boring a small hole

[colin563]

ive got to bore a small hole 0.500" round & 0.600 deep flat bottom

what type or were would i purchase such a small boring tool

or is any other way to do it

i have limited resources & space 


i did think of a d bit never made one also i have no way of heating it up


thanks colin

[Dean W]

Colin, grind one from a HSS tool bit.



Dean

[colin563]

thanks for the reply dean

does anybody know of any links to help me grind a boring tool


im still learning this i went for the diamond tool holder for ease

ive only got the use of 1 arm just make thing a bit difficult


thanks colin

[andyf]

Hi Colin,

I reckon Dean's pics are a pretty good start on the sort of shape required. A bit of relief under the front cutting edge (on his middle tool, that's the edge resting on the ruler), and sufficient relief under the point so that the part under it it doesn't foul the side of the hole when the tool is at centre height, should get you there.

If the material to be bored isn't too hard, a trick I have used here at Poverty Acres is to find an old Allen key, cut off most of the short leg and grind what remains into the required shape. A decent Allen key works quite well; avoid the sort that Ikea issues with flat-pack furniture.

Andy

[Lew_Merrick_PE]

ive got to bore a small hole 0.500" round & 0.600 deep flat bottom

what type or were would i purchase such a small boring tool

or is any other way to do it

i have limited resources & space 


i did think of a d bit never made one also i have no way of heating it up

Colin,

What is your basic tool for this job?  Lathe, mill, hand tools?  The answer will depend on the foundation.

If you have a barbecue or coffee tin (hobo stove), charcoal, and a hair dryer (blower), you have all you need to heat treat steel.  Good even red glowing coals are sufficient to heat up a reasonably sized piece of steel to the Curie point (where it ceases to attract a magnet).  Hold it at that temperature for a few minutes (20 minutes per inch of the thickest dimension is a pretty good starting point) and then quench in (salt) water or oil.  Keeping the piece close to the coals gives you a carbon monoxide "blanket" that will protect you from some of the bad-nasties that can happen when working with gas.  The American "steel industry" was charcoal based well into the 1830's.

[Dean W]

Colin, this may help with visualizing some of the angles:
http://www.sherline.com/grinding.htm

The main thing, and I mean most obvious once you look at it for a few minutes, is to keep the part of the tool that is
directly below the cutting edge from rubbing on the work. 
The top of the cutting edge of the tool tool needs to be right on the centerline of the work piece.
On the front edge of the tool, that is, the end that faces directly toward the lathe headstock, it needs a small taper
from the cutting edge back toward the center of the tool so the entire front surface of the tool does not hit the
bottom of the hole at once.

Another way to do it is with an old drill bit.  If you grind the end of a drill bit flat and look at the end you just ground off,
you will see that it forms two sides that make a kind of a 'hook' shape on the flutes.  One of the flutes can be used as
a boring tool edge. 
Remember, drill bits are quite flexible, so go at it easy.  Also, if you grind off the end of a tool bit, take care not to get it
too hot.  They represent a rather thin section of metal, and will over heat quickly.  If you get it too hot, especially if it
a carbon steel bit, it will loose its hardness.  That's not so much of a problem with HSS bits, but you still shouldn't get
them really hot.

What Lew asked is pertinent.  What machine are you using for this?  It would also be good to know what material you
are cutting.  Steel, brass, aluminum, etc. ?

Dean

[75Plus]

Could this job be done with a  1/2" center cutting end mill? I would think so unless I am missing something.

Joe

[Ned Ludd]

Hi Colin,
You say you do not have a means of heating a D bit, do you not have a cooker or some other means of heating your food? Microwaves excepted of course. Gas rings are great for heating tools, especially if you only have the use of one hand, as there is no need to hold a torch.
Ned

[Lew_Merrick_PE]

Hi Colin,
You say you do not have a means of heating a D bit, do you not have a cooker or some other means of heating your food? Microwaves excepted of course. Gas rings are great for heating tools, especially if you only have the use of one hand, as there is no need to hold a torch.
Ned

Ned,  Electric stovetops rarely work for heat treating.  American natural gas is often so poorly plumbed as to be worthless (my current kitchen is supplied by an incompetent gas company).  Anything larger than ø.250 inch is "challenging" on our stovetop -- which is why I have 70 lb propane cylinders.

It's currently in storage, but I have a foundry/forge made from a 24 inch truck brake drum.  The tuyere is a piece of 3-1/2 inch pipe with a PVC elbow at the bottom (to melt out if I spill a load) coupled to a set of 4 24 VDC muffin fans with a variable voltage power supply.  I have several ceramic "spacers" that allow me to throttle down the size of the fire area, but I can heat 20+ inches of 2 inch bar to hardening temperature quite easily.

Just be careful when discussing coked coal around cops.  A friend of mine and I were discussing "coke" at a bar some years back.  About 50 cops came screaming in thinking that they had some major "dealer" to hand when they overheard us discussing "pounds of coke"...

[colin563]

thanks for all the great replies

the machine im using is a myford super 7

cooker is electric

if you look at my post here you will see how much room  i have http://madmodder.net/index.php?topic=1611.0 needs updating

the item is a mild steel its for saddle clamp from hemingway kits


i have got a 6mm boring bar from rdg replaceable tips i dont trust my grinding yet

hoping this will do the job

just got to practice a lot more 

thanks colin


thanks colin

[No1_sonuk]

Could this job be done with a  1/2" center cutting end mill? I would think so unless I am missing something.

I'd go with this option.
A 1/2" slot drill will do the trick.
The problem with a boring bar would be getting into the centre of the bottom of such a small hole.

[sportandmiah]

I searched ebay and found micro boring bars for $15 shipped, and they're carbide as well.

[Lew_Merrick_PE]

I searched ebay and found micro boring bars for $15 shipped, and they're carbide as well.

Cheap carbide is cheap carbide.  It can rarely (if ever) be well sharpened.  Well hardened and tempered tool steel is (almost always) superior to carbide for this type of cutter.