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Member postings for Keith Long

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

Thread: Questions: Myford ML 10
31/01/2019 18:47:35

"Single tooth dog clutch" is the important point of definition Mick

Yes but the clutch needs to be at the input end of the screw-cutting gear chain not at the output end to the lead screw.

Thread: Drummond parts
30/01/2019 14:47:21

Ian, yes there is, the M type is a well respected lathe. You might do better to join the Yahoo Drummond and users group as folk on there are always looking for bits to keep their machines running.

Keith

Thread: Copper tube wall thickness & pressure withstood.
12/01/2019 15:43:58

If you download the publication in this https://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf it will probably give you all the information that you need as well as a load more that you didn't know that you wanted.

Thread: Reverse Sewing Machine Motor?
10/01/2019 17:40:39

Most likely NOT reversible from experience. The motor that I bought in the last 3 years or so has offset brushes so is optimised for single direction operation. Also to get at the connections for the brushes or the coil would have needed some serious surgery to moulded plastic parts. The motors are sold as unidirectional but you can get either clockwise or anti clockwise versions. I sourced my motor from a sewing machine and spares supplier via EBay and bought the uprated (100 watt) version rather than the normal 60/70 watt type.

Thread: Part built Allchin 1.5 inch
08/01/2019 12:39:22

Just a thought after reading this thread that might help Derek.

As you've now got to machine a liner from scratch, would it be feasible to machine the cylinder casting right through at the bore of the designed annular space, and then machine the liner with ends that fit the larger bore but with the centre part waisted down a bit to make the annular steam space. Having a uniform bore through the cylinder casting would be easier than trying to machine the recess and machining the liner od down locally is just straightforward turning.

Thread: Nylon for axle boxes ?
06/01/2019 14:45:13

Pete the data in the spring table gives you the following.

OD - simply the outside diameter of the wound spring, the Free Length is the overall length (or height if it's vertical) of the wound spring just sitting there with no load on it. The Max solid length is the length of the fully compressed spring with all it coils touching - "coli bound". It won't get any shorter and it won't fit into a smaller space. The Lb/in is the "spring rate" ie how much load you'd have to apply to shorten the spring by 1 inch. So the "load for full compression" is the maximum load that any of those springs will support when JUST fully compressed. Taking the first line the difference between the free length and the max solid length is 0.75-0.3 inch or 0.45 inch. Now the spring rate in 21 lbs/in so 0.45 x 21lbs give you the 9.45 lbs that the spring will need for full compression - and still be a spring. If you loaded that particular spring up beyond 9.45lbs it would still support that load but would in effect be a solid tube with no spring in it until the load dropped below the 9.45lbs at which point it would start to extend again.

From that table you can work out what length any of those springs would be at a given load and then you can see which of them will fit your application or conversely how much room you need to allow in order to be able to fit springs.

Another point to bear in mind is that for springs used in parallel (side by side) you add the individual spring rates to get the overall rate, for springs used in series (end to end) things get more complicated and you have to use

(R1 x R2)/(R1+R2) to get the effective rate where R1 and R2 are the spring rates of the separate springs. The overall effect of springs in series is that the net spring rate is lower than that of either of the individual springs

Keith

Thread: Rocket design
05/01/2019 10:43:45

Fizzy if you do a google search on "Stephenson's Rocket, history" you should find a Wikipedia page about the Rocket. Part way down is a heading "modifications". According to "The Engineer" publication at that time, 12 months after the Rainhill trials Rocket had been modified so much that it looked like a different locomotive - with near horizontal cylinders.

Thread: Denham lathe
11/11/2018 16:22:44

Michael

Just to save you a bit of frustration, the common change wheels for Drummond lathes are 14 DP NOT 16 DP so you could have problems fitting them to your Denham, depending just how much room there is for gears.

Keith (multiple Drummond lathe owner)

Thread: Drummond round bed lathe - belt removal
29/10/2018 11:16:03

Hi Peter,

I guess what's stopping the shaft coming out is the collar that you've removed the screws "A" from - it's threaded onto the shaft! It's the collar used for removing end play in the spindle and acts to pull the spindle towards the rear bearing to adjust the end float. It's a normal right hand thread - quite fine pitch about 20 tpi I think - but if the grub screws are out it should unscrew quite easily. If it hasn't been adjusted for some time you might need to use a bit of rod as a tommy bar into one of the grub screw holes to get it started. The other thing to check is that the pulley can rotate on the shaft now that the long grub screw is out. There is no key there so the pulley should turn fairly easily. If it doesn't have a look down the hole in the pulley, there might be a second grub screw down there, 2 screws down the same hole is a common method of locking the first screw in place so that it doesn't work loose. You won't be the first to be caught by that and you certainly won't be the last - guess how I know!

The other possibility is that there is a burr on the main spindle caused by the grub screw in the pulley. The nose of the grub screw should enter into a dimple on the spindle to prevent that. If in the past it's been tightened onto a plain part of the shaft then it could have raised a burr. If you look down the grub screw hole you should be able to see the shaft and check that. If there is a burr then removing it before resorting to force to get the shaft out would be preferable, but access down the hole would be difficult. If you need to do that them a small circle of wet and dry stuck to the end of a rod or dowel might work for polishing the shaft locally - it isn't hardened so is quite "workable". I don't think there should be any problems due to wear ridges on the shaft, the spindles that I've seen show some scoring in the bearing areas but nothing significant otherwise. If wear was an issue you'd feel it with the bearing being slack.

Do you need to remove grub screws B and E - YES - and leave them out!! Those holes are for oiling the bearings and you definitely don't want a permanent screw in there to stop the oil getting through. On my round bed lathes those holes are generally plain NOT threaded. If I was screwing anything into either of those holes it would be an oil cup to help with lubrication or a knurled thumb screw to keep debris out. A plain shanked cap would be just as good. The bearings run on a total loss system so you need to be able to add a few drops of oil a regular intervals as you work - it doesn't need a lot - but having to remove grub screws to top up would be a significant disincentive for me!

Good to hear that you got the back plate off - you're getting there.

It would be worth you having a look at - and joining - the Yahoo Drummond lathe Owners and Users group. There is a stack of useful information there and a sizeable body of Drummond owning enthusiasts who can help with queries etc.

Good luck

Keith

27/10/2018 19:16:45

Hi Peter, assuming the lathe hasn't been altered in the past, then yes it's a standard right hand 3/4 inch BSW thread. It's probably stuck due to oxidised oil varnish or in the worst case a bit of rust. You won't do any harm by using a hot air blower (paint removing type) on the flange, warming it may soften the hardened oil. If your changing the belt anyway then use that as a strap wrench to get extra purchase on the pulley, you could also bolt a bar of some sort across the backplate to give you extra leverage. I see your lathe has the later type of integral cast iron bearing, the pinch screws are the big slot headed ones, back those off to give a bit more clearance for withdrawing the spindle. If you cant shift the back plate in situ, the spindle will come out along the bed towards the tail stock and you could then work on freeing the back plate in the vice.

Keith

27/10/2018 17:53:04

Peter if your round bed is standard the the chuck back plate unscrews from the spindle - it's a 3/4 inch, 10 tpi (BSW) thread - unless in the passage of time someone has changed it. The 3 step pulley is secured to the spindle by a grub screw in the smallest diameter pulley. Undo that and the pulley should then turn on the spindle. Slacken off the pinch bolts on the bearings , remove any collars, gears or spacers from the left hand end of the spindle, and the spindle should come out, either towards the tail stock or in the opposite direction. It's not fussy, the spindle is a constant diameter so can go either way. Look out for the thrust washer that fits between the pulley and the left hand bearing. That can be a bit of a fiddle to put back in but a bit of 1 inch bar popped into the left hand bearing while you slide the spindle back in from over the bed makes things a lot easier.

On my round bed the belt is joined with a "crocodile" or "alligator" clip (different trade names for the same thing) and I can just remove the coupling pin and take the belt off. You have to put up with the "click - click" noise as the lathe runs - I find it quite soothing actually!

HTH

Keith

Thread: Myford Super 7 metric change gears
15/08/2018 15:27:31

Martin - for occasional use or in en emergency then you'd probably get away with running 14.5 and 20 deg pa gears meshed but running a pair like that together by hand you can definitely feel the "notchiness" as each tooth engages and disengages. I'm pretty sure that at some point the teeth are actually a slight interference fit the the tooth space on the mating gear. I suspect that they would pretty soon both wear together and become effectively an "intermediate" pressure angle. My feeling is that the "notchiness" could lead to poor surface finish on the job.

Thread: Reducing Volts and Amps
11/08/2018 11:10:10

Ron you're thinking about this from the wrong end. Your controller will control the VOLTAGE to your motors which will then draw whatever CURRENT they need at that voltage setting. If the motors are running light - ie not driving anything and you set the voltage to 24 volts then they will draw little current. If however you were to lock the shafts and then apply the 24 VOLTS they will try and draw a lot more CURRENT. What blows up in the latter case could be the controller if the motors try to draw more than 100 amp or if could be the motors burning out if the controller can supply all that the motors demand.

Without knowing what current your motors will draw at full load it's pretty much impossible to say what size controller you need, you need to do more homework and supply more information. If you're worried about the motors demanding too much current from the controller then stick a fuse in the lead to each motor and a master fuse in the lead from the controller. With car batteries as the power supply then fuses are essential in any case - have you seen what happens when you short out a car battery?

Thread: Can you recommend a paint/enamel/coating?
12/07/2018 18:41:38

Tim try Halfords or any reasonable car accessory shop and ask for "engine enamel" or "engine lacquer". It should be available in a limited range of colours, probably black red green and blue. Intended for just the job that you want to do.

Thread: spiral spindle cutter
19/06/2018 18:01:42

Hi John

No you don't need a motor on the lathe, in fact for what you what to do you don't WANT a motor on the lathe, things would happen at frightening speed! With the way the gearing would work turning the hand wheel on the end of the lead-screw will turn the main spindle as well quite easily.

The hand wheel on the slide (aka saddle) will move the saddle along the lathe bed but not under control of the lead screw. That hand wheel shaft has a gear on the far end which engages with a rack mounted on the lathe bed, if you look carefully you should be able to make out the teeth on the rack behind the lead screw. For your purposes you'll want the engage the half nuts onto the lead screw - operated on the lathe shown by the lever sticking up at approx 30degs. on the left side of the saddle. That will engage the saddle with the lead screw which will then control the movement along the bed.

If you're thinking of the Unimat with the twin parallel round bars for the bed - don't bother, it used an entirely different means of thread cutting which isn't suitable for your requirements and would require a lot of fiddling to make it work for you. Also as you've noticed they tend to go for gold plated prices generally.

19/06/2018 15:04:31

John - have a look at the following webpage (http://www.lathes.co.uk/winfield/index.html). This is a simple (old) screw-cutting lathe. Along the front you can see the lead-screw with a hand-wheel on the right hand end and a set of gears at the left hand (headstock) end. Those gears are mounted on a slotted bracket, usually called the "banjo". The gears are located on the bracket by short axles that can be moved along the slots to accept the different size gears. The gears connect the lead-screw to the main spindle and you can change the gears around - or use additional ones to get (within reason) whatever gear ratio you like between the main spindle and lead-screw, that's how you set up to cut different screw thread pitches. Normally for cutting screw threads the gearing will be such that there is a reduction in speed between the main spindle and the lead screw. For your application you'll be looking for a speed increase from the main spindle to the lead screw so you'd assemble the appropriate gear train basically the "other way round" so that the small gear was on the end of the lead screw and the large gear on the end of the spindle. You'll see in the picture 4th from bottom of that page that the gear train isn't just a "simple" train but is a compound train - 2 gears rotating on the same axle and locked together, each connected to further gears in the train - that's how you get the flexibility in the ratios.

I'm not suggesting that the lathe on that page is the one you should look for - although it would do the job you want perfectly well, but picked up that page a showing a typical older style screw-cutting lathe so that you could see how the gearing is arranged. There are many lathes of that type knocking around and they can often be picked up quite cheaply. If you can find one with a good set of gears (change wheels) the so much the better, but gears can be adapted and modified as needed, the trick is to try and make sure that the gears that you want are a common pitch (tooth spacing) as that will mean that they are more readily available and usually cheaper. The bore of the gears can either be machined out or bushed down to suit and key-ways are pretty easy to cut (for one or two) with basic tools. Some lathes used pin drive into the face of the gear in which case you just need to drill a hole in the right place.

If you do go down the old lathe route don't be tempted by one with a screw-cutting gear box, the gear train will be completely wrong for your application and a nightmare (if even possible) to convert.

19/06/2018 13:42:50

As Jason says above, it can be done on a lathe - easier than messing around with a mill and dividing head etc.

Assuming that you haven't got a lathe or milling table etc yet, keep a look out for an old simple lathe that has screw cutting abilities, ie one where you can gear the lead screw to the main spindle. For your usage you probably won't be too worried about the state of the bearings on the main spindle - so long as the spindle isn't flopping around everywhere, you won't need the sort of rigidity and precision that metal turning would. The issue to solve then is getting the gear train to connect the lead screw to the main spindle and here you needn't stick to the "correct" gears so long as you can construct a working gear train. Gears can be bought from EBay as well as dealers, but for your usage gears from the like of Technobots would also be suitable.

If you haven't got access to metal working machinery (a lathe) for making the odd bits that you'll need, give us a clue to whereabouts in the country you are, the chances are that there wi8ll be someone near to you who would the able and willing to help you.

Thread: Knurling tool design & wheel size
15/06/2018 17:37:17

Nige - on the page for Cromwell linked to above, when you see the picture of the parallel knurl there is a highlighted heading "more information", click on that and you'll find the diamond knurls. The picture is just a typical knurl wheel of a given size. if you look to the left side of the page you'll see a menu, against knurls it says 56 entries so you've quite a few to go at.

Thread: 3 in 1 Oil
13/06/2018 15:30:32

Here's a link to a more up-to-date (2014) version of the MSDS, I'm not sure that "Severely hydrotreated heavy naphthenic oil" is castor oil - sounds rather like a distillation product from crude mineral oil.

Keith

Thread: Rotary table
26/04/2018 12:38:21
Posted by Michael Gilligan on 25/04/2018 21:34:22:

Richard,

133 is a prime number, and doesn't feature on your set of plates

Er - no it's not - it factors as 7 x 19

So it may be possible to devise a way of indexing for 133

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