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Member postings for Douglas Johnston

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

Thread: Bandsaw - wood and metal ?
11/04/2021 12:51:11

In the past I wondered if I could get away with one bandsaw for wood and metal but it is not really a good option. The speeds are different and so are the blades. You would be forever changing the blades and that can be a real pain. I ended up with one of the 6 by 4" horizontal bandsaws for the metal and a vertical one for wood. A wood one will cut aluminium at a pinch but not large chunks of the stuff.


Thread: Recommended suppliers and services
08/04/2021 11:35:13
Posted by Pete. on 07/04/2021 22:49:58:

Douglas, the 18pc 5 micron max runout set is currently £224+tax on offer which I thought was quite reasonable, the normal price is £280ish +tax.

Thanks for the information Pete, that seems quite reasonable for a quality item that you can rely on. I know you can get collets a lot cheaper but the quality can be suspect to say the least. More information on the website about pricing and special offers would be helpful.


07/04/2021 10:53:14
Posted by Pete. on 07/04/2021 00:26:21:

I'll start it off by recommending a company called D & J WORKHOLDING

They can have collets for obscure old machines made, and supply high quality kit, I just bought from them an 18pc 0.005mm max runout er32 collets of German manufacture, branded Fahrion, they're so finely ground they look chrome plated, turned up at my door the next day, and they are very helpful if you need any help.

Fahrion er32 collets

Hi Pete, that source you mentioned for ER collets looks interesting but I notice the website does not give any prices. If you don't mind me asking, what did you pay for the set you bought ?


Thread: Removing a J2 arbor from a drill chuck
28/03/2021 11:17:22
Posted by old mart on 27/03/2021 19:54:35:

If you end up deciding to leave the chuck and arbor together, there are R8 adaptors for tanged MT2 chucks. We have one chuck still with its MT2 taper which can be used in the lathe tailstock as well as the mills.

That sounds like a good idea since I have not managed to budge the M2 arbor. I am amazed at the grip these tapers provide considering the relatively small surface area of the taper. I suppose the previous owner may also have put some high strength Loctite on the taper before fitting and in that case it will never come apart.


27/03/2021 18:09:37
Posted by Peter Tucker on 27/03/2021 16:05:23:

Hi Douglas,

I would make a new pair of split wedges; probably quicker than hunting for the old ones. The split wedges I made work a treat.

Hope this helps.


That's probably a good idea Peter, and it is almost certain to make the lost ones appear. Like most workshops I have a gremlin that hides tools until they are no longer required and then gives them back.


27/03/2021 14:29:31

Thanks for the replies, the chuck is a Metabo-Futuro one and might dismantle in a similar way to the Albrecht type so will give it a go.


27/03/2021 10:55:50

I have just acquired a good 0-10mm keyless drill chuck with a MT2 arbor. I want to replace the arbor with an R8 arbor for use on my mill but cannot remove the MT2 one. Somewhere in my workshop I am sure I have a pair of wedges for this task but I can't for the life of me find them. I last saw them about twenty years ago and vaguely remember having little success with them.

Is there any technique that others have had success with in removing an arbor or is it a case of once fitted they are there for life and I should just give up now.


Thread: Ball Races and 'Brinelling' (whatever that is).
10/03/2021 11:33:33
Posted by not done it yet on 08/03/2021 19:46:13:
Posted by Douglas Johnston on 08/03/2021 13:26:42:

I wonder if the huge bearings on wind turbines suffer from this when the blades are stationary on calm days. There must be a huge static load under those conditions.


Here we go again. Yet another fantasy problem for our wind turbine haters.

The cause is known. Engineers are not stupid once they are aware a problem they take remedial action. Wind turbines are designed to last twenty five years without swapping bearings at regular service intervals. They are likely not stationary - there is probably some tiny electric drive barring the rotor gently, while the turbine is out of service.




Oh dear , I seem to have touched a raw nerve with my comment. It was just an idle thought I had while reading the thread. I rather like wind turbines, I have a couple of large ones close to my house and can spend ages just watching them.




Edited By Douglas Johnston on 10/03/2021 11:34:31

08/03/2021 13:26:42

I wonder if the huge bearings on wind turbines suffer from this when the blades are stationary on calm days. There must be a huge static load under those conditions.


Thread: Crowning a pulley for a flat belt Question
04/03/2021 11:19:20

When I built a belt sander I faced the same problem and solved it by keeping the pulley parallel and then wrapping some insulating tape round the central third of the width to create the crown. Worked a treat and is still in use after 20 odd years.


Thread: Countersink bits
27/02/2021 14:26:55
Posted by Philip Rowe on 27/02/2021 13:41:43:

Since I switched to using spotting drills instead of centre drills, I have found that they also make excellent countersink bits with no chatter at all.


+1 for that. I discovered this quite recently after buying a set of various diameter 90 degree spotting drills on the bay. They cut a treat and give a very neat countersink if you pick one just a tad bigger than the screwhead.


Thread: ml10 or some other?
23/02/2021 11:55:23
Posted by Liam Cook on 19/02/2021 16:38:26:

Doug, could you give me some exampels of things you've made or things you've struggled with on the Speed 10?

Hi Liam - sorry for the delay in replying, just noticed your posting. I see you have decided against the Speed 10 so not really relevant now but I have made a lot of small tooling and projects. The most frustrating thing has always been the small bore through the headstock (about 5/8" if I remember ) .I am not into making models so things like large flywheels have never been an issue for me but may well be for others. Probably the largest thing I have made with the Speed 10 is a Quorn cutter grinder.


19/02/2021 16:01:13

I have been using the same spec machine for the last 30 years and like it a lot. Having said that it does have issues that you need to consider like the low centre height and small bore through the headstock . They are nicely made machines but quite small and not suitable for big projects.


Thread: Using an old microwave transformer
27/01/2021 13:36:58
Posted by Ian P on 27/01/2021 13:14:05:


When dismantling an old oven to extract the transformer be aware that there may still be lethal charge in the capacitor even though its disconnected from the mains. In theory the oven manufacturer will have fitted a bleed resistor but its best to be safe.

I have no bad experiences or anecdotal knowledge but suggest that anyone contemplating repurposing the transformer does some research beforehand.

Ian P

Very well said Ian, you can't be too careful when dealing with mains and charged capacitors, I have had a few minor shocks in my time and am now ultra careful when dealing with electricity.

With regard to bandsaw blades, I too have used silver soldering with good results and don't really need to try welding but just thought I would give it a try after reading the article in MEW. That article by the way was very interesting but resulted in a device that was rather over engineered. My idea is to pare the idea down to the bare essentials. It may well not work but as they say- nothing ventured...


27/01/2021 11:28:52

Hi Joe, you are a mine of good information. With regard to the bandsaw blade welding, I want to try welding 1/2" by 0.025" blades for my ubiquitous 6 by 4 inch horizontal bandsaw and as you mentioned the MOT should be up to the task. I think it will take quite a bit of experimenting to get the correct conditions of power and preload etc but it will keep me amused for a while during lockdown!


26/01/2021 11:53:14

Wonderful explanation Joseph and that spot welder you have made really looks the business. The spot welder I have in mind is a much more modest affair for use with very thin gauge metal. I also want to experiment with band saw blade welding with another microwave transformer along the lines of an article in MEW 41.

Perhaps I should start collecting some more old microwave ovens in case I find other ideas to investigate, since it would seem more modern ones are less likely to have a good old beefy transformer.


Thread: ebay purchases : VAT
26/01/2021 11:29:03

Am I right in thinking that if I buy an item at less than the threshold of £137 via ebay from China there will only be VAT to pay, and that will be collected by ebay. The postman will not be standing at my doorstep demanding more money for import duty and handling charge.


Thread: Using an old microwave transformer
25/01/2021 11:16:29

Thanks for that information Dave, the theory behind the operation of the shunts would probably tax my aging brain to the limit, but at least I can ditch the shunts without any problem. I wonder if modern microwave ovens still use these large transformers or if there is new electronic wizardry to replace them.


24/01/2021 17:29:03

Thanks for the reply John, so it would seem that I can dispense with the shunts if I need the extra space for the secondary winding. I would love to know why they are included in the first place for use in the microwave.


24/01/2021 15:17:29

I have started to make a small spot welder using an old microwave transformer ( I never throw anything away! ) and have a question I can't seem to get an answer to despite trawling the net.

When the redundant secondary winding was removed I noticed that there were two stacks of about half a dozen iron laminations separating the primary and secondary windings. I believe these are called shunts, but I have no idea what their function is and whether they can be removed to create more space for the thick welding cable secondary winding.

Can some electrical guru explain the function of these shunts and should I leave them in or discard them ?


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