Here is a list of all the postings john halfpenny has made in our forums. Click on a thread name to jump to the thread.
|Thread: Centec mill cutter speed|
Or use a cycle computer. I have an £8 one. Set the wheel size as 1667mm, and the km/hr display is an analogue of rpm - ie for 24.4 km/hr read 244 rpm. The pick-up is small enough to put just about anywhere accessible on the spindle. A bit of maths on wheel size will accommodate a reduction gear.
Edited By john halfpenny on 10/08/2020 17:33:37
|Thread: Training school auction|
Nevertheless Dave, we cannot all wash each others windows.
|Thread: Make your own Tokamak|
Have a look at Iter site tour videos on you tube. The latest, from a day or two ago, shows the massive engineering effort as assembly starts. The magnetic field confined within the Tokamak is alleged to have power sufficient to lift an aircraft carrier. I can't help thinking we shall more likely rely upon windmills and solar panels.
|Thread: Sieg SC4 Carriage travel limited by collision with splash shield|
James, probably not an immediate issue, but make a plan to fix it - otherwise it will get in the way when you least need a problem
|Thread: Lathe turning speed in relation to different metals|
Mr Wheeler, I thought it was incisive and excellent advice-but it disappeared.
|Thread: 33mm Spanner|
That's a good spot for a large mouthed, slim spanner that is not too long. I'll be getting one to keep by my mill.
Edited By john halfpenny on 26/07/2020 08:44:29
|Thread: Kennedy Hacksaw|
Half a turn clockwise opens the valve to allow the blade to drop more quickly. In other words it gets the blade quickly down to the workpiece , then turn it back to reinstate full damping. With 160 weight oil, the fully damped downward movement is very slow, so the valve speeds things up.
You'll have to make one. Here's a simple version I made last weekend; single bolt mounting underneath is ok. 160 weight oil ( like treacle) works well in the dashpot; much better than engine or axle oil, which is far too thin.
|Thread: Attempting To Make My (new to me) Zyto Beautiful|
At least link rhe bottom of the leg frames, and put in a diagonal to stop lozenging. No much work, but a big increase in lateral rigidity. The toppling risk is not insignificant.
|Thread: Interesting bike ride today|
We have bats, and when building a new workshop the local authority insisted on a bat brick, with a narrow slit as entrance. I put a bat box on the inside, with viewing panel normally covered by a hinged flap. But when I look, all I have ever seen is a startled blue tit. The bats are happy in the house loft, judging by the piles of droppings at one end.
|Thread: Fiber change gears|
Henry Ford used layered tufnol for camshaft gears on millions of cars. Later he used macerated tufnol, and later still a type of nylon. No problems from engine oil.
|Thread: How to join?|
Well, it's got two chances. Not very helpful I know, but an unknown.
I think 'Nivellator' is a trade mark, or at least an invented word -not uncommon in German. The title of the patent document translates as 'Level (surveyors) and measuring device'. Knowing this I suspect it belonged to my wife's grandfather, who was a sewage works foreman in the 1920's, no doubt with an interest in the flow of fluid through pipes, probably without the assistance of pumps in his home location.
See my post above about language. Thank you Neil
I think you are right Robert. The scale allows for 1-10 yards, which would fit with drainage works. The spring is very very strong; not sure why that is so, but suspended from the loop, the scale reads 0 degrees with the bubble level. Thank you.
|Thread: is it a flycutter ?|
How about a tool for twisting wire strands together?
Guys, the french and german is simply a translation of rise and fall. I wonder if it can be used to estimate the hieght of, say, trees. Certainly the inclination can be set with help of the level bubble, but why the string and spring? A tape could measure base line, and give hieght using tangent tables. But why the complication?
You both have got no further than me. Plenty of pictures on the net, but I can't see it being a parachute tester. Any idea of how to use it? DRPa is reference to a German patent application, but without a number that is another dead end.
Can anyone identify this measuring tool? It seems to be some kind of gradient measuring tool, with a thin string on the winding drum which passes through a slot at the end of the black arm. The plated ring can be pulled against the return force of the very strong spring. The conversion dial is 'degrees to inches per yard, fall or rise', and 'degrees to proportion, fall or rise'. A spirit level bubble sits in the oblong feature at the centre of the 'nivellator' dial, which rotates with respect to the black casing.
|Thread: is it a flycutter ?|
A tool with plain shank and sideways peg would rotate into the slot and be retained by the plate. Clockwise rotation would keep the tool in the bit at the slot end, whilst perhaps drilling, screwing or cutting something, thus ensuring no rotational slippage of the tool in the bit. That implies much applied torque. Guess the tool?
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