set screw in an aluminum mold

[Kevin Stenberg]

My newest Lee mold doesn't have a setscrew for the sprueplate pivot screw. And it wants to backout very regularely. I went to the HW store and bought a matching drill bit / tap / and set screws. Is there anything I should know about tapping a hole in an aluminum mold before I screw anything up.
Would I be wise to make a wood plug to put in the pivot hole. So I don't damage the threads when drilling into them?

 

[300BLK]

Use an oily cutting fluid so the chips don't stick to the drill or tap, and try to drill as centered as possible on the pivot screw hole. Don't put anything in the hole or you'll have trouble removing the shards after drilling through.

 

[smokeywolf]

Kevin, center punch your targeted start point of your set screw hole. If you have a number 1 center drill follow the center punch with that. No center drill? Pre-drill at least 1/8" deep with a drill that is about 1/3 the dia. of your tap drill, then go in with your tap drill. A little wax on your drills and tap should alleviate chip-welding (chips adhering to the cutting edges of your drills and taps).
As 300BLK said, don't stick anything in your pivot screw hole.

 

[fiver]

I would mark the pivot screw and file a little flat on it so the set screw can bottom out evenly against it without rolling the threads over then you can still remove it later.

 

[Brad]

I have done that exact thing many times. Never put anything in the hole. Figure out location, center punch, drill. Tap hole with some oil on tap. Clear chips, put it back together.
Like fiver said it is never a bad idea to get the screw just right then file a little flat where the set screw hits the pivot screw. Locks screw tight and prevents bunged up threads.

 

[Ben]

I'm no machinist.
If I can do this , anyone can !

It is very possible that there are other sizes of taps and drill bits to do this job with.
This size works well for me however :

I don't like a lot of pressure on my sprue plates ( on any of my moulds ).
This set screw system with a Lee mould allows you to select any amount of tension you desire on your sprue plate, lock things down and begin casting.

 

[Gary]

Seems to me that Lee could do that at the factory. You know, help out a little.

 

[Ben]

I think they have been asked to do this about a bazillion times.
Guess they just aren't listening.
It is interesting that all other mould manufacturers have this set screw, but not Lee.

With automated machinery, it would probably add about .12 to the production cost of the mould.

Ben

 

[300BLK]

I tend to run my sprue cutters on the snug side. If I can see light under the sprue cutter on the end opposite the handles, it means that bullet bases won't be square. I recently added a sprue plate hold down screw on one of my older Lee double cavity moulds so that I can run less tension on the pivot screw and still have square bases. It does require filing a notch in the sprue cutter.

If you've ever removed the pivot bolt and set screw from an RCBS mould you might have noticed that they had a small, brass cylinder between the set screw and pivot bolt. This prevented scarring the threads. I've used copper plated shot to do the same.

 

[Ben]

I've used copper plated shot to do the same.

Or cut a small piece of #12 copper wire.
Flatten it into a circle with a small hammer .
Drop the copper in the hole, put in your set screw, you're good to go.
You will not damage your sprue bolt threads using this system.

 

[Brad]

I use a piece of lead shot at times.

Lee could do this but why would they? More cost, more labor, and 99.9% of their buyers wouldn't know the difference.

 

[300BLK]

I've used copper plated shot to do the same.

Or cut a small piece of #12 copper wire.
Flatten it into a circle with a small hammer .
Drop the copper in the hole, put in your set screw, you're good to go.
You will not damage your sprue bolt threads using this system.

Good idea on the copper wire! The shot has been known to melt.

 

[Ian]

+1000 on the copper wire. I use #6 set screws on mine and a little wafer of 12-gauge copper house wire fits right in. This not only saves the pivot screw threads but makes a pretty decent threadlocker for the set screw.