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Member postings for Alan Jackson

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

Thread: Chipmaster variator
16/11/2020 18:49:59

I did a similar thing to my old chipmaster. I described it in MEW 253. Repacing the variator with a modern inverter solves the problem of a worn variator.


Thread: Vickers Bl 8 inch Howitzer cannon of 1917
26/10/2020 10:08:58

Magnificent work Mal. It will be great to see this when it can be exhibited.


Thread: Why is this guys mini lathe parting off so well?
23/10/2020 11:02:09

Here is my version for a parting tool. The cutting tool is in compression, avoiding the flexure due to the conventional cantilevered parting tool


Thread: New Moderators
31/08/2020 18:02:17

Welcome Mike & Dave, well done by you.


Thread: The Workshop Progress Thread 2020
09/08/2020 10:33:12

Roderick, your guitar is a beautiful work of art - congratulaions


Thread: ML7 3jaw pratt burnard
21/07/2020 17:08:50

fastdave & Martin kyte, I am certainly not nimble fingered; it is not hard to adjust the jaws so that each spacer can be pushed in position with the jaws set to a push fit so to speak. Once this is set up I just tighten the jaws up more and have 'not yet' found that the spacers have moved due to centrifugal force etc. I run the chuck at about 300 rpm or so, no problem. If you are very safety orientated I suppose you should make the ring arrangement shown earlier, but its a lot of work for such a simple process.


Edited By Alan Jackson on 21/07/2020 17:10:15

19/07/2020 18:20:10

I made three equal length spacers cut from a steel ring and insert them as shown . Works very well


Chuck jaw grind

Edited By Alan Jackson on 19/07/2020 18:21:56

Thread: Help please identifying a large vertical slide
14/07/2020 13:12:19

It is a Harrison vertical slide. Strong and solid


Thread: What’s the tolerance??
04/07/2020 10:50:49

The benefit that model engineers have is that they are the only one working on their project and as such can make any part near enough to the dimensioned size on the drawing. The mating part can then be made to match, but the art is knowing how the mating part has to fit and work to suit the required operations. If drawings were provided with machining tolerances, it would force the maker to comply with rigid requirements that would make the part much harder to produce, as well as require remaking in some instances to achieve a size which is often really only a dimension put on the drawing to show the general outlines etc. Tolerances are required for components made by various outside sources in order that other parts from other sources can fit together and comply with the design requirements.

Imaging making the drawings for a clock, say, with toleranced dimensions. It would force the designer to now legally comply with ensuring that every clock made to these drawings will run like clockwerk, sorry could not resist it. Have you ever tried to go through a design ensuring that the tolerance build ups (that is adding and subtracting the variations in a design due to component tolerance extremes) to ensure it can still function when the worse variations of the mating components come together?


Edited By Alan Jackson on 04/07/2020 10:53:43

Thread: Which Lathe???
02/07/2020 12:43:19

Very happy with my old Chippee - yipee!


Thread: ER32 frustration
29/06/2020 11:42:36

On my Stepperhead lathe the ER32 collet nut has two hardened discs positioned 120 degrees apart to act to remove the collet. I did it this way to avoid making the eccentric ring. This method has advantages in that it is easy to insert the collet and the hardened discs can be machined to a diameter and thickness to ensure they do not interfere with the concentricity of the installed collet.


Hardened discs for removal

Thread: Parting off
12/06/2020 18:36:24

With apologies for being flippant I wrote this some time ago


Vertical Parting Tool

A while ago I tried out a vertical parting tool it worked ok but I must admit I did not give it exhaustive testing to destruction etc.

In order to clarify the operation of a vertical parting tool here is my rather primitive description of how I think it works.

Imagine that you are the parting tool holder whereby your two hands are held straight out from you body. You hands are gripped together and your fists are the cutting edge. You have a friend who represents the metal being cut and he (If you are a front parting tool) pushes down on your hands while you do you best to resist him pushing down. You can see that he can quite easily push your arms down. If you want to now become a rear parting tool you can turn round 180 degrees and your friend would now push your hands upwards still he can easily overcome your resistance to him pushing up. So in order to stiffen you up, say you are frozen solid or have rigor mortise and are wearing a large pair of lead diving boots to anchor you down. When your friend (or should I now say de-parting undertaker) pushes down on you hands he will not be able to move your arms down because they are rigidly fixed to your body and he have to apply more force until you tip forward on you toes. Note that as you tip forward you rotate about your toes moving your cutting tool hands deeper into the metal being cut. If you are now rotated 180 degrees to become a rear parting tool your friend (some friend) now has to apply more upward force until you tip backwards on your heels. Also note that your cutting tool hands now move away from the metal being cut as you rotate backwards on your heels. Now you have to play the part of a vertical parting tool as I am proposing, so you now can be thawed out or de- rigor mortised. So lay flat on your back and push one arm vertically upwards and clench your fist to form the cutting tool. Your friend now has to apply considerably more force to overcome your vertical arm. Your arm will be in direct compression and until your elbow or wrist give way you will have much less a problem resisting his downward cutting force. It will also not matter if you are a front or rear vertical parting tool as long as the rotating force is pushing down on your hands. You can now get up and go back to your work or whatever you were doing. I apologise for being so flippant but I hope it does explain the reasoning.



Thread: Tallyho project
10/06/2020 16:19:24

Sorry I mis spelt the Topic title can it be corrected?


10/06/2020 16:04:11

I have just been watching on youtube the rebuilding of an old sailing ship see

This is certainly not model engineering but it shows the superb skills in being a shipwright on a wooden boat. Well worh watching


Edited By Alan Jackson on 10/06/2020 16:09:19

Thread: Colchester chipmaster worm box removal
25/05/2020 11:03:07

Hi Adam,

In MEW No 187 John Connaghan describes how he dismantled and improved the fine feed knock off and dropped worm assembly. This will help you.


Edited By Alan Jackson on 25/05/2020 11:03:32

Thread: Sort of a Straw Poll
13/05/2020 10:43:14


Tell your son you are going to buy a brand new top of the range luxury car. He may think this is wonderful only to find out that it has probably lost about half its value by next year and so on. Machine tools may not be a financial investment but they will still be returning the interest and entertainment value to you.


Thread: Power feed for a VM32L mill
21/04/2020 10:43:32

Hi Iain,

This approach might solve your problem;  the worm attached to the stepper motor shaft can be rotated on its eccentric mounting to engage or disengage with the worm wheel on the feed screw. You also get a good reduction drive (say 20 :1) to give a slow speed and high torque. The stepper motor speed seems to be just about right.


Cross slide stepper drive

Edited By Alan Jackson on 21/04/2020 10:44:03

Thread: A Benchtop Surface Grinder
17/04/2020 15:14:19

Hi all,

I have just seen the latest MEW No 293 ( May 2020). In the magazine is an article I wrote about a Benchtop Surface Grinder and I have realised that I have ommited three photos and this has probably messed up the photo numbering in the article. For this I can only apologise to you the reader and also the Editor.

So in an attempt to put this right I have added the three photos in my album and here. Sorry about this I hope it has not created too much confusion.

photo 9.jpg

Photo 9 Keyway mounted in the vertical support casting

photo 10.jpg

Photo 10 Keyway groove in the vertical column

photo 11.jpg

Photo 11 Motor mounting table



Edited By Alan Jackson on 17/04/2020 15:15:27

Thread: Hi From Denmark
28/03/2020 15:39:07

Hi Erik,

Welcome, I am also happy with my old Chipmaster. I have happy memories of working in Esbjerg for offshore platforms.


Thread: Annealing stainless steel
16/03/2020 16:50:15

The problem with stainless steel is that carbon carbide and chromium like each other too much and at high temperatures form austenite which is a solid solution of one mix. The affinity is so strong that it does not come out of solution very easily. This is the very fact that makes stainless steel stainless, Its the dissimilar mix of ferrite and iron that make carbon steel go rusty.


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