Here is a list of all the postings duncan webster has made in our forums. Click on a thread name to jump to the thread.
|Thread: Tube Seam|
If you do have a go at a barrel with a seam then you'd be better with a butt strap rather than a joggled joint. Not only is it stronger it's also easier to make
|Thread: How many threads please?|
All these rules for depth of thread are aimed at developing full strength, but you don't need anything like full strength on this application. Assuming 80 psi steam, you have 2.2 lbs force. The pitch diameter of the thread is near enough 11/64" and the thread length is 1/8" (again near enough), so the area of thread in shear is 11/64 * pi * 1/8 * 1/2 = 0.034 sq.in, so the shear stress is 65 psi, which is not a lot. Go for it, use sealant and don't over-tighten
just for interest, a 1/4" bsw nut is only 0.2" thick, 0.8D, your 3mm is 0.63D
Edited By duncan webster on 12/02/2019 23:50:39
|Thread: The Workshop Progress Thread 2019|
Edited By duncan webster on 11/02/2019 20:10:09
|Thread: Thick walled copper tube|
If using an external feed I'd put it right next to the boiler under the cladding to keep it hot. I've seen at least one loco at our track with water droplets coming out of the blower as the feed pipe was running in fresh air. Two of my locos are done as suggested successfully
|Thread: anyone recognise this milling machine|
Thanks chaps, I even managed to find a spec sheet in an old thread, so it's going on the classifieds in the next few minutes
I'm going to advertise it on behalf of a friend who is having to give up due to ill health. It would be easier if I knew what it was. I know it's from Chester, but can't find a model number anywhere
|Thread: Every Tea Room needs a toaster topic...|
many moons ago I discovered that you could make toast on the wall mounted electric fire in my room, Clip the bread to a wire coat hanger and hang it from the front grill. Always tasted better somehow, but not much good for making toasties
|Thread: Single phase verses 3 phase motor|
Wouldn't go back to single phase for all the tea in China. 1.5 HP single phase is going to be quite a lump as well, as Brian says you'll get S/H 3 phase if you search. Try Gavin Oseman who sometimes advertises on **LINK**. Never dealt with him but I know a man who has.
|Thread: What is this electric clock mechanism|
Please don't debase it by fitting a quartz movement. I've got several slave clocks driven by home-brewed electronics. 555 is not go not accurate enough. The simplest is to use the crystal out of a quartz clock to give you a 1 second pulse and feed this to an arduino to further subdivide it to the (probably) 30 second pulse required, but if you're not into Arduino then you could use decade counter chips. You can also use decade counters from the mains, divide by 10, 10, 10 and 3. Arduino is simpler!
If you're interested send me a pm and I'll send further details
|Thread: Pitched aluminium rings. Any ideas how to machine them?|
You could also use one of those pointy inserts, but for cutting ally I'd use HSS
Edited By duncan webster on 05/02/2019 16:03:35
|Thread: Displacement lubricator - with or without valve ?|
That's not how it works, steam enters all the time whilst there is steam in the feedpipe. It condenses and sinks to the bottom displacing oil back into the steampipe. I think you need to make sure there is no trapped air.
|Thread: Pitched aluminium rings. Any ideas how to machine them?|
+1 for SOD method, but I'd have machined a groove with a parting tool so that the outer chamfer ran into fresh air rather than becoming a wider and wider cut.
|Thread: Unused Xmas Gift|
If it's one of these
I've got one fitted with a 2MT shank on my Centec, and it works a treat. I'm gentle with it, 0.03 depth of cut, 800 rpm and 8" per minute feed rate. Gives a very good finish on steel. The tips that came with it are absolute rubbish, not even flat on the back where they bolt up, but they work, I haven't chipped one yet. When I've used up the stock that came with it I'll buy some decent ones. Even with the small depth of cut it is shifting metal as quickly as a smaller cutter going more slowly. You do need cotton overalls and safety glasses, the chips are hot and fly everywhere
Edited By JasonB on 04/02/2019 14:57:08
|Thread: Fitting a Reversing Switch to a Motor on a Myford Lathe|
That's pretty much what I did when the centrifugal switch died on a very old motor I had on my ML7. It was so old that in the 1990s there was no-one at the makers (Crompton Parkinson) who was working there when it was made. Despite this they sent me some capacitors to reduce the start current and a diagram of how to connect it as Martin has. Worked a treat, just need to use some intelligence, hold down the start button till it's got going. You don't get that sort of after sales from Banggood
You can actually get a reversing NVR contactor, my 254S had one before I converted it to 3 phase, if you're interested I could photocopy the wiring diagram from the manual, but if you've already got a reversing NVR and a Dewhurst I'd use them
Mine whines all the time and continues to do so for several seconds even after the power is switched off, which is what made me think it was a cooling fan. Eventually the noise reduces in frequency and stops, and I can feel the cooling draft tailing off at the same time, still sticking to my fan theory! The newer one on the milling machine doesn't, it is completely silent
Edited By duncan webster on 01/02/2019 12:53:58
One of my vfds from about 15 years ago does have a whine, it's the cooling fan I think, but later one is silent. I think it's the MCB that trips under inrush current, you can get slow action ones that will cope. I have a normal 30A MCB supplying the workshop and a local distribution board with a 15A fuse for the VFD
3 phase is so much better, but If you do go down the route of reversing your single phase, don't use a Dewhurst switch to start/stop, keep the NVR and use the Dewhurst when it's stationary to change direction
|Thread: Centec question|
Of course I do, just testing!
If your motor is built into the cabinet I strongly advise you to stick with 3 phase motor, a single phase motor makes the cabinet vibrate like mad and you need ear defenders. Mine was transformed by fitting 3 phase. As others have said you'll get an inverter for less than the cost of a singe phase motor, provided tat is you can reconnect the existing 3 phase as star.
I have a stepper motor driving the table, with the inevitable Arduino really handy to be able to wind the feed rate up and down
Do you really mean 3mm OD? That is going to be very small ID. As for material, use what you can get, I doubt you'll have much choice
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