Need Part Holding Help

[ddickey]

I have to pin (2 dowels) and tap for 3 1/4-20 SHCS. The piece (2) is 1" x 8" on a 16" x 18" plate. Both pieces are aluminum. I was able to get the first one as it was on the edge of the plate and clamping was no problem. The other piece is parallel to the first four inches away. I could maybe get one clamp on the end and then just one screw after that would be able to hold it in place.
My thought though was to glue it in place for the drilling and tapping. I tried Loctite super glue but never took hold.
Any suggestions for something that will bond aluminum to aluminum?

 

[mikey]

A picture would really help here.

 

[ddickey]

 

[mikey]

Would it be allowable to drill and tap two holes to enable you to use standard hold down clamps?

 

[brino]

perhaps

1) clean both and dry both parts and then try cyanoacrylate adhesive on one part and accelerator on the other
or
2) clean and dry both parts and try double sided tape?

-brino

 

[ddickey]

I probably could Mikey. I have some Mitee Bites that would probably work.
Double sided tape also a good idea, thanks brino.

 

[chips&more]

Get a piece of plastic/metal, make it to the appropriate width/dimension. And use it to properly space the 2nd piece from the 1st piece that is attached. Then clamp...Dave

 

[JimDawson]

Drill & tap the plate first. Then drill & C-bore the parts. (or vise-versa) Bolt the parts down and align. Then come back and do the dowel pins once the everything is anchored.

Just out of curiosity, why the dowel pin locations on the outside? Normally I would put them between the outside and center screw, maybe 2/3 of the way out from the center on each side. Put the outside screws where the dowel pins are. Too late now though.

 

[ddickey]

Another good option, thanks Jim.
The dowels are a guide as I tighten the screws it hold down the column and holds in place. I'm sure the dowels in the position you suggest would work well also. I'm following the plans of Mark Frazier's "Another Tool and Cutter Grinder". See post #94

Another Tool & Cutter Grinder

The mill table on my lathe worked great. I got straight holes with a good slip fit on the brass rod for the split cotters.

www.hobby-machinist.com

 

[Chewy]

Now you are building stuff like I do. Looking at the picture, think of the two pieces of aluminum as railroad tracks. Place two pieces of soft wood across them like railroad ties, extending some past the one you are trying to drill. Pieces of pine or cut in 1/2 - 2x4, as small as you can get away with. Then place two strong pieces across the "railroad ties" extending past the piece of metal. Can use wood, but metal would be better. Place one in the center and the other outside the piece you are drilling. Your picture shows mill table on each side of metal. Put hold down clamps on mill table and clamp the two strong pieces. NOTE: don't get carried away! It is possible to seriously deflect the plate metal. Try moving one parallels to very close underneath to piece being drilled. Don't over tighten the long, strong pieces! You can bust up the tee slots!
Option B is to use a piece of metal under the plate and clamp the long pieces with C clamps. Make a sandwich. Harder to do but that eliminates the bending, or possible tee slot damage. Getting it accuratly placed is your problem. Adjustable parallels maybe? Holding it so it doesn't move is easy.

Just did this on a 3' X 4' X 12" high box on a wooden work bench. Had to posistion ten dividers into it. I used end of bench instead of mill table to clamp to. Have done this before on saw horses. Now that gets exciting!