Member postings for Andrew Tinsley

Hello All,

I want to contact an advertiser here, called Rich Platt, he doesn't leave any contact details. I tried a PM to Rich Platt and got an answer back from someone else!!!

Andrew.

Most of the ML7s that I have seen have had the Myford lettering picked out in red. I have also seen a couple with white lettering.

As I am repainting my lathe, I may as well get the lettering colour correct, so is it white or red?

This is for the standard grey ML7.

Thanks,

Andrew.

I would chuck a long bar maybe a foot or 18 inches. Set up a DTI on the lathe bed and position it so you can grip the bar and push it fore and aft. Then reposition the DTI to measure vertically and push the bar up and down. You can also reposition the DTI on the end of the bar and push and pull along the lathe axis. This should measure the end float

If the DTI only registers a thou or two, then you know the bearings are good. The problem comes if the measured play is a good bit greater than this. I think each one of us would have their own ideas on the allowable amount of play, before the headstock and bearings needed attention!

Andrew.

Thanks gentlemen,

All information has been absorbed, looks like I need Graham's book before I start this one! It will be some considerable time before I will be able to do this job, meanwhile I shall have a good read up!

Thanks to everyone who contributed to this thread.

Andrew.

Simple question. I have been screwcutting with HSS bits, jig ground to the correct angles. I am reasonably pleased with the results. I just thought that I would give an indexable carbide tool a go for comparison. I am having difficulty in finding a supplier for the tip angles required.

Anyone point me in the right direction?

Thanks,

Andrew.

I am looking for a module one 50 and 40 tooth gears. I have a 127 and wish to use them for metric screw cutting on a Myford.

Thanks,

Andrew.

Thanks Guys,

The microswitch idea sounds good! I am always a bit bothered by instant reversing in case the chuck comes off. I know it is only at slow speed, but the chuck / work inertia must still be a bit on the high side!

Making the dog clutch seems to be a most interesting project in itself, so I may well go ahead in the future, but will try the instant reversing first.

The references above are for a Myford Super 7, are there any snags with modifying an ML7.

Regards,

Andrew

I have been reading Martin Cleeve's book on screw cutting. I was very taken with his dog clutch fitted to a Myford.

In the fullness of time I would like to make a similar unit. Does anyone know if drawings were ever made available?

Regards,

Andrew.

When I was a lad, I was a BMC car enthusiast, my friends laughed at me because the Ford cross flow engine was so much better!

However I later learned that the Ford engineering of their engines was far inferior to the BMC A and B series engines. The BMC heads had proper pressed in guides that could be replaced. The Fords had holes bored into the cast iron cylinder head, no guides. When this wore oversize the only option was a new head or internal knurling of the hole to reduce its diameter. Needless to say, this didn't last too long!

Andrew.

Hello again,

I am still unsure of how do this job. Do I simply put in the new white metal bearings, then put the mandrel back and shim the headstock top retainers, until I get a smooth turning of the mandrel, without it binding up?

Does one then use engineers blue and scrape the bearings in?

I have seen that people sometimes use a flat block and reduce the bearing half diameter to get a good fit. Seems odd to me as this will make the bearings none round and hence they probably will need scraping.

I have one mandrel that is in visual good condition (i.e. no scoring marks). This doesn't mean that it has not worn undersize. Does anyone know what size the mandrel bearing surfaces are? I also have brand new white metal bearings. These are as rare as hen's teeth, so I do not want to make a mess of this job!

So anyone that can make some helpful suggestions would be very welcome. Maybe this is a straightforward job for those that know, but I am a scientist and really not into the ins and outs of practical bearing fitting!!

Andrew.

Edited By Andrew Tinsley on 29/03/2017 12:17:41

Thanks for the link. Not quite as helpful as I hoped. I have the old unhardened mandrel and a brand new set of white metal bearings. With this combination, I expect to have to do some scraping, also I have this awful feeling that the finished combination will probably have a different centre height to specification!

Andrew.

The title just about says most things. The lathe mandrel appears to be in excellent condition and I have a new set of white metal bearings.

My scraping abilities were learnt off full size locomotive axle boxes and to say the least are not good for small size bearings! So hopefully any scraping can be kept to a minimum.

Andrew.

I stick by what I have said about piston rings. I am not going to get involved in discussions that usually lead nowhere. I have made enough piston rings t learn the hard way what works and what doesn't.

If the rings are not pressing against the cylinder wall then, you will have blow by and the pressure on the outer face of the ring will be marginally higher than behind the ring (dynamic set up, not static as many people seem to get confused with).

I know nothing about the work of Sir Harry Riccardo, so I am unable to comment. It doesn't seem to be appropriate to quote 1915/16 work, as I am sure things have developed since then!

Best regards,

Andrew.

Hello Neil,

I would not disagree with Tubal Cain, I have not seen his articles that you mention. But too much radial spring, increases friction and promotes wear. My final step is to anneal the ring and then to use diamond paste to lap the ring. Amazing what you can see in the way of high spots as the lapping process continues. The finished product shows excellent fitting of the ring. However it SHOULD exert some positive pressure on the cylinder. Don't forget we are talking of compression ratios of 1 : 10 or so for these engines. Diesels are a different kettle of fish having far higher compression ratios. I do not have any experience of rings for such engines, so I am hardly in a position to give advice.

Andrew.

My main interest these days is in vintage spark ignition engines intended for speed.

The idea of "pressure" behind the ring expands it, is totally flawed and can easily be shown to be untrue. I had to learn the hard way.

Dykes rings on the other hand ARE designed to expand under pressure, They are L shaped and have been used from time to time in model aircraft engines. They show almost zero compression when flicked by hand. I have obtained several Dykes ring engines for next to nothing, because the seller thought they were "clapped out"!

Rings should have plenty of spring in them and they should push against the cylinder wall. I will not go into the proper way to make rings as this is getting off topic.

The ring should be a relatively loose fit in the groove, otherwise they are likely to stick and then compression is compromised.

Andrew.

Hello Hopper,

You don't need to cut a template for the shaper tool. All that is needed is a plain old HSS tool ground to whatever pressure angle you are using, plus the "bottom edge" ground off at the appropriate width that one would use for the bottom width of the gap, in an equivalent rack gear. I hope that makes sense!

If you rig up the shaper as discussed in a prior post, then that is all that one needs to do, in terms of making the shaper tool. The beauty of this system is that it will cut perfect involute gears. NO expensive cutters to buy or make and don't forget, a cutter is only accurate for one size of tooth. Using the shaper method, described previously, you get accurate gears cut for any DP.

If you have a shape,r then make up the required rotational jig (not difficult) and make perfect involute gears for any size you may want.

Andrew.

Hello Michael,

I have been on my back for the last couple (?) of days with acute sciatica. Now moving again thanks to some potent pain killer, that makes my normal morphine seem like aspirin. So NO workshop for me, this stuff is NOT compatible with moving machinery!

I now have Ivan Law's book on gear cutting, but no mention there of how to derive "d" (the bottom width of the "tooth" gap).

It seems that I will have to stop being lazy and work through the geometry of the involute gear form, to derive the correct formulae for "d" and then calculate from published data.

Mental acuity is definitely not at its best right now and I shall wait until I can leave off taking the medicine!

All the best,

Andrew.

Thanks for the information on the Drummond pins. I do intend to make a full set as I expect the ones that come up on Ebay are probably in the same condition as my existing change wheels.

I now have a shaper, courtesy of one of the advertisers on this forum and will shortly start making the required jig for involute gears, as discussed here on the beginners forum. I think the actual cutting can be accomplished in a few days. One lives in hope that it will work first time!

Regards,

Andrew.

Edited By Andrew Tinsley on 03/03/2017 17:43:48

I intend to manufacture some changewheels for my old Drummond round bed lathe.

The few changewheels that came with the lathe are pretty battered, especially with the two pin locating holes. I am told that the two holes take tapered locating pins. It is very difficult to check, as at some stage, the holes appear to have been drilled oversize. As I intend to make a new set of wheels , I may as well do this as Drummond intended!

So the queries are,

1/ Do one, or both holes have a taper? If so, is this a standard taper like the usual 1 in 40 taper?

2/ If only one hole has a taper, then what was the original straight pin diameter?

3/ If both holes have a taper, then do they taper in the same or opposite directions?

I appreciate that it isn't too important to get the details correct (except maybe the answer to 3/). But no point in getting them incorrect and then finding that the wheels do not fit on other Drummond lathes!

Thanks for any information, as it does not seem to be readily available here or elsewhere.

Andrew.

Hello Michael,

Thanks for giving me the link. I am in some considerable pain at the moment and cannot get my head around the gear blank rotating as the shaper moves across the work. I cannot even see how to mount the blank on my rotary table, which I think is far too big for the job in hand.

I shall take some painkillers and print out the link, that should make it more understandable!!!

Many Thanks,

Andrew.