Here is a list of all the postings John Rutzen has made in our forums. Click on a thread name to jump to the thread.
|Thread: Repair on cast base.|
You can silver solder cast iron. Heat the bits red hot first which burns off any carbon. Then wire brush, use Tenacity No 5 flux and silver solder it.
|Thread: oxygen concentrators|
The process on the Fre02 website which refers to the Africa project is described as low cost compared with cylinders. To quote;-
These devices contain ‘molecular sieves’ of zeolites, which are made from an abundantly available, low-cost mineral. When air is compressed and brought into contact with zeolite, nitrogen in the air is preferentially adsorbed over oxygen.
A look for zeolite on eBay shows it costs about £10 a kg. I don't think they would have considered it if it was costly. They were talking on the World Service programme about very low costs. I think the programme is still available on Iplayer.
Yes , it's called pressure swing absorption. You have two canisters of zirconia and they are used sequentially. The BBC programme though emphasised that it doesn't have to be high tech and could be repaired by mechanics because its intrinsically safe. There are no high pressures or tanks of oxygen. I couldn't find any references to anyone trying to make one however.
I was listening to the BBC world service the other day and there was a programme on about providing oxygen in Africa for Covid 19 patients. As it said 'what happens when the electricity fails'? It went on to describe a technique for producing oxygen from the air without using electricity. Here's a link to the idea;-
I think you might have to copy that into your search bar. Anyway the idea seems very simple and I wonder why we buy oxygen cylinders from BOC at huge cost when you can extract 95% pure oxygen from the air around us with just a compressor and a canister of zirconia which is apparently abundant and low cost. Take a look at it and see if you can see any reasons why it couldn't be used for a welding or brazing torch.
|Thread: vfd question|
Thanks Martin, I much appreciate your help. I've read the other thread and think I can understand that OK. I haven't got the inverter yet but I can source the buttons and enclosure now.
I have ordered another vfd to put on my lathe which has a 3 phase motor. I would like to fit a remote push button switch. Please could you tell me whether these should be momentary push buttons or latching? There is nothing on the instructions to help and the Youtube videos aren't very clear on the matter. Thank you , John
|Thread: Sharpening Fine tooth slitting Saws|
That's my point Michael, they work as a single tooth [ or maybe 4 or 5 tooth] cutter. The rest of the teeth don't do anything. I use circular saws on wood as well and the difference is I guess that the feed rates are so much higher cutting wood.
The question is why are they eccentric, even new ones? Do other people find that they run true? They are not visibly eccentric , but they don't cut evenly.
I have a question about slitting saws. I have several from different sources over the years and have never had one that cut evenly. They all seem to be eccentric. I've used them on different arbors and in different machines but it doesn't make any difference.
|Thread: Mill Wobble|
Hello Graham Meek, Thank you for your helpful reply. I have made a collar today from a piece of 57mm mild steel I already had and loctited to the spindle. I had to alter the spanner to fit but it fits a lot better now and is much more secure. I checked it at 1500rpm and no vibration so I haven't any unbalance either. I think it's a worthwhile mod if you have an R8 spindle on one of these mills even if you haven't any cracks, just a worthwhile precaution.
The drill chuck that came with my Amadeal mill wasn't accurate but I had a spare new [30 years ago] Jacobs chuck that I took off the MT3 arbor and fitted to a new chinese arbor I bought on eBay. That is much more accurate.
I have an Amadeal VM25L with an R8 taper so I just went and checked it. No crack thankfully but i don't tighten the drawbar very much, just snug it up. My spindle isn't very hard at all, I can scratch the outside very easily with an ordinary steel scriber and the nut flats show some wear after 4 years use. I was a bit concerned the spindle wasn't hard enough but I'm glad now it isn't harder. There is not a lot of metal around the taper, only about 4mm. Would it be a good idea to turn up a steel ring and loctite it in place?
|Thread: taper roller headstock adjustment|
I did the string wound round the chuck setting some years ago. With the lathe warm if you spin the 4 jaw chuck by hand with the gears all disengaged it turns about 11/4 turns before stopping. The headstock gets barely warm after prolonged use but I use 550 rpm most of the time. Actually I use this speed because it seems to suit nearly everything and it's the quietest! I am going to fit a vfd to reduce the motor noise and vibration, I've ordered one on Amazon last night. Chinese so I won't get it for a while. I've already got a chinese one on my drilling m/c and I'm very impressed with it. I got a 2.2kw one because the motor doesn't have a plate on it so I'm not sure of the HP. I've read through the 1947 letter from Timken, that's the one which says pre-load isn't a good thing which seems to contradict the graph above.
This method of running 3 phase motors on single phase is well known, Its described in the MAP publication 'Electric Motors'. I also had a milling machine running on this method for over 20 years and no problems with that.
Thank you for all the input. I've tried putting an 11/4 steel bar in the chuck and a dial gauge touching the top. It's impossible to get more than 0.01mm of movement so I think the bearings aren't slack. I think that's just the bar bending. I tried to take photos but they don't show the problem. It's more of a touch thing. It could be just that some mild steel doesn't cut that well. I usually stone the face of the tool and that helps a lot. I looked at the manual and taking the spindle out is a no-no. There are big circlips holding the gears in place. The motor is interesting. My machine has a 3 phase motor but I run it on single phase using a capacitor bank so I could just get a vfd unit now they are cheap from China. I got one recently and converted my drilling machine and the smooth and silent running is a revelation compared to the old 3 phase motor, never mind the speed control.
I don't fancy taking the mandrel out. I can imagine gears falling out of place. Has anyone removed a mandrel on an M250? It could be the motor, it certainly vibrates. I've stuck a lump of wood onto the underside of the cabinet to stop the drumming to some extent. Oldvelo, where did you get the DC motor etc? My mill has one and it runs like a sewing machine but I think very expensive? I will try the dial gauge check and see if there is movement in the spindle. To get a good finish I've often resorted to a dead smooth file and cutting oil.
This is a machine I bought secondhand. It was made in 1985 and was a high speed version. I converted it back to the normal speed range. I was doing some cutting today in hard steel [ bits out of a printer]. The finish was poor just holding it in the chuck but a turned a section with the end supported by a fixed centre and that improved the finish. Same tool so maybe its an adjustment problem. Some people say they need to be tight, others say they can be quite slack. I always thought they needed a pre-load.
I have a Harrison M250 which I have owned for about 30 years. I've never been happy with the turned finish. I've tried all sorts of tools and angles and I still don't get as good a finish as I used to with a Smart and Brown Sabel that that cast iron plain bearings and a glass hard mandrel. I've adjusted the bearings as described in the manual. I only post this because I was watching the video about Colchester lathe manufacture and it was saying how good the taper roller bearings are and how great the finish is on the part being turned. I just wonder whether others have the same issue?
|Thread: Centre finding|
That's interesting , how do you get spotting drills? I've always struggled starting holes with centre drills. Back to the thread I have the same problem with edge finders. I've been trying to work out how to make an optical edge finder.
|Thread: Shoe repair glue advice?|
I've always found that cyanoacrylate [super glue] works best for shoe repairs where the rubber sole has come away from the leather . I mend all the family;s shoes this way and they stay stuck. You have to hold the join together until the glue sets.
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