Ways to secure/weld studs/bolts to a plate

[NCSU1980]

I need to weld or secure bolts to a steel plate that will be an mounting adapter plate. We are replacing an older gearbox (quite large, about 800 pounds) with a newer one, which, of course, has a different bolt hole pattern. The adapter plate will have studs protruding down into the old bolt holes of the original mount, and have studs protruding up to match the bolt holes in the new gearbox. I plan on making holes through the plate (about 1/2" plate) for 3/4" studs and welding the studs into place from the back side, possibly with a chamfer in the hole to get a good weld (The back side of the plate at each stud must be flush). I understand that something like this was done before and a stud wrung off when tightened during installation. I know that welding will weaken the studs. Any suggestions? Bolt or stud? Material? How to weld? Where to weld? Shape of hole? Thanks, Steve

 

[HgTX]

What about threaded Nelson studs? Even if you can't shoot them in your application, they should be weldable, no? (Shear studs may be fillet-welded, so I'm generalizing.)

Hg

Eng-Tips policies: faq731-376

 

[CoryPad]

Use fasteners that are designed to be welded. For example, here are projection weld studs:

http://www.emhart.com/products/pk/screws.asp

HgTX mentions Nelson studs - they specialize in discharge weld studs that don't require holes, which are usually used for lower force applications.

http://www.nelsonstud.com

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MikeHalloran]

I'd be inclined to tap the adapter plate, thread the studs in, and secure them with Dutch pins.

(e.g. small roll pins installed in blind holes drilled parallel to the stud axis but offset through the thread pitch cylinder.)




Mike Halloran
Pembroke Pines, FL, USA

 

[MintJulep]

Have you asked the new gearbox manufacturer if they can match the old hole pattern?

 

[csd72]

There is a simple solution to have blind fixings for non-weldable bolts.

Get a tubular wrench head from the hardware for each bolt (i.e the type you interchange for a ratchet spanner) put this around the head of the bolt on the blind side, and weld this to the plate rather than the bolt head.

This will be sufficient to tighten the bolt.

 

[MikeHalloran]

Or, if you can get the size you need, Keenserts studs:

http://www.merko.no/Kataloger/Gjengeinnsatser.PDF

Mike Halloran
Pembroke Pines, FL, USA

 

[Tomtation]

Use studs made from SA36 rod. These can be welded.

 

[dvd]

Countersink the backside of the plate deep enough so that a flathead screw can be welded in place. The countersink geometry of the flathead screw keeps the screw from pulling through and the weld prevents the screw from turning.

 

[dimjim]

If the bolt pattern is on the same bolt circle
diameter. What are the hole patterns? Do any of
the holes match?

 

[unclesyd]

I had a similar problem about 25 years ago and solved it by a trip to a truck parts store. This was supposed to temporary but I just checked today and the gearbox is just like we left it

http://www.aetnascrew.com/wheelhvy.htm