Threading tool
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Luis
Threading tool
I will like to learn how to thread in the lathe, but before I start I need to buy the tool for threading.Can you guy give me any insight as to were I can go to buy one? What do I need to know before I purchase one? TIA for helping me out.
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Bingo Bob
Re: Threading tool
I would suggest grinding a threading tool from a square high speed tool bit, before going for the high dollar ready made ones.
Bob
Bob
Re: Threading tool
Yes Luis,
I fully agree with Bob. Grind your own from a square high speed steel tool blank. It's really pretty easy. Leave the top flat without any rake. You don't need it. But you will need a 60 degree gauge. Sometimes called a fishtail gauge. The correct name is a 60 deg. center gauge. This is an inexpensive stamped metal gauge that is used to shape the tool by holding it up to the light and looking for a light-free fit of your tool. The 60 deg. notches in the side are used to square up the tool against the work as you position it. This little gauge is a "mandatory must have" for any machinist tool box.
I fully agree with Bob. Grind your own from a square high speed steel tool blank. It's really pretty easy. Leave the top flat without any rake. You don't need it. But you will need a 60 degree gauge. Sometimes called a fishtail gauge. The correct name is a 60 deg. center gauge. This is an inexpensive stamped metal gauge that is used to shape the tool by holding it up to the light and looking for a light-free fit of your tool. The 60 deg. notches in the side are used to square up the tool against the work as you position it. This little gauge is a "mandatory must have" for any machinist tool box.
"The machines are gaining ground upon us; day by day we are becoming more subservient to them" ~ Samuel Butler (1863)
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dgoddard
Re: Threading tool
Luis, I am only a little more advanced in this lathe threading thing than you are but perhaps my experience will be of help.
1
Get the "fish tail" gage you will need it for grinding the tool to an accurate 60 degree point. You will also need it to make sure that you have the tool aligned to the work. You put one side of the gage against the work like a straight edge and then you adjust the tool in the tool holder or the whole tool holder until the point of the tool precisely fits the notch in the side of the gage.
2
Using a high speed steel tool bit is great for beginning because they generally cut properly at much lower speeds than carbide, and you will need to be going slow to maintain control of the lathe.
3
I bought a 5/8 inch tool steel bit and then ground the 60 degree point on the left side of the end of the tool bit. Don't grind it in the middle or you won't be able to make threads close to a shoulder. I hand grind mine on a bench grinder and use the fish tail gage to get the point angle right. But I first put layout dye on the tool rest of the grinder and scribe some lines on it to guide me in grinding the tool.
4
Set the angle on the compound on your lathe to 29 to 29.5 degrees and use it to feed the bit into the part. About .005 in per pass
5
Unless you have ground the tool for one and only one specific pitch of thread, you will probably have brought it to a fairly sharp point. This will mean that the bottom of the groove in your thread is sharper than standard. Not good in a brittle material but a ductile one won't matter much. BUT You will have to feed the compound farther than standard to cut a thread that fits a standard female thread. Theoretically this would be 7/8 times the pitch but depending on how rigid your lathe is you may find problems with that. What this means is that if you were cutting a thread that was 10 threads per inch, the pitch is 0.1 inches and you would have to feed the compound 0.1 x 7/8 = 0.0875 inches at about .005 per pass. The best bet is keep trying a nut on the part until it goes on, then dress off any burrs and it should be right.
6
In the unhappy event that you are making an oddball thread for something that you don't have a nut for and can't try on the lathe, try this trick. When you think the thread is right, paint one jaw of the chuck and the adjacent piece with layout dye and make sure that you can control how far the part is stuck into the chuck precisely. Scribe alignment lines in the dye. Then if the part needs more cutting you can return it to the chuck in the exact same position (pretty much) and cut some more. But use a magnifying glass when you align your scribe marks.
7
Good luck and don't feel bad if the first thread you cut looks awful. You will get better. By the way if you use 1018 Cold Rolled steel, getting ugly bad threads has proven real easy to do. [img]/ubb/images/graemlins/tongue.gif"%20alt="[/img]
1
Get the "fish tail" gage you will need it for grinding the tool to an accurate 60 degree point. You will also need it to make sure that you have the tool aligned to the work. You put one side of the gage against the work like a straight edge and then you adjust the tool in the tool holder or the whole tool holder until the point of the tool precisely fits the notch in the side of the gage.
2
Using a high speed steel tool bit is great for beginning because they generally cut properly at much lower speeds than carbide, and you will need to be going slow to maintain control of the lathe.
3
I bought a 5/8 inch tool steel bit and then ground the 60 degree point on the left side of the end of the tool bit. Don't grind it in the middle or you won't be able to make threads close to a shoulder. I hand grind mine on a bench grinder and use the fish tail gage to get the point angle right. But I first put layout dye on the tool rest of the grinder and scribe some lines on it to guide me in grinding the tool.
4
Set the angle on the compound on your lathe to 29 to 29.5 degrees and use it to feed the bit into the part. About .005 in per pass
5
Unless you have ground the tool for one and only one specific pitch of thread, you will probably have brought it to a fairly sharp point. This will mean that the bottom of the groove in your thread is sharper than standard. Not good in a brittle material but a ductile one won't matter much. BUT You will have to feed the compound farther than standard to cut a thread that fits a standard female thread. Theoretically this would be 7/8 times the pitch but depending on how rigid your lathe is you may find problems with that. What this means is that if you were cutting a thread that was 10 threads per inch, the pitch is 0.1 inches and you would have to feed the compound 0.1 x 7/8 = 0.0875 inches at about .005 per pass. The best bet is keep trying a nut on the part until it goes on, then dress off any burrs and it should be right.
6
In the unhappy event that you are making an oddball thread for something that you don't have a nut for and can't try on the lathe, try this trick. When you think the thread is right, paint one jaw of the chuck and the adjacent piece with layout dye and make sure that you can control how far the part is stuck into the chuck precisely. Scribe alignment lines in the dye. Then if the part needs more cutting you can return it to the chuck in the exact same position (pretty much) and cut some more. But use a magnifying glass when you align your scribe marks.
7
Good luck and don't feel bad if the first thread you cut looks awful. You will get better. By the way if you use 1018 Cold Rolled steel, getting ugly bad threads has proven real easy to do. [img]/ubb/images/graemlins/tongue.gif"%20alt="[/img]