Excessive Finning

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  • Last Post 25 April 2017
OU812 posted this 22 April 2017

I was wondering why nose diameter was larger than advertised and finning was excessive. I believe that over tightening of handle pivot bolts caused this NOE brass mould to bow. Over tightening causes handle gap to spread and cause bow or not being flat. I will repair

To expose high areas, I applied Dykem layout die (black marker) to female mould face then sanded on flat surface using 800 grit paper.

Sand female halve only and be extra careful not to sand away vent lines from top halve area of mould face.

Fitting bullets to a “new barrel” can be a problem if bore ride section is too large or alloy is too hard.

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OU812 posted this 22 April 2017

Sand down bottom of mould face or cut away bottom portion to close gap between halves. And do not tighten hinge bolts too tight.

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onondaga posted this 22 April 2017

 OU812

Perhaps you have taken steps you didn't write about because what you have written does not include anything about using indicator ink to “spot in” a fit.

When one half of a mold is inked, the halves are closed and tapped. Then high spots will show and are then relieved. That is “spotting in". It can take many “spot in” steps to get full closure indicated in ink. An even blackness with no high shiny spots indicates fit.

You don't indicate spotting in a fit together of the mold blocks. Did you not know this method? or, did you do a “spot in” and not write about it?

If you are just sanding away ink and not checking fit with the ink and tapping and not doing a “spot in", you are worsening fit. If you aren't “spotting in” you are ruining your mold by making fit loose where there should be full contact.

 

Gary

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OU812 posted this 22 April 2017

Gary, I applied die to one side of mould halve then clamped halves together. This is result

What can I do to reduce gap?

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JeffinNZ posted this 22 April 2017

Stop what you are doing and send the mould back to the manufacturer NOE.

Cheers from New Zealand

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onondaga posted this 22 April 2017

OU812

Your method is so different than mine and your ink marks aren't as conclusive because you use so much ink and it looks like you did it wet with ink. Try  it like I do.

1) clean all ink off.

2) put mold block handles back on blocks.

3) open handles and put ink lightly on one block face and allow to dry.

4) While squeezing handles with light hand pressure  tap the handle extension bar in the mold blocks lightly with a plastic or leather mallet.

5) open handles and look to see how the ink has been disturbed with optical magnification 6-10x

6) the pre-contacting areas will be indicated by disturbed ink

7) reduce the indicated areas

8) Clean off ink and repeat steps 3-7 until you get even full surface contact of the mold halves. Cleaning each time before applying new ink is necessary for true readings.

It is a very methodical thing to do. If you have a friend that is an old machinist, ask him to demonstrate “spotting in with indicator ink” He has done it thousands of times.

 

There is a number of machinists on this forum, I hope one will chime in too.

 You have a very small amount of metal to remove, likely .001 and it is delicate. If you don't have the hands for this send it back to the maker with YOUR handles and ink marks.

 

 

Gary

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OU812 posted this 22 April 2017

Thank you Gary.

Accurate Moulds states on their web site that brass will warp easier than aluminum. I believe overtightening of hinge pins was partially the cause.

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OU812 posted this 23 April 2017

I think I fixed it...one side atleast.

 

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OU812 posted this 23 April 2017

Bullets now have WAY less finning and measure very close to smaller advertised bore ride diameter of .219 (actually.2188-.2192). Alloy is about 14.5 bhn.

Before fixing mould  the as cast bore ride section measured larger .2205 diameter with same alloy. These large bullets would not fit tighter throat of new barrel.

These can be bumped larger if need be   “i"

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onondaga posted this 23 April 2017

Your bullets have a nice overall velvety frost finish indicating maximum fill out. Nice work!

Gary

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OU812 posted this 23 April 2017

Thanks for your help Gary. I got lucky and did this correct (not easy)

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BigMan54 posted this 24 April 2017

OK, got to show my ignorance here. How the heck can you over tighten mold handles ?

I've never worked with NOE or NEI. Or any of the new companies like: ARSENAL or ACCURATE.

LYMAN, OHAUS, LACHMILLER, H & G, RCBS, LEE & I even have a couple of T/C molds: whom so ever made them. Somebody please enlighten me.

 

 

 

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.

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onondaga posted this 25 April 2017

BigMan54, you said,

"OK, got to show my ignorance here. How the heck can you over tighten mold handles ?"

Note the side of the mold block opposite the cavity side has a slot cut for the handle extension. That slot  divides the surface and tightening the bolt through the slot draws the top and bottom toward each other.. The location of the handle extension can cause leverage exerted on the block.

The handle hinge bolt can also be over tightened effecting mold closure.

Without interference from the blocks or handles, you can still over squeeze the handles or under squeeze causing poor mating of the block.

It is a finicky hobby and Murphy's Law was not cancelled for bullet casting.

 

Gary

 


 

 

 

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