Indholdsfortegnelse for August 2022 i Model Engineer & Workshop

Recent Changes I hope you enjoy the cover of this issue. Regular readers will notice the new publishers have introduced a few improvements to paper quality and finish over the last few issues, and now we have given the cover style something of a refresh to make it brighter and more informative. We have retained the issue number triangle, something that we know is close to the hearts of many readers. I’d be interested to hear your reaction to the new style, and any other ideas you have for improving Model Engineers’ Workshop. Share your thoughts with me by emailing meweditor@mortons.co.uk. During June, the forum at www.model-engineer.co.uk was moved to the servers of Mortons, our new publisher. This effectively ‘broke’ a few things, most of which were resolved quickly. My…

Readers! We want to hear from you! Drop us a line sharing your advice, questions or opinions. Why not send us a picture of your latest workshop creation, or that strange tool you found in a boot sale? Email your contributions to meweditor@mortons.co.uk. Free Pendulum Clock Dear Neil, I looked with interest at Tony Jeffress article in Model Engineers Workshop No. 316 regarding building a “Free Pendulum Clock”. Unless I’m missing something, he seems to be making an electronic copy of a mechanical Hipp Toggle. Commendable as this is, the result presumably will be a time keeper which acts just like a traditional Hipp Toggle and as such will not provide any improvement. With this in mind, would it not be wise to consider using a linear Hall effect device…

There are three main ways of joining metal parts: mechanical, fusion (welding, brazing and soldering) and adhesives. Many, but not all mechanical methods are reversible while fusion methods are generally permanent. Adhesives can range from the very temporary (like double sided adhesive tape) to effectively permanent. The strength, accuracy and permanence of joints in your work will be critical to their success, so it’s always worth considering what will be the best solution for a particular task. Mechanical Methods The simplest way to fit two bits of metal together is to make a hole in one and a plug on the other, slightly oversize, and force them together. Though it sounds primitive such interference fits can be both strong and accurate and they find wide application for duties such as…

As an aside, roughly 0.49 seconds error in a minute amount to roughly 700 seconds error over the course of a day. With a 1 second pendulum, a daily rate of 1 second corresponds to a change in length of 0.0009”; alternatively, a full turn of my 24 TPI rating nut will change the daily rate by 46.29 seconds. My pendulum bob would therefore appeared to be roughly 0.63” too low; around 15 full turns of the rating nut would lift the bob to more nearly the right position. After trimming some excess, the overall length of the rod, from the armature to the threaded end for the hook, is now 44”/1117mm. The electronics Somewhat in parallel with doing the mechanical work, I did some more detailed work on the…

MEW Workshop Photography Competition In the last issue we announced an ongoing Photography Competition. Here are some more details, note that we have changed the range of subjects that can be entered. In 2015 we produced a ‘special’ that celebrated 25 years of Model Engineers’ Workshop. A number of copies of the special, which we thought had sold out, have come to light. We are offering them as prizes for a photography competition. The subject of the photograph has to be an activity in hobby engineering workshop, it can include a person, but this is not essential. It can be a self-portrait or of someone else in their workshop. The photos on this page are examples of winners in a previous competition in 2015. The best photographs will be published,…

When I bought my WARCO economy mill/drill in the early 90s, part of the package was an inserted tooth shell mill. The teeth carried brazed carbide inserts. The finish that it provided has never been spectacular, but I thought that it was the nature of the beast. The performance of the milling cutter has deteriorated over the years, to the point where something had to done. Either to replace the cutter or to regrind it. Having a Worden cutter grinder and a diamond wheel, courage was taken in both hands, and the decision made to have a try at regrinding it. After all, there was not much to lose. If it went wrong, a new cutter would be needed, anyway. If it went well, the cutter would be useable again.…

A good friend was in the process of acquiring a small clone of a Bridgeport mill, the whole bottom section of which had still to arrive once lockdown transport restrictions have been lifted. The model is sold by Chester Machine Tools as the 830-VSR turret mill. An identical looking machine is sold by Grizzly in the USA under a different machine number. He had already received the head. The whole machine had previously been used rather unusually as a CNC tool with stepper motor drives controlling the motions, including that of the quill. Because of this the head was never finished or equipped for manual operation. In its new location my friend wants to use it manually and while he is more than capable of doing the work himself, I…

I recently received the news that Stan Bray, Model Engineers’ Workshop’s founder and first editor had passed on after a brief illness, indeed Stan was still bright and active up to a few days before the end. Everyone who has been involved with and enjoyed MEW over the years has a debt of gratitude to Stan. All of us here at the magazine would like to express our sadness at his passing and our condolences to his family. Below, Stan’s son, John Bray, shares a little more of his life story. Stan was born in 1925, he spent the war working as an engineer. He did sign up and passed his medical, but the application was subsequently cancelled as he had trained as an engineer and had some knowledge of…

As I have retired, I expect the impact of lockdown on me is far less than on a lot of other people but the restrictions in place for going out were significantly felt. I decided that a project, home based, was needed and that this would yield something at the end of the period. I could have concentrated on something in the workshop but the temperature at the start of the period still had a bearing on the amount of time that could comfortably be spent in the shed so initially it had to be something indoors. My mind turned to my large collection of MEW back issues. I have copies of the typical indexes issued from time to time, fig 1, and there is a spread sheet version for…

I have, for want of a better word, a pole chainsaw branded as Expand-it listed as a pole pruner/chainsaw it fits most brush cutters that have a two-part pole or shaft as shown in photo 2. I wanted a new chain for the pole chainsaw and I had a redundant chain from an old electric chainsaw of what appeared to be the correct size of chain. Photograph 3 shows a section of the old chain on the pole chainsaw, it is 3/8 inch pitch, the replacement is also 3/8 inch pitch but would the drive teeth be the same? To check that the other chain has the same drive teeth thickness as the replacement chain I used a small gauge to check both chains. Photograph 4 shows the shorter of…

WHEN Springs are standardised and made to a specification, the user is often supplied with basic data to test when deterioration occurs-because springs which are weakened or shortened cannot function as designed. In the case of coil springs; A, the free length “ X ” is given in inches and fractions, and the compressed length “Y ” when the spring is supporting the specified load in pounds. Both lengths can be measured with a rule or calipers, the compressed length being taken when the spring is weighted as shown. Alternatively, the weight can be suspended from below, as it would be in the case of an extension or tension spring. Testing compression springs To test coil compression springs, A, by suspending a weight from below, a hole should be provided…

When you are setting-up work or marking out, do you sometimes sigh ‘oh for a pair of eyes’? In this ingenious feature ‘Bluey’ comes to the rescue with an easily made pair of aids for your workshop. You’ll find this optical centre-punch and centre-finder indispensable and they’ll cost a fraction of what you’d pay for commercial items. Centre punching is a tricky business although in theory there is nothing to it! What should happen is that the centre punch should be used at the junction of two scribed lines and should be drawn along one until the intersection is felt and then at that point tapped with a hammer. I am sure most of us follow this excellent advice only to find that the punch has slipped out of position…

Mill Gib lock Screws TIP OF THE MONTH WINNER! This month’s winner is Peter Webb of Felixstowe, with a tip for using knurled thumb screws to gib locks. You may be interested in attached photo showing fitting of knurled thumb screws to gib locks of an SX2P mini mill. They are so very much easier to use than having to fiddle about with a hex key, especially when accessing the gib lock screw hidden under the table. Before fitting the thumb screw, I would so often hope I would get away with not bothering to lock a gib. The thumbs screws work well but I may be tempted to replace knobs with small tommy bars to give more torque to ensure locking for heavy machining operations. I found it necessary…

Over the years, using my workshop facilities I have constructed many projects but the one outlined below is easily the most important at this stage in my life. Suffering from vascular dementia for the last few years has gradually reduced my wife’s ability to walk or stand. She was admitted to a local hospital in January 2020 for assessment. Whilst in hospital she was unable to manage movement using a Zimmer frame and needed to be moved on a hospital “Stedy”, photo 1, to ensure she did not fall. She was discharged home in March 2020 subject to care package involving four visits per day by two carers who attend to her personal care. Although she can still move her legs and feet the long hospital stay has weakened her…

In order to find the derivation of the equations used in Part 1, with the help of my friend Pete, I tried to find the origins of the two movement approach described in Ref.2, see below. Alas, we were unsuccessful, but the trail went back a long way. References led back to 1891 an article by A D Pentz (Ref 4) but we were unable to access a copy. In the absence of the original work, the only way to verify it was to attempt a derivation from scratch. By way of a simple start, consider an annular disc which is milled with a small diameter end mill of dia. d, to form a radial slot, both parallel sided and parallel depth, fig. 1. To convert the slot to the…