Enlarging a Sizing Die

[country gent]

As I have stated in past posts true lapping or honing of a sizing die is way different than what most do. While sand paper emery cloth around a dowel will work and can be done its more a polishing than lapping. Or honing. Lapping with a brass or lead lap and compounds impregnated into them. Using a fixture to hold every thing square and centered. Slow rpms with high feeds never coming completely out of bore Produces true round holes to size and finish.

Running a dowel wrapped with paper Or even the actual lapp in a drill motor by hand will produce out of round or egg shaped holes do to center and squareness not being maintained while polishing.

A good drill press or lathe will work well to hold everything where it needs to be. Put the die in a 7/8 14 nut and stand up right, set table so when spindle is raised lapp is in the bearing portion of the die set spindle stop to where it doesn't go all the way thru. Loosen belts. turning chuck by hand raise ad lower spindle so that the feed lines appear to be a figure 8.

A true lapp job or honing is a slow process and takes time to do right and accurately. Most home drill press wont run slow enough but most lathes will. Mills also will get down to desired speeds. Done right with care and attention its very accurate

[leadhead]

What do you do if you need a sizing die that no one makes?
I shoot mostly old military rifles and there bores run much
larger than our sizing dies... like .268... .270... .302.. etc.
You either have to get a machine shop to make it, or hone
them out yourself.
Denny

[country gent]

Having a job shop do a one off is going to be expensive and more time making the drawing up so they know whats needed. Its going to be expensive to do also. Afriend or hobbyist with a lathe can do it and probably be cheaper. Other wise its get a sizer close and open it up the last little bit.

[leadhead]

I do have a buddy that's a gunsmith and he makes sizing dies for him
and me all the time.... I keep him supplied with boolits, and he keeps
me supplied with dies and such.
Denny

[Conditor22]

I switched to NOE sizing dies, Cheaper in the long run after buying the die body.
$9.75 per body bushing (sizing part)
$7.50 per such rod (only need 1 per caliber
http://noebulletmolds.com/NV/index.php?cPath=104_396

I wrap wet/dry sandpaper around a brass rod or wood dowel, stick it through the die and roll the die on my leg.

If you're only going .001 I would use 600 or 800 grit paper and check by sizing a boolit frequently. It's durned hard to put the material back on/

[mvintx]

I have a Lyman 450 die in .401" that I want to use as a push through sizing die. The die must be tapered because bullets measure .400" when I push bullets all the way through. I'm trying to hone the die to .402" but man is it hard! Are you guys using emery cloth or 600 wet or dry sandpaper?

[country gent]

I use wet dry paper with light oil. You might want to start around 400 grit and get close then 600 to finish. A wood dowel or brass rod turned to .400 impregnated with clover 400 grit lapping compound might cut better for you

[mvintx]

Thanks for your suggestion country gent. I've tried 600 wet or dry with both oil and WD40 using the hand lap method. It did nothing. Then I chucked a wooden dowel with 320 paper into a hand drill, more WD40 and then with oil, nothing. This afternoon I chucked a 3/8" dowel into my drill press with both 320 and 600 paper, no measureable difference in the die. Bullets still come out at .400". I don't have the capability of accurately turning a wooden or brass dowel to .400" but what if I used a drill bit just under .400" and wrapped it with just enough sandpaper and a coating of lapping compound? The drill bit will resist flexing and maybe I can get a tight enough fit to remove some material from the die. That thing is harder than a hens teeth.

I really wanted to use the Lyman as a push through system but I may be forced into buying the NOE sizing dies if I can't get this honing technique to work.

[Kenstone]

Make a barrel lap
Take a 4"-5" length of 3/8 steel tubing and pinch it oval about 1" from one end.
Pinch it oval and try putting the .400" die over it.
You are looking to get the tube oval enough to just slip thru the die with some resistance.

Chuck the tube in either a hand drill or drill press, smear some lapping compound on it and lap the die.
My 1st choice is always using a drill press and the item being lapped can be hand held and allowed to float around with the oval/wobbly lap but not spin.
If all you have is a drill, clamp in a vise and hand hold the part being lapped.
The tube will wear but you only need to re-squeeze it, making it bigger, and continue to lap the .400" die until it measures .401".
Done right and you will end up with a true round hole without any taper.

This will be way more affective than anything mentioned in this thread and is true "lapping", not just polishing with paper and calling it honing/lapping.

You can also make a lap from tubing by cutting/hacksawing an upside down "L" cut into the tube end, and bend out the resulting tab until it fits thru the die with some resistance and lap the hole with that.

edit: vise grips are great for the oval pinching because of their positive stop and can be precisely adjusted.

[mvintx]

Make a barrel lap
Take a 4"-5" length of 3/8 steel tubing and pinch it oval about 1" from one end.
Pinch it oval and try putting the .400" die over it.
You are looking to get the tube oval enough to just slip thru the die with some resistance.

Chuck the tube in either a hand drill or drill press, smear some lapping compound on it and lap the die.
My 1st choice is always using a drill press and the item being lapped can be hand held and allowed to float around with the oval/wobbly lap but not spin.
If all you have is a drill, clamp in a vise and hand hold the part being lapped.
The tube will wear but you only need to re-squeeze it, making it bigger, and continue to lap the .400" die until it measures .401".
Done right and you will end up with a true round hole without any taper.

This will be way more affective than anything mentioned in this thread and is true "lapping", not just polishing with paper and calling it honing/lapping.

You can also make a lap from tubing by cutting/hacksawing an upside down "L" cut into the tube end, and bend out the resulting tab until it fits thru the die with some resistance and lap the hole with that.

edit: vise grips are great for the oval pinching because of their positive stop and can be precisely adjusted.

OK, I think this sounds better than using a drill bit. I'll give it a try and thanks for the suggestion.

[country gent]

With an actual lapp you want a softer material for the lapp. Don't just smear the compound on it but lightly coat a flat steel plate and roll the lapp between it and another plate under force to impregnate the lapp with compound this "carries" the compound in the softer material cutting the harder material.

[mvintx]

With an actual lapp you want a softer material for the lapp. Don't just smear the compound on it but lightly coat a flat steel plate and roll the lapp between it and another plate under force to impregnate the lapp with compound this "carries" the compound in the softer material cutting the harder material.

Great. So what kind of material should I use? Brass or aluminum? I don't thing stainless steel would be as hard as that die.

[Kenstone]

Great. So what kind of material should I use? Brass or aluminum? I don't thing stainless steel would be as hard as that die.

I have used many split laps that are steel and just as many barrel laps that are usually brass, mostly on hardened steel.
Here's an expandable barrel lap that will work for what you're doing, but not needed for one hole:
https://www.mscdirect.com/product/details/05060264
Here's a STEEL split lap, sometimes called a midget lap, too small for what you're doing though:
https://www.mscdirect.com/product/details/05082508

I just mentioned the basics in my prior post, there's no need to go beyond applying lapping compound on the lap while it's spinning and sliding the bushing/die up and down over the expanded/ovalized part of the lap.
Compound slurry will collect in the narrow part of the oval of the spinning lap and be pinched into the area between the lap/die via rotation.
Adding some oil to the lapping compound on the lap to create a slurry that stays on the lap and is not flung off will help the operation too.
Keep in mind, my normal lapping is done in a drill press, with the lap vertical, so try and do it that way too.

[mvintx]

[QUOTE=Kenstone;4678723]I have used many split laps that are steel and just as many barrel laps that are usually brass, mostly on hardened steel.
Here's an expandable barrel lap that will work for what you're doing, but not needed for one hole:
https://www.mscdirect.com/product/details/05060264

Hey, it's not very expensive either...what did you mean by "not needed for one hole"? I only need to modify one sizing die.

[Kenstone]

[QUOTE=mvintx;4679217]

I have used many split laps that are steel and just as many barrel laps that are usually brass, mostly on hardened steel.
Here's an expandable barrel lap that will work for what you're doing, but not needed for one hole:
https://www.mscdirect.com/product/details/05060264

Hey, it's not very expensive either...what did you mean by "not needed for one hole"? I only need to modify one sizing die.

Yeh, That's what I meant, I'm tuned into the usual re-loader's cheapness
That barrel lap would make short work of that sizing die...
All in with shipping that barrel lap could be close to $20-$25, a poultry some to me, but shipping would be painfully slow, I'd be inclined to just make one, and be done with it.
Have fun whichever direction you go,

[mvintx]

Yeah, Kenstone. $25 is pretty close. Shipping is more than the cost of the lap. I'll have to give it some more thought. I appreciate your comments.

[Kenstone]

Yeah, Kenstone. $25 is pretty close. Shipping is more than the cost of the lap. I'll have to give it some more thought. I appreciate your comments.

Yeh, $25+ for .001"

[Petander]

Yeh, $25+ for .001"

$ 25 000 / inch!

I have polished many Lee sizers with 800/1200/oil/cordless drill -method. They are not hard at all,go easy. It's easy to make them oval,too.