Re: Single Point Left Hand Threading


Steve Wells
 

Thanks Ted, I'll correct that.
That means it is the only one left, and I have the saddle off the other one.
I keep breaking the old style finisher bit, my fault, not the machine, but
I might have to switch over to the carbide tool holders as you suggested.
I found the print for them in the big book.
On a different note, are you about out of felt yet?
I am close, so I'll probably submit an order this month.
Also ECL (Roy Dean) spec'ed for me, an upgraded replacement grease
for DE-112, SBL-CE1625. can you remember those Roy Dean tubes?
Were they 2 oz? I'm trying to nail down what the fill quantity is.
I'll send you some of the new grease to try when it arrives.

Steve

-----Original Message-----
From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> On Behalf Of sblatheman via groups.io
Sent: Sunday, March 7, 2021 10:25 AM
To: SouthBendLathe@groups.io
Subject: Re: [SouthBendLathe] Single Point Left Hand Threading

Steve,
FYI: there were only 2 special crossfeed screw machines at the SBL plant.
There were 3 or 4 of a similar design for leadscrews.

Ted

On Mar 7, 2021, at 9:50 AM, Steve Wells <wswells@earthlink.net> wrote:

https://youtu.be/9P-Qqc0uGyM

Steve


-----Original Message-----
From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> On Behalf Of Steve Wells
Sent: Sunday, March 7, 2021 9:45 AM
To: SouthBendLathe@groups.io
Subject: Re: [SouthBendLathe] Single Point Left Hand Threading

Saving subject posts for the FTE webpage...:)

Correct, the SBL automatic feed screw machine threads at 0 degrees, straight in, in both directions, reversing the spindle and leadscrew direction on front and rear tool bit passes.
Another little strange fact, at the minor flat of the acme thread, the SBL print has a 0.010 depth square clearance cut. This is cut by the front "rougher bit" flank minor, which has this square flank extension profile.

Steve


-----Original Message-----
From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> On Behalf Of m. allan noah
Sent: Sunday, March 7, 2021 9:06 AM
To: SouthBendLathe@groups.io
Subject: Re: [SouthBendLathe] Single Point Left Hand Threading

On Sun, Mar 7, 2021 at 8:24 AM Guenther Paul <paulguenter@att.net> wrote:

You can through that book away American and metric thread is 60 degree not 58 you set the compound on 30 degree.
The British withworth thread is 55 degree

Sigh. Think about it. The angle of the compound in-feed does not set the angle of the thread- the shape of the tool does. The 29 degree thing is so you always cut a little on the back side, leaving a clean flank, but do the bulk of the cutting in a direction that keeps the backlash taken up in the compound. So, the angle does not matter at all. I thread with the cross feed going straight in, and don't touch the compound at all, regardless of handedness. I certainly don't make a 0 degree thread :)

allan

--
"well, I stand up next to a mountain- and I chop it down with the edge of my hand"
















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