what kind of washer on the sprue plate?

[troy_mclure]

what is the washer on the sprue plate called? mine went rolling somewhere and is gone.

[BABore]

I use wave washers on mine.

[Bob J]

Mine uses a wave washer as well.....

[cheese1566]

I found the wave washers at my local NAPA Auto Parts store. They only had metric, but they seemed to fit my Lee and Lyman sprue screws OK. They were like $0.10 a piece.

[troy_mclure]

thanks guys!

[theperfessor]

I just use a stainless steel flatwasher on mine. Anything is better than the lousy split lockwasher Lyman used for years!

[JIMinPHX]

The cupped ones are called Belleville Springs or Belleville Washers or cup washers or cup springs or disc springs or conical compression washers. The wavey washers, I think are just called wave washers. You can get them from places like McMaster Carr industrial supply or you can go directly to spring companies like this one - http://hubbard.thomasnet.com/category/washers?&plpver=1003 or this one - http://www.bellevillesprings.com/belleville-washers.html or this one - http://www.solonmfg.com/springs/index.cfm The spring companies usually require large minimum purchase quantities though.

More info here - http://www.engineersedge.com/belleville_spring.htm

Most of the steel grades are rated for use up to 350 degrees. The bronze ones are usually good up to 400 degrees. The stainless ones are generally good to about 550 degrees. The inconel, & tool steel varieties are generally rated for much higher temperatures, like 1100.

[machinisttx]

JiminPHX beat me to it.

[Changeling]

So witch washer would be the best to use, or does it really matter?

[MtGun44]

Not much of a big deal whichever kind you use. I set mine pretty loose anyway.

Wave washer is fine, but you could use a light bellevue if you want to have some tension.
I think too much tension can be a bit of a problem, tho.

[HORNET]

I prefer a stainless wave washer, usually between 2 stainless flat washers. I think the tension on the Belleville washers changes too fast as the mold temperature changes.

[montana_charlie]

The tension a spring-type washer exerts on the sprue plate can be looked at this way.

If the sprue plate was laying loose on top of the mould, the lead might be able to make it float when the cavity filled up. Assuming lead can form a dome like water can (skin tension) you could produce a bullet with a rounded base. Of course, this is an extreme example, but the problem can exist in more microscopic amounts...and everybody wants perfectly flat bases on their bullets.

If the sprue plate is held solid to the top of the mould, with no springiness in the washer, the plate can't rise to allow hot air to escape. That can cause rounded corners on the base...another mortal sin.

A plate held in firm but gentle contact with the mould will lift to allow the air out, then drop back down (under tension, not gravity) to keep the base flat. The amount of tension isn't real critical, but needs to be at least able to counteract the tendency of the plate to float on the lead.

Running the pivot screw down far enough to flatten the wave is just wasting a good spring washer.

CM

[Changeling]

What you say makes good sense, at least to me, thanks.