Member postings for Maurice

Thanks for the kind comments gents. I first made one from balsa wood when I was eleven, after being told about them at school. Always promised myself to make a better one. It took me long enough! I'm glad you like the handle Neil. You can find many examples of cranks of this shape on old machinery, from the pumps in "De Re Metalica", to treadle fretsaw machines and some textile machines, etc. I've often wondered if there was some perceived advantage to them, or was it just the appearance?

regards Maurice

Can anyone identify these castings please? Had them for years!They look as if they may be for some sort of tool. Perhaps to fit into vise jaws? Any sugestions welcome! Thanks Maurice

I though that perhaps some might like to see the Archimedes" screw that I made a couple of years ago. The screw itself is seven inches long, and two inches in diameter. The cost was minimal. The screw part is made from halves of "lolly" sticks, and the casing from coffee stirrers. It just needed a few simple jigs to get all the bits the same. Properly, the screw element should be sanded smooth rather than left stepped, but I left it like that to show the construction; and it looks nice! The lower end is copied from a picture of a full size one that I found on the internet. I suspect that it makes it less likely to get damaged. I added the brass lip to stop it dribbling when in use. In full size it would not be an issue. The tanks are base on a picture I saw of an early chemical works. Children love to try it out.

Having just thoroughly cleaned my lathe after machining some cast iron, I was sorry to find that I had a little more of the same stuff to machine. To prevent it from messing up my nice clean lathe, I held a magnet, enclosed in a plastic bag, near the tool. Result, a small bag of iron dust ready for disposal! I can't believe I haven't done it before! I intend to make a dedicated fixture with a magnetic base, for future use. I am now searching eBay for a brass magnet!

Hi Rod,

Your reassurance about the functionality of these gears is reassuring. I will lap them together as advised previously, and use them like that; see how it goes.

The gears have 9 and 18 teeth. The diameter of the larger gear is 1 5/8" by 1/2" face. The small one is 5/16" (aprox) by 1/2"face. This means that small one is only just large enough to bore out to fit the crankshaft, and the bed will have to be "excavated" to clear the large gear. I may turn the crank shaft to a smaller diameter on one side, as far as the gear, fit the gear, then sleeve the shaft back up to 1/2" diameter. I'll decide what to do when I actually do the job. All good fun!

regards Maurice.

Further to my last post; I could go down to ask for my money back. In fact our advertiser did offer this. But then I end up with no gears at all! I have been unable to find another source of gears that will deal with small quantities, that is, one of each. I think I shall have to make the best of what I have; hence my enquiry.

Regards Maurice

To be fair, I must point out that the photos always make machined surfaces look poor due to light reflecting off any minute imperfection. The apparent pitting or "holes" are not visible to the naked eye. It is the faceting that is the source of my complaint. It does make you wonder if all this firm's output is made down to this standard!

Maurice

Thanks Jason, here are the pictures. The second teeth down show the problem best. These gears came from a gear specialist via our advertiser, and I am very surprised that they consider this to be an adequate finish!

Thanks Jason and John. I did think of lapping the two together, but I was afraid of spoiling the small gear as the finish on the large one is so poor. I suppose that if they are only ever going to run together then an" unusual" profile will not matter too much. I do have a couple of acceptable pictures now. I have them in my album. Just got to find how to put the into the thread and then I will do so. Done it in the past, but it seems to have changed. Or is it me? Probably!

Regards Maurice

I did try, but failed miserably. The finish is like hammered pewter but smaller dents, and with some of the "dents" elongated. In bright light, the "good" flanks have a similar finish but not so deep. It is very disappointing! I will try again with the pictures.

Regards Maurice

I am helping a friend to complete a "Centaur" gas engine. I have a problem with the timing gears supplied by one of our advertisers. The finish on the flanks of the teeth on the larger of the two helical gears is very poor. Each flank is a series of flats and peaks. This is so all the way round the gear. There seems to be a bit of a pattern to it, perhaps caused by a blunt hob? I have rejected one pair, but the replacement is little better. I was thinking of getting a straight cut spur gear of the same D.P. and running the two together, with some lapping compound, to improve the surface. I would of course have to move the "lap" endwise to cover the full length of the teeth. Should this work? Is there any other way that I can improve the teeth?

Regards Maurice

I think perhaps, that not enough information on a model is worse than none at all. I have restored an old Stuart number one that predates the adoption of B.A. threads by the firm (1918), so is probably approaching one hundred years old. It carries a plate; "T H CLARK MAKER". That is all. Not even the area where he lived. Such a pity. Mr Clark was obviously proud of his work, and thus he marked it; but now its history is lost. Even if it is hidden, I think that marking your work is a very good idea.

Regards

Maurice

I have just read through this thread again. I know this sounds a bit obvious, but, since the spindle has been dismantled, when put back together, was the spacer between the bearing outers refitted? If this was accidentaly left out, the preloading would not work and the spindle would be able to float endwise. Just a thought.

Regards Maurice

I don't know if it is still available, but many years ago, when employed by the G.P.O. To repair teleprinters, we used a barrier cream called Rozalex. It took a little while to rub in properly when applied, but was very effective and washed off readily. As for washing hands, the same employer issued glycerin and borax hand soap. It was dark green and felt very gritty when used, but did get the grime off. I wonder if it's still about?

Regards. Maurice

This thread reminds me of the time I went to visit a fellow model engineer who I discovered nearby. He had an indoor workshop. As he let me in through the front door, he turned to me and said " I work mainly in brass and aluminium; when I open this door and the sun is shining, my carpets scintillate! " I can see me getting away with that; I don't think !!

Maurice

Thanks for the explanation Stick, I'll have to see which route the chap who actually owns the engine wants to go down; you have been a great help.

Regards Maurice

Hi Stick, I've just had a closer look at the list of gears from HPC Gears. As I see it, to achieve a ration of 2:1, the 24 tooth gear you used would have to be used with the 12 tooth one. This has an O.D. of only 0.53". How did you accommodate this on a 1/2" crankshaft ? Is the shaft smaller than on the drawings?

Thanks for your help

Regards Maurice

Thanks for the feedback gents. The HPC gears website is very interesting. This would seem to be one problem solved. Just got to solve the rest!

Thanks again Maurice

I have got involved in finishing a second hand Centaur Gas Engine, that a friend has bought. Has anyone out there built one, using the alternative timing gears supplied by A.J.Reeves. The centre distance of the gears is approximately 9/32" greater than shown on the drawing. This of course will alter the geometry of the valve gear. Also, it will be necessary to cut a crescent shaped cavity in the cylinder support casting, 1 1/4" long by 9/32" deep, to accept the larger diameter gear. I could reduce the cavity size to 15/16" long by 1/8" deep, by packing the camshaft out sideways by 1/8", but this will change the geometry still further. Any input about this would be most welcome.

Regards Maurice

I have just come across a thread gauge in my workshop that is a complete mystery to me. The case is marked "Whitworth 55deg." and the blades match a conventional one that I have. However, the blades are marked 12G 1/2" 9/16" or 18G 5/16" and so on. Can someone tell what it is for please?

Regards

Maurice