Member postings for Mark C

I did mention Ambersil. The stuff I use is "Tufcut" and lasts for ages if you use it carefully. It can be used for more than just tapping but I have coolant so only use it for tapping mainly. It is less than 14 quid at Cromwell for 400ml aerosols tin. There is a Rocol product that is also extremely good. They make a HUGE difference when tapping in almost all circumstances.

Mark

I thought I would "improve" a design on a machine by changing from a coarse to fine thread on a jacking screw. I applied the simplistic view that a fine thread would be better due to the lower helix angle giving more force per turn - how wrong I was! It resulted in having to go red faced to the machine shop and have a new set of parts made with the old thread form as the operators could not turn the things when they were loaded up - not even with a 6 ft pole on the end.... Ever since then I have given considerable more thought when making "simple" improvements - especially when threads are concerned.

Mark

humble arborist perhaps?

Mark

Back to drilling tapping holes, we really should consider the material carefully as tapping soft materials (soft plastics and such) would probably require slow spiral 6.8 drills?

Mark

(because I refuse to use the silly little icon things, I have resisted the temptation to insert the one with little horns, but it was an effort... )

"might be several hundred posts and the need to buy new gear" sounds like a really good reason to keep posting if I can have more stuff without clearing it with the accounts department first!

Mark

Roy, that is a bit brittle for a high tensile brexit do you not think? should be more like 54 Hrc I should imagine

Mark

Tony, sorry about that, it seems Theresa forgot to email me the briefing notes....

Mark

Neil, we don't have BS standard nuts yet, that will be after the hard brexit

Mark

A spanner is no good, you will be needing a certified and approved/calibrated back to national standards torque wrench

Mark

Dave, that is probably the most sensible post so far, putting you in the "I am doing this from an informed point of view" catagory.

Mark

Oh dear Roy, that should see us well past 200 replies!

Mark

Rod, try 70% as they suggest if you don't know the engagement required (read, standard or general purpose value) - it works out much closer. I doubt the flute form or point design has much influence on tapping drill but it certainly effects the swarf formation. One point to remember with spiral flute is the swarf comes out the same side as you tap from and is very keen to damage fingers.

Mark

John W, that is a better link than your last attempt......

Here is a picture of something especially for you, everyone else will be able to manage without them but for someone who has been in engineering design that last statement is mostly just nonsense.

Mark

Michael, that is a useful link. Did you take a look at the link I posted in my post of 12/10/2016 17:43:19 ? I have not taken time to check it for accuracy but it looks right for M8. Using the two calculators should give all the information you could possibly require regarding metric thread dimensions to enable an informed decision on any given application.

Mark

PS. what is the red flag all about when I cut and paste?

Neil, that seems to be a common problem with postings here, people comment without getting the facts. The taping set I show are Guehring spiral flute complete with nicely labelled 6.8 drill.

So back to the last post:

point 1 - several = more than 2 but not many.....

point 2 - does the din standard show a dimension linked to the thread size or not? please advise what it says if not.

point 3 - please see my first comment above.

point 4 - I am not criticising anyone, simply stating what is (apparently rather annoyingly) a fact that the accepted drill size for standard (sometimes described as coarse) M8 threading in standard (read normal steel/aluminium etc) engineering materials is 6.8mm. Walk in any fastener supplier selling thread cutting tools and ask for an M8 tapping drill and you will either be questioned about application and materials (I doubt that very much) or presented with an 6.8mm drill..........

Mark

By the way, this now the 100'th post.....

Oh and also, in-between all these posts I have just managed to get to grips with the Samba Baiao rhythm I was given by my drum instructor. To say I am chuffed is an understatement! 

Edited By Mark C on 12/10/2016 20:56:46

I agree with you Jason, perhaps we should just listen to the most vocal minority given the majority probably can't be ar......

Neil, did you notice what make my taps are along with the drill size supplied?

Mark

Howard, problem with a simple question that acquires 5 pages of replies is that little simple tips like that (it is in my first reply - 7th post on first page) get lost!

I belive it would work with any 60 degree thread but only the metric ones are listed by pitch, all the others are in threads per inch or something similar.

I belive the quote goes along the lines of "fools follow rules without question" hence my use of the Plato quote (or Socrates?) you would need to look it up.

Mark

PS, it works for all metric as long as you have the pitch

Edited By Mark C on 12/10/2016 19:43:03

And on the subject of showing yours, here are mine....

the second picture shows the markings on the tap - and you can also see the abuse it has had! If you don't tighten the chuck enough for M8 it will slip..... especially on the mill

Mark

PS. this set was 48 quid last year - on offer in local machine factors. 7 taps and 7 drills to suit = average at 3.48 an item.... can you afford to buy cheap junk by comparison?

Edited By Mark C on 12/10/2016 17:52:49

Neil, the whole point of what I said was that for standard applications the drill size is dictated by the DIN standard - by definition of the minor diameter D1 for external threads. If you drill it bigger the D1 dimension will no longer meet the standard. Regarding the use of the word Nut in the standard, it is there to clarify the difference between internal and external threads I think. The standard still applies to threads even if they are not in a nut or on a bolt. By that definition the standard would only apply to bolts (being threaded over a portion of it's length rather than screws with full length threads!

To add to your last post try this link **LINK** you can look at the thread class and see what changes happen. I don't know if it is accurate (it is a good idea to be careful with random information on the Internet). It should also give you an indication of the measured diameters you can expect for the thread class you have.

Rod, that seems very apt - it might also follow that another quote may be in order from Plato? (a wise man knows he knows not). At any rate, I have been saying all along that it is up to the personal preference in your own workshop. (Neil, this applies to one of your earlier posts regarding DIN standard, you can do what you like if you know what you are doing - just don't call it a DIN standard any more).

Mark