Three toads in the hole

[student123]

My novice oscillator build continues...

Needed to tap m3 into a vent hole in the upright on an oscillator.

Tapped the first hole fine, got blase on the 2nd hole & broke the tap (my only quality tap) in the hole. tried to drill out unsucesfully. Found a dispensible sharp thing (an electrical tester ) & tried to knock the tap bit out wth a hammer. end of the elctrical tester managed to also break off into the hole. Thought *** this I'll go back & drill em out. The drill bit snaps so now I have 3 things in the hole.
Eventually get the lot out heres a pic of the culprits (or are they the victims & I the culprit ??)

 

[wheeltapper]

And I suppose the hole now looks like a small bomb crater........some days you shouldn't get out of bed. ;D ;D

Roy

( who's been there too)

 

[zeeprogrammer]

Sorry to say, you are both the victim and the culprit.
Been there too. My commiserations.

 

[Blogwitch]

Don't worry too much Student.

As you gain a little more experience, the attrition rate for tooling does start to fall, and your hammers will start to get smaller.

Having a friend with spark eroding access is one of the best tools I have. I think the last time I used it was about 3 years ago.


Bogs

 

[Lakc]

Been there, done that, and will probably do it again. Sorry for your misfortune.

I swore the next time I do that I will try one of the chemical tap dissolving tricks, assuming I dont break it in steel.

 

[mklotz]

Did you have the tap supported by some sort of tap alignment guide?

Most tap breakage is due to bending the tap as opposed to overtorquing the tap. A tap alignment fixture solves that problem.

 

[tmuir]

Bummer.

As mklotz says if you don't already have a tap holder that you can use on the lathe or drill press they are simple to make and well worth the effort.
Another point to remember is you don't need 80% or 90% thread engagement for most things and a lot of charts for drilling and tapping threads are up at that level.
For most of the things we do 65 to 75% thread engagement is enough which considerably lowers the torque required to cut a thread so makes it much less likely to break a tap.

I've attached a metric tapping chart for you.

View attachment tapping Chart.xls

 

[student123]

Did you have the tap supported by some sort of tap alignment guide?

Marv, nope... unless you count a thumb & 1st & 2nd fingers...

Joking aside realise down to me, with other easy & succesful attempts I had got blase. Need some more practice etc. which will come.
At some point I will need to tell my wallet to take a deep breath & go get
some quality taps, dies & accesories.

Thanks for the commiserations, advice & data sheet.

Mike

 

[Blogwitch]

This is a job I finished yesterday. Instead of the recommended tapping drill of 2.5mm for a 3mm tap, I used a 2.6mm instead.

A razor sharp bottoming tap held in a portable drill with plenty of high pressure lubricant had the holes freehand tapped thru the steel plate in no time.

A thing not recommended for beginners, but as you become more experienced and get the 'feel', things like this becomes second nature.

Bogs

 

[Artie]

Just in response to Bogs post...... I cant recommend enough a comprehensive set of drill sizes. As an Aussie Im very much a metric user and I have a full set of .1mm incremental drills (as it seems does Bogs), the options this allows you is immense, again, as per Bogs post. With a normal drill set what he has done here is impossible..

Moral? In my opinion, spend the money on the best available options..... not necessarily the best quality, but the best options..... cheap drill sets will last well with a little care taken.....

I use Suttons and P&N Wiltshire (aussie brand) drills and taps where possible, when I first started as an apprentice, I couldnt afford that stuff..... now I can.... crawl before you walk and walk before you run.....

As an aside, Bogs, how did the lad go with the job application?

RT

 

[mklotz]

Tapping guides are easy to make. Here are some I made and use...

Using a larger tap drill to reduce the "depth of thread" is, as has been mentioned, a good way to ease the process of tapping and reduce breakage.

If you're not sure about which larger drill to use, download the DRILL program from my page. It allows you to specify the depth of thread when calculating the required tap drill.

Of course, there is a simple formula for this but everyone seems to be so put off by mathematics. I'll supply it if you request it.

 

[Blogwitch]

RT,

IMHO, having the full drill range set is a necessity.

Nowadays they are not as expensive as you think, and there is no need to go for the very expensive sets. In fact my imperial number and letter set is very accurate and four facet ground, for about 40 squid.

If you have the right sized hole (or one sized larger in tough stuff) then the only problem that usually occurs is with blunt taps. If you are using a good tapping lube and the tap 'squeaks' while cutting, dump the tap and get a new one, as invariably, very soon it will be broken off down a hole.

I know that it is difficult for some people to afford good tooling, but it is false economy to use really cheap cutting tools or ones that have gone past their best, all they cause is grief and anguish.

I am one of the lucky ones, and I have just finished upgrading all my taps and dies to HSS, and you would call me demented if I told you how much it cost me. But to me, if I want to drill and tap all materials, the cost was classed as a necessity. But on the other hand, I don't just use them for my hobby.

BTW, the reason I used a power drill to tap the steel plate is because there were so many holes to do. Normally, I would have used my tapping stand.


Bogs

 

[Lakc]

I know that it is difficult for some people to afford good tooling, but it is false economy to use really cheap cutting tools or ones that have gone past their best, all they cause is grief and anguish.

Those are both words of wisdom, and a belief, that only comes from learning things the hard way. oh:

 

[robwilk]

RT,

IMHO, having the full drill range set is a necessity.

I have 2 sets of drills 1-6mm in 0.1mm increments and 1-13mm in 0.5mm increments. I have been looking for ages for a set 6mm> in 0.1mm increments because i have needed them on a number of occasions and had to change a drawing to the nearest half mm because i haven't got the drill required and cant seem to find any so this is a good time to ask if any body knows where i can get some in the UK. Thank you.
Rob......

 

[Troutsqueezer]

Of course, there is a simple formula for this but everyone seems to be so put off by mathematics.

Math is one of those things that unless you use it, you lose it, if you ever had it. Not like riding a bicycle. I know I'm not telling you anything you don't already know Marv.

In my line of business, I use those formulas and equations that relate to what I am doing (narrowly-focused mechanical, electrical and thermal) and most of the algorithms I learned in college 40 years ago have now gone by the wayside. While I won't say my brain has become lazy, it does prefer the path of least resistance for some things, like math.

-Trout

 

[Blogwitch]

Rob,

Not the cheapest you can find, but I have used these and they really are rather good.

http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Twist-Drills/Drill-Sets

These aren't too bad either

http://rdgtools.co.uk/acatalog/DRILL_SETS.html


Bogs

 

[robwilk]

Thanks for that bogs
Rob....