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Member postings for Brian Wood

Here is a list of all the postings Brian Wood has made in our forums. Click on a thread name to jump to the thread.

Thread: 3/16 Cast Iron Rod
28/09/2020 12:27:37

Circlip,

What a heap of cast iron turnings that would create bringing a sash weight down from about 35 mm diameter to a little under 5mm while at the same time hoping it isn't full of inclusions and holds together while you are working on it.

It is a curious requirement anyway and even in sound material it will be about as fragile as egg shell in that size.

I doubt you could machine it successfully over a length beyond an inch or so. Maybe Nick's scientific supplier is quite right to charge properly for such material!

Brian

Thread: Another scam
27/09/2020 16:32:11

Hello Trevor,

A scam it most certainly is but don't run away with idea that the scammers are getting stupid, far from it.

There are plenty of very convincing and sophisticated means of fleecing very cautious people in circulation.

I'm sad to say that while there are still people foolish enough to answer the phone and be talked into taking all their money out of the bank, then giving it to a stranger who calls at their door later in the belief that he can be trusted to take care of it for them, simple scams of this sort will continue to operate

Brian

Thread: Bent woodworking lathe spindle
26/09/2020 13:37:05

Hello Larry,

I have found such methods very successful in the past and only simple tools were needed. Two examples

A bent track rod on our old Landrover after some idiot put a tow rope on it yielded to nothing more than a hole in a fence post and putting weight on the component in strategic positions.

I straightened a 5 foot long lathe leadscrew on a commission job with two vee blocks and a bent steel yoke bolted to the workshop floor as the fulcrum point for a long bar I could lean on.

The beauty of these simple methods is that progress can be seen as it takes place and there is a " feel" to the job that helps prevent overshooting

It might even save Robert money into the bargain!

Brian

25/09/2020 17:36:11

Hello Robert,

Is it badly bent? I ask because I have straightened a 3/4 inch diameter shaft from a screwcutting gearbox that had been abused by rough handling [forcing gears to ride over each other]

I made two softwood Vee blocks and belted the thing with a lump hammer via a length of 3 x 2 inch hardwood to the point where it ran true within a couple of thou over the length when held in my good lathe chuck. The job took most of the afternoon and I sweated off several pounds!

Perhaps worth thinking about

Regards Brian

PS You have a press I now recall, you could use that with care with the spindle supported on wooden Vee blocks

Edited By Brian Wood on 25/09/2020 17:40:49

Thread: TV Premier
24/09/2020 20:16:38

Sorry, I forgot to add that rather important information

Brian

Thread: Turbine blades
24/09/2020 17:58:38

Aero engine practice for blade anchorage is with fir tree roots which would be much too fancy for this turbine.

The steam turbine alternative is with a round anchorage formed on the end of a short stalk, an easier alternative in this case. The blades should have a little radial freedom, ie not held rigidly, and kept in place with plates either side of the root to prevent them 'walking out' of the turbine disc.

Regards Brian

Thread: TV Premier
24/09/2020 17:49:35

This release from the Rolls-Royce Heritage Trust will be screened on Monday 28th September at 9 pm

Enjoy

Brian

Thread: Why are BA taps so blooming expensive??
21/09/2020 09:41:03

Jim,

I know you have bought your taps now so I may be hounded out as a heretic by suggesting that near metric equivalents would be every bit as suitable; they are readily available and at sensible cost

JasonB pointed out that BA taps and dies are obsolete and made mainly for ME buyers at a premium price. As an example M3 at 0.5 mm pitch compares well to 7 BA at 0.480 mm pitch and to me it does seem like a rather expensive way of sticking to a drawing requirement just for the sake of it.

Brian

Thread: Dore Westbury milling machine
17/09/2020 15:15:58

Hello Kevan,

I noted Cornish Jack's comments--my own version is a Mk II with the gearbox in the head which I built about 28 years ago. It has served me well over all that time and done things which might have been very difficult or even impossible on a similar sized machine with a rigid back.

Some owners will condemn the round column and yes it can be a pain, but it has the real advantage of allowing you the freedom of use that a radial arm machine possesses. I use a laser lecture pointer mounted on the head to return to position, a matter of moments to use and over the length of the workshop for the beam it is accurate

It has one design weakness which could be disastrous and that is the key engaging the coarse pitch square thread in the column for height adjustment over the table. Mine cracked and because it is hidden inside the capstan it remains unseen. I was lucky and found mine in time by sheer luck to put it right. The fix is easy but of course it requires a lot of stripping down to get to the capstan

I specified my kit with a 3 MT bore, try and find one thus equipped if you can

Regards Brian

Thread: Taking Leave
17/09/2020 08:44:39

Andrew,

Will you not reconsider?

Your input to this forum is always to the point and you bring with it a lot of knowledge and experience. It would be a real shame to see all that walk away.

Take a break by all means and get some of your work done instead, you need to get a balance in the demands on your time and maybe reassess the topics you post on to reduce the pressure.

Kind regards Brian

Thread: Loc Tite
15/09/2020 18:20:11

Hello Alan,

Try drilling it out using a 5 mm drill, with the drill held in a pin chuck so the the operation is done by hand

Regards Brian

Thread: Change gear alternative material
10/09/2020 18:01:51

Hello Paul,

I have just restored a Churchill Cub lathe from 1947 which is in the same sort of size range as your Student. The larger tooth count wheels that came with it are all made in Tufnol. They run quietly without any of the 'ringing' associated with steel wheels and they are stronger than those made in cast iron in that the teeth will absorb punishment rather than chip or break off. I had metal chips to dig out in several places without leaving significant damage that would interfere with their function..

For a lathe of that size I was surprised to find them to be fine pitched at 20 DP like Myford wheels, albeit a bit wider at 1/2 inch

I would recommend them from about 55 teeth upwards

Regards

Brian

Thread: Change Gear Setup
10/09/2020 11:43:27

Correction, The 40--50 gear set up above should of course read idlers as the link, not drivers. Sorry if that has confused things

10/09/2020 09:45:19

Hello David, Roderick and Howard

Having slept on the ideas of yesterday, there is in fact a very simple general calculation method that will give David all the pitches [within reason of course] he might care to find

If we treat the Myford metric banjo as purely a means of introducing external gearing ratios and marry that with the ones available from the screwcutting gearbox, the formula becomes

Pitch in inches = R (outside) x R (box) x leadscrew pitch in inches, where R is the ratio in each case

Taking David's example of 60 tpi

P [1/60] = Ro x Rb x 1/8 Hence Ro x Rb is 8/60= 0.1333. Matching that with a gearbox ratio of 0.1667 [the value for 48 tpi] gives a nice simple result for Ro of 0.8

So, in this example, David needs to set up a 40 tooth driver meshing with a 50 tooth driven wheel,linked by driver(s) as necessary, select a gearbox setting of 48 tpi and the resulting pitch will be 60 tpi

So David it is up to you now. You have been silent thus far.

Send me a PM stating your email address if you would like a copy of the whole 32 values of gearbox ratio. I can't unfortunately post it this way, there is a compatability issue with my computer that I am unable to resolve

Regards Brian

09/09/2020 18:02:06

Hello Rod,

Yes, the calculation does agree, but as you say, they may not all mesh happily. Thank you for flogging through the workings

Regards Brian

09/09/2020 17:07:47

Hello Howard,

You have unfortunately fallen into the trap of ratios, otherwise nice try!

You actually need to HALVE the input gear size to achieve the necessary reduction to get a result of 60 tpi which means in this case fitting a 16 tooth gear in place as the driver. Without testing it I think the key to drive it will try to split the gear.

As a point of interest, a 64 tooth wheel would fit with my modified fitting to lower the banjo, in fact 80 teeth will clear the spindle.

Regards Brian

09/09/2020 12:59:24

Hello again David,

I have played about with your example pitch of 60 tpi.

There are limitations caused I'm afraid by the physical gearing in the gearbox itself and 60 tpi is really at about the finest pitch it will deliver. However, all is not lost and without trying the effects of gearing reductions in place of the metric gearing set up, these are the results I came up with

First of all, using the regular fixed pin quadrant, the closest match I could find was with a driver gear of 22 teeth matched to a gearbox setting of 56 tpi. That will give you a pitch of 0.0164 inches [ 61 tpi]

By altering the parameters of the metric conversion quadrant, a driver of 29 teeth coupled to a leadscrew wheel of 65 teeth will give a pitch of 0.0166 inches [ 60.23 tpi]. Another value is achieved using more readily available wheels of 20 teeth as a driver and 45 on the leadscrew..The result is 0.01653 inches [ 60.5 tpi]

These values are obtained when the gearbox is set for 8 tpi

Beyond these results you will have to consider operating the metric conversion as a further external gearbox and test for new input gears matched to gearbox settings. It gets rather complicated I'm afraid

Regards Brian

08/09/2020 08:43:17

Hello David,

I can help, but it would be more productive if you can list the additional pitches you would like to achieve. It isn't that I am keeping information to myself, far from it, but you will need to have a table of all the ratios the gearbox can provide and marry that information with the pitch you want to achieve to find a driver gear that will give it to you.

The maths is not hard, just time consuming to test the combinations and find a pitch outcome that is close enough to the required value.

In my book on the subject I already have listings for the following pitches if any of those are the values you are looking for, none of which are in Myford tables. These have all been calculated for use with the standard arrangement of fixed pin quadrant that the lathe is used for without having to install the metric quadrant at all. It preserves the fine pitch operation when the 57/19 tooth combination gear is reversed but it does need drivers with tooth counts that are not commonly supplied

Viz; 5, 6, 7, 15, 17, 21, 23, 25, 27, 30, 33, 39, 42 and 50 tpi

I hope that is helpful

Regards Brian

Thread: Soldering aluminium
06/09/2020 17:20:20

A Google search for aluminium welding gives plenty of choices for low temperature 'brazing' joints using bars made from zinc/aluminium alloy. Lots of videos showing how it is done too

I was sceptical and tried them on extruded square section aluminium with success, the repair on a casting should be even better. Scrubbing the joint area with a stainless steel wire brush is the key to a good joint

Brian

Thread: Tyler Spiral Blades
06/09/2020 10:53:34

Hello Michael,

Thank you for a blast from the past with your references to the Short Wave magazine. My father was a radio ham from the early days in the 1920s with call sign G5RZ and he used to 'net' on a Sunday morning as a regular event with Austin Forsyth, the magazine editor and one or two others. One of these, Walter G5WW, was blind from birth and I remember being enormously impressed with his memory recall when visiting us.

He would stop in the doorway to the lounge and point out the rearranged furniture in there before walking confidently to the chair he used on visits. Quite how he did that I never knew. He also built his own radio equipment and a garage for the family car!

Pop wrote intermittent articles for the magazine from time to time under the non-de-plume of A. A..Morse

Sadly his key went silent in 1963. And rather sadly it is not a hobby I took to either

Kind regards

Brian

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