Bridgeport milling questions

Richard,

It seems I was taught incorrectly how to use a Clarkson autolock holder and you above post is the correct technique. A quick google turned up the following which I shall try the next time I use it.

Cheers

Dave

Not just secured by a collet -- but you might be able to use a releasing tap holder (made to be used in late turrets and in automatic screw machines) as long as you carefully set the depth stop based on where the dog clutch releases so you don't drive down into the bottom of the hole and break the tap off in the workpiece. :-)

O.K. You know that there is a keyless chuck by Albrecht which has diamond dust impregnated jaws, so it *can* grip a tap or a mill without slipping. And -- there are versions of the Albrecht chucks which are designed to lock as well. Both features are only found on quite expensive Albrechts -- usually with R8 shanks instead of a female Jacobs taper to allow interchangeable arbors.

Nice. I think that the quill return spring on mine would be the slowest to disengage and reset later.

The telescoping ones which I have seen have been designed to slide on a rod held by the tailstock, and to be prevented from turning by gripping either a knurled surface or a short T-handle. When the tap reaches the proper depth, you release the handle and let it spin.

But the releasing tap holders (commercial product for older turret lathes and for automatic screw machines) could be used in a mill. You stop feeding and the threads draw the tap down just a little more to disengage the dog clutch. Then you stop the spindle, reverse it, and pull up (many are designed with a directional dog clutch, so it will hold in reverse even though it has released in forward.

I'm familiar with these because I have a bed turret (replaces the tailstock) for my 12x24" Clausing, and I use it form time to time with turret tooling acquired from eBay auctions.

Generally, if I have more than two or three holes to tap (and I'm not on the lathe) I'll use the tapping head. Particularly nice when I had to tap about 30 1/4-20 holes in 3/16" thick steel to make a new apron for the 24" DiAcro shear which I got last year. Any manual method of tapping that many holes that large in steel gets old fast. :-)

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Most of us like sharing what we have learned -- to save others the time which we spent the hard way. :-)

Well ... as an example, my killfile zapped about 2/3 of the articles. It was worse prior to the election - 3/4 was being zapped at a time. :-)

If you chase down a version of slrn for your system (I believe that it is available for Windows as well as unix/linux systems and Macs), and drop me an e-mail, I can send you my current killfile to give you a quick start. (I'll strip out the parts which apply to other newsgroups.) Among other things, I have a lot of blocking by IP range to keep the Chinese shoe knockoff vendors out of my newsreader, and the various Indian scams.

(Hmm ... were you posting under a different name back then?)

Indeed so. He is still missed. DoN.

Thanks. I had not known that. If I ever get a set of mills to match my holders, I'll have to remember that.

Enjoy, DoN.

I was thinking that I had seen some of the telescoping shop-made tap guide/holders for lathe tailstocks that had a key or pin to keep the tap from turning, but allow the tap to self-feed into the rotating part. Stopping the spindle would then be the method to stop the feeding.

I suppose if I happened to stumble upon a tapping setup with the dog clutch, I'd be inclined to buy it because they sound versatile.

Oh, the other tapping with power that I've done has been #6-8-10 taps in steel panels for mounting relays and controls.. works a treat for lots of thru-holes. I wouldn't wanna try it with a non-reversing drill motor though.

I was aware the diamond dust filled jaw chucks existed, but don't think I've ever paid much attention to the pricing. I just got a nice, used, 3-piece set of TRW USA tap handles with the opposed handles, and a moving jaw that closes on the square section of taps, but like you said, hand tapping a lot of holes gets old fast.

When I was lurking and just observing RCM interactions/frictions, Tnut, Fitch, Albrecht and numerous others were regulars. When I started posting in RCM I was probably with the ISP tcis or usachoice, then Goog, and Teranews briefly, using the moniker kwag98 initially, then others similar to the present one, as WB was my sig for a number of years of posting in sci.electronics.repair.

The non-metalworking posts don't cause much aggravation for me, as I can just ignore them, since most of them generally, and the participants' opinions on those topics, aren't of any more interest to me than the spam sales messages.

Hey WB,

Most of those tailstock tap accessories have two slots opposite one another in the carrier of a size to allow a T-tap handle to slide into it. In operation, the "depth of threading" is set by advancing or retracting the tailstock and barrel to set a point of release for the T-handle, which allows the T-handle to just spin when it reaches the preset depth by moving/being pulled out of the slots so it is no longer held by the tailstock carrier.

Take care.

Brian Lawson, Bothwell, Ontario..

That sounds a little hazardous -- if your reaction itme is poor, or if you switch through "STOP" to "REV" and your lathe happens to have a single-phase cap-start motor, it will keep going forward and bury the remains of the tap in the workpiece. :-)

Now -- if the key is not full length, and you position your stop properly so when the tap reaches the needed depth, it pulls clear of the key and starts to free rotate, you have an approximation of the dog clutch, and you can use it safely.

They are better with a turret (bed or otherwise) with individual stops for each station, and lever feed (four levers like a turnstile) so you can feed at a reasonable speed until you reach the stop. The total travel of the dog clutch is on the order of 1/8" or 3/16" typically, so trying to keep up with it with the hand crank on a standard tailstock is awkward.

A lever feed tailstock would work well.

Or -- mount it on a boring bar holder and set up a turret bed stop with one station to stop the carriage at the right point for the tap. For that matter, you could use the same setup with other turret tools like "roller box tools" (turn to diameter in a single pass with a set of roller steadys associated with the cutter), or Geometric die heads (there are other brands more common in the UK) for threading to depth at speed, and which release by letting the chasers (like 4-jaw chuck jaws) spring outwards at the end of the thread -- so you don't even nave to reverse the spindle to pull it off, because the threads are disengaged.

For that matter, there are Geometric "Collapsiing taps" which are like a Geometric die head turned inside out. Probably start around

1" ID, and increase in size to whatever limit the size of your lathe may impose. My bed turret has 1" shank holes in the stations. I've got a couple of the collapsing tap setups -- but I am limited to the chasers which came with them -- I don't seem to see the chasers very often on eBay.

Also -- there are T-bar knurling tools which are fed on over the end of the workpiece with the knurling rollers on two shafts which come in from opposite sides of the workpiece for balanced loads on the machine.

All of these on a quick-change toolpost with boring bar holders would require carefully setting the cross-feed and the height adjustment properly before starting, while the turret is always on center. But once set up, if all of your boring bar holders had the same offset from dovetail to center of the bore, then you could change tools and change a turret type carriage stop to use them almost as easily as you do the turret -- except that you have to be careful to keep them in the right order and matching the turret bed stop.

Agreed. I've done that with gun taps in that range -- with 6-32 being the one most likely to lead to disaster. It is just too weak a thread thanks to the coarseness of the thread vs the small OD leading to a very small root diameter. :-)

You know -- a non-reversible electric drill could be fitted with a stop for the radial arm on a TapMatic head and that could be used by hand with reasonable care -- up to significantly larger taps if you have a hefty enough drill motor, and perhaps a helper to keep it from twisting. :-)

Since these come only with the permanent R8 or NTMB 30 or 40 type shanks, they tend to be quite expensive.

I guess that you could get replacement jaws for one and fit them to a standard one -- if you did not need the locking feature as well. :-)

Hmm ... just the match for my set of TRW taps and dies (staring, plug, and finishing) from 0-80 to 1-8. Big flat metal case with fitted plastic foam liner. I bid on it on eBay many years ago in an auction where there were no photos. I think that others skipped it for that reason. I forget what I paid for the set -- but I think that it was about $100.00. The taps and dies showed no sign of every having been used. :-)

Yep -- I wish that Fitch would return, since his move is complete. And I would like to see Pete Albrecht back, too.

O.K. So you were lurking back in those days -- and the username was switching as well. And I tend to notice the username more than the real name.

I've had the same username since about 1985 or so, when I set up my first unix box and got a uucp feed for it from uunet. I got my domain at the same time.

The killfiles save me the trouble of identifying a lot of them, and off-topic threads which start I usually add the "Subject: " to the killfile with a 30 or 60 day fuse before it is turned off. Otherwise the killfile would get so big that it would take forever to process. :-)

Enjoy, DoN.

See McMaster p/n 2559A14. I've got one that came in auction lot, but don't find it very useful. Gripping the lower half of the housing takes the place of the torque arm on a normal tapping head. Your comment that a helper would be nice is on the money. If you're driving a tap that's large enough that the gearing might be an advantage, it's hard holding on tight enough to stop the housing's rotation.

That explains why is is so limited on tap sizes. The TapMatic warns you to not try to hold the arm by hand, so it probably has a lot more torque to deal with.

And that is without the tapping adaptor's housing being locked to the drill motor's housing. With that, you have that adding to the torque that the tap creates under load.

It might be fun to try it once -- but not at that price. :-)

If I get a drill motor with a cylindrical bearing housing, perhaps I'll make a clamp-on sleeve to hold a pin for the torque arm so I don't have to play with holding the bottom housing too. Enjoy, DoN.

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Your

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Gentlemen. This seems like an appropriate thread to inquire about an equipment item I recently bought. It is a Dumore automatic drilling/ tapping machine. I bought it at an auction because there were no other bids. Apparently, it is a pretty expensive tool but I still don't understand exactly what it is.

However, after going to the Dumore site they describe it (although not in these exact words) as an automated drill press for dummies. I will give the model number later since I don't remember it now. But apparently, by changing pulleys, the speed can be cranked up to 7500 rpm. It is air controlled and the plunging operations can be programmed and are repeatable to .0001 accuracy or something like that. I think they call it an "automatic drilling machine".

Anybody know what I'm talking about and have any experience with these? I thought I might try to sell it on ebay.

Regards, Vernon

Gentlemen. This seems like an appropriate thread to inquire about an equipment item I recently bought. It is a Dumore automatic drilling/ tapping machine. I bought it at an auction because there were no other bids. Apparently, it is a pretty expensive tool but I still don't understand exactly what it is.

However, after going to the Dumore site they describe it (although not in these exact words) as an automated drill press for dummies. I will give the model number later since I don't remember it now. But apparently, by changing pulleys, the speed can be cranked up to 7500 rpm. It is air controlled and the plunging operations can be programmed and are repeatable to .0001 accuracy or something like that. I think they call it an "automatic drilling machine".

Anybody know what I'm talking about and have any experience with these? I thought I might try to sell it on ebay.

Regards, Vernon

Sounds a lot like a Snow tapper that I tried to give away on this NG earlier this year - ultimately we took it apart for scrap, saving some solenoids and motors - and a little hardware. The tool worked perfectly, but no one uses these any more. Basically you set it up (speeds, depth, force down, force up), put your part in and step on a foot switch, it does the rest.

** Posted from **

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If it is for tapping as well, it should also have provisions for a precise feed per revolution, so it will feed that tap at the thread rate.

It would be excellent for the job which the original poster is doing -- *if* it has the necessary feed gears for the 32 TPI which he is tapping. (Hmm ... I wonder whether this one might have a floating tap chuck which senses when the tap tries to get ahead and provides more feed to keep up?)

It sounds like a lovely toy when you have a lot of the same thread to tap. If it needs change gears to set up the feed for a given thread pitch, then it could be expansive to change to a different pitch.

Enjoy, DoN.

I'll let you try mine all you want for considerably less than McMaster's price. Seriously, for smaller taps I find a drill with a convenient reversing switch much more useful, like the older Milwaukees with a flipper right above the trigger.

You got me excited for a minute there thinking I could do something similar with my attachment. I have a 1/2" drill that has a cylindrical boss behind the chuck where the cross handle clamps. Unfortunately, I forgot that you restrain the bottom half of the housing to go forward, and the top to reverse.

Thanks Brian, I see what you described, similar to those sockets for turning wingnuts.

I think I've seen some tap holders that didn't release, instead, the user just stops the spindle motor. I dunno what speeds most home shop operators are tapping at, but I run 'em slow. If shutting the motor off to stop threading near a shoulder is successful (for me it is), then stopping at a thread depth with a tap isn't a big problem. I've put masking tape on the tap for a depth indicator, when I've used a tap in a tailstock chuck, with the tailstock lockdown bolt slightly loose.

Nothing disasterous happened with the above method, and I was tapping 3/8-24 NF threads in 316 stainless steel. Slow speed, cutting lubricant and a high quality tap.

Those parts were adapters for desoldering irons, to allow common 1/8" desoldering tips to be used with an Ungar desoldering iron that utilized essentially unique tips that were machined from 7/16" diameter steel stock, then plated. The adapters allowed the users to swap out much less expensive tips with a set screw in the adapter body. BTW, the set screw was #6-32, but hand tapped.