Member postings for Andrew Johnston

The lever operated tailstock on my cylindrical grinder uses a spring to load the dead centre.

Andrew

No problem with the measurements, I'm bilingual.

The gauge plate will be ground on the wide surfaces as standard, so the 1/4" dimension will be accurate but the 3/4" dimension will not be. The only exception is that square section gauge plate is ground on all four sides.

Personally I'd draw file one edge to fit rather than lapping. I use micrometers for accurate measurement, not verniers.

Andrew

Rectangular gauge plate is ground to tolerance on the wider sides (usually a thou or two) but left as sawn on the narrow sides. What size did you order?

Andrew

Lever operated tailstocks often come with a stop for accurate, and fast, depth control.

Some of us do repetition work:

All done on a lathe with a lever action tailstock.

Andrew

There is an art to reading datasheets. They're often concise, important information can be in footnotes, or missing, and they aim to present the part as the best thing since sliced bread without telling outright porkies. Standards vary from country to country as well.

For example MOSFET datasheets sometimes quote a headline current rating, but in the real world that rating is not achieveable.

Andrew

Yes, it's a spiral point tap, intended for machine tapping of thru holes; the swarf is pushed ahead of the tap. Like spiral flute taps they work fine when used by hand.

Andrew

Not strictly true; imperial taper pins are 1:48, whereas metric are 1:50. More confusihgly imperial taper pins are specified by the diameter of the large end, while metric taper pins are specified by the diameter of the small end.

Andrew

A plug tap is the last in the sequence of hand taps to be used. It has a very short taper, 1 to 1.5 times the thread pitch. One might get away using only a plug tap in brass, but not in gauge plate. If only one tap can be purchased buy spiral flute taps. They are machine taps intended to blind holes, but are fine when used by hand.

Andrew

In the fully tempered state gauge plate is between 15 and 20Rc, so not particularly hard. However, you will struggle with plug taps only, unless you go for a shallow thread engagement. I expect you will need rather less than 50%. It would be sensible to use a taper tap. New ones, from Drill Service, are around a fiver.

Andrew

It's not normal, should be capable of much bigger depth of cut. Stalled means the motor slowed and then stopped. Is that what happens, or was the belt slipping instead?

Andrew

A roughing cutter has lower cutting forces, so can be run at higher feedrates. A big advantage is that the swarf produced is in the form of chips rather than long and thin chips, so the swarf is easier to clear. While roughing cutters do not leave the best finish it is adequate for many applications. To sharpen roughing cutters the flutes need to be ground on a helix, which is why the the lead is listed on the cutter shank.

Andrew

Correct, although it's all Greek to me.

Andrew

Speak for yourself, but don't presume to speak for others.

Andrew

It can do, by probably not critical in this case. It will be best to start at the beginning. First, is the relay coil specified as AC or DC?

Andrew

Forward drop for white LEDs is generally 3-4V, plus a drop across a series resistor, makes 6V about right.

Andrew

I use a very fine Arkansas stone to remove dings on my milling machine tables, and elsewhere, without damaging the surface. Any professional tool supplier will stock them. Can't see the point in trying to make one.

Andrew

Running at slower speeds makes the wheel appear softer, and therefore it will wear quicker. Practically I expect that running at 25000rpm will be fine.

Andrew

Probably 1206, ie, 120 thou by 60 thou, or 3216 in metric. Huge, should be no problem removing it.

Andrew

Same as 66110rpm.

Andrew

How big is the resistor and what sort is it? For standard thick film chip resistors I use two 80W irons, one on each end. Even with glue once the solder is molten the resistor can be removed by pushing gently with the irons.

Andrew