MEC Powder Bushings - Need Help!

[Freshly Minted Georgian!]

Gentlemen/women, need a bit of an assist. I have an MEC loader but unfortunately gave away all my bushings some years ago. I can machine new bushings myself and know the internal diameters of the various MEC bushing numbers but I need to order a smaller boring bar since the smallest I can bore currently is half inch.

In order to grab the correct sized boring bar I need to know the external measurements of an MEC powder bushing. The key thing is height but also interested in outer diameter (so I can make sure I have the right sized aluminum rod stock on hand). On the boring bar, the smaller diameter ones, they tend to have very limited depth of bore capacity so the height is key.

Someone please slap your calipers on one of those bushings and tell me the body diameter and height/depth.

Thanks,

Bill

 

[Markn30135]

Hmmmm.....external diameter of the powder bushing would it not be 0.002" < than the charge bar hole for the bushing? As for the height equal thickness of the charge bar? Inside diameter will determine the powder charge so reaming the bushing a few thousands at a time while weighing the powder will do it.......... Or just order the busing you need.

 

[Freshly Minted Georgian!]

You are correct sir! I didn't have a charge bar either but did pick one up this morning along with a "reference sample" MEC Factory bushing. I was just looking for a quick reference on the height because it takes a pretty small diameter boring bar. The smaller MEC bushings are just over a quarter inch on the bore so I basically have to use a .180" boring bar. Most of those .180's have a very short length of cut (LOC), aka boring depth. Since it is small diameter it's prone to chatter. To control chatter, ideally you want as short an LOC as you can get away with that still provides the clearance needed for the height of the bushing. Readily available choices are a .800 LOC, 1.000 LOC, 1.200 LOC and 1.500 LOC.

It's been years since I used a MEC so I just couldn't remember the dimensions. Fortunately a couple of kind souls here slapped a tape measure and got me in the ball park which allowed me to order the proper LOC boring bar.

Eventually I'll get around to building a full set of bushings, plus some in between sizes for custom charges.....just needed to start off with the proper bar!

 

[jglenn]

why not simply buy an adjustable bar.. I gave up on the bushings years ago

 

[gh1950]

I admire anyone who has the skill and equipment to do that, but seems like a lot of work to save $50, and when you get done, you have exactly one bushing for one load of various powders,

 

[Freshly Minted Georgian!]

I used an adjustable bar years ago and didn't care for it. For whatever reasons the one I had was inconsistent.

As for bushings, I'll eventually build a full set.

 

[jglenn]

My adjustable bar has been very good... both 12 and 20 gauge Mec grabbers go figure

 

[gh1950]

My adjustable bar has been very good... both 12 and 20 gauge Mec grabbers go figure

used one for years, you have to remember to tighten the set screw.