Most effective method to drill / tap holes in 1" Sq Tubing 6

[samjessen]

Currently estimating the cost to fabricate a welded frame constructed of 1 inch square tubing. Frame members have holes and tapped holes. These are my issues : drilling and tapping is expensive. Punching is less expensive , but is there a good method for punching 1" tubing (.125 wall ) while maintaining a quality hole for tapping ? Annual volume is 1000-1200. As usual when estimating I can only make two mistakes. Bid too high and lose the job or bid to low and send money out the door with each assembly

 

[fastasleep]

An EAU of 1000-1200 seems way too low to justify the cost of punching a hole, then tapping in a separate operation. Depending on the length and width of the tube, you should be able to drill and tap in one CNC operation, saving yourself an extra material handling step.

 

[BillPSU]

Have you considered self drilling screws. 1/8" material is not well suited for drilling and tapping of any kind because of the small length to diameter ratio. Punching 1/8" material with normal die clearance causes break-out in the lower half of the material causing hole to be even larger giving less pull out strength.

 

[DaveWW]

I saw something a couple of years ago, that may be suitable. Check out

http://www.flowdrill.com.

Dave

 

[griffengm]

Samjessen,
We have used the flowdrill on some tube but it does take some time.
Other possibilities, depending on location along the length of the tube could be: punched hole with a short collar extruded to give extra grip length to your screw(could be tapped or use a self tapper screw); a punched "nail hole" which simply pushes a pointed punch thru the wall and leaves an irregular shoulder; or punch or drill a hole and use a press nut like PEM or a clinch style. If this part is to be assembled/disassembled multiple times, I'd recommend the last option.

Griffy

 

[Tmoose]

studwelding ?

 

[finman]

We use Flowdrill, with a fair amount of descussion and further experimentation we have reduced speeds quite considerably, it's worth trying.

Have you tried rivnuts?

 

[bugnut]

I'd suggest a drap (the good ole drill and tap combination) these are cheap and readily available if the drill portion is to long for the tubing-ie the hole is only through the upside have your local tool and cutter shop cut it shorter and regrind. Then the drilling and tapping can be done in one setup. Good luck!