Spure Sharpening

  • 286 Views
  • Last Post 24 January 2018
David Reiss CBA Membership Director posted this 23 January 2018

Recently I noticed in a post by John Alexander that he commented on using a gloved hand to cut the sprue. It got me to think about something else. During a phone conversation with John discussing his hand cutting technique, I brought up the fact that I have a couple molds, one about 40 years old, the other not so old. However they both suffer from "base bump" syndrome. John had thought that his hand cutting technique my solve my bump issue. But it did not, the bumps were still there and then I had a very sore palm (going to use a little more padding next time).

Then in a moment of horror, we both admitted we had never sharpened a sprue/cutter surface in our lives. Now we are talking over 100 years combined casting skills. We exchanged some ways we might exach try, but neither knowing whos right, 

We need a good sole on the forum with sprue plate sharpening expirience to step-up and tell us how it's done. Then we will have achieved "all knowledge", until we forget something. 

PLease help us out.  

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
-Services: Wars Fought, Uprisings Quelled, Bars Emptied, Revolutions Started, Tigers Tamed, Assassinations Plotted, Women Seduced, Governments Run, Gun Appraisals, Lost Treasure Found.
- Also deal in: Land, Banjos, Nails, Firearms, Manure, Fly Swatters, Used Cars, Whisky, Racing Forms, Rare Antiquities, Lead, Used Keyboard Keys, Good Dogs, Pith Helmets & Zulu Headdresses. .

Attached Files

Order By: Standard | Newest | Votes
RicinYakima posted this 23 January 2018

I will admit to having done three or four over the years, all on Lyman single cavity where the cut was simply not deep enough. For many years people complained about the hole being too large, so for a long time they would have a small square edge. When you use a mallet, you would never notice. So I take my L.E. Wilson neck chamfering tool and rotate it in the hole. The tool is hardened and the plate is soft from all the heat cycles. Like other machining skills, hand work just takes some practice and care. HTH, Ric

Attached Files

R. Dupraz posted this 23 January 2018

I never have had a need to sharpen a sprue plate on any of my molds. After using a small plastic hammer on the arm of the plate to cut the sprue, and then moving the flat surface of the plate over the cavities, I just tap the plate lightly as a matter of routine. Perfectly flat bases and sprues. It also helps to keep the tension of the plate adjusted.

Some shudder in horror at this practice, but at this stage the casting is still soft and the blocks are locked  up tight and all it takes is the slightest tap. All my molds are going to outlive me anyway. 

But then maybe none of the plates on my molds need sharpening.  

Attached Files

BigMan54 posted this 23 January 2018

I use a chamfering tool like RIC does, but then I use a hard wood block with 600grit stapled to in to polish the bottom of the sprue plate. I don't know if polishing the bottom of the sprue plate helps. But I do get clean sharply cut sprues and any lead residue is cleaned off the bottom of the sprue plate.

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

Attached Files

GP Idaho posted this 23 January 2018

After taking a very SMALL amount of metal out of the hole with a chamfering tool, I use a very fine abrasive to polish the bottom of the plate on a very flat surface. This is the most important step in my opinion. Gp

Attached Files

onondaga posted this 23 January 2018

I have sharpened a couple with common stuff. I got an assortment of abrasive rubber points for my Dremel, some were 1/4" diameter and some were 3/8 and 1/2" 

I removed the plate and worked with my magnifier visor using a 1/2". rubber point that  I had turned to match the angle of the sprue funnel and kept the angle very close to the original angle, Then I took as little as possible metal off to sharpen the hole from the top with the rubber point. After that I used a soft Arkansas bench stone with oil and verified the flat of the bottom of the plate with a few strokes (about 10) on the bench stone. This took off a tiny amount of metal at the hole and leveled the bottom of the plate. This also took off some edge nicks.  The job enlarged the sprue gate hole by about 1/32" and that was harmless to function.

I cold blued the metal where I worked on the plate and reassembled for use. It worked fine.

I purposely did not use my drill press because i believe doing that would easily take off more metal than I wanted to.

 

Gary.

Attached Files

Eutectic posted this 23 January 2018

Some of the Lyman blocks I have bought had a short cylindrical section at the bottom of the plate. I used a  chamfering tool to cut down to the bottom and polished the recess with 360 grit carbide paper with a cloth backer using a drill. 

Modifying the hole diameter is another matter and I have tried this AFTER purchasing a new sprue plate. Required hole diameter varies with pour technique and bullet size. Generally the provided diameter works quite well.

Steve

Attached Files

Notlwonk posted this 23 January 2018

I take a 3/16 dia. ball bearing seated in the C'sink and lightly tap it enough to push a little metal towards the cutting face and stone it flat.

Attached Files

OU812 posted this 23 January 2018

I sharpened one of my sprue plates using a case chamfering tool and drill press. To achieve smoothest cut and to prevent chatter you must turn drill press chuck slowly by hand while putting pressure downward on plate (do not cut too deep) I cannot remember if sprue plate cut smoother afterwards?

I have a couple of 22 caliber MP Moulds that have a very large sprue hole. This makes opening sprue plate by hand much too difficult and distorts bullets at base.

I think most mould makers in USA use the correct size hole for caliber. NOE hole sizes seem to be perfect size and cut smoothly.

You must lube sprue plate more often when opening by hand , because of the downward pressure added during opening. A Qtip with a little of NOE's lube works great. Brass moulds gall way less than aluminum and require very little lube.

Attached Files

OU812 posted this 23 January 2018

Chamfering tool and a slow tuning variable speed drill will work also.

Attached Files

R. Dupraz posted this 23 January 2018

 400 wet or dry paper on a piece of plate glass to polish the bottom side of a sprue plate of a new mold does wonders.

Attached Files

BigMan54 posted this 24 January 2018

Wait a minute, I just realized the title said SPURE not sprue.

David is from texas, and we all know texican's ain't the britist of follks, maibe he'ins meened spers fur his'en cowboy bootses.

Doan knowded whyen ya'll wanna sarpenened yore spers, caus I bee thinken'on thim's mite hutz yore'n hoss'y. but themthar texican's'es is kinda perkular follkses. 

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

Attached Files

Close