts: 174
Schedule 40 frame question

For a large cat frame, is there any real reason to use 1 1/2 over 1 1/4, as far as strength or other intangibles. Is the larger pipe overkill, or are they worth the extra 10% weight.

festivus is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 03-16-2010   #2
 
Hillsboro, Oregon
Join Date: Jul 2009
Posts: 10
Overkill. I think it's more important to use whichever you prefer the accessories for.
veilside180sx is offline   Reply With Quote
Old 03-16-2010   #3
 
Groveland, California
Join Date: Nov 2008
Posts: 228
I think that the builders that use 1.5" are bending the material so they have to use 6063 which is roughly half the strength (from memory?) of 6061. I assume they make up for this by increasing the diameter of the pipe (over 1.25" 6061.)
HPMG is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 03-16-2010   #4
 
John the welder's Avatar
 
Delta, Colorado
Paddling Since: 1971
Join Date: May 2009
Posts: 197
In the t-6 temper 6063 is 77% of 6061 in tensile and yield strength. Remember deflection changes with the cube of the diameter. The size of the boat, load ect. can make a difference.
John the welder is offline   Reply With Quote
Old 03-16-2010   #5
 
Denver, Colorado
Paddling Since: 2002
Join Date: Oct 2007
Posts: 93
Do you know what your frame width and length is going to be? Or how many cross bars and drop cross bars you are going to use? These types of questions should be thought about when you are thinking about pipe size. If you can get a piece of 1.25" and 1.5" pipe that will be about as long as your frame. Mock something up to create a span and stand on each piece of pipe.

I would highly recommend the 1.5" for cat frames, especially if it is going to be over 90" long. I would also recommend a double rail frame. This will shorten your cross bars and provide more torsional stability. For cat frames over 96” long we add a vertical brace and a horizontal brace.

Please give me a call if you have any questions or would like some suggestions.

Sincerely,
Zach
www.downriverequip.com
888-467-9489
zboda is offline   Reply With Quote
Old 03-16-2010   #6
 
Join Date: Apr 2006
Posts: 174
Thanks for the insight.

Zack, I am building a frame for a 10 foot cat, but am trying to plan ahead because I will be building a frame for a 16-18 foot cat in the near future. Your comment on the duel rails is also appreciated regarding the longer boat. I understand the size is overkill for the smaller boat, but given the price of dies for decent pipe benders, I only want to buy one set. I have found stock 6063 in both diameters, but it does seem more readily available in inch and a half. I will definitely call and chat before I design the larger boat frame; I will be stopping in anyhow to get some parts if your in the store.

HPMG, your comment would be a good explaination for the difference between NRS and DRE frame size, as NRS uses alot of 6061.
festivus is offline   Reply With Quote
Old 03-21-2010   #7
 
Willi..., Willimina, OR
Paddling Since: 68
Join Date: Jan 2007
Posts: 482
1.5 nps vs 1.25"nps

Quote:
Originally Posted by festivus View Post
For a large cat frame, is there any real reason to use 1 1/2 over 1 1/4, as far as strength or other intangibles. Is the larger pipe overkill, or are they worth the extra 10% weight.
The 1.5" nps offers roughly 35% increase in strength over the 1.25" pipe size alloy for alloy. Long span i.e.72" 1.25 nps cross bars will bend every time when a 200#dynamic point load is applied. Do the arithmetic. The dynamic load will produce a moment of PL/2 or 7200 in lbs. For 1 1/4" pipe the section mod is around .2 in ^3. This puts the 1 1/4" pipe on the yield plateau...the 1 1/2" pipe in in the working stress range.

However, A boat pinned sideways in a strainer needs all the strength it can get. Look in the archive of utah rafters at the 1 1/4" frames that were ripped apart by boats caught in strainers. The force of the water on the fabric decks shreaded the boats with the 1 1/4" frames.

Do your homework and you'll build a better boat.
garystrome is offline   Reply With Quote
Old 03-21-2010   #8
 
Join Date: Apr 2006
Posts: 174
Thanks Gary,

Great information. Mountainbuzz at its best.

I will definitely go with the 1.5 inch.

By the way, I looked into that sight you recommended and hopefully will have 16 foot tubes lined up soon.

Also, your specs you quoted on the tubes I spoke to you about [The frame question] must have been based on the 9 footers. The 10 footers are 18.5 inch tubes and have 2 valves each.
festivus is offline   Reply With Quote
Old 03-21-2010   #9
 
mountains, Colorado
Paddling Since: '92
Join Date: Mar 2008
Posts: 418
"However, A boat pinned sideways in a strainer needs all the strength it can get. Look in the archive of utah rafters at the 1 1/4" frames that were ripped apart by boats caught in strainers. The force of the water on the fabric decks shreaded the boats with the 1 1/4" frames."

...ok, so I'm an idiot. Could you link me to this page? I searched and couldn't find it.
caseybailey is offline   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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Topic Thread Starter Forum Replies Last Post
frame question bth Kayaking | Gear Talk 9 03-11-2010 11:48 PM
NRS Frame question smallie Kayaking | Gear Talk 4 01-22-2010 02:27 AM
Fishing Frame Question? madriver Whitewater Kayaking 1 12-19-2009 05:42 PM
Raft Frame Question sportychik Rafting | Gear Talk 10 05-15-2009 09:51 AM
Raft Frame Question FatmanZ Rafting | Gear Talk 7 04-28-2009 07:53 PM

» Classified Ads
Powered by vBadvanced CMPS v3.2.3

All times are GMT -6. The time now is 03:14 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.