Member postings for Andrew Johnston

The normal CCMT inserts work fine on brass. For aluminium use CCGT inserts. They are polished and have a large positive rake. With aluminium watch out for the swarf bird nesting.

Andrew

I have a professional 2-axis DRO on my vertical mill and nothing on the lathe.That suits me fine. The DRO on the mill is the single most useful accessory I have bought, but I simply don't see the need for one on the lathe. I am pretty sure the DRO scales on the lathe would interfere with operation, and clash with other accessories, whereas on the mill they are clear of any interference with operation.

Andrew

My standard cutters are the YG K2 range from Cutwel, they last very well despite being driven hard.

Andrew

It's an old school trick that should work, although I haven't tried it. The modern equivalent is a cutter with a radius (less than 1mm) ground on the corners. These cutters are expensive, circa £45 for a 10mm diameter one. I reserve them for final cuts when I need a good finish and a flat surface. I used one to finish the valve chest faces on my traction engine cylinders. This shows the sort of finish that can be achieved:

The part is a heat spreader, in copper, for an experimental high power inverter using silicon carbide power devices.

Andrew

Drill Service have a 10-32UNF bottoming tap for £4.60p, plus VAT of course.

Andrew

Correct! My Bridgeport is flexible in two senses. It is versatile, but also not very rigid. It performs better with smaller cutters running reasonably fast, unlike the horizontal mill but that weighs 3500lb.

Andrew

The plate refers to an RMS voltage, the capacitor needs to be rated to withstand a peak voltage.

Andrew

Current BGA guidance is to use oxygen above 10000ft, although I have been to 14000ft without. My oxygen system is constant flow, 2 or 4 litres a minute, whether you need it or not. The cylinder capacity is 630 litres and 137 bar when full. The highest I've been in a thermal was 16000ft, in the Alps. When I went to put the mask on the rubber economiser bag failed, so I ended up sticking the low pressure pipe from the regulator in my mouth. The highest I've been in wave is 23000ft, over Cheviot in Northumberland.

Andrew

It's definite that they don't know what they are talking about!

I have oxy-acetylene, argon and propane cylinders at home. The first three are in the workshop and the propane cylinder lives outside. All welding, silver soldering and gas heating is done outside. If i have the oxygen cylinder from my glider at home it lives in the house along with the parachute.

As a private individual one is entitled to transport a small acetylene cylinder in ones personal transport provided ventilation is provided, in other words open the window.

Andrew

I've got three, two from the 1940s and one from the 1990s. They are my go to source for engineering information. The older ones in particular have good information on imperial threads and old metric thread standards.

Andrew

I use a mix of 12mm and 16mm holders. With the 12mm holder I can take cuts that will stall my 3hp gearhead lathe running from a 3-phase supply. The choice of holder is down to availability. Holders for some of the less common inserts are only available from 16mm upwards.

Andrew

Thanks for the explanation. I have the originals of most of my photos, so I'm not worried about my albums disappearing. I doubt I'll bother creating galleries, time is precious and there are many other things to do.

Andrew

Only two methods, the switch only changes the motor direction. That is because the backgear is only two gears and therefore reverses the spindle direction for a given motor direction.

Andrew

So does that mean that my albums will disappear and I will need to upload all the photos again?

Andrew

In my experience a slitting saw on an arbor unsupported at the outer end will go walkies if the depth of cut in more than a few millimetres. On the other hand using a horizontal arbor, supported at the outer end, one can go as deep as the saw will allow with no tendency to wander.

Andrew

Thread depth for a 40tpi Whitworth thread form is 16 thou. So core diameter is 0.2" minus 32 thou, equals 0168". Say we want 75% thread depth so add 8 thou to the core diameter to get 0.176". Call it a number 16 drill or 4.5mm. In brass I'd probably drop down to 4.4mm. Not a lot of thread to play with!

Andrew

I have an inkling that the WF stands for Whitworth Form.

Andrew

No interest personally, but there are quite a few people on here who are. You might find it worthwhile to reflect upon why those people haven't replied to your posts.

Andrew

I have a Haimer Centro:

Claimed accuracy is 2 microns not that I have any way of confirming that. The only problem is that (as Bernard says) it does need a fair amount of headroom.

Andrew

Now I see why the OP wrote in his profile that he'd never taken a class in anything.

Bored now, so going to carry on making parts on the repetition lathe.

Andrew