Square tubing that will fit in another piece of tubing

LoneGunman · Dec 16, 2009

I want to make a detachable tool holder for my welding table, I've seen people use hitch receivers, they add up though. Is there a standard size square tubing that will fit in another piece of tubing close enough to secure with just pins?

rsanter · Dec 16, 2009

take the dimension of the insert piece you want to use. go to the next material dimention and then do a little math to come up with the wall thickness you will need for a fit.
most metal places will have them

bob

Zrexxer · Dec 16, 2009

Standard square steel tubing has a longitudinal weld seam inside that interferes with free sliding fits. Hitch tubing is seamless for that reason.

MP&C · Dec 16, 2009

What people normally refer to as 1/4" wall thickness is actually about .22 thick (give or take), so a 1-1/2 sq tube should fit snugly inside a 2" piece with that wall thickness.

If you can't find seamless, there are ways around it, as I did on this rotisserie fabrication:

CamarosRus · Dec 16, 2009

I too built a rotisserie and many brkts to work with it.

Too my knowledge there is only one size 2 1/2" x 2 1/2" sq that is made w/o the inside weld seam. This is with .238 wall and then will accept most 2" sq inside of it.

I can tell you from experience that having too snug of a slide in fit, will often times wind up with a bind.

Red Green · Dec 16, 2009

There was a long discusson about this before I would recomend buying one of these http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_357085_357085 for the base and then you can make you inserts out of 2x2 square tubing and just drill your own hole.

ears · Dec 16, 2009

You can get by with quite a bit of play if you use a set screw to tighten it down. Another way is to run a quick bead on the outside of the smaller tube.

Jack Olsen · Dec 17, 2009

I got a bunch of the Harbor Freight receivers when they were on sale. Then (as others have pointed out) you just use 2" square tubing for the insert piece. The fit is pretty loose on most pre-fabbed combinations, too. I welded in nuts and added threaded tighteners to lock them down. (I also used double receivers, for the torsional strength of two mounts.)

nissan_crawler · Dec 17, 2009

People have also ground a groove down the outside of the smaller piece to clear the weld inside the larger piece.

A_Pmech · Dec 17, 2009

4130 seamless aircraft tubing is available in telescoping sizes.

However, it is not inexpensive.

larry4406 · Dec 17, 2009

Here is a link to a chart of standard square structural tubes http://www.bmgmetals.com/hr_struct_square.shtml#channels

The shapes are based on constant outside dimensions, yet different wall thicknessess. The outside dimensions are in increments of 1/2 inch, so for example a 2" will nest in a 2.5 inch, but a question of the fit as you questioned.

If you do the math, the 1/4 inch wall thickness will be a zero clearance situation, 3/16" wall thk will net 0.124" total clearance, while a 0.12" wall thk will net 0.26" clearance. Then there is the problem of the internal weld as Robert pointed out.

I have been looking into this to build a rotissorie (Robert - please start a new thread and post pics of your rotisserie).

Hope this helps.

Mario428 · Dec 17, 2009

Try McMaster-Carr

http://www.mcmaster.com/#4931t49/=4yx21m

Only .105 wall is one problem. But if you use larger pc and anchor well thiuck wall will slide in and out. Tubing is welded in the corner not on the flat, radius on tube then clears.

bimmer1980 · Dec 17, 2009

depends on how tight of a fit you need. If you have a long length of tube sliding into another, just use 3/16" wall tube for the outer one and make the inner tube be 1/2 smaller.... example: 4x4"x3/16" can accommodate 3.5x3.5 tube. 3.5x3.5x3/16 and 3x3. and so on.... I used this method for building a robust cherry picker a while ago....

keep in mind, any welds along the length of the outer tube can warp it enough that the inner piece will not slide easily......

akdiesel · Dec 17, 2009

I know some will think I sell this stuff because of how many times I have mentioned it on this site, but I don't. It has a lot of uses and here is one for ya.
The P9000 and the P9200 are designed to work together and they have holes already incorperated in them.
http://www.unistrut.com/Browse/cat_pg.php?P=product_ts

Major Ramifications · Dec 17, 2009

Jack, nice job!
Do you have a slick way of storing them when they are not in use?

zmotorsports · Dec 17, 2009

Depending on how heavy you need these to be 2" receiver tubing is quite overkill (and you are correct expensive) for most removable fixtures. I used 1" sq. tube to slide into 1.250" sq. tube with .125" wall thickness for my transmission fixtures on my workbench. I think it was only around $0.87/ft. for the 1" and &1.15/ft. for the 1.250". As already mentioned you will have to grind down the weld on the inside of the larger tube where the tubing was electric welded. Not a big deal on fairly small pieces but when the lengths get longer it is more difficult. Mike.

Jack Olsen · Dec 17, 2009

Major Ramifications said:
Jack, nice job!
Do you have a slick way of storing them when they are not in use?

That is my slick way of storing them.

jimmy p · Dec 17, 2009

Red Green said:
There was a long discusson about this before I would recomend buying one of these http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_357085_357085 for the base and then you can make you inserts out of 2x2 square tubing and just drill your own hole.

I got the same thing for $7 at harbor freight and an 18" for $12...on sale!

Beater · Dec 17, 2009

What about using a square drive shaft and related parts from a tractor PTO? Tractor Supply sells square drive shafts for mower attachments, etc. They're about a 1" shaft.

The front drive shaft on my truck is made from 2" and 2.5" receiver hitch tubing, one sliding inside the other to allow extension and compression. Where the two pieces overlap the the shaft walls are .5" thick. Sure it's unbalanced, but it's bulletproof.

As others mentioned above, receiver hitch doesn't have the weld running down the inside. Another difference is that the corners are rounded and slip inside one another easily. Standard square tubing, even though the dimensions might make sense and they should fit together, may not slip inside each other because of the corners fitting too tightly.

IDASHO · Dec 17, 2009

Im my experience, the actual receiver HITCH stock is the spendy stuff. The receiver stock is not too bad.

Harborfreight stocks receiver hitch items for very cheap.

Take a look at this item
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=97093

18" long, that is good enough for 2 "hitches"

t. jones · Dec 17, 2009

Thats agreat idea Beater ! I have a couple of old 2 piece driveshafts that were going to scrap
Thanx Trevor

madjack · Dec 17, 2009

I stock 2" DOM at my shop. We build a lot of custom receiver hitches for motorhomes. I sell it at $5.25 per foot on a walk in sale. I'd check the local steel supplier or welding shop. (my cost is 2.44 per foot as a 20' stick)

Mike_27 · Dec 21, 2009

Square tubing broaches;

http://bbs.homeshopmachinist.net/showthread.php?t=29409&highlight=square+tube+broach

hth,
Mike

arvidj · Dec 23, 2009

jimmy p said:
I got the same thing for $7 at harbor freight and an 18" for $12...on sale!

I have also purchase the harbor freight ones when they are on sale but at least the ones that I got were different from the norther tool versions in that they are only 1/8 inch wall tubing. Not a 'show stopper" dimensional issue as the interior really is 2 x 2 and it is seamless the same as the norther tool or "regular 1/4 inch wall receiver tube" - which I also have purchased as a 20 foot stick - but the wall thickness might be a consideration to some people.

jimmy p · Dec 23, 2009

arvidj said:
I have also purchase the harbor freight ones when they are on sale but at least the ones that I got were different from the norther tool versions in that they are only 1/8 inch wall tubing. Not a 'show stopper" dimensional issue as the interior really is 2 x 2 and it is seamless the same as the norther tool or "regular 1/4 inch wall receiver tube" - which I also have purchased as a 20 foot stick - but the wall thickness might be a consideration to some people.

mine are 1/4", I was actually trying to find 1/8" wall but they didnt have any

LoneGunman · Dec 23, 2009

I like the idea of the Unistrut, I am an electrician and use a lot of it, didn't know they made square strut though, I think it may be a little light though. It would be fine for everything but my vise, maybe I use the strut for everything else and use a receiver tube for the vise. Thank's for all the other great ideas, now I just have to decide which way to go.

British Car Nut · Dec 25, 2009

LoneGunman said:
Is there a standard size square tubing that will fit in another piece of tubing close enough to secure with just pins?

Check out McMaster-Carr. It's a large mailorder house catering to industry but I've used them also for personal items. They carry solid as well as perforatedf square tubing that fits into each other. If you don't see what you need you can call them on their toll free number. Mike

kevinstj · Feb 22, 2010

You want what they call "nestable tubing" Mc Master Carr carries it. It's called Nestable because it slides into each other.

gahrajmahal · Feb 23, 2010

My vote is for the Unistrut products. It is reasonably priced and most larger cities have a distributor for it. The versions with the holes work great with hitch pins and bolts making even less work for you.

Square tubing that will fit in another piece of tubing

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