.png)
Tweet
Hello all:
I am relatively new to this forum and thought while I had the time today to contribute a little I would.
While planting corn a few days ago the ball joint that steers my tractor had unscrewed itself from the steer cylinder because I didn't have the check nut tight enough. In the process as the last several threads neared their end it ripped itself out as I turned a corner. I didn't have the time to spend on the lathe at that time so I purchased a new one and thought I would repair this one for a spare when I had time especially when I seen the cost of the new one...103 bucks !
This is for the folks who may not know how to do this task. This is assuming that you already know how to chase threads from scratch. I also used an aloris type tool holder but can also be done with the lantern type. I was taught from my Step-dad several years ago. He is a retired life-long machinist who has forgot more than I will ever know. The first step to repairing any damaged thread is of course to know the thread pitch and to chuck it up in the lathe. In order to do this for a balljoint I had to use a 4 jaw chuck and indicate it straight. This was a little tough to do because I was dealing with several planes. In order to use an indicator on the exposed threads I had to set the lathe to 14 tpi and engage the half nuts and then set an indicator on the crown of the threads ( good ones). By placing the headstock in neutral I was able to turn the head by hand and the indicator stayed on the crown of the threads as I turned to indicate zero. All of this wouldn't have had to be done if the piece was straight but is a good scenario for the parts that can't be chucked in a 3 jaw or where you have nothing but threads to indicate on.
Now that I have the part indicated straight and true I am ready to set up for chasing the threads. Install your typical 60 deg.cutting tool into the holder and at this time just leave it loose. Make sure your lathe is ready to cut the proper thread ( 14 tpi in this case) and go ahead and engage the half nuts.Cutter is not ready to cut at this time ! At this time we wanna take all the slack out of the machine ie: leadscrew, slop anywhere else there may be some. You can do this by turning the head by hand or slowly engaging the machine with it running. Once the slack is out go ahead and position the crossfeed ( tool) close to where it needs to be...set zero on the cross however you do it with your lathe. Compound should already be at 29 deg. Now bring the toolbit which is still loose in your holder to fit in one of the threads in the damaged part. The part is acting as your fishtail setup tool that you normally use to set up with. Of course the center hight should be set as well. With tool bit in threads lock it down now ! Disengage half nuts and back out the crossslide. You are know ready to proceed with cleaning up the threads. If you have it all setup right your lathe will follow the existing threads perfectly removing any damaged material. The threads will never be as good as they once were but usuable ! I'm not much of a writer so I hope this makes sense. If ya have questions ask away I will do my best to answer. I grabbed a few pics of the project.
Ball joint in dicated in the 4 jaw
A lousy pic of the damaged threads
Threads repaired...sorry the pics arn't very good
I am relatively new to this forum and thought while I had the time today to contribute a little I would.
While planting corn a few days ago the ball joint that steers my tractor had unscrewed itself from the steer cylinder because I didn't have the check nut tight enough. In the process as the last several threads neared their end it ripped itself out as I turned a corner. I didn't have the time to spend on the lathe at that time so I purchased a new one and thought I would repair this one for a spare when I had time especially when I seen the cost of the new one...103 bucks !
This is for the folks who may not know how to do this task. This is assuming that you already know how to chase threads from scratch. I also used an aloris type tool holder but can also be done with the lantern type. I was taught from my Step-dad several years ago. He is a retired life-long machinist who has forgot more than I will ever know. The first step to repairing any damaged thread is of course to know the thread pitch and to chuck it up in the lathe. In order to do this for a balljoint I had to use a 4 jaw chuck and indicate it straight. This was a little tough to do because I was dealing with several planes. In order to use an indicator on the exposed threads I had to set the lathe to 14 tpi and engage the half nuts and then set an indicator on the crown of the threads ( good ones). By placing the headstock in neutral I was able to turn the head by hand and the indicator stayed on the crown of the threads as I turned to indicate zero. All of this wouldn't have had to be done if the piece was straight but is a good scenario for the parts that can't be chucked in a 3 jaw or where you have nothing but threads to indicate on.
Now that I have the part indicated straight and true I am ready to set up for chasing the threads. Install your typical 60 deg.cutting tool into the holder and at this time just leave it loose. Make sure your lathe is ready to cut the proper thread ( 14 tpi in this case) and go ahead and engage the half nuts.Cutter is not ready to cut at this time ! At this time we wanna take all the slack out of the machine ie: leadscrew, slop anywhere else there may be some. You can do this by turning the head by hand or slowly engaging the machine with it running. Once the slack is out go ahead and position the crossfeed ( tool) close to where it needs to be...set zero on the cross however you do it with your lathe. Compound should already be at 29 deg. Now bring the toolbit which is still loose in your holder to fit in one of the threads in the damaged part. The part is acting as your fishtail setup tool that you normally use to set up with. Of course the center hight should be set as well. With tool bit in threads lock it down now ! Disengage half nuts and back out the crossslide. You are know ready to proceed with cleaning up the threads. If you have it all setup right your lathe will follow the existing threads perfectly removing any damaged material. The threads will never be as good as they once were but usuable ! I'm not much of a writer so I hope this makes sense. If ya have questions ask away I will do my best to answer. I grabbed a few pics of the project.
Ball joint in dicated in the 4 jaw
A lousy pic of the damaged threads
Threads repaired...sorry the pics arn't very good
Comment