Member postings for Kettrinboy

At Metals 4U a metre of 2" x 1 " bore PB1 bronze tube is £253 so using that as a guide I reckon that bit would be say 210 quid.

For a displacer piston the ideal metals are stainless steel or titanium bored out to give a wall thickness of 0.25 mm or so , they have low heat conductivity and can stand high temps ,and the piston is as light as it can be , just to give you an idea the one in the pic is stainless steel, an aluminium bung is then usually loctited in the open end but there must be no air leakage into the piston or that can stop an engine from working , the reason Bengs have specified a solid aluminium piston is as its a solid piston there are no leakage problems and it is the lightest metal apart from magnesium to make a solid piston from , if you make a solid brass piston it will probably be too heavy unless you bore it out to lighten it and fit a bung , but if this is done properly it will be as good or better than a solid aluminium one

Edited By Kettrinboy on 07/01/2016 10:17:41

Edited By Kettrinboy on 07/01/2016 10:18:22

Edited By Kettrinboy on 07/01/2016 10:23:14

I made something similar to a Repton out of odds and ends a while back and it works fine , in fact the first job for it was to make the ball ended handle , i used a ball race for the pivot bearing but found a bit of play was evident when used so I put a bronze thrust washer underneath and that solved the play problem.

Edited By Kettrinboy on 04/01/2016 09:14:11

On a fine thread like this i would check the tool angles with a magnifying glass as its easy to get the side clearances a bit vertical ie no or not enough clearance and have 10 to 15 degrees of top rake for aluminium , as said above 6061 (HE15) and 6082 (HE30) type alloys should cut nicely but some of the softer stuff can be a pig to get a finish on at times , especially if you are limited to using low speeds.

Whichever way you decide to finally fix the cylinder assembly to the base plate wait until you have the whole thing running and then adjust it until it runs at its fastest until tightening it down as stirlings wont tolerate much if any misalignments that cause friction , just choose a method that gives a little wiggle room to let it all run as freely as possible, the brass angle method sounds pretty good to me , leave say 0.5 mm clearance in the holes for fine adjustments before tightening down.i definitely woulnt go down the silver soldering route as it could distort the base plate then you would have problems.

When the table leadscrew nut stripped on my Dore Westbury mill , i obtained a 1/2 inch x10 tpi second tap and proceeded to tap a scrap bit of bronze to try it out , i found that it took so much force to make it cut even a few mm i was afraid the tap would break , but looking on a forum i saw a guy had used a hot moulding technique using polyacetal plastic to make a new crosslide nut for his lathe with good results and i had a bit of that plastic to hand albeit in bar form , it was easy to tap 35 mm of thread and completed and fitted to the mill works just fine , should cause less wear to the leadscrew as well ,

Ive got 3 bench grinders and the wheels vary from 0.1 to 0.3 mm runout on the side of the wheels so 0.5 mm doesn't sound too bad , perhaps trying different positions on the spindle and moving the card wheel grips to a different position on the sides of the wheel might improve things, if the side of the wheel really needs to run true I would lightly dress it to run true if not I,d leave it be.

Edited By Kettrinboy on 29/12/2015 16:26:05

Good choice of lathe getting an L5 though had my 1963 L5 for nearly 30 yrs and done god knows how many jobs on it and its never missed a beat...mind you now ive said that...

Sounds like the tailstock is set over off centre by a mm or two , i think on the ML7 the adjusting screws are on the bottom of the tailstock near the back should be allen type grub screws, a quick way of setting it fairly accurately is to face a piece a bar in the chuck and leave a very small pip then put a dead centre in the tailstock and bring the point up to the pip , lock up the tailstock and adjust the left and right hand screws until the pip and dead centre points line up , that should be good enough to centre drill , i am assuming the jacobs chuck will hold the centre drill pretty true as they can be a bit out sometimes , turning them through 180 degrees can sometimes help there and if it does mark it so you can put it in the same orientation each time , to turn a length parallel between centres or chuck and centre you will need a clock (DTI) to fine tune the tailstock alighnment which can sometimes be a tricky task for even an experienced hand.

Edited By Kettrinboy on 28/12/2015 20:26:25

No need to scrap that cylinder you will be ok to either press in a small piece of brass or soft solder a piece in because if your heating the hot end with meths it wont get hot enough to melt the solder , and a brass plug will expand at the same rate as the cylinder so no worries there either , as far as gaskets go stuff like the cylinder covers as long as the machined surfaces are flat and have a good finish should be able to fit together with no gaskets and seal , on all the 6 engines i have made so far i have not needed any gaskets anywhere i have just relied on good machining to create airtight joints , for the frames a silicone gasket goo used on car/motorcycle engines might be better than bathroom sealant as they are meant to seal at higher temperatures maybe something like "Hermatite" used for sealing crankcases etc , or maybe even make a thin paper gasket.

Edited By Kettrinboy on 28/12/2015 10:02:21

I made a front axle for a Yamaha FZ750 out of EN58J which is the equivalent of 304 many moons ago and though it was ok in use when I took it out it had bent like a banana , after getting a bit more knowledge of materials I next used EN57T martensitic stainless , its 55 tons tensile but does rust very slightly but is more than strong enough , my current bike a Kawasaki ZX6R has all titanium axles made by myself out of 6242 alloy which is light and strong and corrosion free , the rear axle has bent slightly by about 0.2mm but its no bother as it springs straight when fitted to the bike , they are now 10 yrs old and still going strong so certainly good enough for a road bike.

Edited By geoffrey marriott on 21/12/2015 17:44:12

I use mineral based 20W50 motor oil in my 1963 Harrison L5 , and have done since 1986 and just change it every few years and its been no bother at all , but then the maximum spindle speed is only 750 rpm and I rarely even use that ,so its not that highly stressed , on a lathe that can do high speeds and is used often at say 2000rpm or more the oil quality and viscosity is probably more important to prevent premature wear.

Hi all

My names Geoff and ive just joined the forum , i,m a now retired time served engineer and now have time to make full time use of my workshop , kit wise ive got a 1963 Harrison L5 lathe , a mid 70,s vintage Dore Westbury MK1 mill and a pillar drill and all the common ancilleries to go with them , my interest is model stationary engines , mainly hot air but some IC engines as well , look forward to learning from as well as helping others on the forum

regards Geoff