Member postings for Stuart Bridger

Thought it was amusing that he reversed the spindle rotation before starting his parting adventure

For me the biggest issue with the US and older UK plans is not threads, but the use of fractional dimensions. They are OK for woodworkers but don't sit well with the lathe or DRO. A recent rediscovery of my 1980 Zeus book really helps here.

I am currently going though this exercise with Elmers Mine Engine, no issues so far
2-56 > M2
3-48 > M2.5
5-40 > M3 etc.

Mind you I am still working in imperial for the main dimensions ....

I remember asking this exact question to my metalwork teacher at school. He told me off for being a smart arse, most likely because he couldn't ask the question. There is a lot of info on this subject out on the internet, the TLDR answer is the hole does get bigger.

I was taught in metric at school in the '70s. Started an apprenticeship in 1980 with British Aerospace and all apprentice training projects were imperial. The only "metric aircraft" at the time was Concorde, athough the airbus work was coming online. I do still "think" in imperial, I can visualise 5 thou but can and do work in both systems. Luckily my lathe has dual dials and I have a DRO on the mill.

I was working in the USA earlier this year. Hotel shuttle bus had a dry powder extinguisher behind the drivers seat. The pin was missing. Person sat next to me manged to kick the trigger getting out of the bus. That was a surprise!

+1 for the Volkel set, but somewhat surprised that the price is nearly double what I paid, but it was a few years ago.

I bought a carbide spotting drill 5mm x 50mm from MSC a number of years ago. It gets used in the lathe and mill. It certainly wasn't cheap, but a worthwhile investment.

Bit of time in the shop today, initial conclusiion is that the issue was a dodgy die.
Brand new split die from Tracy Tools, stock turned to dead on size, no lead in taper, Trefolex.
Thread cut under power with no issues at all.

Howard,
I can confirm that the die holder is on a sliding mandrel. I now have all the pieces in place to get this sorted.
Just need some shop time....

This a a downright dangerous and potentially lethal situation,

Two pin plugs are designed for double insulated equipment, where there are two independent functional levels of insulation that prevent contact with anything that could come into contact with live components. One of these is typically a plastic case. The fact that a machine tool has exposed metal means that it can never meet this criteria.

It needs to be properly earthed, end of....

Edited By Stuart Bridger on 12/09/2019 14:57:34

Hi Chris, how did you work out how much to "beef up" the original design?
Also having read Mike's article, I did find his rapid/return feed logic a bit difficult to get my ahead around, but i guess it makes sense when you understand it.

Nice project, inspiring. Especially given the cost of original equipment units.

A few observations, no time for practical tests yet
ID of my dieholder is 20.72 mm (a bit bigger than 13/16 - 20.64mm)

Original die is 20.48mm OD
New split die is 20.49mm OD (Tracy Tools)
Both are a slightly loose fit in the holder, without tightening screws - I will most likely make a new holder a bit closer fit.

New solid die (from Arc Euro) is 19.90mm OD - New hold holder to be made

Screws in the die holder are cup point, not cone point, so they need to be replaced

Thanks for for all the advice, some really useful stuff there. I have today ordered up some trefolex
and a couple of new dies, one split and one solid. I will update further when it arrives and I have had time to experiment.

Thanks for the feedback. I must have a very short memory. Last weekend I successfully cut two threads M2.5 on a 3/32 bar. Apologies for the mixed units 2.5mm is 0.098in on 3/32, 0.09375, so about 4 thou under.

So three possibilities, 4-5 thou under is the trick, I got lucky with the die adjustment or the die is a better quality.

I will try again with 4-5 thou under the nominal major and see how I get on.

I am fairly sure that the answer here is practice, but would appreciate any advice.

Trying to cut an M3 x 0.5 thread with a split die on mild steel. Two attempts have failed so far with stripped threads. Adjusting the die, I'm either not getting the thread to start or the thread is so fine that it strips very easily.

I am using a lathe with a tailstock holder, by hand.

What major diameter would you recommend starting with? Dead on 3mm?
Possibly the die is not of best quality, would I better off going for a die that isn't split? If I do carry with a split die, what's the best way to set the size?

Thanks

Just don't use a conventional silicone based sealant. I made that mistake

Had a few minor "belts" over the years. Nothing too serious and 100% caused by lack of concentration. Only ill effects being muscle strain in the arm closest to the contact. It's certainly not a pleasant experience.

The answer is to prevent current flowing across the heart, resulting in a cardiac arrest.
One hand in the pocket means that current should flow down the arm and then down the body to ground.
If the other hand is contact with the casing of the machinery, then the current will flow from one hand to the other across the chest. The one handed technique should make a shock much more survivable.