Long tap for Joss and OB weight bolts?

Kim Bye

AzB Silver Member
Silver Member
I`m having trouble finding a long tap for these bolts, I believe the bolts are 1/2-13.
Atlas has an extra long 3/8-16 tap for their weight bolts, but I would like atleast a 7" 1/2-13 tap for cleaning and repairing the threads on OB, Joss, Viking and others who uses those bolts.
Where can I get one?
 

john coloccia

AzB Silver Member
Silver Member
Kim do your search as 1/2-13 pulley tap. This will get you where you want to be.

they are not cheap but excelent quality McMaster-Carr http://www.mcmaster.com/#standard-taps/=138i44k

Just FYI:

A pulley tap will generally have a shank OD that's larger than the thread size, so you will not be able to thread deeper than the cutting edge of the tap...like an inch or 2. They're designed to be long to get to the center of a pulley, but you only need to tap a very short distance to tap for the set screw.

The McMaster-Carr tap can only tap 5 1/4". I don't know if that's deep enough for you.

MSC has one that's almost appropriate, but it's a spiral point tap (not spiral flute). The spiral point is designed to push chips forward as you tap and is generally used for through taping. I haven't tried it, but it may work.

I ended up having an 8" tap custom made by Western Tap. It was very expensive (around $150 or so). If you go that route, be sure to ask for a "plug" tap and tell him what you're using it for. He'll probably even remember me since this is a very odd request. It just took him a couple of days to make it, and it works extremely well. If you're only cleaning up threads, you may get away with a bottoming tap, but if you ever want to tap a bolt hole from scratch, you'll have a hell of a time. :)

I almost started a thread on this a couple of weeks ago myself because I came up absolutely empty handed looking for an appropriate tap for what I wanted, but instead of beating my head against the wall, I just went ahead and ordered from Western. I hope someone chimes in with a better source because it really was a bit pricey.
 

Kim Bye

AzB Silver Member
Silver Member
I found a 7" tap on ebay, I`ll give that a try, if not I`ll have one made. Guys from: Atlas, Prather, Cuefits or Unique, if you`r reading this, there might be a market here...

Oh, and IF any cue supplier are reading this. 5/16-14, 7/16-14, 7/16-20, 3/8-10 and 3/8-11 bottoming taps, would be sweet. I have made my own, but I rather just buy them pre made...
 
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Kim Bye

AzB Silver Member
Silver Member
Just FYI:
A pulley tap will generally have a shank OD that's larger than the thread size, so you will not be able to thread deeper than the cutting edge of the tap...like an inch or 2. They're designed to be long to get to the center of a pulley, but you only need to tap a very short distance to tap for the set screw.
That shank can be turned down, can`t it :)
 

rhncue

AzB Silver Member
Silver Member
That shank can be turned down, can`t it :)

The reason that long shank taps are so expensive is that the shank is the same steel as the cutting edge which is an expensive hard steel. I bought a 10" 3/8X16 pulley tap years ago and ground it down on the lathe. It took what seemed like hours because had to turn it slowly and used a portable electric hand grinder. There's no way that I could single point turn it on my lathe.

Dick
 

john coloccia

AzB Silver Member
Silver Member
That shank can be turned down, can`t it :)

I don't know...I've never tried it. You could have a bit of trouble when you get to the hardened HSS, assuming the whole thing isn't hardened. If you've ever turned down a drill shank and gone too far, you'll know it for sure once you run into the really hard part of the tool. :) Anyhow, I wouldn't have thought to try that. If you do it and it works well, I'd love to know that. Would make things a lot cheaper in the future.
 

Kim Bye

AzB Silver Member
Silver Member
The reason that long shank taps are so expensive is that the shank is the same steel as the cutting edge which is an expensive hard steel. I bought a 10" 3/8X16 pulley tap years ago and ground it down on the lathe. It took what seemed like hours because had to turn it slowly and used a portable electric hand grinder. There's no way that I could single point turn it on my lathe.

Dick
But it would in theory be possible to grindt it down with a grinding wheel in my Kress and mounting the router on the lathe and turn it down like any other piece of metal?
Might have to do it in many, very thing passes as to not overheat the steel though?
 

conetip

AzB Silver Member
Silver Member
The non interrupted section of the tap can be turned with ceramic turning inserts or with CBN inserts. Out here , pulley taps are often sold with the shank of the tap being slightly smaller than the root diameter of the thread. And yes they are expensive.
A cheaper option is making an extension for a regular tap. As you are tapping wood, there is not the same torque as there would be tapping steel. It can be soft soldered or it can be glued with Loctite 620 very successfully.The 620 is a high strength high temp adhesive.
Neil
 

Kim Bye

AzB Silver Member
Silver Member
The non interrupted section of the tap can be turned with ceramic turning inserts or with CBN inserts. Out here , pulley taps are often sold with the shank of the tap being slightly smaller than the root diameter of the thread. And yes they are expensive.
A cheaper option is making an extension for a regular tap. As you are tapping wood, there is not the same torque as there would be tapping steel. It can be soft soldered or it can be glued with Loctite 620 very successfully.The 620 is a high strength high temp adhesive.
Neil
Interesting. I think I will try the CBN insert route, if I need to.
I have come to enjoy machining stuff for my own use, so this project suits me :)
 

conetip

AzB Silver Member
Silver Member
Here is an M12 extended tap I made. You get the idea. This is only glued with the 620 loctite , there is a flat to let the air and excess glue out. They can be made as long as you want. Just use a decent steel for the extension. In this case I used some 10mm bright 4140 stock.
Neil
 

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