CamBam
News:
 
*
Welcome, Guest. Please login or register.
Did you miss your activation email?
October 15, 2018, 22:45:08 pm


Login with username, password and session length


Pages: [1] 2
  Print  
Author Topic: Tapping tiny threads  (Read 1833 times)
Dragonfly
CNC Jedi
*****
Offline Offline

Posts: 2015



View Profile
« on: January 23, 2018, 20:08:18 pm »

I have a problem Sad
I have a task to make a 5 mm thick aluminum plate 100 x 100 mm with numerous tiny holes on it and then tap a thread through them. Thread sizes are M1.6; M2 and M3. Out of 100 holes  67 are M1.6. The customer gave me a .DXF file with the holes at their exact positions.
I drilled the plate quite easily using carbide drills with 3.175 (1/8") shanks. Then cut it to size. Then reamed (sort of) the holes using normal HSS drills to ensure the diameters are as required.
And then there came the headache. I have no means to do the threads by machining. Had to resort to hand work. On the sixth hole the #1 tap snapped and there seems to be no way to remove the broken part. I tried by leaving the plate for 3 hours in nitric acid but no visible etching of the steel piece in the hole.

Anyway, I can make another one on the router, it's a done work already.
What I am looking for is some advice on how to make the tapping with minimal risk for the tap to break. I am using cutting oil, dipping the tap on every new hole. Perhaps I need to buy or make myself some kind of guide to at least prevent inadvertent bending of the tap while rotating it.
Almost lacking any experience with such tiny taps. (I know there are people here for whom M1.6 is huge Smiley )
« Last Edit: January 23, 2018, 20:10:05 pm by Dragonfly » Logged

Before asking a question do some effort and walk through all menus and options in CamBam.  Maybe the answer is there. Please.
Bob La Londe
CNC Jedi
*****
Offline Offline

Posts: 3365


^ 8.5 pounds on my own hand poured bait.


View Profile WWW
« Reply #1 on: January 23, 2018, 20:33:43 pm »

https://www.youtube.com/watch?v=XNmd1-v62tw  

Just watched this yesterday.  

Nitric acid might work, but I think you need to scratch at the part and circulate the acid as a sludge coating may form preventing further work of the acid.  I seem to recall hat was the case with saturated alum solution as well. 
« Last Edit: January 23, 2018, 20:36:14 pm by Bob La Londe » Logged

Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com
lloydsp
CNC Jedi
*****
Offline Offline

Posts: 7626



View Profile
« Reply #2 on: January 23, 2018, 20:41:13 pm »

Tiny taps require a 'touch' that can only be had with experience and time.

A tap-stand helps a lot on flat work like that.  About 90% of broken taps for 'experienced' users result from a minor misalignment from the vertical, which causes the tap to bend as it cuts.

IF they're available in #1 (never looked) spiral taps will help clear chips.  Lubricating MUST be done way-more than just 'once per hole' when hand-tapping, because the lubricant flows away faster than you can tap the hole.  And you should use a tapping fluid designed for that aluminum alloy.  "Just oil" hardly ever hacks it in gummy materials like Al.

Lloyd
Logged

"Pyro for Fun and Profit for More Than Fifty Years"
jk
Wookie
****
Offline Offline

Posts: 258


View Profile
« Reply #3 on: January 23, 2018, 20:48:14 pm »

While waiting for experts to answer ... :-)

Recently I've made a simple guide with holes for M2.5-M5 taps. Tried with M3 and M4. Clamp lightly, slide until the tap is
centered by feel, clamp more and do tap.

Here is a similar commercial construction (quick google seach):


Maybe it will work with M1.6 too.
Logged
Bob La Londe
CNC Jedi
*****
Offline Offline

Posts: 3365


^ 8.5 pounds on my own hand poured bait.


View Profile WWW
« Reply #4 on: January 23, 2018, 20:54:30 pm »

I do not have to tap such tiny holes often, but I like the way Joe Pi does it in his video.  Looks like he just positions the spring loaded guide in his CNC mill for each hole and then taps by hand with his little knurled tap holders.  I think its neat that it can also work as a depth stop.  I plan to add those to the list of tools I need to make.  Well, and a spring loaded tap guide like his.  Looks like it has a cupped end to be able to hold the smaller taps in position that do not have a center hole like larger taps. 
« Last Edit: January 23, 2018, 20:56:07 pm by Bob La Londe » Logged

Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com
Dragonfly
CNC Jedi
*****
Offline Offline

Posts: 2015



View Profile
« Reply #5 on: January 23, 2018, 22:09:09 pm »

Bob,
the spring loaded idea is a precious one. Even more, I can make a program to move from hole to hole and wait on M1 optional stop thus eliminating the probability of missing a hole or two.
Logged

Before asking a question do some effort and walk through all menus and options in CamBam.  Maybe the answer is there. Please.
dave benson
CNC Jedi
*****
Offline Offline

Posts: 973


View Profile
« Reply #6 on: January 23, 2018, 22:44:47 pm »


Joe Pi also has a video for drilling small holes as well which is quite good.
Logged
Bubba
CNC Jedi
*****
Offline Offline

Posts: 2493



View Profile
« Reply #7 on: January 24, 2018, 01:08:48 am »

get some tap magic, you will thank me later...

http://www.tapmagic.com/

That's only thing I use.
Logged

My 2ยข
Bob La Londe
CNC Jedi
*****
Offline Offline

Posts: 3365


^ 8.5 pounds on my own hand poured bait.


View Profile WWW
« Reply #8 on: January 24, 2018, 01:25:48 am »

get some tap magic, you will thank me later...

http://www.tapmagic.com/

That's only thing I use.

Totally.  Extends the life of my taps too. 
Logged

Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com
dwc
CNC Jedi
*****
Offline Offline

Posts: 516



View Profile WWW
« Reply #9 on: January 24, 2018, 09:13:23 am »

IF they're available in #1 (never looked) spiral taps will help clear chips.
Spiral taps are the way to go.  I have them down to 0.4mm  (look at http://www.schurch-asco.com/)
I also use tapmagic.  But tapping aluminum is always a nightmare.
Don
Logged

Dragonfly
CNC Jedi
*****
Offline Offline

Posts: 2015



View Profile
« Reply #10 on: January 24, 2018, 12:39:10 pm »

get some tap magic, you will thank me later...

http://www.tapmagic.com/

That's only thing I use.
I am afraid it will come to Bulgaria at the price of liquid gold Smiley   If there's anything I envy you guys beyond the big water it is the availability of what you need.

Spiral taps are the way to go.  I have them down to 0.4mm  (look at http://www.schurch-asco.com/)
I also use tapmagic.  But tapping aluminum is always a nightmare.
Don
Now that's a more realistic source for tools. I'll consider it. Thanks, Don.
Logged

Before asking a question do some effort and walk through all menus and options in CamBam.  Maybe the answer is there. Please.
Arie kabaalstra
CNC Jedi
*****
Offline Offline

Posts: 568


why buy one, if you can build one?


View Profile WWW
« Reply #11 on: January 24, 2018, 14:43:40 pm »

M1.6, M2 and M3?..

I thought you said TINY threads?..  Grin

guiding the tap is important.. releasing the chips is important.. Tapping fluid is important.. and most of all, indeed.. Feel... feel what the tap is doing.. '

I've been tapping M1.6 in Titanium.. now that's a pain in the lower regions  Grin
Logged
Bob La Londe
CNC Jedi
*****
Offline Offline

Posts: 3365


^ 8.5 pounds on my own hand poured bait.


View Profile WWW
« Reply #12 on: January 24, 2018, 15:31:43 pm »

I've been tapping M1.6 in Titanium.. now that's a pain in the lower regions  Grin

How does that make your feet hurt?   Huh

For me M4 and 6-32 are tiny.  I have tapped smaller, but very rarely.  6-32 has a reputation for being a difficult thread to tap, and some machinist claim that a 4-40 is easier somehow.  It all depends on what you are tapping.  On sheet steel I tap 6-32 for standoffs and mounts with a cordless drill. I've done it with forming, spiral point, and hand taps.  In general spiral point taps tap easier than any other tap, but only on through holes or blind holes that are 2-3 times deeper than the thread. Spiral flute taps tend to work best for blind holes since they "supposedly" draw the chips out of the hole, but my experience is that you should back off every 1-1/2 to 2 diameters and blow the hole clear of small chips that are not drawn out and can pack up in the hole preventing bottoming.  If bottom is necessary I like to use two taps.  A spiral flute starting tap and a spiral flute bottoming tap.  Obviously hand taps should be backed off as often as every half turn and rarely further than every turn  depending on the material and how grabby it is.  Sometimes with a well lubricated steel cut the chips will ooze out of the hole, but its still better to back it out and clear the chips. 

As to cutting fluid.  WD40 has an overblown reputation for cutting aluminum.  Its better than nothing.  Kerosene is better.  Diesel fuel is better.  Automatic transmission significantly better.  Heavy cutting oil works ok on steel, but I do not feel it works that well on aluminum.  Tap-Magic is the panacea for me.  I use Tap-Magic "for all metals" formula.  I buy it by the gallon, and I have three pint bottles I keep in various places around the shop.  It works fantastic on my drill presses with tapping heads.  Tap life has increased probably two orders of magnitude.  I have a 10-32 spiral point tap in my small tapping head that gets used every day and has been there over a year.   I use the stuff for hand tapping, cordless drill power tapping, power tapping on the lathe.  I use it for steel, stainless, and aluminum.  Its good stuff.  Tap-Magic does have a formula specifically for aluminum as well, but I have never used it.  The all metals formula works so well I don't need to try anything else.  
« Last Edit: January 24, 2018, 15:51:21 pm by Bob La Londe » Logged

Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com
Garyhlucas
CNC Jedi
*****
Offline Offline

Posts: 1154


View Profile
« Reply #13 on: January 24, 2018, 18:51:24 pm »

Bob,
It's the agony of de feet!

I wonder if anyone has a made a tapping head like the procunier for very small taps.  They have slip clutches that give you a great feel and control while tapping.
Logged

Gary H. Lucas

Have you read my blog?
 http://a-little-business.blogspot.com/
Dragonfly
CNC Jedi
*****
Offline Offline

Posts: 2015



View Profile
« Reply #14 on: January 24, 2018, 19:48:45 pm »

I've been thinking about making a motorized tap adapter. Using the reduction gear and slip clutch with adjustable threshold from a battery powered drill/screw driver. But using a stepper to drive it. Then, with the help of not very sophisticated uCU (some 8 bit Atmega) program it to do forward/backward rotation - i.e. one turn forward/half turn back and similar.
At this moment I am making a spring loaded attachment to be fixed on the Z-plate so that all holes are walked through by G-code after the plate is drilled and while still fixed on position. Will report the results later.
Logged

Before asking a question do some effort and walk through all menus and options in CamBam.  Maybe the answer is there. Please.
Pages: [1] 2
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines

Valid XHTML 1.0! Valid CSS! Dilber MC Theme by HarzeM
Page created in 0.168 seconds with 19 queries.

Copyright © 2018 HexRay Ltd. | Sitemap