Pin and Bushing help needed

[dfkrug]

What I did for the many pivots on my CADDigger was buy the
1" ID DOM tubing and cut bushings. I welded them into the holes
in the steel plates then used a 1.000" hand reamer to
get each bushing pair into alignment for the 63/64" pins. There
would always be some tiny mis-alignment due to heat distortion
of the steel. The hand reamer was about $30 and
had 6" flutes. Heat management in these kinds of welds is very
important!

For the pivots in the rectangular tubing, one chunk of DOM tubing
went all the way thru, so it was much easier. No reaming necessary
here as the clearance with a 63/64" rod was about perfect. If you
use 1" pins and 1" ID DOM, you would need a 1 1/64" reamer, or
sand it out as described. Or you could sand your pins down. If the
1" bolts are a little less than 1" OD, that would work, too.

 

[Danno1]

.

Two places to try for metal are

Metals Depotï½® - Buy Small Quantity Metal Online! Steel, Aluminum, Stainless, Brass

and

Steel, Aluminum, Stainless, and Brass - All Metals Incorporated


Of course depending on what you buy, shipping could be expensive.


A longboard is used to fair the hull of a boat. The sandpaper would be strips ~ 2-4 in wide by the length of the board, anywhere from 12-24 inches. IOW, buy a 50 ft roll and cut the strips to the length you need.

.

 

[EddieWalker]

Thanks again for all the help. I never heard of the DOM, so that's what I'm going to ask for when I buy the 2x4 tubing.

This is one of those rainy day projects that I'll buy the materials for and wait for a wet/muddy day to put together.

Eddie

 

[hankus]

Eddie I think when they refer to DOM tubing they are referring to the round stuff, not the square stuff. Someone correct me if I'm wrong.

 

[GuglioLS]

Eddie,

DOM = Drawn Over Mandrel (Seamless Tubing) I hope you don't mind that I posted some pictures for you to take a look at. It's not cheap, of course nowadays what is? DOM is what I used on my grapple jaw bushings. 1" ID x 1/4" wall I used 1" hitch pins (0.997") OD the pins fit no problem, If you can't get the pins to slip into the DOM you can use a 99 cent H/F break cylinder hone on the ID of the DOM to get a nice slip fit.

DOM:.......................... 1" Pin FITS.................Welded in Place........... Jaw Brackets:



Larry

 

[MrJimi]

Eddie, do you have pictures of your twisting grapple, I was going to make mine like yours but after reading this, I am at a stand still, I do like 3RRL's and GuglioLS way much better but they have some very neat tools and skills that I don't have

 

[firefighter9208]

Eddie,

DOM = Drawn Over Mandrel (Seamless Tubing) I hope you don't mind that I posted some pictures for you to take a look at. It's not cheap, of course nowadays what is? DOM is what I used on my grapple jaw bushings. 1" ID x 1/4" wall I used 1" hitch pins (0.997") OD the pins fit no problem, If you can't get the pins to slip into the DOM you can use a 99 cent H/F break cylinder hone on the ID of the DOM to get a nice slip fit.

DOM:.......................... 1" Pin FITS.................Welded in Place........... Jaw Brackets:



Larry

Eddie,

DOM tubing is what is used to build roll cages in race cars. It is stronger, because it doesn't have a seam. Check with a local hot rod shop that builds roll cages. They might have some DOM scrap pieces they would give you. If not they can tell you where to get it or might can even order it for you at a discounted price.

Chris

 

[dfkrug]

Eddie,

DOM = Drawn Over Mandrel (Seamless Tubing) I hope you don't mind that I posted some pictures for you to take a look at. It's not cheap, of course nowadays what is? DOM is what I used on my grapple jaw bushings. 1" ID x 1/4" wall I used 1" hitch pins (0.997") OD the pins fit no problem, If you can't get the pins to slip into the DOM you can use a 99 cent H/F break cylinder hone on the ID of the DOM to get a nice slip fit.
Larry

Great pix and clarification of DOM tubing, Larry. I have not used 1" hitch
pins before, and the fact that they are undersized makes them an
excellent choice here.

I see in your last photo that you have some 1/2" plate with a pivot. You
may have already thought of this, but even 1/2" plate will bend easily
if not braced every 4-5 inches or so in grapple or thumb applications. You
don't want your grapple to twist.

 

[dfkrug]

Eddie,

DOM tubing is what is used to build roll cages in race cars. It is stronger, because it doesn't have a seam. Check with a local hot rod shop that builds roll cages.

That's a surprise. It seems (seams?) wastefull to use this expensive
tubing for roll bars. There are thickness requirements in the racing
rule books, but no requirements to use DOM. I recall reading in my old
SCCA book that you had to provide a test hole in the roll bar to verify
thickness. I would be shocked to hear that someone has fabricated
a roll bar with the 1/4" wall DOM tubing we are talking about here. Even
the thinner wall stuff would be wasteful.

DOM steel tubing is hot or cold roll-formed and welded, then drawn over
an internal mandrel one or more times to remove the steel flash from inside the tubing. The welds used in making tubing is specced (ASTM) to be as
strong or stronger than the base metal, so DOM tubing is not stronger
than other welded tubing of the same thickness and metalurgy. One
might even argue that removing the flash at the weld seam weakens the
tubing a tiny bit.

Is an entirely different subject to talk about BENDING tubing using
EXTERNAL mandrels to get the best possible bends in roll bar
fabrication.