Member postings for Neil A

I think Farmboy has the right idea, this cone type bearing arrangement is used a lot on toy gyroscopes. The spindle is fixed to the wheel and the outer bearings are adjustable screws, easy to take apart. I would not use a centre drill for the cone as it will give you a hole where the slurry will collect. You could also harden the parts as HOWARDT recommended. I also think the suggestion of washing it after use will help extend its life. It's going to have a hard life what ever you choose to do. Let us know how you get on.

Neil

As has been said, the real problem is the clay slurry getting into the bearing. The particles imbed themselves into the softer material and then act as a lap on the harder part. Can your design be made to incorporate a V-Ring seal each side, this may give you a fighting chance for a longer life in such an aggressive situation. Simply Bearings sell these in quite small sizes. Might be worth considering.

Neil

I have just read Hopper's posting on "The Bad-Ass Librarians of Timbuktu", I must get a copy of that it sounds a good read.

The fact that they had to collect the manuscripts from family homes and desert caves just goes to show how easy it is for valuable documents to be lost forever.

Mike Poole's suggestion that as a project we each scan a set number of issues from our collections in an agreed format is a very sound idea. Many years ago I was one of a group of volunteers involved in the transferring of over 270,000 hand written records into a computer database, it did not take forever, so it can be done. Just needs that first step.

This need not be confined to just ME or MEW, between us we probably hold many very interesting books and documents that are now not available, even to the British Library.

Up to ME issue 4584 there are probably less than 300,000 pages that need copying, and that includes the very interesting covers and the advertisements inside which can be a valuable source of information.

Any volunteers?

Neil

Reading this forum post, I am reminded that many old, valuable and rare documents and items have been thrown away and are still being destroyed by well meaning relatives while clearing a deceased persons property.

They get thrown away simply because the person doing the clearing has no idea what they are looking at.

Unfortunately there is no way of stopping this happening and so many out of print reference books and old magazines will disappear unless they are recorded in someway for future generations.

I'm afraid copyright issues will remain a problem in this respect.

Neil

If you are looking for ideas on building a new workshop, I can recommend buying a copy of "Workshop Construction" number 23 in the workshop Practice Series. It gives a great deal of information on various methods of construction and some advice on planning regulations, although these may vary from district to district. I am sure you will find something in the book which will be of interest.

Neil

Just out of interest, AISI 4140 is closer to EN19 (or 709m40) in composition. It has a Chromium and Molybdenum composition which EN8 does not have.

Looking at the hardness, HRC35 roughly equates to a V condition, 65 ton. It's a bit in the "Hmmn" region for me, but still machinable with a good machine and tooling.

Neil

Gear Engineering by H.E.Merritt gives the following advice:

"A general-purpose rule, for the avoidance of tip interference at standard centres, is to make the difference between the tooth numbers not less than

(T-t)min =10 + t/5

By strict geometry, the minimum tooth number difference at which tip interference begins is approximately 8, for 20 degree full depth proportions, at standard centres. But this is a marginal condition."

Using this advice I designed a small reduction gear box for a governor drive in 10DP with a 21 tooth pinion and 36 tooth internal gear. Addendum modification was +0.25 for the pinion and -0.25 for the internal gear. This was about as close as I thought it prudent to go. The gear boxes have been in service on US Coast Guard vessels for over 30 years now, and I have not heard of any problems. So I would say it's a fairly good rule to follow.

As far as actually cutting the gear, personally I would follow JasonB's advice and use the lathe to plane the profile.

Neil

Hi Michael,

I suspect that I'm being over cautious, probably comes from working on the design of large high speed diesels engines. They are not very forgiving and will always find any weakness if you let them.

All I can really say on the subject is that the success of these retainers is down to the people machining the parts and applying it to the cleaned surfaces, not the people like me who only specify where to use it.

Neil

Just spotted you last post. It does look as if the left hand does not know what the right hand is doing!

Perhaps we should both say that these data sheets seem to be more of a rough guide and go by our own experiences on how we decide to use them. I suspect Loctite would hedge their bets if asked them directly.

All that I am really sure of is that any solvent you use to degrease the surface needs to have evaporated completely, otherwise you end up with a sticky mess, and that's from experience!

Edited By Neil A on 07/12/2017 21:38:43

Hi Michael, that's a very good question and I hope that I can answer it.

If you follow the link in my previous post it will take you to the LOCTITE Retaining Compound Design Guide. If you look at the bottom of page 14 you will find a paragraph on joint gap where it refers to the gap as being "diametrical". Also the chart on page 17 refers to "maximum gap fill diameter".

My personal view, and it is only my personal view, is that the graph on the data sheet for cure time against gap is misleading, unfortunately there is no graph for bond strength against gap, which would be more informative. Yes, LOCTITE will cure in large gaps, but its bond strength decreases with increased gap.

In my work and in my contacts with LOCTITE it has always been understood that the gap figures were diametrical as we were usually discussing the fitting of cylindrical components.

Of course, what we do in industry may not always applied in a home workshop. In industry "might be alright" is not an option, but at home, where you can monitor the success or otherwise of your work it is a different matter.

You will understand that the opinion I offer is from my own experiences in specifying LOCTITE in industrial applications. But, as my old boss would say, "design specifications are not tablets of stone". If you find that the larger gaps work for you, then go with it, there is probably some latitude in the LOCTITE specification, but not for industrial use where the product has to perform to the specification or you might be in trouble.

Well Michael, I hope that has explained my statement, sorry if I have rambled on too much.

Neil

I'm afraid that I am with Clive on this one. Maximum gap fill on diameter for LOCTITE 641 is quoted as 0,2mm   or  0.008" . I don't think you would achieve a satisfactory bond at 0.018" oversize on diameter.

LOCTITE 660 is an alternative, but expensive.

Personally I would be looking to sleeve and rebore if possible.

Have a look at the link to the brochure, see what you think.

**LINK**

Edited By Neil A on 07/12/2017 12:07:09

Edited By Neil A on 07/12/2017 12:07:55

Have a look at *Rapid Electronics* web site, they have a very large selection of multi pole crimp connectors. I have usually found what I am after there. Otherwise I go to RS. They are not always the cheapest, but you only want to do these connections once.

Neil

This Saturday, 12th August, Tornado is leaving Liverpool Street in London at 7-20am to travel to Walton on the Naze. During the day it is running shuttle trips to Colchester Town and back before leaving Walton at 20-30pm to returning to Liverpool Street.

As an early birthday present I have been given one of the last tickets available for one of the shuttle trips. It should be an interesting day. The last time I travelled behind a steam train on that line was just before they were all withdrawn. I am just hoping that the weather will be fine.

Neil

Looking at the photo of the teeth, particularly near the number 16, they do appear to be cycloidal rather than involute. 0.65mm module could well be the right size.

Blick Time Recorders was a marketing company rather than a manufacturer, many of its designs where made by the National Time Recorder Co. in the UK. Have a look at WorkClocks.co.uk website for more information.

Neil

I see that both of these books have been reprinted and are listed on the TEE Publishing website.

As Hopper says, probably still covered by copyright.

I like a book I can thumb through!

Neil

Diametral Pitch was used in BS 436: 1940 Machine Cut Gears.

I also have a copy of Machine Cut Gears from David Brown dated 1921 which refers to Diametral Pitch. The introduction in the book says that it is a reprint of their 1903 book.

I have nothing earlier, but the term seems to have been in use for a long time.

But I agree with Duncan, we all know what you mean, most of the time we just use the symbol DP and not worry what it stands for.

Neil

Edited By Neil A on 20/06/2017 14:06:43

I'm afraid circular pitch cutters are not too common these days. You may find it easier and cheaper to make your own cutter. The book you have ordered may have information on making them, they are not difficult.

I have cut some small gears in aluminium using a single point flycutterin the past, producing the approximate involute in the lathe on round silver steel then filing down to half the diameter and hardening rather than make a complete circular cutter.

You could make it as a disc in a similar fashion with just one cutting edge, and mount it eccentric to give the cutter clearance. It would be more robust than my way.

Hi James,

I have been thinking about this. Considering the age of the machine it is highly likely that rather than a DP series cutter being used to produce the gears, they were cut with a 0.25 CIRCULAR PITCH cutter. This gives dimensions very close to those that you have measured.

The tolerance on the OD of a gear blank is usually +0.0 to -0.002 but can easily be a bit smaller, it does not matter provided you allow for it and cut to the correct depth of tooth.

It would be possible to check the gear geometry further if you could measure the BASE TANGENT SPAN. This would eliminate variations in the OD and also confirm your pressure angle.

Oh dear!

Improved out of all usefulness.

I've been using the 11th edition for the last 30 years or so at work, has not failed me yet.

This is an example of how easily useful information is lost.

The original Vee belt for the Flexispeed lathe was a Z section 3/8" wide x 1/4" deep. I have just measured the length of the belts on mine as best I can, the size markings have long since worn off. The first reduction from the motor is approximately a Z21.5 (measures 23 1/4" outside length).The second reduction( 3 step pulley) is approximately a Z17.75 or could be a Z18.5 (measures 19 1/2" outside length). The belts have probably stretched a bit over the years. It does not get used very much now.

Just a thought, when I got my Flexispeed from the Norfolk Lathe Co. in North Walsham one of the 3 step pulleys had been incorrectly machined with an A section groove. Could be worth checking as a Z section belt does not drive properly in an A section groove.

I have been using a Dell C1760NW colour laser printer for the last two years without any problems. It is wirelessly connected to all our computers so there are no extra wires and it can work as a stand alone printer. Dell colour cartridges are a bit expensive, but I have used the Premium Crystal Wizard cartridges from StinkyInk since I bought the printer with no problem. It is currently on Ebuyer at £99-99. There are a lot of good colour laser printers out there now, it depends which maker you fancy most and how much you want to pay. I don't believe there is very much between any of them now. The only thing to look for is the running cost.