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"homemade" boring bars

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Diamond
Joined
Jun 2, 2005
Location
North Central Montana
How many of you guys make your own boring bars? Carbide or steel. Solid or braze on tips? What machines do you use? How do you do the final sharp?

I make my own and was curious as to the % of guys making them. The last two places I've worked you were somewhat and oddity for knowing how and everyones best friend when they needed a bar quick. :D

Ted
 
I am interested in making my own boring bars but they will have to be out of steel. I just got my mill working two days ago so I haven't moved that idea forward.

My first trial was to be a copy of an existing bar because I expect a lot more challenges with the holder part than the bar section.

If you are willing to educate others I look forward to reading about your experiences.

Raymond
 
For HSS I make mine. For the bits I use 1/4" and 1/8" HSS rounds that are 4 inches long; for the bars I just use common cold rolled steel.

Mine are made entirely on the lathe. To drill the holes in the bar I place it in its holder on the lathe's compound and the drill bit in the lathe's chuck or collet. I drill the hole at a very slight angle starting on the bars face so that it takes about 3-1/2 inches for the hole to come out of the side. Then reset the compound 90 degrees from the drill angle and drill and tap a hole for a setscrew to hold the HSS round bit. Sharpen the HSS bit to proper clearances and you now have a perfect boring bar with a bit that can be sharpened for many years. Total cost? About $2.50 and may last a lifetime for the homeshop machinist. ;)

As one can see it requires no additional clamping fixtures as one is only using what is needed for boring anyway. Also, this method allows the boring bar to face the bottom of a hole.

I get my HSS rounds at Enco but I'm sure there are many other vendors as well.

[ 11-24-2005, 11:31 AM: Message edited by: Mike Burdick ]
 
If you want to use square HSS, there is a way to cheat. Mill a slot for the tool and then silver solder a piece of key stock to close the slot so all that you are left with is a 1/4 or 3/8 square hole.
 
Mike Burdick,
That's a good idea you have there, particularly for the home shop. You can also buy carbide round blanks to use in your bars. It saves having to wack up toolbit stock into short little pieces to bore with.
 
Yup. Make 'em right on the lathe. Grab an endmill in a collet to mill a little fitted space in the end of a hunk of cold roll for a short piece if square HSS. Then you either drill and tap for setscrews or silver braze in the tool. And experience hand may have a dozen home brew boring bars. I usually machined a short taper on them and bent it at the big end of the taper so the tool side was straight.

I used to use those all-HSS Armstrong bars. All they were was a piece of round HSS with an inch or so of the end bent into a right angle. You ground them to suit the jab. Not cheap but convenient especiall for the little stuff.
 
For small holes there's another way: Take
a 3/8 inch square HSS blank, and grind away
3/4 of the shank, an eight of an inch back
from the end.

This is pretty tedious but when you are done
you have a 3/8 square tool, with a small
shank extending out from the front, that
terminates in a hook. Then you carefully
grind the hook into a nice cutting edge.

This is the poor man's bokum boring bar.

Jim
 
For a fast and easy boring bar, I have used a HSS endmill.

If you put it in a boring head, you insert it within the hole such that the sharp corner aligns with the slide as it is adjusted radially. If you are cutting a really deep hole, then you may need to grind away some of the side cutting edges of the flutes. I also have used an endmill in the lathe toolpost for boring a hole.

At the shop where I sometimes work, usually there is a two-flute endmill with one chipped corner or some other such end mill which can be sacrificed for this sort of purpose. But they don't seem to stock many boring bars. So it is necessary to make do with what is available.
 
I had chatter problems boring a deep hole (3" diameter X 6" deep). The boring head has 2 vertical holes. So I turned the end of 2 7/8 dia rods to 3/4, made up 2 spacer blocks to hold the rods at the correct distance apart and welded them together. Next I ground off the excess parts of the spacer blocks and milled a slot through both rods for the toolbit. I was finish boring a bronze bearing, so a 1/4 toolbit was large enough.
 
I needed a small one on a Sunday morning once. I made it from a pice of .750 1144 and a broken 1/4-20 tap for a cutter. drilled the hole for the tap shank and drilled/ tapped a set screw hole in the end to lock the shank in place.
whatever shape you want to make the cutting edge...
 
What ive been known to do is take a used up or broken carbide coolant thru drill or just a carbide round and braze a used carbide insert on the end. Grind the needed cleanances and your good to go. Normally I just need to do things like this for small bores are when i need a bar for special undercuts and things.
 
Yeah I make a few here and there... mainly for really odd jobs like internal O ring grooves, or deep machining bores etc..

I currently have to make 2 holes 20 mm in diameter and 2 holes 25.4 mm in diameter - through aluminium blocks - about 23mm deep.

These are once off drillings and I don'thave the drills and they will set me back about $160....

I figure that drilling them out to the biggest undersize that I have and then boring them out, will be the easiest thing.

Make the end slightly smaller than the biggest drill, drill through the bar to fit some HSS cutting bar, and then drill the end of the bar for a locking screw and mount the alumin blocks

Away we go.

Humphrey Davey who first discovered / refined Alumin called it Alumin.
 
Had to make a fairly long one and was taught a good trick. Drill bar most of it's length about 3/4 of OD. Heat and fill with lead or if not available 50/50 solder - chatter problem solved by vibration absorbing bar.
 
For my little lathe I use small solid HSS Bokum bars, getting a SB 13" soon so I will have to make a real boring bar soon.
 
Not boring, but for slotter. Rectangular shank is .980 X 1.750"
 

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I want to make a boring bar set up for my 30in L&S and 40in Hendey that replace the compound and bolt directly to the cross slide.

Although I don't even have enough time to get these lathes running, much less time enough to make tooling for them, so haven't done it yet.
 
I want to make a boring bar set up for my 30in L&S and 40in Hendey that replace the compound and bolt directly to the cross slide.

Although I don't even have enough time to get these lathes running, much less time enough to make tooling for them, so haven't done it yet.

How many giant d**n lathes do you have? At least 3 it seems..........

........sitting here with my 6'' craftsman.......:D
 
How many giant d**n lathes do you have? At least 3 it seems..........

........sitting here with my 6'' craftsman.......:D

How do you define "giant"?

I've got 2 large lathes, not monsters, but they are on the larger side.:D

I want the heavy duty Greaves and Klusmann in New Orleans. And if Ken's model X ever comes up for sale like he said it would, I want it too, got to have some nice machines around.

And BTW, I almost got a 12" atlas....
I'd been looking for a lathe for over a year and was getting very desperate, but I got my Sheldon instead.
 








 
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