Clamp key and catch bar for Pollard tapping head

Hi folks :)

eBay has been a bit of a goldmine for inexpensive engineering items recently, which is great, because I run on very meagre budget for this game and some of the items I've managed to aqcuire would normally be well beyond me without some serious saving.

One such is a Pollard auto tapping head, which I managed to grab for a shockingly low £37 (shipping included).

I had a hunch there would be a catch as such expensive items don't usually go for so little without one. The catch with this one turned out to be the head, which was totally filled with chip infused crud and was jammed closed with the last used tap still in it:
https://i.loli.net/2018/03/03/5a99ccd264879.jpg

Now I may be new to the engineering game but it didn't take me long to work out how the head was supposed to be operated and the issue largely revolved around the clamping mechanism, which uses something akin to a chuck key to close the clamps onto the tap flats and it's two tiny set screws. I must apologise at this point as I didn't take many pics, this was all new territory for me and I wanted to be focused on not screwing things up.


Unfortunately the head didn't have the clamp key with it, or the catch bar (? Don't know it's proper name but its the bar that stops the main body from spinning while your tapping), so I set about making both of them while I let the head soak in some WD40.

The catch bar was made from a piece I chopped off a treadmill frame and took seconds as it was just a shade oversize and was already coated, which is a very close colour to the head so I just got lucky with that one:
https://i.loli.net/2018/03/03/5a99d5bd17f6a.jpg

The key on the other hand was entirely the opposite and represents many hours on my part spent working out setups and playing musical chucks with the dividing head and lathe for the various turning, drilling, tapping and milling operations performed while making it:
https://i.loli.net/2018/03/03/5a99ce8b513d9.jpg
https://i.loli.net/2018/03/03/5a99ce8ab0985.jpg
https://i.loli.net/2018/03/03/5a99d5bd17e3b.jpg
https://i.loli.net/2018/03/03/5a99d5bd18049.jpg

I actually went too deep with the first set of flats in the pic above, so I turned the end off and started again. As such it ended up being a bit more stumpy than I'd intended but it's a perfect fit now so I'm happy as Larry with it :)
https://i.loli.net/2018/03/03/5a99d5bd18022.jpg

I was then able to use the key to aid in the repair of the head, the only part I couldn't save was a twisted and broken spring in one of the three jaws in the head but other than one slightly shorter spring now, everything works as it should, though I made one last modification of my own, which was to cut the tang off the shank so it would fit into the spindle of my Dore Westbury mill, which is a little on the shallow side for standared MT2 tapers.

Great buy, worthwhile repair on a super timesaver. Thru or blind hole, power-tapping makes better threads. What makes these run best is a smooth quill especially with smaller taps. Good grade taps help too.
In the US, these tap heads go under the brand 'Ettco'. That might help with parts, just in case, apparently they might still be manufactured too. You have a good find, looks set for steel flex collets, like ER's. Rubber-flex is other option; not better or worse, just different.
I did tooling for a company making a well-known screw ID plate among other machinist tools. Women [better sense of touch] on sound but old drill presses were threading with ETTCO's; 1-80, 2-56 etc with ease.

Here is a good breakdown on why tapping heads endure in the face of modern processes.

https://www.ctemag.com/news/articles...ng-attachments

<!-- BEGIN /var/www/html/homemadetools/protected/modules/zeus/views/tool/postUpdate.php -->
Thanks Canobi! We've added your Tapping Head Catch Bar to our Tapping and Threading category,
as well as to your builder page: Canobi's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-tapping-head-catch-bar"> <img src="/uploads/211069/homemade-tapping-head-catch-bar.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-tapping-head-catch-bar">Tapping Head Catch Bar</a> <span> by <a href="http://www.homemadetools.net/builder/Canobi">Canobi</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/tapping'>tapping</a> </div> </div> </div> </div>
<!-- END /var/www/html/homemadetools/protected/modules/zeus/views/tool/postUpdate.php -->

<!-- BEGIN /var/www/html/homemadetools/protected/modules/zeus/views/tool/postUpdate.php -->
Thanks Canobi! We've added your Tapping Head Clamp Key to our Tapping and Threading category,
as well as to your builder page: Canobi's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-tapping-head-clamp-key"> <img src="/uploads/211074/homemade-tapping-head-clamp-key.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-tapping-head-clamp-key">Tapping Head Clamp Key</a> <span> by <a href="http://www.homemadetools.net/builder/Canobi">Canobi</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/clamp'>clamp</a>, <a href='http://www.homemadetools.net/tag/key'>key</a> </div> </div> </div> </div>
<!-- END /var/www/html/homemadetools/protected/modules/zeus/views/tool/postUpdate.php -->

Quote:

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Originally Posted by Toolmaker51

Great buy, worthwhile repair on a super timesaver. Thru or blind hole, power-tapping makes better threads. What makes these run best is a smooth quill especially with smaller taps. Good grade taps help too.
In the US, these tap heads go under the brand 'Ettco'. That might help with parts, just in case, apparently they might still be manufactured too. You have a good find, looks set for steel flex collets, like ER's. Rubber-flex is other option; not better or worse, just different.
I did tooling for a company making a well-known screw ID plate among other machinist tools. Women [better sense of touch] on sound but old drill presses were threading with ETTCO's; 1-80, 2-56 etc with ease.

Here is a good breakdown on why tapping heads endure in the face of modern processes.

https://www.ctemag.com/news/articles...ng-attachments

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I lucked out on the Pollard for sure, though my plan is to make a hand tapping jig for anything smaller than M3 and use the Pollard for everything upto M10.
Just been reading a thread relating to changing the shank type on a Pollard No.2 and one of the posters mentioned Ettco, handy to know they're still going.

I managed to source some springs which are an almost identical match to those used by the jaws, so I'll be able to effect a full repair.

Cool article, thanks for sharing :)

I have the same type of tapping head which I must have had for over 55 years. I don't think that the name plate says Pollard or Ettco but it is from the US. The tap holding system is different to yours. It is 01:15 right now but in the morning (I should say later in the morning) I'll take a couple of pix and post them here.
If you haven't done it already, I would suggest pulling it apart (there is nothing to be frightened of inside) and giving it a good clean. Muck tends to build up on the clutch surfaces and they work much better after cleaning. I probably use mine at least two or three times a week, in fact it lives semi-permanently in one of my drill presses.

I couldn't help but give it try earlier today, I've been making some t nuts for the mill which needed drilling and tapping, so it was the perfect excuse....
https://i.loli.net/2018/03/04/5a9b44cce50b7.jpg
https://i.loli.net/2018/03/04/5a9b44cb8c4fb.jpg

It slipped in the quill a couple times so I'll have to stick it in the 4 jaw on the lathe and put a threaded hole in the shank for a draw bar but otherwise it ran smoothly and did the job nicely. I'm glad you mentioned how simple it is inside though, I have been pondering having a look but wanted to get the chuck operational again first while I plucked up the courage.

On a side note, I think I read somewhere that there's a kind of slip clutch or some system for the head so it doesn't break a tap, is that right?

Quote:

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Originally Posted by Canobi

On a side note, I think I read somewhere that there's a kind of slip clutch or some system for the head so it doesn't break a tap, is that right?

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Yes there is a clutch but at what torque it slips depends on how much vertical force you apply so you could still break a tap but you have to try harder to do so.

Here are some pix of the tap holder on mine. It is basically just a collet system. I have always thought that something should fit into the large cross hole but the collets are complete as is. I use the small cross hole to put a bar in when tightening the collet nut.

Attachment 22532 Attachment 22533 Attachment 22534 Click thumbnails for full size pix.

It is an Ettco as can be seen by the name plate, hard to read in this pic but it is a model 1-B

Attachment 22535

I must have had this tapping head for at least 55 years. I think that it was given to me by an elder workmate. I do have another tapping head which is newer but I prefer to use the Ettco. However, the Ettco collet doesn't accept taps with large shanks but the other one does, with that one it clamps on the driving square of the taps.

Perdy ♡
Intersting chuck head design, looks like the alignment screws for the clamp are still present too, so I removed the clamp from mine and took some pics, in case you, or anyone else that's missing theirs will have some kind of reference to make replacements.

By way of explanation, the clamp comprises of a bi threaded stud, one side being left hand (which also hosts the squre hole for a key) the other is right hand. Screwed onto either end of the stud are two thick threaded collers with matching left and right hand threads. The collers have a thin slot milled into the side which correlate with the two alignment screws in the chuck head, though the slot doesn't travel the entire length of the coller. This provides a "stop" for the clamps winding mechanism as the un-milled metal (positioned facing centre of the assembly)) catches on the two alignment screws, preventing the assembly from coming appart when unwinding an also prevents the assembly from falling out when not in use.
It should be noted that the parts are hardened steel, mine had a burr which prevented it's removal when fixing it and had to stone it off. Also, the surface of the collers appear to have a fine ground finish, not bearing fine but close:

https://i.loli.net/2018/03/04/5a9bea0cb29be.jpg
https://i.loli.net/2018/03/04/5a9bea0c726da.jpg
https://i.loli.net/2018/03/04/5a9bea0d0896a.jpg

Unfortunately the threads are damaged on the LH thread side and I can't get the coller off so I hope the pics and blerb are enough to go by.

Quote:

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Originally Posted by Canobi

Perdy ♡
Intersting chuck head design, looks like the alignment screws for the clamp are still present too, so I removed the clamp from mine and took some pics, in case you, or anyone else that's missing theirs will have some kind of reference to make replacements.

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Many thanks, I have wondered what the two small screws were for on mine. However, I am at a loss to understand how the parts that you have shown will have any effect on mine. Like I said, the collet works fine as it is but it is quite obvious that something is missing. I am very puzzled.
Any more info on yours would be welcomed.

Not only excellent photos, a perfect description of the parts and their interaction. I've known mechanical engineers who couldn't do as well.

Quote:

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Originally Posted by tonyfoale

Many thanks, I have wondered what the two small screws were for on mine. However, I am at a loss to understand how the parts that you have shown will have any effect on mine. Like I said, the collet works fine as it is but it is quite obvious that something is missing. I am very puzzled.
Any more info on yours would be welcomed.

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Admittedly, in your case it would only be cosmetic, I just saw the screws there and couldn't help but share the info as I daresay others have missing clamps too, even if it simply clears up a mystery as to what the big hole is for.

I don't know much about my Pollard but I'll share info here as I find it. I may have only used mine once so far but I love it already ♡

Quote:

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Originally Posted by Toolmaker51

Not only excellent photos, a perfect description of the parts and their interaction. I've known mechanical engineers who couldn't do as well.

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Thanks you very much indeed kind sir :D

Canobi,

I am not 100% clear on how yours works.
It seems that you have some collets as does mine, tightened by the collar at the bottom, but the pieces that are missing from mine close up onto the square of the tap. Those pieces are free to float laterally for alignment. The collets hold the tap centrally and the other pieces ensure zero slip.
Is that correct?
I do sometimes have the tap slip. What is the largest tap shank that you can fit?

BTW. Are you snowed in around your way?

Quote:

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Originally Posted by tonyfoale

Canobi,

I am not 100% clear on how yours works.
It seems that you have some collets as does mine, tightened by the collar at the bottom, but the pieces that are missing from mine close up onto the square of the tap. Those pieces are free to float laterally for alignment. The collets hold the tap centrally and the other pieces ensure zero slip.
Is that correct?
I do sometimes have the tap slip. What is the largest tap shank that you can fit?

BTW. Are you snowed in around your way?

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No collets, mine has three spring loaded jaws:
https://i.loli.net/2018/03/05/5a9c459ac5927.jpg

The rest is correct though, here is a pic of the clamp with a tap installed, largest I can fit in the chuck is M10:
https://i.loli.net/2018/03/05/5a9c483911c89.jpg

Yes, winter pulled a right Columbo on us, haven't seen snow drifts like it since I was a kid back in 82, where I was literally able to sledge from out of the upstairs bedroom window, those were the days...

There were drifts reaching 6ft in some places this time and I got all exited so I broke out my snowboard again and took the kids out on a sledging trip, only to find the fields were hardly covered at all as it was mostly powder snow and we were having heavy winds at the time, most disappointing :(

The snow is already beating a hasty retreat and should be totally gone by Tuesday, just the flash floods to get past now and we should be back to normal..

Quote:

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Originally Posted by Canobi

No collets, mine has three spring loaded jaws:

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Much the same.

Quote:

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Originally Posted by Canobi

The snow is already beating a hasty retreat and should be totally gone by Tuesday, just the flash floods to get past now and we should be back to normal..

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"Normal" is why I left the UK in 1987.

Thanks for the extra pix. I'll make something to hold the squares. I'll check my taps to see if there is a limited number of square dimensions, if so then I'll broach some squares into pieces of rod with an OD equal to the large hole. If there seems no standard to the squares then I'll make something like you have.

My Ettco accepts up to 8 mm shanks so I measured the squares on all my 5, 6 and 8 mm taps and between them there were 7 sizes, 3 metric and 4 imperial even though they are metric taps. here is a list in order of size;
5/32", 4 mm, 11/64, 3/16", 5 mm, 6 mm, 1/4"

I have formed an idea for a simple single piece design for a square driver, which should solve the slipping problem that I get sometimes and only take 1/2 hour to make.

My other tapping head, an AH made in the US, takes up to 1/2" shanks which means up to 12 mm for me.

Quote:

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Originally Posted by tonyfoale

I have formed an idea for a simple single piece design for a square driver, which should solve the slipping problem that I get sometimes and only take 1/2 hour to make.

My other tapping head, an AH made in the US, takes up to 1/2" shanks which means up to 12 mm for me.

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Canobi,
Thanks to your pix and description I was inspired to make a positive drive on the tap squares. i didn't attempt to copy the stock setup that you have and I went for a very simple to make implementation.

1/4" is the largest square that I have measured on my 8 mm and smaller taps, so I broached a 1/4" square cross hole in a loose fitting bar. From one end I drilled a hole to take a plug that will bare on one side of the square clamping the tap end. I tapped the outer portion of the plug hole for a clamping bolt to push on the plug.

Attachment 22546 Click thumbnails for full size.
Sketch showing the pieces.

Attachment 22544 Attachment 22545
Photos of the actual implementation.

As the bar is a loose fit in the tapping head it will self centre on the tap square but still provide a positive drive.

I like it, very neat take on the theme, kudos :thumbsup: