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  #1  
Old 01-18-2022, 07:37 PM
mastuart mastuart is offline
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Default E wheel frame tube stiffness question?

E wheel frame tube. I got a lead on some 3x7x3/8 tube. I think its a good price $100 for some 8 to 9 foot sticks. Anyone good with the frame stiffness calculator? If so could you calculate a 26 inch frame with this material? I already cut up some material that was 3x6x1/4 . But if the 3x7x3/8 material will be much stiffer. I will go get some and have it cut up.
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Old 01-19-2022, 12:24 AM
hillman hillman is offline
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Maybe this still works, I have not checked it


https://www.allmetalshaping.com/atta...2&d=1323619312


I can open this file but Microsoft won't let me use it because I don't have an account with them,
It won't work on this new computer but still works on my old one
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Old 01-19-2022, 12:38 AM
hillman hillman is offline
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Search for "stiffness calculators" in the wheeling machine section
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Old 01-19-2022, 03:13 AM
Jaroslav Jaroslav is offline
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Mark. It probably doesn't matter what material you use. The result must be a solid frame. The stiffer, the better. Rails, cast iron or concrete are best. It's a rolling machine. Flexibility is not desirable.
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Old 01-19-2022, 10:11 AM
mastuart mastuart is offline
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Quote:
Originally Posted by hillman View Post
Maybe this still works, I have not checked it


https://www.allmetalshaping.com/atta...2&d=1323619312


I can open this file but Microsoft won't let me use it because I don't have an account with them,
It won't work on this new computer but still works on my old one
I have the same problem as you. Thats why I asked . I know its going to be stiffer but how much? Just want to know before I spend more money. The 3x6 1/4 cost plenty now days. Its cut but not welded.
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Old 01-19-2022, 10:17 AM
mastuart mastuart is offline
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Quote:
Originally Posted by Jaroslav View Post
Mark. It probably doesn't matter what material you use. The result must be a solid frame. The stiffer, the better. Rails, cast iron or concrete are best. It's a rolling machine. Flexibility is not desirable.
Thanks Most would say the 3x6x1/4 will make a solid enough 26 inch frame. The 3x7x3/8 would be stiffer. I would like to know by how much before i spend more money.
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Old 01-19-2022, 12:45 PM
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Kerry Pinkerton Kerry Pinkerton is offline
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Mark, the stiffness calculator is hard coded for specific tubing. Im not smart enough to change the formula. Id not build a 26F frame out of that material. It will be too stiff.

A good frame will have just the right amount of vertical deflection. Too little and it wont work. Too stiff and it becomes a rolling mill trying to make everything the same thickness.

The 26F is my favorite frame. If i could only have 1 ewheel, it would be that.
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Old 01-19-2022, 05:22 PM
mastuart mastuart is offline
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Thanks Kerry Would you care to make a guestimate of the stiffness number?
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Old 01-19-2022, 07:28 PM
billfunk29 billfunk29 is offline
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Default frame stiffness

Doing the math in my head, I'd say the stiffness would about double. Assuming solid joints. That said, I have used real stiff, fabricated wheels and they provide a constant gap between the wheels. Force will vary a lot with material thickness variation. A little flex will provide a more constant force. I'd use the 6". spend the extra money on good anvils and adjuster.
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Old 01-19-2022, 07:43 PM
crystallographic crystallographic is online now
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Quote:
Originally Posted by billfunk29 View Post
Doing the math in my head, I'd say the stiffness would about double. Assuming solid joints. That said, I have used real stiff, fabricated wheels and they provide a constant gap between the wheels. Force will vary a lot with material thickness variation. A little flex will provide a more constant force. I'd use the 6". spend the extra money on good anvils and adjuster.

Agreed - When one aircraft job required 2024T3 .032" for an 8ft top skin, I widened the flat on the lower to 1.5in.
Tonnage went up to 2.0 and ball/race bearing life dropped to 18 MINUTES.
Sigh.
Re-bored the roll for roller bearings at quadruple the tonnage.
Cruised to a fine finish on that polished skin.
(37in throat frame is of 1/4" plate. Plenty stout.
1.25in x 6tpi acme thread lift-jack running in a bronze bearing/nut.)
Load cell gives accurate pressure readings.
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