how to lap inside holes

[pasofino]

Anyone got any special home methods for lapping inside holes

[Arthur.Marks]

These are a rather effective, inexpensive option: Expandable Brass Cylinder Laps

[Mcgyver]

what size?

[mister honey]

As opposed to lapping outside holes?

Mike

[ahidley]

The cheap easy way. Get a rod alittle smaller than the hole and cut a slit in it lenghtwise and slide emery cloth in it and put the whole thing in thehole and spin with a drill. Maybe some lub/coolant . I use zippo lighter fluid, useat yourown risk

[jack3140]

accordin g to mike outside holes must be a bitch lol

[TDmaker01]

The cheap easy way. Get a rod alittle smaller than the hole and cut a slit in it lenghtwise and slide emery cloth in it and put the whole thing in thehole and spin with a drill. Maybe some lub/coolant . I use zippo lighter fluid, useat yourown risk

I have a whole series of these different lengths and such that I use with my die grinder. the only thing is when you use a piece of 2 1/2" wide emery and your holding the die grinder in one hand and the part in the other DO NOT PULL THE EMERY TOO FAR OUT OF THE HOLE. same principal for thru holes dont go too far out the other end. that emerycloth spinning very fast actually can give you a good smack across your palm and the inside of your thumb. I find this a very effective method for making a smooth bore, Ive ever done it for anything that needed to be within less than .002" for anything better i uses those brass barrel laps

[snowman]

Wish you were closer. I've got a whole box of cast iron laps I've been trying to get rid of on Practical Machinist, but nobody seems to want them.

[JRouche]

As opposed to lapping outside holes?

Mike

What?? Ya never seen outside holes? Really got to get out more often, and up earlier, they go quick JR

Donut holes, yes, outside holes.

[oldtiffie]

Its a dogs life

Anyone got any special home methods for lapping inside holes

Just about every dog is a subject matter expert in that activity - seem to be addicted to it.

Just ask 'em for a demo.

Make an appointment with your Physiotherapist though.

[JRouche]

Not really a lap but produces a good finish. Ball hones. I have a bunch that vary in size from .25" to 4.5". They are as small as .157"

http://www.brushresearch.com/product-line.php?line=1

[smiller6912]

What?? Ya never seen outside holes? Really got to get out more often, and up earlier, they go quick JR

Donut holes, yes, outside holes.

HEY!
That ain't funny, there is diabetics on here you know.............Geezzz! That looks goooood.

[Rustybolt]

You can make a lap out of a piece of alum bar stock.
Turn it just slightly smaller than the hole you want to lap.
Drill and tap the end for a set screw.
Slit it lengthwise past the tapped hole
Charge it with lapping compound and have at it.
As the lap wears and the hole gets bigger adjust the set screw.
You can get lapping compound from an autosupply store or McMaster-Carr

[Toolguy]

Lapping

I use the "sandpaper on a stick" method a lot to get a better surface finish. If you do that, don't come out of the hole very far - maybe 1/8" - or you'll make the opening of the hole bigger. On a through hole it will be hourglass shaped.