Member postings for Dinosaur Engineer

A simple 2D CAD app. can solve many trig calcs quite quickly.

Over the years I have seen quite a few big 4 Jaw D1 chucks with bruised taper sockets. I think it is essential to provide some support for these heavy chucks when fitting to the hardened lathe spindles so that the chuck is supported & aligned to the spindle. A properly made chuck board to support the chuck at the correct height should do the trick. Chucks of 8" or over are too heavy to manually fit to the lathe spindle without some kind of aid to align & support.

Make sure these boxes are stored away from direct sunlight - they don't like U.V. radiation . Pleas don't ask how I know !

You could use a milk container with water if you haven't a suitable weight. Should be a little more accurate than sack of spuds ! You could use the supermarket veg scales to check.

Most torque wrenches are only accurate to 4%. I have a widely inaccurate but consistent old 60's snap-on wrench that I have to use with revised torque values ( on paper).

Most industrial checking equipment is by electronic torque analysers these days.

South Bend's "How to run a lathe" is free on the internet . I think the last free copy was 1958 which is a bit later than the link copy above. A few Google searches should find it quite easily.

If ever you wish to produce a slightly smaller size tapped hole to give a "snug" shake free fit on a commercial bolt/screw, then using the number 2 tap from a serial tap set ( 2 rings) will give the desired result.

And the worse thing you can do is to use a posi-drive screwdriver in a Phillips screw and vice- versa.

I stand corrected Silver steel is an alloy steel - normally contains Chromium and Manganese in addition to the carbon.

Gauge plate is similar in composition but contains further additions such as Vanadium & Tungsten to give improved properties.

All British gauge plate I've ever seen is oil hardening to minimise cracking /distortion. Quenching in water/brine is asking for trouble. Gauge plate is not a plain carbon steel & is an alloy steel formulated for oil quenching.

The D bit round stock mentioned is probably "silver steel" which is a plain carbon steel & is water /brine hardening. I've never oil quenched silver steel so cannot voice an opinion on this.

The more exotic "tool steels" have various additives to give high hardness/toughness/min distortion to allow for oil quenching.  

Edited By Dinosaur Engineer on 03/08/2015 02:14:15

Making the bar from tungsten ( if you can find any & expensive !) is one of the better ways of reducing vibration.

It's many years since I've seen one of these. Morse taper and brass/bronze hammer in a very convenient design.

Not sure about adjustment . Have you tried a little lubrication ? I would think you would need to knock out the roll pin & dismantle to find the cause of the problem.

Edited By Dinosaur Engineer on 05/07/2015 17:58:39

A simple internet search will reveal lots of information on "removing broken taps".

Edited By Dinosaur Engineer on 02/06/2015 21:41:32

Edited By Dinosaur Engineer on 02/06/2015 21:42:00

A lot of TV programs are made without the support of "technical experts" ( sometimes with but the recruiting people cannot tell an expert from a layman !). It does make for some hilarious viewing. My wife can't understand why I sometimes burst out laughing !

Tapping stainless calls for sharp taps. Tapping lubricant is a must. Oversize tapping drill size helps a lot. Using serial taps reduces the amount of metal removal with the 1st tap.

Boxford used to specify a low torque value as a preload to its' small range lathes ( 4 1/2 & 5" . This was checked with string wrapped around a chuck and a small weight.

lathe manufacturers purposely apply the tailstock height tolerance so that it may be a little high . This is to allow for wear.

A small height error will have an almost negligible effect on the diameter being turned.

If the M8 hole is only stripped half way through the 25mm section ( or is only tapped half way through) then re-tapping with a standard size M8 tap(s) and using an extra long bolt may be the answer . It's unusual to have a 25mm deep hole completely tapped through for an M8 thread . Normal practice is approx. 2D deep for say aluminium.

If you can shine a light through the hole this may help you to decide what to do.

I've had good experience with Helicoils but they do need to be put in properly. If they are good enough for aircraft parts they should be OK for most applications.

I've used High tensile steel inserts in VW engine cases without any problems ( ( 1/2" BSW cut down H.T. bolt with M8 tapped hole)

Edited By Dinosaur Engineer on 04/12/2014 21:02:26