Countersinking

[Walltoddj]

With c/s head screws I only buy the socket drive type and usually put a drop of loctite under the head.

A good many potential model engineers are put off the hobby by the quantity of tools and equipment others would have you believe you need.
Most of the recommendations are un-necessary and usually made by armchair engineers.

First off they are flat head screws and if used properly you would never need Loctite to hold them.

You don't need any tools but if you are a tradesman you learn to to make or procure the tool you need to do the job right without cobbling it, to use a drill point would be a last resort to any true tradesman. So you want to think about what is because was an Engineer and a Tool maker for over 30 years!

Todd

 

[abby]

"to use a drill point would be a last resort to any true tradesman. So you want to think about what is because was an Engineer and a Tool maker for over 30 years!"

Obviously rattled someones cage, only 30 years toolmaking ! not a time served apprentice then Todd ? a toolmaker does not consider himself a "tradesman" that's for plumbers and electricians.
Like I said , this is model engineering , you know a hobby , we make toys .
http://en.wikipedia.org/wiki/Countersink

 

[Heffalump]

I think this is getting a bit personal.

Thanks for the advice everyone.

 

[Tin Falcon]

Gentlemen While Viper Venom is an excellent product for cutting threading reaming ect it should not be used near the computer keyboard and NEVER be applied to forum threads !!! Understood ??
Tin

 

[goldstar31]

From your new avatar etc, you seem to be within easy reach of one to one advice as there seems to be at least one active club . Whilst my membership of such things is no longer possible, I feel that it will be to your advantage to seek one to one contact with a club.

Again, much of the information which you are presently seeking is contained in some or all of the classic books. I was thinking of Advanced Machine Tool work by Smith which is American, free on the net but contains graded exercises in machining. It may be 'full size' but the book is sufficiently old fashioned to include most beginners' needs. Again, I would commend the Amateurs Lathe by Lawrence Sparey who actually made 'model engines' From my copy, bought as an erk in Royal Air Force days, it does contain direct information on what were called Slocombe drills. Again, though a bit beyond what appears to be your present abilities, more information about more Slocombe drills than has been raised here is George Thomas's Model Engineers Workshop Manual which was edited- wait for it- an expert on drills. Dr Bill Bennett has 52 years in since he qualified( with my wife) as a dental surgeon.

So you have every opportunity to build up your skills.

Regards

Norman

 

[Heffalump]

From your new avatar etc, you seem to be within easy reach of one to one advice as there seems to be at least one active club . Whilst my membership of such things is no longer possible, I feel that it will be to your advantage to seek one to one contact with a club.

Again, much of the information which you are presently seeking is contained in some or all of the classic books. I was thinking of Advanced Machine Tool work by Smith which is American, free on the net but contains graded exercises in machining. It may be 'full size' but the book is sufficiently old fashioned to include most beginners' needs. Again, I would commend the Amateurs Lathe by Lawrence Sparey who actually made 'model engines' From my copy, bought as an erk in Royal Air Force days, it does contain direct information on what were called Slocombe drills. Again, though a bit beyond what appears to be your present abilities, more information about more Slocombe drills than has been raised here is George Thomas's Model Engineers Workshop Manual which was edited- wait for it- an expert on drills. Dr Bill Bennett has 52 years in since he qualified( with my wife) as a dental surgeon.

So you have every opportunity to build up your skills.

Regards

Norman

Thanks Norman, new avatar as this one contains less of me and perhaps less embarrassing!

I think you may be right about my skills (or lack thereof) but I'm looking forward to improving. I will do some research on those books, they sound like a great resource.

 

[goldstar31]

Rest assured, you'll not be disappointed. In the meantime, you have a very useful offer on a PM.

Regards

Norman

 

[Sshire]

With countersinking tools and techniques, as with anything else in this hobby and on this forum, you'll get much good advice. A great deal if it from people who have been doing this professionally, or as a hobby, for many, many years.
In addition, books, magazines and videos cover virtually every topic.
This is how I'm learning. Ask questions; use Google and YouTube.
As with so many things, if you ask a questions, you'll get 10 different answers. Interestingly, the majority are correct. Skinning a cat and all that.
The differences in correct answers is due to many things. Different apprenticeships, different vocational or military training, or the "I figured this out on my own and it works for me" school of experience.
When I started, I was on a few forums. The reason I stayed here and MEM, was that a few of the others were not very friendly to hobbyists. Instead of answering a question, they made one feel embarrassed for asking or were just plain rude.
You shouldn't get that here. We want to help. Some of the more interesting and educational threads with the most responses, resulted from, what appeared to be, a simple question.
Make each engine you build a little better, a little more precise and a little more complex than the last one.

 

[Swifty]

Coming back to the original posting, countersink bits cover a range of holes, a set of 4 would cover most fasteners used by the home hobbyist, for example the smallest might cover 2mm to 5mm, the next 4mm to 8mm etc. If you think that you will be staying with your new hobby, purchasing the counter sinks as required will last you a lifetime. And of course, countersinks are also used to remove burrs from straight holes as well, so you will use them all the time.

I always use metric screws, so the countersink angle is 90 deg. Keeps it simple.

As to how deep to go, I always make them so the screw is just a bit under the surface, check with a few screws as the manufacturing tolerances may see some heads slightly thicker than others. Nothing looks worse than the head still being a bit proud of the surface.

Paul.

 

[bazmak]

Good one swifty as you say csk angles can be 82-90o and head dia varies between slot hd and HSocket
I always use 90o and multi touch until the head height suits the application.I also self grind suitable size drills
to 90o if the screw is required to go well below surface.Nothing wrong with that.Model engineers will do lots
of things (not proper Eng) to get jobs done.I also highly dislike people being arrogant in their replies
when answering someone who does not know what he is doing now but trying to learn
WE WERE ALL AT THAT STAGE AT ONE TIME,lets not forget it.I like to browse many threads for an
interesting read,and try only offering positive advice.This is a very informative forum,even with
subjects i have no interest or knowledge of, but i still like to browse

 

[Tin Falcon]

As with so many things, if you ask a questions, you'll get 10 different answers. Interestingly, the majority are correct. Skinning a cat and all that.

And that is only if 6 guys answer the question.
Tin

 

[kvom]

Most of the SAE flat head fasteners that are most common in the US seem to be 82 degree, so that's the set I bought. I used a lot of 8-32 flat head screws in the loco build.

I generally run the countersinks at fairly low RPM. 400 seems to work well in HRS.

 

[Swifty]

Unless absolutely necessary, I try not to use flat head / countersunk screws. The sockets are shallow and easily damaged by over tightening, and the heads want to pull around the plate being clamped. If the countersink favours one side of a hole, the screw won't contact all around and looks odd.

Paul.

 

[bazmak]

As previosly stated,csk fixings are used when a flush surface is requ ie when a component fits over the top.I like to use them if a part needs to be removed
and replaced fairly accurately.As stated previosly a tapped hole and a ssk screw
will replace dowels (up to a point) as a precision location fit

 

[Heffalump]

The reason I'll be using a countersink in this instance is to attach the frame of an engine to the base plate. The screw will go through the bottom of the base plate, so needs to sit flush or the base plate will not sit flat!

 

[kvom]

The reason I'll be using a countersink in this instance is to attach the frame of an engine to the base plate. The screw will go through the bottom of the base plate, so needs to sit flush or the base plate will not sit flat!

For cases where the screw head is not visible, it can be just as easy to counterbore and use a socket head.

 

[bazmak]

Thats true but csk bits are more readily available and cheaper than c,bore bits
I use std drills as cbores but have to machine the uside of the cap hd to 118o
usually when the screws are exposed,again the tapped hole and csk give a
precision location fit but sometimes flush cap heads look better than hex hds
I also like hs button hds.I specifically dont like slotted csk screws on models
They dont seem to look right for scale.The problem with multiple csk screws to
tapped holes is that you cant mark them accurately,so have to fit 1 then assemble and drill/spot thru.Its a lot easier for multiple stip downs and
accurate reassembly.Best regards barry

 

[barnesrickw]

DeWalts brad point bits work well. Except for in brass, because it's the Devil's drilling metal.

 

[kvom]

For counterbores of small screws I use an endmill.

 

[Omnimill]

I (mistakenly) used countersunk screws on some archery equipment many years ago as it was easier for me to countersink than counterbore at the time. I found the screws self tightened in use, to such an extent that on one occasion I had to drill the screw out to remove it. I try to avoid them now if I can as a nicely seated cap head socket screw looks so much nicer to my eye at least. I also avoid slotted or cross head screws in favour of hex and Torx but that's a personal thing.