Member postings for Neil A

What a lovely little watchmakers lathe, even if you never actually use it. It deserves to be looked after.

A similar lathe, described as a "Burin Fixe" watchmakers lathe sold for £550 in 2018 at Flints Auctions.

A search under that name brings up quite a few images, you may find a suitable image to copy.

I think you were very lucky to find it.

Neil

Just an observation, the near equivalent of BS970 431S29 is actually EN57, usually supplied in the T condition (55 ton tensile), although the impact strength is only about 60% of the alloy steels. The EN58 series cannot be heat treated and are supplied in a soft condition (35 ton tensile). Could make a difference to your project.

Also be aware that you acquire material close to your finished size, remember that the core of a larger diameter bar will not have the same properties as the outside layers because of the "speed" of the quench through the material in the hardening process. In small diameters this is not a big issue.

As others have said, getting small quantities of the right material can be your biggest problem.

Neil

We get these supposed calls from Amazon Prime at least two or three times a week, it's a definite scam as the others have said. We don't even bother to listen to the whole message now, just put the phone down. Just another irritation to have to put up with.

Neil

I gave up on file handles that you had to drive onto the file tang after I found Vallorbe blue plastic "Crocodile" handles at one of the Model Engineer Exhibitions about 40 years ago. These handles have a hardened metal insert that you just screw onto the tang and it cuts its own thread, they can also be easily removed when you replace the file.

I bought a set from No1 to No 6, although I notice that I have never used the No 6 when I checked just now. The file it would fit still has a good well fitted wooden handle on it so I never changed it.

Cousins stock these if you want to give them a try.

Neil

You don't say if it is a parallel or tapered thread, if it is a parallel thread where the seal is made on a joint, then Tracey Tools stock 7/16 x 19tpi Whitworth form tap and dies in carbon steel. This might be what you are after. Your O/D could be the result of a slightly truncated thread form.

If your threads are tapered then this will not be any help I'm afraid.

I hope that you can solve your problem and let us know the outcome.

Neil

I always go for Hylomar for metal to metal joints, you only need a very thin smear to fill the machining marks and you have plenty of time to assembly the parts. It has the benefit that you don't need to try and guess gasket compression when you are designing an assembly of parts.

You need to be careful if there are any nitrile O rings though, the solvent in Hylomar causes the rubber to initially swell, but as it disperses the rubber shrinks to less than its original cross section and you can get leaks. Not sure if Viton and Silicon is affected in the same way. You can get away with it if you let the solvent evaporate before assembly. Not an issue in your case.

I can't see if the tapped holes break through into the oil space, that will dictate where you apply your sealant. Oil will always find its way down the threads.

Neil

Meccano Index drawings give the angle of the pulleys as 64 degrees.

**LINK**

Hope this helps.

Neil

Many years ago when I was an apprentice we cleaned components in what was referred to as the paraffin tank. It was only when I saw it being cleaned out and refilled from a 45 gallon drum that I realised that it was actually white spirit that was being used. White spirit removes grease and other muck very effectively and does not leave an oily surface when it evaporates, but it does dry your hands up dreadfully.

I stopped using paraffin for cleaning a long time ago, surfaces always seemed to rust more quickly with paraffin than with white spirit.

Neil

My reference book, Gear Engineering by H.E.Merritt, gives the same formula for the minimum number of teeth without undercutting and with zero addendum modification as DC31k has quoted. It works out as a theoretical 22.1 teeth for 17.5 degree pressure angle.

You can go lower if you apply addendum modification, this increases the diameter of the blank that the teeth are cut on, but there is a limit to how much you can apply before the teeth become pointed and you start to lose the top part of the profile.

With regard to the method used by Helicron, you may start to see more facets as the number of teeth reduces. I seem to remember that the Sunderland gear planer rotates the gear blank and moves it sideways relative to the cutter for a number of strokes before resetting for the next tooth, reducing the number of facets. Someone may correct me on this, it has been a while since I watched a Sunderland in action.This would be much the same action as a Maag or Niles gear grinder if I'm correct.

Perhaps someone else has made some gears in this manner and can share their experience.

Neil

I would suggest that you size the belt section to be close to the width of the pulley V groove, if you go narrower the belt will run too deep in the groove and may bottom out. Some of the modern metric sized belts can be a little fatter than the old imperial versions, but I would not go smaller than the groove width.

Measuring the belt length can be a bit tricky, in the past I have run a dress makers fabric tape measure over the top of the pulleys to get the outside length of the belt. I have then used the "Simply Bearings' website to find out what belt I need. They give both inside and outside dimensions for V Belts, which makes life easier. You can get the belt from wherever is most convenient for you once you know the belt designation.

Measuring at mid-adjustment should be alright, but it might pay you to measure the lengths at both extremes to see what difference it makes, just to make sure you can get the belt onto the pulleys at the minimum centre distance.

Neil

Some years ago there was talk of all engines having valves controlled electronically using solenoids. If I remember correctly helical solenoids under the name "Helenoid" where considered as producing enough power to open and close the valves, either fully open or partially open, at any point in the timing cycle.

Koenigsegg seem to be using a pneumatically operated system which is electronically controlled.**LINK**

Seems a shame that it is proposed to ban the sale of petrol, diesel and hybrid cars in the near future!

Neil

I don't think I would worry too much about what your rule shows the printed paper drawing scales. It's probable that he has forgotten to alter the scale on the drawing.

When I worked in a drawing office all the drawing sheets had "DO NOT SCALE" pre-printed at the bottom of the sheet. In the days when drawings were hand drawn there was always the possibility that a dimension had been altered, but not the actual component feature. Took too much time to rub out and redraw.

Now, with most drawings produced by CAD this is probably less of a risk, but it is always best practice to only go by the dimensions. If the dimension is not there then you have every right to complain very loudly. If I had missed a dimension I would not expect someone to have a guess at what it might be.

The drawing sheets still had "IF IN DOUBT, ASK" printed at the bottom and we hoped everyone would follow the advice. Sometimes it was in vain!

Neil

Edited By Neil A on 25/01/2020 23:09:34

It may have absolutely no relevance at all to the Suffolk Tractor, but the next two boiler designs by John Haining that appeared in the ME both had working pressures of 85 psi. One was made in copper, the other was steel.

Not to have the working pressure on the drawings seems to be a serious omission, I could find no further references to the Suffolk Tractor after the one in vol 147 issue 3664. As there have been a number of these models built, someone must have this information, I hope that it was not an inspired guess.

While it is possible to recalculate the working loads, without knowing what factors John Haining took into account in his original calculation, it may be frustrating work. Perhaps someone with access to some FE software might like the challenge.

Are new designs of boiler published in the ME accompanied by a set of the designer's calculations so that boiler testers can see what assumptions have been made or do we just go on trust?

Neil

I've had a rear coil spring break a few years ago, it failed on the last lower coil, not much of a bang, I could not work out what had happened for a while. The man at the garage said that nowadays he gets a couple of cars a week with broken coil springs, he put it down to the poor state of the roads now, years ago he said it was unusual occurrence.

We do put great faith in the way parts are designed and even greater trust that if and when parts fail it will not be in a catastrophic manner. Does not always bear thinking about.

Neil

Thanks for letting us all know what action you have decided on. I'm sure you feel much happier in your own mind with this rather than attempting what could be a difficult repair.

One of my colleagues at work always said that you need to be very careful when attempting repairs that you are not just enhancing the value of scrap.

I also remember listening to him one day explaining to someone from Quality Control, who was trying very hard to get him to accept a repair that was "better than new", that he must have scrapped tens of thousands of pounds worth of components that "might have worked", but why should he take the risk? You have to consider the consequences of the repair failing.

Good luck with your project, we all what to see how it turns out.

Neil

I have to agree with Howard Lewis that simply resurfacing a nitrided area can be very difficult. The problem is usually the transition area where you grind through the nitride surface, unless done very carefully and gently you can create micro-cracking in the nitriding which will propagate when under load.

I think that you may need to completely remove the nitrided area before considering resurfacing, doing a crack detect at each stage. Even then I would not be sure of the long term success of the repair.

It may be safer to start again, you will have to decide on the cost of remaking against the value of the finished item.

Sorry not to be optimistic.

Neil

You could have a look at the Simply Bearings website, you might find what you need there.

Neil

The usual salvage in industry is to drill and tap to a larger size, plug with a suitable material fitted with either a retaining compound or just peened into place. Then re-tap the hole the the correct size. This keeps all the fasteners the same size.

Another fix that was sometimes used, if the fastener was a stud, was to make a stepped stud with a oversize thread at one end and the other end would have the same thread as the other fasters. This requires a special fastener which you may not want to do.

My preference would be to plug and start again, it depends how much metal you have to play with.

Neil

I have just checked the screws for the gibs on my Flexispeed, as I had remembered they are UNC thread.

The cone pointed adjusting screws are 0.135 OD x 32 TPI, this is No 6 x 32 UNC, the hex locknut is 0.25 AF.

The cap head locking screw is 0.110 OD x 40 TPI, this is No 4 x 40 UNC.

The spindle nose thread is 1/2" x 16 BSF as mentioned by John Carruthers earlier.

I find thread pitch gauges difficult to judge between 55 and 60 degree thread angle on these small size fasteners, not much flank to sit on.

My Flexispeed was made at the end of 1975 by the Norfolk Lathe & Tool Co Ltd at North Walsham, so there may still be some variation in the thread schemes that were used depending on who made them. Measuring the thread OD may be the best indication of what you have.

Let us know how you get on.

Neil

P.S. The tool post screws were 2BA.

Edited By Neil A on 22/08/2019 16:28:24

I think you will find that most of the threads used on the Flexispeed lathe are UNC. I had to replace the gib adjusting screws about 40 years ago, they were UNC, but I would have to search out the old packet to find what the actual size was. I think the cap screws in the tool post are 2BA, but I will have to check tomorrow to make certain.

Neil

Just had a thought, Flexispeed manufacture went though a number of different owners, there could be variations in what they actually used for their thread system. Whitworth and UNC are dimensionally very close on some sizes, best to check carefully before retapping any holes.

Edited By Neil A on 19/08/2019 23:04:01