1 - 1/4 8tpi thread drill size

[jucasan]

The title say it all. Need to mill a 1 - 1/4 8tpi thread in a part but can't find what is the size of the drill.

Thanks

 

[litlerob1]

Have you ever heard of Google? Very easy to use.

This is what I typed "1 - 1/4 8tpi thread drill size". But I think you should learn how to use it too, so I'm going to let you.

R

 

[Hazzert]

Take any 8 tpi thread and the difference between the tap drill size and basic OD will be the same for any 8 tpi thread if the object in question isn’t going to space.

 

[precisionmetal]

Or... the easy way: major diameter minus the pitch

That's never far off.

PM

 

[DMF_TomB]

The title say it all. Need to mill a 1 - 1/4 8tpi thread in a part but can't find what is the size of the drill.

Thanks

8tpi is .125 between threads so 1.250-.125 = 1.125 tap drill i believe for roughly 75% thread
.
thats why .250-20 thread is 1/20=.050 so .250-.050=.200 tap drill for 1/4-20 you can check other sizes on any tap drill chart for example 1.000-8tpi thread is .875 tap drill

 

[Dan from Oakland]

I'm getting old, so I do silly things like pull out the drawer in my toolbox that has the machinery handbook in it, and open it to the tab that says "threads" on it. Sorry for the bit of sarcasm but. . . . .

 

[jucasan]

8tpi is .125 between threads so 1.250-.125 = 1.125 tap drill i believe for roughly 75% thread
.
thats why .250-20 thread is 1/20=.050 so .250-.050=.200 tap drill for 1/4-20 you can check other sizes on any tap drill chart for example 1.000-8tpi thread is .875 tap drill

Thank you DMF, I must be screwing something up in the parameters of the thread. In the simulation with the 1.125 diameter the thread tool barelly scratches the surface. I guess this is something for the Fusion forum.

Thank you anyway

 

[litlerob1]

Thank you DMF, I must be screwing something up in the parameters of the thread. In the simulation with the 1.125 diameter the thread tool barelly scratches the surface. I guess this is something for the Fusion forum.

Thank you anyway

Good God!! That's painful.

 

[DMF_TomB]

Thank you DMF, I must be screwing something up in the parameters of the thread. In the simulation with the 1.125 diameter the thread tool barelly scratches the surface. I guess this is something for the Fusion forum.

Thank you anyway

.
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most CNC need to know if you have a sharp vee tool or a tool with a 1/8 flat on tip. that is if thread is .125 apart the flat on the tool tip should be around .0156" width
.
this obviously will effect thread depth when doing the OD threads on a screw. and CAM needs to know how to set the tool tip zero. obviously if you zero to a sharp vee tool tip the pitch diameter will be off. hard to describe but quite obvious when you try to screw a nut on to screw

 

[Lynn R.]

If you are using fusion360 you must use the pitch diameter offset setting if the hole is not modeled to the major dia.

 

[shanesuan]

I agree with the Ø1.125 drill diameter. The Tolerance on the minor diameter ranges from Ø1.140 to Ø1.115 so depending on the thread percentage your aiming for, you could fall anywhere within this zone and be ok

 

[npolanosky]

Make sure your Thread Depth is correct in Fusion- It doesn't know anything about the thread you're trying to cut unless you tell it. The thread assigned in the hole tool doesn't talk to threading in CAM. Thread depth will be Major Diameter - Minor Diameter.

 

[Larry Dickman]

it's hard to believe there's 12 responses to a question you just need to look up on a god damn tap chart. 1.115/1.140 for a 2b

 

[DMF_TomB]

it's hard to believe there's 12 responses to a question you just need to look up on a god damn tap chart. 1.115/1.140 for a 2b

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its not taught now a days cause people use a chart but 8tpi (or .125 thread pitch) thread then screw OD minus thread pitch
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in metric M6-1.0 so 6-1=5mm tap drill
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8tpi in inch is .125 thread pitch or space between threads so 1.0-8tpi is .875 tap drill.