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rjw
Chief Bottle Washer
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PostSubject: Re: tapping   Tue Jun 23, 2009 10:58 pm

While I do have a tapping head, I don't have a collet that small...hahaha

So YES....all the holes are tapped by hand

They are all metric and the majority are 2.5mm x .45 which is a lot of turns All screws are shcs and grade 10.9 or better.

2 things

1) We only use machine taps, so you don't have to back up the tap...just keep turning until it doesn't go any more.

2) A small light tap handle helps keep things straight and eliminates tap breakage

Also, by design, no holes are tapped in the Ti, except in the ends of the weapon shafts, so it's all into the softer aluminum.

There are NO nuts in the robot. Cover screws are 2mm and the BIG stuff(lol) is 3mm.

This is scaled down from our 15 pounders which have 70 or 80 10-32's, 8-32's for the covers and 6mm x 1.0 for the BIG stuff...hahahaha

I use a tapping head for those

Imagine scaling up to a 200 or 300 pound version...we're talking 3/8 to 3/4" bolts...now that's when I would bring out the REALLY big tapping head or leave town until all the holes are tapped.

Tapping Ti is no picnic....3mm holes in the ends of the shafts is a slow and scary ordeal to say the least.

Once the bots have been around for a bit, I'll share some of the technology used in them...these little guys are a generation better than the 15 pounders in several ways...I think you'll agree when the details are revealed.

Also, we modified all the 24mm bbots gearboxes...the've been pretty much buleprinted, and they all have Ti shafts as well. The original boxes were flinging the planet gears off their shafts...it was somewhat humerous, but frustrating at the same time, but they sound and run great at the moment.

We are also running them at almost 4 times the original speed....they are running in a special high speed oil , so the boxes are sealed as well.

By doing this, our top speed went from 5 mph to 17. They spin like fbs's...I'll put up a video when I get a chance to breath and shoot some.

btw: at least for an old fart like me, a typical tool and diemaker's 5 power headpiece is a must...everything is so TINY
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rdubard
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PostSubject: Re: tapping   Wed Jun 24, 2009 10:28 am

rjw-
Many thanks for your reply--it amazes me that you tapped so many holes by hand successfully! I thought it was kinda funny that you said a using larger taps gave you headaches--I typically can tap anything above #10 (into aluminum) without breaking them, but I'm forever snapping off smaller taps.

I must confess to ignorance here--my background/education (hardware stores & education/physics degree) never actually put me in a machine shop, so I'm learning as I go. Is this http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1801855&PMT4NO=0
the sort of thing I should look into buying? Are there places online where I can learn more about what's available and how to use them?
-Thanks
Robert (Bob) DuBard

ps-should I move this part of the thread to another place?
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rjw
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PostSubject: Re: tapping   Wed Jun 24, 2009 10:53 am

Metric threads are kind of easy

for example a 2.5mm screw requires a hole of 2mm, which means that there is only .5mm or around .020" of material to form the thread.

So, unlike the coarse thread inch series holes, theses are more like fine threads and tapping them is almost effortless.

As long as you start straight, it's like butter, and like a fine thread screw, they hold very well.

I have several tapping heads, 1 is similar to the msc model, except it has torque and depth stop adjustment for working with blind holes and smaller taps.

Tapmatic makes some of the best tappping heads, but they're not cheap.

They are meant to be used in a bridgeport style mill or drill press and with a stop rod.

Here's a youtube video I found

http://www.youtube.com/watch?v=W_tkCZgNutI

In that video, notice that the operator applies downward pressure, which engages a clutch and drives the tap into the work. He reaches a stop and then the tap continues for a bit and then goes into neutral. Retracting the feed lever causes the tap to reverse direction of rotation and come out of the piece.

It takes a bit of practice, but once used to it, you can tap a lot of holes in a short period of time

The torque limiting and depth stop is very handy when tapping blind holes.

You can set the release torque so that you don't snap taps.

I only use tapmatic cutting fluid as well....no thick cutting oil.

On the other hand, I know people who tap with a hand drill...lol

They also sell a little tapping bench with a hand feed handle on top, but I've never used it.

As stated before, only use machine or gun taps..they are 2 flute (or 3) that don't require backng the tap out to clear the chips.

I would NEVER tap anything with a hand tap....no way...EVER

Also, being aware of the material hardness and how a tap feels is important. Sharp taps work great, while dull ones snap easily.

I've tapped over 1000 holes with a single 10-32 gun tap in a tapping head.

In these bots, 1 3mm tap will do 3 or 4 holes in Ti, then it gets wierd...but I only use regular HSS taps, nothing exotic.

Ti is a great heat conductor, but that means that it gets very hot quickly when doing anything with it. It expands in all direcctions including onto the tap, causing it to bind. I've had to walk away from a few holes until the material cooled down to avoid tap breakage.

If I were to do a lot of Ti, I would invest in better taps,etc


You can move this part of the thread anywhere suitable..talk to Dan...maybe a tech section or whatever.

Run it through spell check tho...haha

If you ever have questions on anything related to machining, just give me a shout...always happy to help
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rdubard
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PostSubject: Re: tapping   Wed Jun 24, 2009 11:26 am

Thanks! The video really makes a great case for spending the dough (I'm guessing $800 or more, once we buy collets and machine taps!) Even if we don't end up getting the head, the machine/gun taps alone would make a real difference in our productivity and tool life.
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rjw
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PostSubject: Re: tapping   Wed Jun 24, 2009 12:26 pm

rdubard wrote:
Thanks! The video really makes a great case for spending the dough (I'm guessing $800 or more, once we buy collets and machine taps!) Even if we don't end up getting the head, the machine/gun taps alone would make a real difference in our productivity and tool life.

If you've been using hand taps...just buy the gun taps and you'll be in a different world.

They're only a few dollars from Dewitt or whoever you deal with. Buy the cheapo hss imports and give them a try.

If you want to try a tapping head, let me know...I could loan you one of mine
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