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Discussion Starter #1
not talking about HREW here... no pipe...i noticed this hasnt really been covered anywhere

my local metal yard does not carry DOM... however alot of there material is CDS(cold drawn seamless)... Ive taken calipers to it... and its pretty damn uniform in size... ill have to take a piece of DOM and compare it... but the stuff is accurate... its cheap too... sold by weight... ill pay like $0.90/lb for the .120 wall stuff... for 1.5" .125 wall thats 1.836lbs per foot: about $1.80 a foot... and its local

Drawn Over Mandrel (DOM)
DOM is formed from strip and Electric Resistance Welded (ERW) then cold drawn through a die and over a mandrel resulting in improved inner surfaces and dimensional quality. This process, called cold drawing, may be repeated more than once to reach the planned OD, ID, or wall dimension. Multiple draws can also be used to increase the strength or improve the surface finish of the tubes. During the drawing operation, the tubes may be process annealed to increase the ductility of the material. Lower cost alternative to CDS with equal or superior physical properties.
Typical Applications:
Machined parts, rollers, shafts, sleeves, steering columns, axle tubes, drive shafts, bushings and is most readily adaptable in cylinder applications with a 80,000 PSI tensile.

Cold Drawn Seamless (CDS)
General purpose seamless tubing, which is a solid bar of carbon steel drawn over a mandrel to form the tube section. CDS allows selection of chemistry and rough tube size. Cold drawing produces higher physical properties without heat treating. Offers widest range of sizes and chemistries in mechanical tubing. Better tolerances and reduced machining allowances over Hot Finished Seamless (HFS).
Typical Applications:
Machined parts, bushings, spacers, bearings, rollers, shafts, sleeves and cylinders with a 75,000 PSI tensile.


i dont see any problems with using it... you? ill take more measurements.. we can see just how precise it is and where the tolerances lie

discuss

oh and read here :metal stuff
 

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Some assembly required!
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That's interesting, I'm going to have to take a look at that. From the 80k psi vs. 75k psi numbers I'd imagine that they are pretty similar. It would seem to me that good cage design could counteract the difference in the materials strength. I'm going to have to look into that to see what is available here locally. You say that dimensionally they are the same? That's very important for bender die reasons.
 

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Discussion Starter #3
they are measured the same yes... and you can easily find it in THICK wall.. a buddy just made some 2"od 7/16" wall traction bars

ill try to get some measurement pics this week... its interesting becauser it is formed on a mandrel for accuracy.. DOM is electric welded that is drawn down to size and spec

if tolerances are within say .005 +- it may be a budget alternative...
 

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How does the cost compare to DOM from the same source? I see no mention of a welded seam in the description, is it welded or is the seam just butted together?

Looks like some research is in order :paper:

Just did a little reading, I see the CDS is formed from hollow blocks (billets) drawn over a mandrel. Supposed to have better dimensional control than DOM. I didn't get price quotes, but the couple places I checked indicated that CDS is more expensive overall than DOM due to the process.
 

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Wrenching for a Livin'
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That's interesting, I'm going to have to take a look at that. From the 80k psi vs. 75k psi numbers I'd imagine that they are pretty similar. It would seem to me that good cage design could counteract the difference in the materials strength. I'm going to have to look into that to see what is available here locally. You say that dimensionally they are the same? That's very important for bender die reasons.
let me know if you find this stuff cheap in charlotte :thumbup


Does seem interesting thou.

Dc, are you buying new tube or scrap by the pound? that might be the difference....
 

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Discussion Starter #6
Just did a little reading, I see the CDS is formed from hollow blocks (billets) drawn over a mandrel. Supposed to have better dimensional control than DOM. I didn't get price quotes, but the couple places I checked indicated that CDS is more expensive overall than DOM due to the process.
very interesting..didnt find that... ill have to compare cost... i buy this stuff at a local yard... they charge by the lb... ill have to go get some and see.. maybe cheaper... ive always bought my stuff from there when i could and its definatley cheaper

a buddy just got 1.5 od 5/16 wall seamless tube for under 40 bux... i think he bought 40' of it..$2 a foot for 5/16 wall.. hows that compare???

dc
 

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Discussion Starter #9
wow i just looked at DOM price by the foot at ballistic... $18.50 A FOOT for 2.25 OD 1.5 ID ... thats 3/8 wall

im gonna try and swing by the steel yard tommorow... i may just buy some tube then if i can find what i want

dc
 

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Diesel Gynachologist
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i get my 1.5DOM for about 4bucks a foot. that 2" stuff is bank.

ballistic is not a good source to base price on because I cant imagine they are selling that much of it. Im sure my steelyard is cheaper than them and will sell it by the foot. also the more you buy the cheaper it gets.
 

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Discussion Starter #13
yea... just got back from the steel yard... they had 2.25OD 3/8 wall.. whihc just by looking at it i can tell its way too big... i think im gonna shoot for 2.0OD .25 wall... they were out of it ...

1.5 for 4 bux is nice... i paid out the a$$ for my 1.5...

heres CDS tolerances go here CDS tolerances... .006 tolerance for 2" DOM tolerance at that size is the sameDOM tolerances
 

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Discussion Starter #14
DOM-
DOM is cold drawn through a die and over a mandrel resulting in improved surface finish, excellent concentricity and dimensional accuracy. Lower cost alternative to CDS with equal or superior physical properties. Can be used for
machined parts, rollers, shafts, sleeves and is most readily adaptable in cylinder applications

tensile strength 80,000psi
Yield 70,000 psi
elongation 10%
wedlability - good to excellent

CDS-
General purpose seamless tubing, CDS allows selection of chemistry and rough tube size. Cold drawing produces higher physical properties without heat treating. Offers widest range of sizes and chemistries in mechanical tubing. Better tolerances and reduced machining allowances over HFS. Typically ordered as either OD and wall or OD and ID.
Machined parts, rollers, shafts, sleeves and cylinders.

tensile 75,000 psi
yield 65,000 psi
elongation 5%
wedlability good to excellent


ASTM
A519
(CDS)
&
ASTM
A513 TYPE 5
(DOM)
CDS and DOM mechanical tube for
fluid power applications. CDS items
are stocked in finished walls .750"
and heavier. DOM items are stocked
in finished walls up to and including
.625". Available in suitable to hone,
suitable to skive and pre-honed. All
honing is done in Castle Metals'
owned facilities
 

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Discussion Starter #15
metals depot.com quoted me $218 for 20 ft of 2" .25 wall... thats a hair over $10 a foot... its cheaper to buy a full stick from them... for 4ft it was $73!!!!! thats $18/ft ...plus its $167 to ship to my house

just got back from the steel yard...they didnt have the 2" .25 wall i wanted...but i got a price... $0.50/lb!!!
2" .25 wall tubing is 4.673 lbs per foot... thats 93.46 lbs for a 20' stick...
so 93.46 lbs of steel x $0.50/lb =

$46.73!!!!!!!!!!!!!!!! thats right 20' of seamless mechanical tubing 2.0"OD 1.5"ID(.25" wall) for 47 bux!!!! 2.35/ft

beat that

next time i go down(they have another yard) im gonna bring a caliper with me... we will get measurements to the .00x"

heres a cool formula for tube weight... 10.68(Dia - thickness) x thickness = weight per foot
10.68(2.00-.25).25 = 4.673
 

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If this got answered above, ignore me, I didn't see it.

DOM is not seamless. It is plate that is rolled then drawn to flatten the seam and improve dimensional tolerances. That's why it has the blue line down the side.
 

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Discussion Starter #18
yea larson i know..

rept the steel yard is called steel and metal liquidators... they will soon be stocking DOM also including chromoly...its in new castle de...
http://www.steelliq.com/contact.html

they have another yard in pa... i forget where... ill find out for ya... what ya need and how much??? i can order it w/ my 2"... shoot me a PM
 

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Discussion Starter #19
a guy at OFN.com had something to add about elongation...which i didnt cover yet
Acording the specs above:

The DOM has an elongation of 10% vs. the CDS 5%. This means that at that elongation, the material will have yeilded, and will not return to its original shape.

So yes, the DOM will "flex more" under load before failing. However the load that it will flex under isn't much more than the CDS, and with less flex there will be less recoil when something lets loose, or the load changes suddenly.

The flip side is that a well designed part will suffer less fatigue with the greater flexability that DOM provides.

For a load bearing part the DOM would be a better choice, but for bumpers and the like the CDS would be fine when you compare what you are getting for what you pay for it.

That is just from the specs listed above, there may be some metalurgical intracies that will make the DOM superior, but steel is steel, and when you weld it you change the worked structure anyway (when cold or hot forming, it won't matter at the weld because you just basically annealed it, so all the dislocations put into it during a cold work process are negated) and the joints are where the loads do weird things when they combine in the first place (unless you build funky parts with extreme slenderness ratios, like really long control arms that have tendency to buckle) which is why everybody preaches more gussets. If you built your joints strong then a tube will fail, but the joints are where the care should be taken.


basically DOM can bend 5% more and return to its origional shape than CDS... i cant justify 5%... CDS will get less spring back when your bending it, its just slightly more suceptable to becoming "bent" (not striaght or origional bend shape) during deflection

dc
 

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ate lug
88 + 96 broncos, 96 F250
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Sounds pretty interesting. I want to make a new front bumper for my bronco, sounds like this stuff will be a good candidate for it. Sent ya a PM :thumbup
 
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