In message , Dave Baker writes
One drawback is that the shank is left hard and likely to slip in the chuck under extreme load. I guess drills from SKF/Dormer etc. are part annealed to avoid this problem.
regards
For aluminium, the best are fluteless taps. They displace the aluminium, rather than cutting a thread, which strengthens the thread through local work hardening. For hand cutting mild steel, the best are HSS straight flute taps.
You will find all the taps you need, and more, here:
Lidl had tap and die sets for about a tenner - made in Germany.
In my past work experience; the second type you mention was used with small taps mainly, and the first type with larger ones. I don't remember seeing any small straight bar type ones (my Screwfix HSS set has only a large straight bar one). I think that you will find the tee handled chuck type wrench more comfortable and more "sensitive" to use with small taps (in my humble opinion, of course).
Sylvain.
The message from "Dave Plowman (News)" contains these words:
Were they actually made in Germany, or did they just have German approvals?
HSS - no question.
Buy British (or German) because Lucky Golden Hedgehog just aren't worth taking out of the box.
Avoid multi-size sets, unless you really need everything today. In general you're better off buying one-size sets of 3 (taper, second, plug) from someone like Presto, as you need them. With metric there just aren't that many sizes you need, so the cost of decent ones isn't onerous.
Three flute are stronger than 2, twin flute are very easily broken in these small sizes.
Have two sets of M3. It's a common size and they're all to easy to break.
For sheetmetal, you need a second and can manage with just that. For blind holes you need a plug too. For deep holes (thick sheet) then you will start with a taper, especially for large ones and in steel. In thin aluminium, I'd probably start with a second anyway - taper makes such a small cut on each turn that it's too easy to strip them by accident. So yes, for aluminium sheet work on a small budget, you can manage fine with a single second in any size.
You'll need a couple of tap holders, because M6 wants a nice big one with a wide bar and M2.5 needs a really lightweight one, such as a T handle and collect chuck.
Use lubrication. A squirter of real RTD for steel, or anything for aluminium (plain light grease is fine). A squirter of meths, acetone or even white spirit is handy for washing swarf out. Yes, you can cut aluminium dry, but it's a pain and it ruins your taps as the edges gall. You certainly need grease in a deep hole, just so you can back out and clean the chips out with it.
Proper back-and-forth chip breaking action please. Spirals are pretty, but they'll jam.
Where do I buy carbon steel taps from, that aren't made of cheesemetal ?
Secondly, the improved chemical resistance of HSS is preferable for work on aluminium, in case I ever have to clean them.
Facom, the parallel splined pin sort. They beat the pants off any of the tapered bolt-wegders, no matter who made them.
Get the appropriately magic-sized drillbit to go with them too, and keep it with the extractor, not in ther general drills box.
That's because engine building is easy. New, clean components that fit together. You care about measuring instruments and torque wrenches, but wrenches and sockets themselves aren't asked to do all that much.
Now try working on restoring old boat engines, where the part is 80 years old, spent all its working life in salty mud, and is irreplaceble. Now _that's_ when the properly sized and shaped Snap-on
6 point flank drive pays for itself.
You think so do you?
New, clean components that fit
Who do you think strips down the old rusty donor engine that gets turned into a race one?
Before I build a nice shiny race engine with new parts I still have to strip down the old scabby rusty donor engine which might be 30 or more years old with exactly the same problems as your boat ones. As I said in my previous post it's for that occasional badly corroded fitting that expensive tools might help you but for everything else normal quality tools manage just fine.
I prefer a T-handle because I find it easier to keep square to the job and still get a reasonable torque on the first turn or so (M3-M6 into ali mostly).
Chris
I'm sure Dave will correct me if needed, but I've read that high performance versions of production engines often start with old 'weathered' cylinder blocks etc. So they'd have to be re-claimed from old and often rusty engines.
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