Holding taps in a MT3 chuck

[Welderpaul]

We have a pretty decent Startrite radial arm drill that can be used for tapping. Used it to tap for the first time today. In tapping mode the machine screws the tap in; reaches a settable bottom stop position; pauses, then automatically reverses itself out.

We have been holding the tap in a normal Jacobs chuck. Not ideal as it doesnt hold centrally as it is gripped by the flats. Every other time the chuck pulls out of the MT3 taper as the tap is reversed out. I cannot see any function for a drawbar.
Is there a specific chuck type that holds a tap, and fits in a MT3 taper?

Ta.

 

[Paul.]

An auto reversing tapping head is what you need, depending on the size range of taps used more than one may be needed,
this kind of thing,
http://www.ebay.co.uk/sch/sis.html?_nkw=Auto+Reversing+Tapping+Head+Chuck+Tap+M2+M7+drilling

 

[Welderpaul]

The drill already does most of what that attachment does, i just need the ability to fix the tap in the machine.

Looks like i need some sort of collet job.

 

[brightspark]

there was someone flogging a winona 3mt tapping head on here a month back it never sold there made by tapmatic . look it up was 100 quid . not a bad price

 

[brightspark]

jordan whttp://www.mig-welding.co.uk/forum/newreply.php?do=newreply&noquote=1&p=344486as selling it in articles for sale

 

[Paul.]

You can get tapping chucks, they grip on 2 of the flats on the tap using a square key to tighten, and then the shaft of the tap is gripped and centered with a chuck tightened with a "C" spanner.
Been so long since I used one I had forgotten about them.

 

[Welderpaul]

Looks like this would do the job of gripping the tap. - Looks to have 3 points of contact to grip the tap. Not sure how that works on a tap that has 4 flats on it?
Problem still exists in securing the MT shank in the drill.

 

[Paul.]

Maybe the morse taper in the drill is worn, it only shows up when you pull on it, not something that happens with normal drilling, I used to have a Morse tapered reamer for cleaning them up,
Edit: found one http://www.ebay.co.uk/itm/HSS-Hand-..._Metalworking_Supplies_ET&hash=item53ebd72191

 

[Welderpaul]

Possibly, presumably the morse tapers are not hardened then?

 

[Sean]

cant you set the tap deeper in the Jacobs so the jaws are on the body of the tap rather than the square?
And if the tap was off centre surely itll be chattering and that will break the tapers grip on the pull?

 

[scott0031]

We have been holding the tap in a normal Jacobs chuck. Not ideal as it doesnt hold centrally as it is gripped by the flats. Every other time the chuck pulls out of the MT3 taper as the tap is reversed out. I cannot see any function for a drawbar.
Ta.

Can you elaborate on that a bit please Paul. What do you mean its gripping on the flats? The flats of what? A tap has a round shank and a square drive on the end. You should be gripping on the round shank and using friction only as the drive. Its very doable to use a drill chuck to tap with, i do through holes all the time with no tapping head and i do them by the 100s and 1000s.

Second, If the machine is a good one as you indicated and the internal Mt has not been animilised it should be fine and cause little problems. A few keys things to remember, the same as ally welding cleanliness is next to godlessness. If the taper has oil or a residue of dirt inside, Clean it thoroughly, that does not means a dirty piece of rag it means degrease it properly clean it so it totally dirt and oil free. when you have done that you can then feel the condition of the taper with a finger. If its feels good then it is good. If it has lumps and bumps inside dress them. The same goes for the the male taper. The only problems that occur with MT's is totally man made.

Edit: Many people think they are doing a MT a favor by oiling them up prior to sticking them in the hole. Wrong! All ya have to do is think what oil actually does, creates a film between 2 surfaces, the film in the case of a MT it hold them apart and does not allow them to seat properly. This is shown up a lot more when the MT is vertical as in this case.

Kind regards,


Scott

 

[Welderpaul]

Can you elaborate on that a bit please Paul. What do you mean its gripping on the flats? The flats of what? A tap has a round shank and a square drive on the end. You should be gripping on the round shank and using friction only as the drive. Its very doable to use a drill chuck to tap with, i do through holes all the time with no tapping head and i do them by the 100s and 1000s.

Second, If the machine is a good one as you indicated and the internal Mt has not been animilised it should be fine and cause little problems. A few keys things to remember, the same as ally welding cleanliness is next to godlessness. If the taper has oil or a residue of dirt inside, Clean it thoroughly, that does not means a dirty piece of rag it means degrease it properly clean it so it totally dirt and oil free. when you have done that you can then feel the condition of the taper with a finger. If its feels good then it is good. If it has lumps and bumps inside dress them. The same goes for the the male taper. The only problems that occur with MT's is totally made.



Kind regards,


Scott

Thanks Scott,

We are gripping the tap on the square shank on the presumption that the tap will slip if it is gripped on the round shank. We are tapping M8. The machine will tap up to M20.

I will have a feel at the taper tomorrow, i have a feeling it is in reasonable condition as most drills take some drifting back out. I will give it a good dose of thinners at the same time.

Thanks gents.

 

[brightspark]

i have a 3mt reamer i run through by hand if any of the drills or sleeves have slipped. it takes of any burrs off. any rough sleeves or rusty drill shanks get a rub with emery tape before fitting as said above keep clean and dry

 

[scott0031]

Hi Paul,

There is the mistake, the square drive. So in short you have been trying to grip a square drive that has four flats with the 3 jaws in drill chuck.

I can understand your fears of the tap slipping and in part you are right as it can happen. The key to making it all work well is keeping all equipment in good order. The chuck needs to be a good one that's not worn, when they wear the jaws grip in a tapered fashion, which never bodes well. The MT is the second one, this always includes what you stick in the the taper be it a drill or reamer etc. Those with damaged and dirty shanks will in time do the internal MT no good at all. If others use the machine its is pretty important to drum into them the importance of cleanliness and condition of tools.


Doing a M8 should pose little problems if any. If you are tapping deep holes in tough materials where a lot of friction is generated, then yes you may well need to look a better means of holding the tap. Be careful before going ahead and getting a tapping head as there are different types and your machine is really only suited to one type, that is a tension and compression clutched head or even a non tension and compression could be used with a clutch only, as your drill controls the depth. These styles are more readily available compared to the older styles of head. Be waned these styes of head always cover a small tapping range M2 to M6 M4 to M10. It varies from maker to maker, so this means to cover all the machine can do, will be expensive. You do not want a self reversing tapping head for your machine. It could be made to work but not suited.

There are some very old fashion types out there which are literally a tap holder, again this would do well for your machine as i again your machine controls the depth. Harder to find but they would cover the larger scope of the machines ability of M20.


Kind regards,

Scott

 

[langy]

Thanks Scott,

We are gripping the tap on the square shank on the presumption that the tap will slip if it is gripped on the round shank. We are tapping M8. The machine will tap up to M20.

I will have a feel at the taper tomorrow, i have a feeling it is in reasonable condition as most drills take some drifting back out. I will give it a good dose of thinners at the same time.

Thanks gents.

You should grip the tap on the round shank, I use my pillar drill a lot for fast tapping and i do the chuck u just enough to grip the tap, if it snags it will just spin and not break, experience will tell you how tight it needs to be.

 

[Hitch]

I put a blob of weld on the tap shank, allows them not to spin and still be held in a normal chuck.

Auto reversing depth control on the drill?
Just let go of the handle, let the tap unscrew and out it comes.....just keep hand ready as the tap comes out. Shoudn't need to try and pull the tap out.


Give the tapers a good clean up as suggested too.

 

[Welderpaul]

Auto reversing depth control on the drill?

Yup. Not sure why it pulls on the chuck. Saves a lot of fiddling hand tapping mind. Much better quality thread.

 

[hareng]

As Scott has said give the MT3 a good clean.
Not sure if the reamer will get rid or interfere with the tanged lockup.

The actual reason its pulling out of MT3 is due to the return spring pressure on the quill overcoming the fit.

The4 adbantage of gripping on the shank is it can act as a clutch, self slipping rather breaking tap off in job.
M8 p..s easy with even a ****** worn drill chuck. 3/4 Jacobs keyed comes out for BSP threads.

I do a have a few other proper tap fixing arrangements but ultra rarely use. Ones a six clamp type spaced with rubber done up like an ER or Clarkson, hate the things. Others a self centring sliding arrangement.

Alternative is to replace chuck and go for a tapped MT3 to accept a made up drawbar.

 

[julianthegypsy]

That was my first thought, you need a drawbar to stop the chuck dropping out otherwise the tap will pull it off the taper.

 

[graffian]

That was my first thought, you need a drawbar to stop the chuck dropping out otherwise the tap will pull it off the taper.

Shouldn't do. I tap in the mill and lathe, holding taps in a chuck.