Internal Single point threading

Mounted the tool, proceeded to cut the threads and was giving to much chatter so I rotated the tip down abit and that helped a lot since I didn't have enuff clearance on the front of the tool.continued to cut the thread until the profile looked right and lo and behold it fits reasonably well. image.jpgimage.jpg
 
I had the tool mounted on my turret tool post which replaces the entire compound so I had to advance the tool straight into the cut. I will set it up with the lantern tool post and compound and advance the cut with the compound set at 29 1/2 degrees so the tool will only be cutting on one side but for a first attempt I'm quite pleased.
 
I HOPE THAT YOU MADE THAT BACKPLATE OUT OF CAST IRON ---- STEEL IS APT TO GALL UP AND RUIN YOUR SPINDLE.
 
Hmmm, hadn't really thought this thru yet. The practice piece is steel and the piece I intend to use for the back plate is mystery steel which I assume is just hot roll. I certainly don't want to ruin the spindle threads. Going forward I think I'll make a male thread as BG suggested to check the fit of the threads without having to remove the chuck each time to test them and maybe come up with something else to make it out of. I know I could buy a semifinished backplate but am hoping to make one from scratch. Anybody know of something I could repurpose out of cast iron? Weight plates come to mind but not sure the centers are thick enuff. I would need 2" thick for the threads.
 
I would buy the semi finished plate, and yes, the thread gage is the thing to make to fit the threads, and when threading the backplate, do not try to fit the threads too tight, also the counterbore that fits the register diameter on the spindle. I have made thread gages for all the lathes that I have owned it is time well spent. As far as backplates are concerned, on some of my machines, I made a pattern with just enough extra stock to cleanup machine and had them cast at an area foundry.
 
Automotive/truck flywheels are generally made out of cast iron and should be pretty good quality as compared to weights, and you would already have your center bore accurately located. Should be dirt cheap at the junkyard or free if you know the right folks. Mike
 
Ended up buying a semi finished back plate from shars. Turned it down from 8" to 5.25" faced it then turned a 4.000" register. Centered it on my rotary table and drilled the 3 mounting holes 120 degrees apart. Bolted it up and I'm getting about .008" runout. I'm not sure but I think I either didn't get a nice square corner on the bottom of the register or the mounting holes are off abit and to tight pulling it off abit. The register seems to fit excellent with no play but could be made twice as long. The saga continuesIMG_1219.JPGIMG_1220.JPGIMG_1221.JPGIMG_1217.JPGIMG_1218.JPG
 
benmychree said:
I HOPE THAT YOU MADE THAT BACKPLATE OUT OF CAST IRON ---- STEEL IS APT TO GALL UP AND RUIN YOUR SPINDLE.
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Beginner here - I've seen items - collet adapters and thread protectors for example - made out of various materials.

Does your statement about steel apply? The spindle on my lathe is not something I want to screw up!

Thanks,
 
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benmychree said:
I STAND BY MY STATEMENT; DO NOT USE STEEL.
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Hi Benmychree, Just out of curiosity how will it gall the threads on the spindle? I am a newbie and don't understand how/why it would. I am going to attempt a similar project and bought some steel to do it, not cast. Now I am rethinking my purchase...
 
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