Cross feed screw repair advice sought

J

jhmiii

Plastic

Joined

Aug 4, 2016

Location

Carmel, IN

• Aug 14, 2016

• #1

I am currently in the midst of rebuilding a South Bend 9a and have discovered that the threads on the handle end of the cross feed screw are quite mangled. My initial thought is to reduce this threaded portion of the screw, loctite or solder on a cylinder, and cut the new threads in this cylinder. Then after installing the handle, drill for the lock pin. Does anyone know the thread pitch of the original and the length of the threaded portion?

I am also open to any other suggestions you may have for this repair.

Thanks,
John

 

J

jonesturf

Cast Iron

Joined

Aug 4, 2012

Location

PA

• Aug 14, 2016

• #2

12-24 on a heavy 10. Not sure about your 9".

Sent from my SM-N920V using Tapatalk

 

michiganbuck

Diamond

Joined

Jun 28, 2012

Location

Mt Clemens, Michigan 48035

• Aug 14, 2016

• #3

loctite not IMHO. Even solder a poor choice for any strength . Is the thread length that you may turn another 1/16 length then catch the existing thread and turn a few threads more. You don't need a whole lot of strength and adding two more turns adds a lot of strength.

 

jim rozen

Diamond

Joined

Feb 26, 2004

Location

peekskill, NY

• Aug 14, 2016

• #4

This is a common problem as the parts wear on a high-mileage machine. The end of the bushing wears, the face of the
graduated collar wears. So you have to face both of them and you wind up with way too much clearance in the assembly.
So then you reduce the clearance at the end of the screw, under those tiny threads. Eventually you run out of threads.

One approach is to cut the end off and sliver solder on another section of round stock. Then cut the appropriate
features into that. Alternatively press fit the graft in place and cross pin it. If you want to locktite it, use the green
locktite and read about what the correct clearances have to be - hint locktite does not work on a press-fit.

 

S

swells

Stainless

Joined

Dec 29, 2004

Location

Indiana

• Aug 14, 2016

• #5

I would repair as you stated in your post. As Jim stated use Loctite 680 and a slip fit. file an air groove down the shaft or use your cutter bit to make the groove.
no need to pin it the 680 after 24 hrs cure will hold just fine. Turn to match print.

http://wswells.com/download/print-9-10K-dial-handle-shaft-corrected.jpg

 

S

swells

Stainless

Joined

Dec 29, 2004

Location

Indiana

• Aug 14, 2016

• #6

after reading that again, it's the opposite, do an insert repair on the shaft, replace the 3/4 end of the shaft, drill and insert your repair blank and turn the end
back down and re-thread. you will have more stock to work with this way.

Steve

 

J

jhmiii

Plastic

Joined

Aug 4, 2016

Location

Carmel, IN

• Aug 17, 2016

• #7

Thanks for all of the input. I attempted to salvage a few threads and was unable to save enough. So I am now in the process of making a duplicate of the end as Steve suggested. Luckily I have a Sherline lathe that should be perfect for this project. I will let you all know how it turns out. I appreciate all of your advice as I am quite inexperienced at machining.

John

 

G

gadget73

Hot Rolled

Joined

Mar 8, 2016

• Aug 18, 2016

• #8

The handle nut threads are a bit buggered on my 10L cross-feed screw as well. I was thinking of facing the threaded bit off, then drilling and tapping it for a truss head screw to retain the handle. My other thought was to drill and tap the end of the shaft for some threaded rod, pin it in place, and then use the original retaining nut.

I was able to un-mangle the threads enough to get the nut on and its holding for now. If it ever quits holding, I'll deal with it then. I don't have a second lathe, so any repairs I make would involve locking the cross-slide in place and doing everything on the compound. Luckily its a small enough piece that there is plenty of throw on the compound to do that.

 

T

tobnpr

Hot Rolled

Joined

Sep 27, 2015

• Aug 25, 2016

• #9

When I reconstructed the CF screw for my 9A I used sleeve retaining compound, not threadlocker for the geared section /power feed and it has held fine.