How Big is Your Boring Bar?

[BobWarfield]

I still remember when Frank Ford showed that huge lathe tool that he just cut a dovetail in and dropped it on his QCTP. What a clever idea!

Now here is a guy that built the biggest darned boring bar I've ever seen using a similar notion:

I love this kind of thing! I don't know why, easily amused I guess.

The original thread is over on PM: http://www.practicalmachinist.com/vb/showthread.php?t=153603

Cheers,

BW

 

[Hexbasher]

we have afew 4inch dia boring bars (shop made) including one for between centers boring thats about 4 feet long

1 inch slot in them for tooling

 

[Powder keg]

When I first read this I wasn't thinking and thought "how can you bore things when they are between centers?" Then I realized that the boring bar was between centers and the piece being bored was fastened to the carriage somehow. Thanks for sharing.

Wes

 

[rake60]

WOW

That bar look bigger then the chuck capacity of my lathe!

My boring bars are slightly smaller.

Rick

 

[Don Huseman]

I question the value of the boring bar having a dovetail in it. If you have a long part to bore out. say 2 ft long then you need to balance the bar by putting the bar in the middle of the holder and have the left end of the bar go in the hole and on the right end have a lead weight dampen the viberations or chatter. At my fathers company St Louis Bearing company they would bore out babbitt bearings and get the very best finish by using a lead weight on the right end of the bar.
I would like to hear a report on what kind of finish the dovetail bar gets.

 

[BobWarfield]

I wish someone would post pictures of making a big shop-made spade drill and then notes on how to use it. Big Silver and Demings or other twist drills are expensive!

Cheers,

BW

 

[Hexbasher]

I wish someone would post pictures of making a big shop-made spade drill and then notes on how to use it. Big Silver and Demings or other twist drills are expensive!

Cheers,

BW

we have a 4 inch spade drill thats shop made...i dunno who made it, some machinist 2-10 years ago(before i've been working there)

step one rder the HSS spade insert

two turn a morse taper....

three remove chuck and with the spindal adapter pop the turned morse taper into the headstock

turn the head

go to mill and mill a spot in the center for the spade

last step is to drill and tap a hole for the set screw...

done.....easy...some day i'll get my boss to order in some spades so i can make some tooling for my lathe (all our big drills 2 inch and up) are #5 taper and my lathe is a #4 TS....

you can get fancy and do coolant holes, but i only do that for shop made CNC tooling like my center drill holders

 

[chillybilly]

Managed to get myself a good cond bevel protractor ,on recieveing it i have realised that the bevel lock does not function rendering the instrument pretty useless ,anyone have any experience of seperating one of these tools and repairing ???Dont want to force anything .......