Hard turning, finishing the part.

Not to mention good perfect feed and speed...
Thanks
No magic here, began at a conservative 35 SFM and a .004" per revolution feed rate then bumped it up to 50 SFM at .008 IPR, it seemed happy there.
The consistent chip is a result of the constant feed rate which would be difficult to achieve from a lathe tail stock by hand, if not impossible, I am pretty good at watching chip development when drilling by hand but can never duplicate a power feed.

Another consideration when using such a powerful machine is that if you make a mistake and the tool fails the machine will not stop, it will easily explode a 2" diameter twist drill, you do not want to be close when this happens. With any luck it will spin the part or push it through the chuck first.
Or shear the tang off of a 6 MT drill and let it spin, do not do this.
3" drill
 
Bad luck, the second operation machine filled up with chips after 20 parts.


1/4" keyway broaching begins tomorrow, as much as I dislike keyseater machines it is preferable to pumping a push broach in a manual hydraulic press through 30 parts.
This is what they are for after all. 2 hours of set up for one key way is not cost effective unless it can't be pushed.
2 hours of set up for 30 holes is far better.

Did I mention that I hate chips in every possible way?
 
Yikes. I thought the chip/snakes looks dangerous but thinking about a tool failure like that is down right scary.

Thanks for the pics
This is a machine built in the 50's or earlier, safety was not a major concern at the time.
How big of a tool would it take to stop a 25 hp spindle drive from spinning (-:
 
Did I mention that I hate chips in every possible way?

Hatred of chips is what motivates us to dedicate our lives to their removal from the usable parts they are concealing.

Too bad the turret feed can't provide for momentary pauses to break the chip.
 
Drill chips are easy to handle just annoying to clean up.
The chips generated in a lathe turning/boring operation are a different animal especially if a blind bore. These can break tools and damage parts if they will not break, this is one of the reasons why there are so many different chip breaking designs on insert tooling.

1950 era machines do not peck drill, in the 60's tape machines began to appear so I assume that this sort of control began then, I would not know this because I am only 60 years old and it was well before my time.
 
Drill chips are easy to handle just annoying to clean up.
The chips generated in a lathe turning/boring operation are a different animal especially if a blind bore. These can break tools and damage parts if they will not break, this is one of the reasons why there are so many different chip breaking designs on insert tooling.

1950 era machines do not peck drill, in the 60's tape machines began to appear so I assume that this sort of control began then, I would not know this because I am only 60 years old and it was well before my time.

Well I’m older than you and to peck drill in the early days of CNC tool lots of lines of program. Because you program a depth back it out then start again.

I ran a job for a while we had a 5 inch long by 1 inch bore. We used insert drills and drilled half way the drilled the other half in the second operation. Of course you had to change the inserts on a regular intervals or you would have a drill failure an expense proposition


Sent from my iPhone using Tapatalk
 
Today's lovely part, an off the shelf shaft coupling supplied by the customer which means that you only get one shot at doing it correctly, if you bore it wrong you will have to supply another on your own dime, I suspect that this half costs several hundred dollars.

It is a tapered bore with a 3/4" keyway (not shown) the stock part has a 1 3/4" rough hole through it.
A 6 Deg. included taper 2.925/2.937" long. I had no drawings only a sample part, it is difficult to easily measure a tapered bore accurately so I first made a plug gauge that fit the sample.

Once you know the diameter of either end and the length simple math will yield the diameter of the other end, in this case 3.250" start diameter.
The tangent of 6 Deg. is .1051"
.1051" X the length of 2.930 is .307
The large diameter of 3.25" - .307" = 2.943" over a length of 2.930"

I am doing this in a 30 year old CNC lathe so only have to input a start diameter at a known position and an end diameter at a known distance from the start.

If you need to generate a taper that is not dead nuts accurate in a manual lathe a dial indicator in the toolpost moved a fixed distance with the compound slide will get you in the ballpark. Do not do so if generating machine spindle tapers.

Part drawing


Part
 
Small parts for the next few days, 3/8 seamless SS pipe turned to .625 +-.005, a 9/16-32 thread on one end .500 long.
A .518 diameter .375 long non threaded feature on the other end reamed .478 thru the 1.625 length, the OD, threading, rough drilling and parting to length will be done in a small NC lathe, the reaming will be done in a Hardinge turret lathe because it is much faster.
105 parts, or at this point 110 parts after tweaking the program today, pipe is an inexpensive material and I only require 17 feet, we have 20 feet of material, I can make many bad parts while working up to maximum speed.

They look like so


I snuck up on the Pitch diameter, I measured it over wires. The PD over .024 wires should be .584", this one is .582, thus a bit small, in the scrap it goes
The next several were spot on after subtracting .001 from the thread depth. Another 100 parts and I am done.
This should be on Thursday (-:
 
Last edited:
Back
Top