10BA clearance holes

I want to make some 10BA clearance holes in a piece of
spring steel for the support of a pendulum.
Do I need to anneal first and reharden afterwards, or is there
a better way?
(Ham Radio project - chinese copy of a Vibroplex Morse key)
Reply to
gareth
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I think this would depend on what state the steel you have is in and what you require it to do. I have a few thicknesses of carbon spring steel , IIRC 1.5mm, 2.0mm and 2.5mm, and it is in an annealed state as delivered and that is fine for my use. As such it is easy to drill and machine so for your use you may be able to just drill the material you have as is, you should though take advice from the suppliers as to it's strength and therefore determine a suitable cutting speed for the material you have.
Reply to
David Billington
Thank-you David. Unfortunately the material I have to hand is a Stanley tape measure that has pinged irretrievably out of its case.
Reply to
gareth
Carbide drills will go through spring steel easily without the need to anneal, though you would be advised to sandwich it just the same as any other thin metal being drilled.
Cliff Coggin.
Reply to
Cliff Coggin
I recently repaired (well, last year) a Gents Pulsynetic, which had a broken pendulum support spring on receipt. Just measured up the spring, thickness and width, and then bought a cheap clock spring via ebay, where there is quite a selection usually.
A drill wouldn't go near it, so I did anneal before drilling, then hardened and tempered afterwards...
Regards,
Chris
Reply to
ChrisQ
The way I do it is to fold a piece of brass, make, the required size of hole, in the brass Then make punch out of silver steel, harden and temper. It is then easy to put the spring steel between the folded brass and punch the required hole without the need to annealing the spring
Reply to
Bill Lamond
In article , gareth writes
I have heard of a technique; -never used it personally;- "Put a piece of steel rod with a square end and of just over clearance size in the drill chuck; bring it into contact with the spring where you want to drill the hole and run the drill at high speed with a fair amount of pressure. The friction will heat up the spring at that spot and anneal it. Then drill with a normal high speed drill."
Reply to
Chris Holford
If the leading end is still intact you might consider using that. If the hole needs opening out then a tapered grinding tool from a micro drill could be considered.
Reply to
Neil Ellwood
Excellent idea.
Another good point. (Apun my word!)
Thanks to all those who replied, I have enough to be getting on with now.
Reply to
gareth
If the material is thin as in a steel tape you could easily make up a simple punch and die set using silver steel and harden it. you could then punch the holes easily, have a look at making pendulum clock suspension springs. Peter
Reply to
petercolman45
Thank-you Peter. based upon previous contributions that is indeed the way that I have chosen to go.
Now, being of a nervous disposition, I'll need to use a slitting saw to make the slot to take the flat metal spring, both for the die and also for the Meccano***** rod that will form the pendulum.
Are there any dos and don'ts for this exercise, because with what will essentially be an electric saw running with no guard, it could well be a s*
itting saw for me?
*****Meccano still in occasional use here. One "boiler" is used as a soldering iron guard.
Reply to
gareth
Carbide drills in 10BA clearance...? (that is ~1.7mm diam...)
The traditional method, given that it is a PIA to drill thin material, is to make yourself a hardened steel punch. If you want to do the thing properly, then make a matching punching block (think paper hole punch) that wil guide the punch & also help to make the punch cut cleanly, but you can get away with punching through onto soft material (aluminium block, hardwood end-grain).
Regards, Tony
Reply to
Tony Jeffree
Why not? I use carbide drills as small as 0.85 mm to drill spring steel clock suspensions and the arbors of French pendules.
Cliff.
Reply to
Cliff Coggin
This sort of thing
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also available on ebay. I used them for (amongst other things) drilling holes in ball bearings
Dave
Reply to
dave sanderson
Apologies - slight brain fart there - was thinking carbide tipped, but of course solid carbide comes in smaller diameters.
Regards, Tony
Reply to
Tony Jeffree
But this involves added expense :-). If you are making batches, having the right tools is probably a good idea, though carbide drills, at least the pcb drilling types, are very fragile, ime. A stellite drill may be a better choice, though it's years since I even saw one.
For a one off, at no expense, it takes only minutes to anneal, drill, then re harden and temper and it costs you nothing...
Regards,
Chris
Reply to
ChrisQ
Just how long does it take to cut a bit of spring steel strip, warm to red heat in gas blowlamp, allow to cool, centre punch, drill, warm to red heat and quench, polish and temper to desired point ?. About 10 or 20 minutes should get the job done.
There's a tendency to overcomplicate all sorts of stuff these days, when alls that's needed is a bit of common sense...
Regards,
Chris
Reply to
ChrisQ
Find strip Find saw try saw find another saw try new saw find dremel fit rotary abrasive blade cut strip
warm to
Find blowlamp. find (empty) fuel canister go out and buy new fuel canister heat strip to red heat ooops, too hot - cut new strip. heat to red heat
allow to cool,
easy, eh?
centre punch,
find center punch punch turn strip over punch in correct position on other side
drill,
find hss drill try to drill darn, cooled too fast, curled up when drilling. Never mind, the hole would have been in the wrong place anyway.
find Dremel (I _knew_ I shouldn't have put it away) cut new strip heat to red heat allow to cool drill hole.
warm to
ooops, nothing to quench in - get water. oops, left in flame too long. start again
ooops, no strip left. Go out and buy new strip. cut new strip heat to red heat allow to cool drill hole. heat to red heat quench
polish
find wire brush for Dremel oops,broke quenched strip, too brittle, Gave up on polishing idea.
cut new strip heat to red heat allow to cool drill hole heat to red heat quench
and temper to desired point
temper temper!
ooops, no strip left. Go out and buy new strip. cut new strip heat to red heat allow to cool drill hole. heat to red heat quench temper
About 10 or
ITYM 10 or 20 days?
:)
-- Peter Fairbrother
Reply to
Peter Fairbrother
Or a carbide drill....
But buy at least two, if you buy one it will most likely break. If you buy 2 or 3 then either all or none of them will break. Buy 4 and no matter how cackhanded or unlucky you are you should be able to drill one hole.
Of course circumstances (see my last post) may conspire to increase the hole requirement - so buy 10. You will get at least six holes from ten drills. Hopefully that will be enough.
Note, if you buy 2 or 3 then there is no correlation between whether they all break and whether, if you had only bought a single one, that one would break.
-- Peter Fairbrother
Reply to
Peter Fairbrother

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