Boring little things....

[Divided he ad]

Hi All, Made this up this morning on "another site"  and then work happened before I could post it over here
So, here we go....


A while ago I needed to get a nice finish on a cylinder I was making... I hadn't got a boring tool small enough for my application.

So, I came up with this. I used it again the other day and thought it might be of interest to others?


A little show and tell....

First a sacrificial piece of aluminium drilled out at 5mm. (this will work on 3mm upwards.)



Then the tool... A carbide 1/8th burr held in a piece of steel hex by a pair of grub screws.


A slight kick over to prevent fouling as the shaft is slightly larger then the head of the burr.


Add a very fine cut and a quick squirt of WD40 and send it down the bore under a slow power feed...  the result is a mass on very fine swarf shavings.


And a nice smooth bore   







Well, that's it.

Other than to let you know that the spiral flutes on the burr are the design needed... The cross cut burrs don't give a good finish   






Ralph.

[Brass_Machine]

Neat trick Ralph! There have been times I could have used this 

Eric

[Bangkok Mick]

Thanks for your post, this will come in handy.

Cheers Mick

[Stilldrillin]

It's just as good an idea, over here, Ralph! 

David D

[Meldonmech]

Hi Ralph,

                A cool idea giving a fine finish, must get myself a set of burrs.

                                                            Cheers David

[Swarfing]

I used a similar trick but sharpened up cheap glass drills, the ones with the spade brazed into the end. A burr is great idea for that small stuff.

[sparky961]

It sure beats grinding up a piece of HSS into a really tiny boring bar, like I've done in the past.

[andyf]

I've used the good side of a 3mm 2-flute slot drill with a chip on the other side, but the burr is a better idea. More cutting edges to go at, and because it is pear-shaped, varying the top slide angle will bring new bits of edge into play.

But how do you set it on centre height, and is there a danger of two edges cutting at once, one above centre height and one below?

Andy

[Divided he ad]

Glad you guys like it.

Never sure if it's a method that's been used a lot or not 



Sharpened glass drills... Never thought of that one  

And as for sharpening HSS....  I totally suck at it! 

Setting the height.... I rotate it so it looks like a flute is horizontal and set it by eye.... Worked every time I've tried it so far


That's all I can offer Andy. I'd guess that if two edges contact the deeper one would give the finishing cut? But this is a guess.... Never looked since it always worked.




Ralph.

[krv3000]

  brill well dun

[PekkaNF]

very nice one

I once made a small boring bar out of broken threading tap.
This booring bar is made of Dormer thread tap and rectagular mild steel stock. Ground until one "tooth" was left, with all it's cutting angles left.

PekkaNF