[samualt]

Don't freak-out Ninewgt, LOL. I am just thinking out load. I wondering what would happen if someone used lighter steel for the frame. I understand we want it heavy to dampen vibrations and to make it very stiff. I plan on getting the 3/16" thick stuff just like the instructions say. Still, what would happen if someone used 1/8 thick tubing. Would the square rails bow and twist when the machine operates?

2" x 2" Square Steel Tubing

Wall lbs/Ft
-------------------------------
.035" .9350
.049" 1.300
.065" 1.710 ~1/16
.083" 2.164
.095" 2.461
.109" 2.802
.120" 3.050 ~2/16 [1/8]
.134" 3.397
.188" 4.320 * ~3/16
.250" 5.410
.313" 7.181



P.S. Just daydreaming till my welder arrives.

I did some calculations and found that I need 126.48 Feet of Square Steel Tubing, and that it will weigh 546.41 lbs. I thought it would be more actually. I'll have to check my calculations....

[NeoMoses]

wow, 2x2x3/16" tubing ought to be plenty stiff! of course, you lose stiffness with length... I guess I'd just have to take a look at the drawings and do some calculations from there. Likely, the 3/16" wall thickness was chosen to give you less than 0.001" deflection at the maximum expected loading. (at least that's how I would do it if I were designing a machine )

[lsfoils]

Hi Samault,

You may find less twist and deformity in the thicker walled tubing. Deepends on how hot you run your rod and how many passes you make at each joint. Less heat may not give you maximum penetration but still yeild enough strength for the job but you won't see as much aberation. I try to take advantage of this when welding and if I find that things are starting to twist I will turn up the heat and add a little extra weld in the appropriate corner to bring things back to square. Just my 2 cents...

[ninewgt]

Sam

Use the 3/16" IF your going to change it go thicker !

Really - its a heavy duty machine - Dont scimp on your frame !

[samualt]

Anyone know about how much 126 feet of 2"x2" square steel tubing should cost at 3/16" thick? I'm going to be calling around this week and want to make sure I don't get had. Thanks!

[rcrabb]

check recyclers for your tubing. Alot of times they have misc pieces for scap prices.

[mrainey]

If you do a lot of weight calculations for tubing or other shapes, you might get some use out of this free program:


http://bellsouthpwp.net/r/s/rsnmar/MEWeights21.zip

[sol]

Our mom and pop supplier in Frog Level (really!) sells by the pound and 2x2x3/16 weighs 4.31 lbs/ft if I am reading this chart correctly. The price seems to average around 50 cents a pound, again this is a small outfit which probably has a higher markup than would exist in a larger market. Steel comes in 20 ft lengths and there frequently is a substantial cutting fee, like $5.00 per cut so I buy it by the stick. Anyway I would ball-park 126 feet at 126 x 4.31 lbs x $0.50 / lb and expect $300 and hope for $200. It is over 500 pounds...delivery if available, may be worth the added expense.
Hope this helps!
Sol

[sol]

Out of curiosity I just called the local steel supplier... Untaxed, uncut, no delivery 2 x 2 x 3/16 x 20 ft. is $45.00, that is $2.25 a foot ... just over 52 cents / lb. ...so 126 ft. is $283.50. Were it my project I would give them a cut-list and have them cut each piece to the final size unless I had a high quality steel saw. They would price it as shop time rather than per nuisance cut so you would not be hammered with the high cut fee.

Sol

[foamcutter]

Maybe try what I do. I have a friend who has a muffler shop. Most of them have abrasive cut off saws to cut pipe. I just take my tubing out there on my day off and cut it up. I then usually offer to buy him a new blade for the saw, but he never accepts. I always pick a day that he is slow so I'm not interrupting him making money. Muffler shops also have mig welders and cutting torches, that comes in handy from time to time. Of course always wear safety glasses or any other safety equipment recommended for the equipment and know how to work any equipment you use, anotherwords be careful and don't blame me if you cut off anything or get hurt. Good luck Ron

[devo]

There are several places to buy steel from where I live. One of them is 35 cents a lb, how ever the price I am sure has went up since last time I was there. When I need steel I buy it at cost since I work a machine shop and engineering company with lots of steel racks. I just figure out what I need and place the order and say I will pay in cash the day it comes in off the truck.

So I can cut it all there on are large h-bandsaw, weld it, mill it, machine it, lathe it. All on my time of couse not the company time.