Tap for Threading?

[paulkane1]

I've just bought a Hand Tap to thread wood to make a Vacum Chuck System,for my Gradute Lathe.Ive done not too bad,practising ,and,I think I have got the hang of how to do it ok,As you know ,you have Left and Right Threading ,(inboard and outboard sides ,on the Gradute Lathe)I thought the Tap ,would be Dual Thread ,ie,Left and Right turn,but it doesn't seem to be,Will I have to buy a separate Tap,for to get Left Thread action,or,am I missing something,I am a complete novice ,when it comes to Taps and Threads,all help appreciated.

Yours Kindly Paul

 

[CHJ]

Yes a tap will only cut in one direction, it's a spiral.

 

[katellwood]

you will need a left hand tap for the outboard thread or someone with an engineering lathe to cut a left hand 1 1/2" x 6 tpi in your faceplate/chuck

the only occasion where both are applicable is the internal tap on faceplates or chucks which can be tapped both left hand and right hand to fit both inboard and outboard threads

if you are unaware the reason for the differing threads is that the chuck or faceplate will not come undone whilst turning i.e. the direction of rotation keeps the thread tight

 

[paulkane1]

you will need a left hand tap for the outboard thread or someone with an engineering lathe to cut a left hand 1 1/2" x 6 tpi in your faceplate/chuck

the only occasion where both are applicable is the internal tap on faceplates or chucks which can be tapped both left hand and right hand to fit both inboard and outboard threads

if you are unaware the reason for the differing threads is that the chuck or faceplate will not come undone whilst turning i.e. the direction of rotation keeps the thread tight

I've been searching on the Internet,looking for a Left Spiral 11/2 x6TPI BSW Tap,no joy.Is there anyone on the forum who could help me ,as to were I can come across this Tap?

 

[CHJ]

Why are you spending so much effort in trying to locate a device that would have been extreamly rare in it's era let alone in the modern world.

If you want a left hand thread 1-1/2" X 6 threaded hunk of metal to make a faceplate or fit a chuck then just buy an ISO backplate with suitable thread.

Versachuck backplate, threaded 1.1/2 inch x 6 tpi (Dual L & R hand); To suit older lathes such as Harrison/Union Graduate etc.; No locking screw £22.29 +vat and postage

 

[paulkane1]

Why are you spending so much effort in trying to locate a device that would have been extreamly rare in it's era let alone in the modern world.

If you want a left hand thread 1-1/2" X 6 threaded hunk of metal to make a faceplate or fit a chuck then just buy an ISO backplate with suitable thread.

Versachuck backplate, threaded 1.1/2 inch x 6 tpi (Dual L & R hand); To suit older lathes such as Harrison/Union Graduate etc.; No locking screw £22.29 +vat and postage

Thanks,I want to use this backplate for Vacum Chucking ,on the outboard side of my union lathe,(I'll be placing the double sealed bearing on this plate) so I'll need a hole in the center of the plate,to aid Vacum Draw,I've seen no image of it on the Toolpost site,do you know if there is a center through hole on this backplate?

 

[CHJ]

If you do a search on ISO backplates you will see that they all have a clear central bore regardless of thread standard, is in the nature of the design standard.

.

 

[paulkane1]

If you do a search on ISO backplates you will see that they all have a clear central bore regardless of thread standard, is in the nature of the design standard.
.

Thanks, that's it sorted.

Kindly Paul