Member postings for John Rutzen

Thanks John, my fabrication is going ok but it will be a while before I make the valves.

Thanks John , that's great to hear from someone who has actually made them and succeded. I will make them as you say, my valves are 15 mm diameter. I will keep the thickness of the PTFE down to 1/16 th. Did you put any grooves in them as some have suggested?

Hi, they do put piston rings on iron valves and liners though some seem to go over the top. A design in Henry Greenly's book from way back uses 14 rings on each valve head! I haven't been able to find any other designs, they seem to have been seldom used, especially in smaller gauges. However mine are bronze and the received wisdom is that you can't lap bronze cylinders because the grit tends to imbed in in the metal and continue wearing it. Also they say you can't make rings from bronze but I haven't been able to find out why. The reason for using bronze was that it lends itself to fabrication, I haven't heard of anyone trying to fabricate cast iron cylinders though apparently it can be silver soldered.

Yes, £25 an inch. It's a bit much, I've got a long length of PTFE so that would be my first choice.

John Baguley, I was interested in your comment about your use of ptfe piston valve heads. I am making fabricated cylinders according to Don Young's articles and want to use ptfe piston heads. Please could you tell me how much clearance you gave them? I understand that they will expand and jam without clearance.

I have two drawbars for my Amadeal mill. The milling R8 arbor is M10, the drill chuck and boring head are 3/8th BSW. I don't find it a problem, I just use the appropriate one.

Thanks Andrew, I found a place in the uk that sells 25% carbon filled PTFE for a reasonable price [about £21 per metre] but I don't know what they charge for shipping. Does that machine better? A thread about making piston rings from it say it does. The difficulty with all these is getting the small quantities we need.

Edited By John Rutzen on 22/09/2022 11:02:36

Hi again, I'm still hoping to get some information on how to use PTFE for piston valve heads. There seems to be a scarcity of information out there. I've heard of filled PTFE, the carbon filled material isn't much more expensive and may be better. Also flouroscint in mentioned but I don't know of a source where I can buy some small diameter. Anybody help please?

hi, I'm building a 31/2 gauge Schools to more or less the Jackson design and want to fit it with piston valves. Partly this is because I've never made an engine with piston valves but also because it only looks right with walschaerts valve gear. I'm fabricating the cylinders because I want to minimize the weight at the front end. I have the castings for the slide valve cylinders but they are SO heavy. I've been using Don Young's articles about fabricating cylinders and have read the references to fitting the valves. I had already decided to try Fred Cottam's PTFE valve heads and have bought some for the purpose. He says the heads should be loose on the spindles because they will expand and also made about 0.005 small for the same reason. Has anyone any experience with PTFE bobbins please? On a design note I am pushed for space for the valve diameters because the Schools has a flat on the side of the steam chest so what would be the smallest diameter for the valves? I had been trying to get 5/8th but don't think I can manage it.

Yes, maybe I need to arrange a constant coolant drip, I just apply water soluble stuff with a syringe. Its difficult to keep it in the cut because it gets flung out. I think I don't use it much because it's a faddle to clean the machine tray and I don't like it being oily. I've never dared to part off under power feed!

Edited By John Rutzen on 17/09/2022 17:34:55

I have a rear parting toolpost I made for my Harrison M250 but I find that it isn't dig-ins that are the problem. What happens is that a bit of swarf welds itself in the cut , jamming everything up. So I am very cautious about parting off, I keep my hand on the clutch lever all the time so I can stop it quickly if it goes wrong.

Thanks, I'd greased it but then I thought that wasn't right so I will remove it now! I don't have any Way oil.

Edited By John Rutzen on 12/09/2022 08:38:50

Hi, I've picked up one of these vices in good condition and have cleaned it and re-painted it and am putting it back together. Does anyone know if I should grease the swivel joints or just re-assemble clean but dry? I am thinking that grease will tend to make them slip which is the last thing you want with a machine vice joints.

Hi David, thank you, unfortunately my motor isn't the same. The buttons are different and there is no adjustable parameter for the braking effect. I am drawing up a countershaft unit incorporating a freewheel. I don't need reverse since I won't be cutting any threads and there is no rear toolpost.

Hi Clive, yes it's a screw on chuck. Funnily enough I had just thought of the freewheel as well, you can get them on ebay for about £8 made for electric bikes so they are quite robust and only have a 12T sprocket on them. There is room for a pulley so I would have to make up a little countershaft. I had thought of doing that anyway because I would like about a 200 rpm bottom speed. The pulley on the motor seems to incorporate the fan though I can't see how it would do much cooling. It has slots around the centre and radial blades cast in so it is quite a large pulley, about 55mm diameter. Does your motor run cool? The brushless dc motor on my mill always runs cool, even working hard.

Hi Clive, I've got the motor now but I have a problem I can't see the way around. The braking effect is very noticeable and I am wondering what will happen with a chuck on the lathe. I can imagine is flying off spectacularly! I haven't found a way round this. Any input please?

Thanks for the info. I've looked at your photos now Clive and like the very compact arrangement, I need to do something similar because I've very little room available where I am putting the lathe. Good to hear that you have had good results too David.

Clive, thanks, I've just ordered one from Tysew in the UK for £99.99 including post. Please could you send me a picture of yours or a diagram, I'm not sure how it works from the description. I'd just thought of putting a knob on the metal lever and mounting it on the front of the bench. Lathe work is one handed anyway so you could use it as a sort of dead man's handle as is Electric Railway Locomotives.

Clive, please can you tell me if you solved the problem of getting the variable speed range? Did you add a potentiometer?

Hi, is there any further input on this thread please? I've just bought an old but beautifully made plain lathe 65mm centre height and am looking for a better motor and controller. The existing motor is a very small 3 phase with a capacitor across one phase and running on single phase. I could buy a vfd but they have recently got quite expensive so I am looking at one of these industrial sewing m/c motor setups which are still quite reasonable. Does anyone recognise the lathe? There is no name on it.