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Member postings for michael darby

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

Thread: Powder coating
02/03/2020 19:36:21

Powder coating is a con. it is simply paint which is hardened in an oven. the paint drys before the base material is even warm and very hard. Once the item is in sevice,the material expands and contracts and the "Hard " paint cracks,allowing moisture under the top coat (no undercoat used). in all my time in contract engineering, I have never seen 1 successful application

Thread: Special nuts: Any name to what I may need?
11/01/2020 15:55:27

At 5mm you wont have much holding it. The stud will be tapered to allow the cutter to start the thread and the nut likewise

10/01/2020 20:26:23

Sorry, thinking of box section. You could always counterbore the bar and fit a nut in the recess

10/01/2020 20:18:42

You could open the top hole and use a regular nut tightened with a socket

Thread: 13x13x4" square pressure tank
20/02/2017 19:27:36

Yes, its possible. but if the public are anywhere near it, get it built and certified.

Thread: Tig vs Silver Soldered boilers ?
28/01/2017 11:19:45

Tig would be a complete fusion of the joint,if done correctly .where as silver solder is simply a "glue" at microscopic level.A TIG welded joint will out perform silver soldered in all tests.

Thread: gasket material for dishwasher
24/01/2017 14:39:05

closed cell neoprene foam is available,and should do the job

Thread: Bright vs mild steel and 'bananaring'
23/01/2017 16:12:10

Any Gate manufacturer will have 12mm sq black bar.its dirt cheap look for a local place and call in

Thread: Need to get a Welder!
15/01/2017 18:21:26

The problems that most beginners have is that they use either cheap or old electrodes that they are given with the welder, you need electrodes which are suitable for use with the power source you have available.They need to be kept perfectly dry( any moisture turns to steam and creates spatter and holes in the weld)A high volume of iron powder in the coating will assist in the free running of the rod and allow it to be "dragged" along the joint with little weakening of the weld structure.Also choose an electrode size that your power source will cope with . Most power sources will cope with 2.5mm (90-120amp)some 3.25mm (110 -140 amp) and a few 4mm (130-180 amp)

Thread: Oilite bushes
02/01/2017 09:43:08

The so called "upset expert "is nothing more than a pratt . the whole purpose of this type of forum is to exchange ideas and further knowledge.The OP should ask as many questions as he likes, and those with the appropriate knowledge ,I am sure,will be only too willing to help, in order assist the OP.

Thread: Welding
25/07/2016 07:46:42

He would have used a nickel based filler which as I stated earlier would not have "Welded" the joint " because the filler could not use up the free carbon it would have "adhered" to the iron molecules in the casting forming a nickel rich iron moleclue. the problem with this is that you have free carbon atatchments to the iron creating brittle edges within the structure of the material hence the post heating cycle to attempt to reduce the brittle edges

24/07/2016 19:36:00

The only way to "WELD" cast iron is using oxy /acetylene. Any other systenm is adhesion on a microscopic level.The problem is the free carbon available in the cast iron which has a tendency to embrittle any filler material. The use of nickel helps to reduce this tendancy,because it does not combine with the carbon.

Thread: Plating nuts and bolts
22/07/2016 20:32:28

"Stainless" is not always the answer. it does not suit some applications and not all "stainless " bolts purchased are what you expect to purchase. There is a lot of cr&p out there

Thread: Repairing cracks in cast iron
19/06/2016 16:41:18

You can weld that quite easily using oxy/acetylene and cast iron filler material .you will need a flux to float off any carbon in the casting.

Thread: The Workshop Progress Thread (2016)
04/06/2016 06:50:26

For a better finish, try iron powder electrodes they will give a smoother finish with less dressing needed Try esab femax 33.80

Thread: Heat Treatment - hardening and tempering
31/05/2016 07:26:58

You certainly dont want HARD you need tough hard will shatter

Thread: Supplier metal formings
16/05/2016 18:46:33

Try your local fabricators or sheet metal shop,they will have the necessary equipment

Thread: Carburettors!
29/04/2016 19:11:55

its simple really ,as the piston goes down ,it creates a low pressure in the cylinder the inlet valve opens and air rushes into the low pressure area through the carburetor as it passes over the jet it sucks petrol out of the jet into the cylinder. the bigger the jet the more fuel the bigger the carb more air. theneedle is tapered and controls the amount of fuel. small amounts for slow running larger amount for fast running, some carbs do not use a needle and have more than 1 jet to achive a similar result.

Thread: Tuning
29/04/2016 19:01:36

Engines are "tuned" for different reasons, the car engines are set up to be reliable and economical. race engines are usually tuned for outright power.,which loses the reliability and economy. basically its about getting the largest charge,ie fuel/air mixture into the cylinder and producing the biggest bang. this could involve larger carburretor, longer injection timing,higher valve lift,longer valve opening timing and higher compression. but everything is a trade off more power means shorter component life more wear and less reliability.

Thread: Best tool of the day
25/04/2016 18:27:03

The hammer is called a Monday hammer,we had them in heavy fabrication shops for "setting" the edges of plates prior to rolling, My mates dad who was about 10 stone wet through could swing it all day,I couldnt even lift it over my head.

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