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Member postings for Clive Foster

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

Thread: kerry ag lathe
22/10/2019 19:29:30

There is an additional hole for the right hand tumbler plunger in row 2 an inch and a half or so below the normal hole.

That is the neutral position as the tumbler gears are out of mesh with the Norton screw cutting gear cone and cannot drive it. Instead it meshes with the drive gear of the power feed drive rod.  Feeds are selected via the left hand tumbler so the feed range is less comprehensive  than on lathes that drive both leadscrew and feed rod via the Norton cone. See the bottom picture on this page **LINK** which shows both hole and the instruction plate. The manual is not perhaps as clear as it should be.

You aren't the first person to be confused. Generally you don't expect a neutral position in a screw cutting gearbox as normal practice is to provide some way of disconnecting the drive. Whether by separate lever or simple dog clutch.

Judging by the one I had limited experience of the Kerry is good machine.

If the clutch action is iffy or unpredicable verify that the shaft carrying the clutch isn't moving sideways when the clutch is operated. The one my friend had suffered from this because the welch plug holding the right hand bearing in place had become a little loose allowing the bearing to shift sideways in the casting. Press fit of the bearing was tight on the shaft and light in the headstock. Just light enough to sometimes let the bearing move. He fixed it with a suitably stepped alloy cover held by three socket cap screws.

That was one of the older, Mk2 ones with a simple pluger lever to select feeds rather than the excellent gate pattern shifter used on later Mk3 machines. My friend found that the innards are sufficiently similar between older and later machines that DIY conversion to the gate pattern shifter is possible using simple, easily made, parts.

Clive

Edited By Clive Foster on 22/10/2019 19:30:09

Poxy auto spell correct won't leave some correctly spelled words alone!!!

Edited By Clive Foster on 22/10/2019 19:48:34

Edited By Clive Foster on 22/10/2019 19:55:12

Thread: What is this thread called these days? 3/4"-16 SAE
22/10/2019 15:35:25

For all practical purposes in the UK 3/4 x 16 UNF is the same thread.

Theoretically there can be small differences in the specifications, particularly if its old, but nothing that will matter to the fit of ordinary threads.

Clive

Thread: Changing chucks on Harrison L140
21/10/2019 17:24:19

David

When you do wire it finally I suggest that you put a box with decently large shrouded buttons for start & reverse along with a mushroom headed stop button just under the chip tray about where that round hole in the stand is. Buttons pointing out horizontally but not beyond the tray.

I did such with my old SouthBend Heavy 10 toolroom and found it to work very well indeed. Buttons easily found and always accessible. My Smart & Brown 1024 VSL has the factory arrangement with the buttons on an angled panel effectively running up from the inside of the chip tray towards the headstock with its right hand edge a little back from the right hand edge of the headstock. Perfectly functional and button visibility is better but, I feel, placement not so good as being a bit too far to the left.

Tromp bar along the front of the machine is better than a foot button fro the emergency stop. Probably not something I'd change if I had a fully working system but if installing "do it right, do it once".

Clive

Thread: Holbrook Model B No.8 Lathe
21/10/2019 17:12:04

The Holbrook spindle has two parallel registers, one in front of the thread and one behind. Unique with the 1 3/4" BSF thread so no chance of finding a new, commercially made, one. Very unlikely to find a second hand one as these machines were rare, being very expensive new. Even if you do find a used one it may well not fit. It is said that Holbrook fitted backplates individually to each spindle.

You will need to make an accurate dummy spindle for final turning / fitting and, probably, an accurate pair of size gauges for the registers first. You can do the registers by measurement but final fitting gauges generally make it easier to get it right. Sounds the long way round but I've found that properly setting up with a dummy spindle end makes the job go far faster even with ordinary threaded spindles. Never done a Holbrook one tho'.

Best to have practice run on some spare material first. Although its fundamentally simple work getting it right needs concentration. The back register in particular being a pain if not approached correctly. I imagine the auto feed stop on the Holbrook will help if its still in good order.

Be highly tempted to make more than one backplate when set-up and in the groove.

Clive

PS I see Baz did his without a dummy spindle.  Well done mate.  Braver man than I.

Edited By Clive Foster on 21/10/2019 17:13:43

Thread: Yahoo Groups: Heads up for members of e-mail groups
18/10/2019 14:08:57

I'm a member of four ex Yahoo groups that made the jump to Groups.io.

No great issues reported beyond corruption of a few files, a few photos going missing and an inability to deal properly with mail attachments. Most closely connected with the Bridgeport Mill group transition. Being the outgoing moderator for the Yahoo group I'd expected to be roped in for loose end tidying as the new management got to grips with things but in the event the only thing I had to do was correct three of my own contributed files which had become corrupted and re-direct a few membership requests from the old group to new. We did have the luxury of leaving the old group up, albeit moribund, for a couple of months so anything identified as corrupt could be grabbed from the old data.

Free switching to Groups.io has gone. You have to set up a Premium group to switch which costs about £100 a year. Far as I can see all the old Yahoo groups intend to drop back to the lower tier Free groups after the first year. Free groups are very similar to the old Yahoo and seem good enough for what folk like us want to do. Premium has much greater data storage and many bells and whistle that are excellent if you need them. Data limits on the Free version seem to be more than sufficient. I saw discussion in another place concerning moving a very data and photo heavy group. The owner seemed confident that free would do.

Reading the official "Things are changing" E-Mail from Yahoo central its clear they have completely missed that the files / data / photos store is, to folk like us, a primary purpose of such groups. Yahoo say the communications between members is primarily by E-Mail so no need for the data storage. Well DoH, the E-Mail bit is how we communicate but the steady build up of how it works, how to fix, what to get for, this is what it should look like yadda yadda yadda in the files is why we hang around. On an E-Mail or social meadia based system you end up having the the same question asked umpty-six times until thems-what-know get fed up and down pens (keyboards!).

No data reposity beyond photo albums is a weakness of this forum, search only gets you so far especially on popular topics where the number of returns can be overwhelming. Be a nice topic for an AI mavern to develop a forum post distilling bot able to turn many posts on subject into a coherent "how to do it" / "all about it" et al file. At 65 I don't expect to live long enough to see that sorted properly tho'.

Clive

Thread: Surface Mount Switch
16/10/2019 10:37:08

Deleted post, slow typing!

Edited By Clive Foster on 16/10/2019 10:38:06

Thread: VFD and screwcutting
16/10/2019 10:06:27
Posted by DC31k on 15/10/2019 18:03:28:
Posted by Pete Rimmer on 15/10/2019 13:29:31:

...another benefit is that you can use the speed control to back the speed right down as you approach the shoulder so that the stop is almost instant....

And if you had a sliding potentiometer attached to the bed, you could do this automatically, in a similar manner to the trip mechanism on dog clutches used for screwcutting.

DC31k

The speed adjusting potentiometer in the stop is an interesting idea. What do you see as the advantages over using a simple stop switch and relying on the ramp down of the VFD to bring things to a stop. Obvious one is that it allows you to use a different braking profile for screw cutting / feed to a shoulder than the normal stop ramp down.

Mike

I planned to use a switch actuator based on the one in my picture with a 6 position turret type bed-stop head having a short spring loaded slide incorporated in the mounting clamp. As is so often the case it got over designed with built in micrometers for easy setting (gotta do something with those half inch travel heads in the useful box) and interchangeable length rods. So its 15 years on its still at back of envelope stage and I'm still doing fine with the dumb 6 way turret I've had for the last 30 - 40 years!

Clive

Thread: Telescopic bore gauges
16/10/2019 09:48:46

I found the tricky bits were eyeing up things so the gauge was exactly across the diameter and nipping up the lock screw without disturbing things.

The domed ends on the spring loaded bars reduce any errors due to the gauge not being exactly across the diameter. If working to the usually accepted ± a thou (ish) accuracy you have to be pretty sloppy to be out of range. Being short sighted in one eye and long sighted in the other I have an excellent eye for level at a yard or more but it doesn't work so well close up. Visual alignment with the lathe bed got me going but, having got the knack, I now just do it.

Nipping up the lock without disturbing the setting is another knack. Try to do it too tight and the gauge will almost certainly move. Too loose and it will spring out as you withdraw it or shift under the micrometer. The first, cheap and rather rough, set I had didn't help. Over strong springing and rough turning threads made it hard. The well used, well cared for, M&W set I now use are silky smooth and so much easier. Nicely run in I think and almost certainly better than new. Was given a set of three that appear to be almost unused and they aren't quite as nice, just really smooth rather than silky.

Holding the gauge and micrometer freehand to make the measurement is another knack. Especially with the big ones. I frequently cheat and use a micrometer stand.

I'm confident to within half a thou error band if need be. But the care and concentration isn't routine.

Clive

Thread: VFD and screwcutting
15/10/2019 11:17:23

Ramp down times on decent quality VFD units are very consistent, certainly better than (normal) human reactions, so it shouldn't be an issue. You already have motor coast down to cope with. Ramp down time need not be much greater. 5 seconds should be ample, I'd probably try 3.

Consider making a bed stop with a sprung loaded microswitch inside. Connect the switch to the inverter controls and set the stop so the switch operates at the end of the thread. No more worries about stopping the motor in time.

Something like this inside the stop block would probably work :-

photo 3.jpg

That one was stolen from the lid mechanism of a spin drier rusted out after 20 odd years so the concept is reliable.

Clive

Thread: What solenoid to use?
13/10/2019 10:21:18

Generic car door lock actuators are pretty powerful and can be found quite cheaply in various designs and sizes. You need the 5 wire "central" one for stand alone jobs. About a fiver off E-Bay.

I've used them as a powerful solenoid substitute. Around a "long inch" travel I think.

Clive

Thread: Is this chuck mounted on a 5C collet?
10/10/2019 22:24:33

Yup. Its a 5C fitting.

Looks just like the San Jin branded one made in Yantai No 2 Machine Tool Accessories Factory that I got mumble-mumble years ago along with a Spindexer.

Was a bargain price but concentricity and general quality is remarkably good. I'm not ashamed to put it in the native 5C spindle on my Smart & Brown 1024 VSL on a regular basis when I don't need collet accuracy and the regular Pratt Bernard precision 3 jaw is too cumbersome.

Clive

Thread: Sharpening Machine Drills / Clarkson T&C Grinder
09/10/2019 16:32:19

Re the suggestion from Martin about using ER collets.

Before spending serious money on a set (or deciding that you won't be grinding enough drills for the dust to wreck your good ones) it would be as well to verify that the actual parallel holding portion is long enough to properly grip the two flutes of a drill. I imagine two points each side is the minimum for acceptable results.

One of the inexpensive drill attachment breed used Nylon collets witha long taper and correspondingly long collapse range. They were said to be satisfactory.

Clive

Thread: What is the way to put these holes in the right place?
08/10/2019 19:31:49

Probably faster to go the long way round and make up a jig to hold the plates exactly right then use the mill axis scales to co-ordinate drill the holes.

I'd be thinking in terms of clamping them in an L shape channel set at the right angle. Once you have the co-ordinates figured for the first one everything else repeats.

Model Engineer and Home Shop Workshop types have too much of a savings / economy mentality when it comes to materials. Objectively sacrificing a bit of metal to do the job just like that beats the pants out of messing around for a day with knife'n fork methods. One day I'll convince myself (don't hold your breath, haven't managed in 50 odd years so far).

Thread: Triangular Screws
07/10/2019 22:27:09

When the proper GKN Taptite screws are removed they leave a thread amply good enough to receive a normal screw of the same nominal size. Some of the more economically priced brands don't. Good ones work just fine in drilled holes, albeit larger than normal tapping size. Aluminium alloys or ordinary mild steel. I have a box of M5 ones that call out 4.5 mm for drilled holes. I ought to have the full list of drill sizes for original GKN Taptite screws somewhere. But I've not seen it for 25 years or so!

If you simply screw a taptite in the resulting thread is a bit distorted and tight on the screw. Effective inherent self locking. Especially in plastic. Removing it cleans up the thread so the self locking is lost if you re-fit it. The thread is looser too and maximum torque reduced. Using a normal screw brings the torque / strength thing back up but the self locking effect is largely lost. Best to add a drop of screw lock.

Clive

Edited By Clive Foster on 07/10/2019 22:27:31

Thread: DIY glass fibre pulley?
06/10/2019 10:45:07

As NDIY says consider an alternative to flat belts. Getting the crowning right so the belt runs true on all steps without rubbing on the side of the next bigger one at one end or the other can be a right pain.

PolyVee is easiest. The belt will run just fine on the flat pulleys at the other end. You will need a micrometer bed stop (easiest) or plain stop and space setting gauge to cut the Vees at the right intervals.

Getting pulley diameters sizes dead right so the belt tension is equal on all settings is another pain. None of my flat belt sets were perfect although they all worked. The shorter the belt centres the harder it is to get right due to the angle of the belt as it runs between different sized pulleys. Four steps are worse. Six steps, just don't go there!

Sensible man puts a spring or jockey pulley in to accommodate any variation. Makes shifting easier too.

Clive

Thread: Sharpening Machine Drills / Clarkson T&C Grinder
06/10/2019 10:30:31

Clarksons own drill sharpening attachment uses a 6 jaw chuck to hold the drill via the flutes which is clearly satisfactory. The instructions specify the distance by which the drill should stick out from the chuck. Its quite short.

The issue when holding a drill on the flutes is primarily one of getting sufficient contact points to hold the drill securely and in line with the spindle. In principle long jaws on a normal 3 jaw chuck would work fine but thats a cumbersome solution which will almost certainly have accessibility issues.

The Clarkson universal head simply holds the cutter by the shank is a simple parallel sleeve. Its probably over versatile for normal mortals. If I din't have the official tooling I'd probably make a simple bored block to hold each size of cutter arranges to bolt to a right angle bracket with a few indexing steps to get the necessary angles. Three might well be enough. A similarly small number of indexing steps to set the right angle bracket should do. I see no vital need for the graduated scales. To the book angles have more to do with getting maximum life under industrial conditions. Folk like us rarely work cutters hard so sharp at a good enuf angle is all that matters so you want a set up that makes it easy to sharpen cutters. If sharpening is a faff you will run them blunt.

Folk do use collets to hold cutters but that seems a potentially expensive way of doing things given all the grinding dust. Sidelock (weldon) holders in a block having the same taper as your mill would work for milling cutters too and be less vulnerable to grinding dust than collets.

Getting back to drills its a pity no one has published the geometry of the Clarkson attachment. Its fairly straight forward and well within home shop fabrication capabilities. I'd probably start by cutting down a spindexer. But I have the real thing.

Clive

Thread: Mechanisms in modern engineering design Artobolevsky
05/10/2019 22:47:04

All these collections seem to have a fair amount of dross in them. Probably more intended for inspiration when wondering where the heck you start or when your back of envelope sketches just don't seem right than a source of things to copy "just like that".

On the odd times I've pawed through such things the moderately daft, semi Emmett, devices have often been more helpful than the more engineered offerings. Pulling apart something that is, superficially at least, logically right but in practice just plain wrong can be an excellent way of clarifying things to dig your own ideas out of the wrong rut.

Clive

Thread: DIY glass fibre pulley?
05/10/2019 22:39:45

I've made several multi step pulleys, both flat belt and polyvee, by screwing and gluing individual steps together. That way you can start with close to size material for each step. Simplest way is to make them on an undersize mandrel and finish bore to size when bolted together. Need to keep your brain engaged when figuring out the sequence of tapped holes and through holes. I used hex socket countersunk screws 'cos I had a stack in a suitable size.

Sometimes I assembled the pulleys on a central tube which I finish bored to fit the shaft. Other times I just stacked them up on a mandrel. Both worked. However, on reflection, I think the best method is to use the central tube as the mandrel. Hold it in the lathe and mount the pulley blanks on it to cut to size so everything comes out true. If you don't want to put a screw or two radially down through the pulley blank you will needs an extra part fixed (grub screwed?) to the tube to hold the blanks against cutting forces. Start with the smallest of course, especially if they are crowned flat belt pulleys as doing the crown properly with larger step in the way will be a right pain.

I think I'd look for some 1" alloy plate to cut the blanks out of.

Clive

Thread: Would you buy one of these collets?
05/10/2019 22:23:06

Only way thats going to hold anything against cutting forces is if you tap tight fitting sleeve, or better, shrink fit, over the extended part after you've put the cutter in.

A semi permanent job. Which might be worth it if you have a suitably hefty cutter, flycutter, boring head or whatever on a 25 mm shaft sitting around doing nowt.

Considerable risk of the collet snapping where the taper runs out into the extended part.

Better to get a sidelock (weldon) holder and grind a flat on the cutter. At least the holder is all solid.

Although I have full sets of R8 in both imperial and metric I'm rapidly coming to the conclusion that sidelock is the better way for plain shank cutters. But Clarkson is my general purpose go to as I have plenty of screwed shank cutters.

Clive

Thread: Good practice for lathe circuit design
04/10/2019 15:04:40

Rainbows

Your suggested Plug -> Isolator -> NVR switch w/ E stop -> Motor layout is functionally equivalent to standard industrial practice although the machine will usually be hardwired into the supply. The normal electromagnetic contactor does the NVR thing and there will usually be a switch wired in series with the contactor coil to do the E-Stop. Most modern lathes will have a stamp on bar across the front to operate the switch. Common practice is to put extra switches in series to ensure the lathe cannot be started if anything is unsafe.

E-Stop or equivalent usually operates on the spindle and coolant pump motor only.

If you have a VFD normal practice is to wire all the main motor control switches to the VFD. Isolator swithc comes first then sort out the other power feeds as seems logical. Quite common to have more than one swithc on a single button / lever or whatever to interrupt multiple power feeds at the same time. On a machine tool its good practice to run pretty much everything via NVR switches so you know that its all fully powered down in emergency and know where to start from when bringing it back up.

Given the choice I prefer to wire the light direct to the isolator to clearly indicate that the machine has power and can run.

Clive

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