Member postings for John Stevenson

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Bought two drills and 4 battery's for about this price [ each ] some while ago 1 1/2+ years ? from Argos on offer to replace the varied selection of old Hitachi drills and flat batteries I had accumulated over the years.

Very pleased with them, they have done sterling work and still impressed with them.

They are just badge engineered model of the DeWalt at twice the price.

Flog the jeep and buy a new Colchester, you won't regret it.

Last longer and people will respect you No one ever calls a Colchester a hedgehog

Got the bigger brother to that one. Awesome machine.

Biggest job it has had to do was remove the rusted in allen screws from the bed of a 72" Lumsden grinder.

These are big vertical face grinders and the bed consists of many triangular segments that contain the coils for the magnetic table with the top surface being held on by a zillion allen screws. Because these run continuously under coolant when the coils short out it's a major job to replace them.

The small machine like the one in the picture takes about 20 minutes to remove a M10 allen screw. The larger machine takes about 5 - 7 minutes.

From memory, total time to remove all the screws was about 4 days

Is this the type of stud extractor with a tapered left hand thread ?

If so chuck it at next doors cat as all they do is wedge in even tighter.

Think about the action as it winds in.

There are other various types like the shallow taper with 4 hollow ground sides and the spline type where you hammer them in and there is no progressive wedging action.

Also bear in mind that sometimes you just can't remove a broken bolt or stud by unwinding it due to various reasons like galling or real old age, rust etc. In cases like this you have to be prepared to drill out and retap.

Chances are it's a slightly undersize blank and it is 12DP.

PA is more than likely 14.5 given it's year.

Terrible description Michael, it was Grant that invented the Odonograph, not Willis.

What is the world coming to ?

From practical experience over many years I have found that carburetor manufacturers do have their own standards.

For instance on an Amal pre-monoblock and TT carbs, the thread at the bottom to hold the jet block in is 9/16" x 20 - 20 thou.

Tap it out 9/19" cycle and you will get air leaks and it won't run right ever again. Without looking in the special taps drawer thee are others as well but can't recall them off the top of my head.

[ Still have the Amal tap and a 14.2mm spark plug thread tap so you can fit MOD screened plugs into your engine ]

Edited By John Stevenson on 05/05/2017 08:16:49

John,

Can't help at the moment as I'm away from my computer but Geoff has hit the nail on the head in that you need to use the XZ plane with G19

Very political though.

They can ban diesel cars and force you to move to petrol or hybrid but how about vans and lorries ?

There are no petrol vans sold in this country other that possibly a few rare ones and certainly no lorry's.

So are these going to be exempt ? if so it makes a farce of it.

All it will take is two lorries on every motorway slip road and every road into London, lock them up and go home for the day.

Edited By John Stevenson on 03/05/2017 18:57:23

Damn, missed that give me a minute to get it removed...................................

Firstly a good call by Niel A on the 0.25" CP form.

Circular Pitch isn't used much nowadays and even when it was it was usually used on linear movement.

DP always has Pi somewhere in the calculations but CP is a fixed linear move.

Ideally racks on machine tools should be in CP as then the hand wheels will relate to proper numbers. a 16 tooth pinion in 0.25" CP will move exactly 4" per rev.

Anyway to get back to the original problem. If James wants to make a cutter using the method outlined in the Gears and Gear cutting book then the following diagram should help.

The red which is hard to see as the green overlays it is one tooth of a 37T gear @14.5 PA and 0.25" CP or 12.5664DP the circle on the left is how the size was drawn using two chords on the curve to find the centre and mirrored to the other side.

So James wants two buttons at 0.700" diameter, spaced at 0.799" apart and a blank cutter of 0.250" wide.

Once the buttons come into contact with the edges of the blank he needs to infeed 0.224" to form the shap but when cutting the gear he only needs to infeed the cutter 0.175" deep.

This is a slightly different way to how Ivan Law does it in the gears book. He touches the OD of the buttons on the face of the blank and then moves across, then feeds in.

The method above is the one devised by Grant in Victorian times and resurrected by Unwin in the 1980's.

HPC at Chesterfield list Mod 2 gears in Nylon off the shelf, also list Tufnol if you want to use the cheque book engineering approach and get running faster ?

TBH at 6 rpm and made from Delrin a 13 DP, 0.25" CP or 2 Mod in either 14.5 degrees PA or 20 degrees PA will work in this application.

You only have to look at some of the early gears where they were just cut with a 3 cornered file to accept this.

Ok not geometrically correct but it won't be racing at Silverstone this weekend.