knurling kit.

This will test your patience. The nice chap at Hemingway has sent me very quickly a lovely collection of materials and instructions to make a knurling tool.

I have seriously underestimated my abilities , but more importantly my vocab,

I also need a shedload more gear.

I need to drill and tap 1/4 BSF. - can you get taps with the appropriate sized drill , or do i get a 1/4 tap and a 5.3mm drill ?? (= number 6 drill)

The 2 side plates need a spacer and the instructions say 'transfer the

2 side plate holes to the spacer and other side plate' . How is this best done ?.

"..transfer these 2 holes into the spacer and open up these holes to

9/32" dia " - how do you open them up ?, does it just mean drill with a 9/32 drill having drilled them to 1/8" to start with .?

" drill and ream the 2 1/4 " dia holes for the silver steel pins. What do they mean by ream ?. why is not just drill the holes to 1/4.

Thats just the first paragraph !!!!. I think it will be a fantastic project to get me going (or it'll stop me totally).I suspect I could be making too much of it all but don't want to go straight into slapdash mode. Thanks as ever Nick

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Loading thread data ...

If that's the right size (don't care for imperial threads :-)). You can find sets at Lidl or Aldi, but the quality will only be enough to finish one kit.

Drill one piece, clamp them together and then drill through the second piece using the first one -together with the same drill size- as a transfer-guide.


Reaming is done with a reamer. It is kinda not a so good cutting drill making a perfect surface finish. In one word: Reamer.

Seems to be the bearing surface.

Nick (no new words learned )

Reply to
Nick Mueller


The silver steel ping are are ground to size and you want a god fit in the hole. Contrary to popular belief, drills and not good at drilling accurate round holes. The holes tend to be oversized and slightly triangularin shape. To achieve an accurate hole you drill slightly undersized then use a reamer to finish it off. Always keep the reamer turning in the direction of cut.


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In article , writes

Do you mean overestimated?

You will make life very hard for yourself if you use a 5.3mm tapping drill for 1/4" BSF. Most tables of tapping sizes suggest too small a tapping hole, to give 85-90% thread engagement. This is totally unnecessary, and gives very serious risk of breaking the tap (particularly in small sizes or tough materials). A thread engagement of

60-65% will give you more strength than the core strength of the screw, only take about 50% of the tapping torque, and reduce the risk of tap breakage several fold.

I suggest you get hold of a copy of "Drills, Taps and Dies" by Tubal Cain, No 12 in the Workshop Practice series. As well as a very useful text, the tables at the back are the best collection of sensible tapping size recommendations I have seen. Only about £7.

Others have given you some good advice, and the above book should fill it out. You will need to understand the processes involved in drilling; a drill going through solid material will always drill oversize, but a drill opening up a slightly smaller hole will be much less inclined to do so. If you do not have a reamer, use a drill a few tenths of a mm below target size, then follow up with the correct size. I would recommend you get, and use, a 1.0-6.0 mm drill set, and use them even for imperial dimensions as the increments are much more sensible, but YMMV.

Be aware that silver steel expands by a few tenths on hardening; thus your beautiful sliding fit will probably become a heavy interference fit.

And of course learning to use your knurling tool will be a whole new adventure; it is one of the hardest of the basic operations for beginners to get right, though it's fairly easy to get usable "nearly right" results.

Quite right!


Reply to
David Littlewood

In article , David Littlewood writes

Sorry, I meant to say that you should use a 5.6 or 5.5 mm drill (60 or

68% thread engagement respectively).


Reply to
David Littlewood

I've observed this on a few occasions recently when making parts to size using a mike with a vernier reading the 10th, and assumed it was my inability to measure correctly. Thanks for a useful piece of information!


Reply to
Alan Bain

Just as a little background, thread sizes are nearly always quoted in terms of their nominal outside diameter. This is slightly larger than the actual outside (or 'Major') diameter.

You are tapping a hole so the hole needs to be approximately the size of the core of the thread ('Minor' diameter). The ratio between major and minor diameter varies with the thread geometries (BSF, BSW, Metric etc etc........and there are lots!) and the usual sizes are given in many and various tables eg the 'Zeus' book or plenty of other texts. Life is way too short to try to learn all the right sizes so we pretty well all have a copy of our favourite book or table in the workshop and look up the necessary size for the job at hand.

There's nothing 'wrong' with any standard thread, metric has become a pretty universal worldwide standard which makes it a useful system for holding bits of toot together - because it IS universal. But there is a lot of gear still around with Imperial and American-English sizes and for some tasks non-metric threads can be preferred and the sizes more progressive.

It sounds like you could do with a 'Basic Workshop Practice' book and I'm sorry I can't recommend one - I guess it URME .

When you are tapping, you will need some lubricant on the tap grease/tallow/Tapping compound (RTD, Trefolex etc ) and don't try to just wind the tap straight through. Once it's engaged and cutting, go in about 1/2 turn and back 1/4 turn, in succession, you will feel the swarf chips break as you turn backwards. Work your way all the way through in that fashion +1/2.... -1/4. With a 1/4" tap you're pretty safe and shouldn't have any real trouble

Good luck, Richard

Reply to

Unfortunately, he didn't tell you the trick. I'll do that now: Also harden the mike!


Reply to
Nick Mueller

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