Member postings for steve de24

Martin D, thanks for your reply.

Steve

As well as the drilling issue Michael Walters also wrote :-

"Also when parting off, the thinner HSS blades, although good, if too much of it is exposed from it's shank it will deflect and part off in a radial movement rather than a straight one."

Beginners question : how much is too much?

Steve

Rod, thanks for the info on where to get the Mills plans.

Steve

dean Clarke 2 wrote "You could try .......... the Mills 1.3"

Now there's a name I haven't heard in a very long time. Over 50 years ago I bought (for a very small sum) a clapped out Mills , my very first engine. It still started and ran ok if I fitted a large prop but was very down on power. With it I learnt to fly control line sedately until I could afford something better. It ended its days when fitted to an equally cheap, second-hand, much repaired and very over-weight Slicker free flight plane. Who would have thought that this model, with barely enough power to keep it aloft, would catch a thermal and disappear forever. Happy days. I didn't realise it was a bar stock engine.

Steve

I think I'm more worried by the Royal Navy sailing two large ships, designed to be invisible to radar, through one of the world's busiest shipping lanes with lots of other cross channel vessels cutting across their path.

Steve

Bill,

I would recommend :-

Mechanical Engineering Design by Joseph E Shigley.

Get it from your library or buy a second hand copy from amazon (less than £3 at the moment), but make sure you get a metric edition if those are the units you are familiar with (it tells you on the front cover).

Steve

The work complied with MBS (My Bloody Standard) which governs the work in my shed.

Steve

Well I'm just off to the shed to tap 3 M4x0.7 threads and I'm not telling anyone what size drill I'm using - but I know they will do the job I want.

Steve

Iain, thanks for the tilting table info.

Lambton, thanks for the link on tapping drill size.

Steve

Iain, good to hear that you were successful producing a usable thread.

That is a nice tilting table you have in the pics. How big is it and where did you get it from? I'm looking to get something similar for myself.

Steve

Well said Rod and good point Jason.

By coincidence I recently had to make a special M8x1.25 steel nut.

Tubal Cain recommends 7.1mm drill but I used 7mm because that's all I had. Used a £3 carbon tap from Tracy Tools (usual disclaimer) and had no problems at all. The thread the nut is fitted to has an OD of 7.98mm and it is a nice smooth fit.

For interest I've just screwed the nut onto a M8 bolt from a national hardware store. The bolt has an OD of 7.78mm and the fit is poor (wobbly) but is about the same, certainly not worse, than the nuts that came with the bolt (I made sure the same number of threads were engaged when I did the comparison).

Makes me wonder what the strength of these 8.8 grade nuts and bolts actually are compared to what they should be.

Not a scientific experiment but perhaps of interest.

Steve

Bill, very nice engines.

Is it the Nalon the engine with an unusual needle valve - a diagonal slit instead of a drilled hole and a flat ended needle which covers up more of the slit as it is screwed in - or is my memory playing tricks with me?

Steve

Graham, have you considered the 'Warbler', a 3.5cc diesel for model aircraft. It was serialised (with plans) from May to July 1999 in Model Engineer. Steve

Jason, I'm looking forward to reading this build thread. Thanks for posting. Steve

Martyn, I side with the previous posters urging you to consider buying bolts with rolled threads. Machine cut threads could easily reduce the fatigue strength of the bolts by a factor of 2 or more (and that would be with aerospace quality machining/inspection etc). Making sure the bolts are correctly torqued up when fitted is the other important factor to get right with regard to the fatigue strength of the bolts. Steve

Or is it proof that Neil has spent far too much of his life looking at star maps where someone has joined up the dots to make imaginary figures........

Here is my explanation. The ends of a con-rod are pin jointed by the big end and crosshead joints. When the con-rod is about to buckle under compressive load it will be bending into a half sine wave. Bending stress is proportional to rate of curvature which is zero at the pin joints (they are hinges and can't transmit bending moment) and max in the middle of the con-rod. So the rod section can be reduced at either end with no loss of strength - but it has to be large enough to carry the compressive load. Steve.

John, clockmakers use Horolacq. I think it's available in clear. Steve

I think Chris has made the most sensible suggestion. Just use 1", 2" & 3" instead of 25, 50 & 75 mm and calibrate the micrometer at the 0.4mm, 0.8 and 1.2mm points on the micrometer scale instead of calibrating using the 0.0 point.

Would the outer diameter of ball bearing races serve your purpose? Anyone know what typical tolerances they are ground to? Steve