Rivet steel plate to alloy block?

What I need is a way to attach a steel plate to an alloy block where there's no way to get all the way through the alloy block, just a 1/2 inch deep hole to work with. There isn't enough space to use a bolt because the thickness of the bolt heads will interfere with the rest of the assembly. Otherwise I would simply tap a thread.

Will a rivet work in this manner? I've only ever used a rivet to attach 2 plates together with a hole all the way through both materials. Sorry if this is a really basic question.

Also open to other suggestions… spot welding won't work due to aluminum/steel and JB weld is a sloppy way to get this done. Helical and grinding down the bolt heads is another option, but very pricy and labor intensive comparatively.

Countersink and flat head screw?

It's an option. But then I have to countersink everything perfectly, and I'd end up with a steel thread into aluminum, or once again I'm stuck with the helical $$$ problem.

Will rivets work?

If you can get a "pop" rivet in the correct diameter, yes.

Rivets hold by you forming a head on the side it was inserted from with a ball-peen hammer. Now a pop rivet might work if you can find a big enough one.

Yes a Pop Rivet is what I meant. Would this work without a hole through both materials?

Would a drive screw work? http://www.hansonrivet.com/drive-screws.htm You drill a precisely sized blind hole, and hammer it flush from the outside, not the backside. We use them for installing ID and info plaques on molds and machinery.

That actually looks like a brilliant solution! Any idea how they hold up to vibration?

mr2peak wrote: Yes a Pop Rivet is what I meant. Would this work without a hole through both materials?

A pop rivet is meant for a far side in-assessable area, not a blind hole but it might work if the length is perfect.

Now that its been brought up, drive in screws would work great here.

JB Weld was dismissed prematurely. It isn't messy if done properly and is quite effective. Although I dig the drive screw idea.

It looks like the drive screws are only good for Rockwell hardness B70-B85.

6061 T6 is B60 - 7075 T6 is B87

I'm guessing a cast and lightly machined part is 6061, which means that the drive screws are out :/

Have any of you guys used them on cast aluminum?

As far as JB Weld… Would you buy a part that had been assembled with JB Weld? I'm looking for the professional solution here. Drive screws certainly fit here.

mr2peak wrote: That actually looks like a brilliant solution! Any idea how they hold up to vibration?

GM used something similar to those on the bottoms of cast iron and aluminum intake manifolds in millions of V6 and V8 engines over a period of decades to hold on a shield to keep the oil in the lifter valley of the engine from getting cooked by the exhaust crossover... never seen one missing on engines i've torn apart, and i've even removed them with a vise grip to clean out behind the shield and pounded them right back in the same hole without having an issue..

why can't you tap it? use a plug tap then a bottoming tap? 1/2inch is deep for some fine threads.

So...how strong dos this attachment need to be? is it decorative or just a nameplate or heat shield, or is it something that will take a beating?

From the same site linked above, what about some sort of riv-nut like these Flush Nuts? Gotta love that name...

Maybe you could use the flush nuts or similar with a dab of JB in the hole to help lock the threaded insert in? It would be clean and professional if done carefully...

44Dwarf wrote: why can't you tap it? use a plug tap then a bottoming tap? 1/2inch is deep for some fine threads.

There's very little room for a bolt head, I'm looking for an extremely thin solution.

ultraclyde wrote: So...how strong dos this attachment need to be? is it decorative or just a nameplate or heat shield, or is it something that will take a beating? From the same site linked above, what about some sort of riv-nut like these Flush Nuts? Gotta love that name... Maybe you could use the flush nuts or similar with a dab of JB in the hole to help lock the threaded insert in? It would be clean and professional if done carefully...

As far as strength, I'm trying to hold a backing plate onto a motorcycle clutch basket. There's virtually no load on the part its self, it's simply a backing plate. However, there will be A LOT of vibration and very little clearance, it was originally peened together but that will get drilled out making it irreversible.

I'm really liking this flush nut solution. A dab or red Locktite should do the trick.

This is an amazingly helpful thread so far, thanks guys If more solutions exist, please keep them coming.

Use stainless steel recessed fasteners threaded in to the block with thread locker. You should be ok with respect to any galvanic reaction.

A little more research shows that flush-nuts will work, but they still have 50% of the issues of using helical inserts, namely they still require a bolt, and that means I have to deal with the bolt head :/

The bolt head protruding above the plate needs to be 1mm high or less, more than that and it will interfere.

mr2peak wrote: It looks like the drive screws are only good for Rockwell hardness B70-B85. 6061 T6 is B60 - 7075 T6 is B87 I'm guessing a cast and lightly machined part is 6061, which means that the drive screws are out :/ Have any of you guys used them on cast aluminum?

Traditionally, these things hold data plates on cast iron machinery, I think you just need to find a different source of higher quality ones.

How fast is the clutch basket spinning? How far from the shaft centerline are the holes?

I don't want to sound overly cautious, but G-forces can get pretty high if the rpm and distance from the shaft are sufficient. I'd take a look at that before going with a make-shift solution.

The safest option may be to have an aluminum post welded into the hole and recreate the original peaned assembly. Laser welding doesn't require filler and should have very low risk of distorting the clutch basket.

This sounds like you are over-complicating things.

Drill the hole at .5 deep with a standard bit then ream the first .1 with a countersink bit. That leaves you a little over a quarter inch to thread with a flat bottom tap.

Put the plate up against the block and use a punch to dimple it into the recess you made with the countersink bit. (If your plate is thick enough skip all that countersinking business on the block itself and use the countersink directly the plate...).

Then, use a fine thread Flat head cap screw in stainless.

mr2peak wrote: As far as JB Weld… Would you buy a part that had been assembled with JB Weld? I'm looking for the professional solution here. Drive screws certainly fit here.

Yes. Two part epoxies are used in a wide variety of assemblies in a range of industries. Heck, the Lotus Elise is basically glued together. When the correct stuff is used properly, it's a great way to fasten parts. The problem with JB Weld is that it's freely available and often used improperly or sloppily. I've used it to literally glue ears back on to an engine block. Don't bother with JB Quik, the 24-hour stuff is a lot stronger.

Keith Tanner wrote: I've used it to literally glue ears back on to an engine block. Don't bother with JB Quik, the 24-hour stuff is a lot stronger.

+1. The original JB weld stuff is pretty amazing. I inherited a CL ZF transmission with the right side bolt lug attached with JB. It's been in my E30 race car with solid aluminum trans mounts for 4 years and still holding.