I am in the process of overhauling the wheels on my 1500.
The next job is to shrink on some tyres. I have done all the homework and many thanks to Mr G Moore for help, drawings and encouragement. I have turned up rough outline tyres bored out to 4.450inch and machined the wheels down to 4.456inch, thus allowing 6 thou interference fit as per the book.
I have no idea what to expect. except to heat the tyres to say 300degrees and pop the wheels in the centre , and have a hammer available for one smart tap should there be an award moment !
Will they drop in ok / need a little push / be slightly tricky ?? any experience or tips would be appreciated.
Keith
fitting New tyres
Fitting tyres
Keith,
You're taking good advice already. There's little to add save the following which might seem obvious, but I ploughed my own furrow when I first tyred a wheel. Most of mine have been 3 1/2" guage, mostly pacific bogie wheels that have lost flanges due to derailments. The biggest I've done were 6" diameter for a Stirling Single, made from blanks burnt out of a bit of steel plate. the first cuts were a bit rough on the tool!
Put a small chamfer on the leading edge of the wheel centre to make sure it fits snugly to the tyre face.
Make sure the tyre is packed up sufficiently for the wheel centre to pass clear of the support surface. A bit obvious but its easy to forget the wheel hub is proud of the rim.
Make a test bar the same length as the diameter of the wheel centre to try in the tyre when you are heating it. When it just goes in you need a bit more heat.
I'm guessing you've still got the wheel centres on the axle. I would not recommend shrinking a tyre on a wheel off the axle. If the wheel is an easy fit on the axle it won't be after the tyre cools!
When you lower the wheel into the tyre use the hammer if the wheel sticks before it reaches the bottom - TO KNOCK THE TYRE OFF!! Trying to drive it on will end in disaster. Cool the wheel centre and try again. The wheel centre should drop in easily. If it shows any sign of snagging the tyre isn't hot enough and it won't go all the way as the wheel warms up rapidly.
Now just do it. Best of luck.
Eddie
You're taking good advice already. There's little to add save the following which might seem obvious, but I ploughed my own furrow when I first tyred a wheel. Most of mine have been 3 1/2" guage, mostly pacific bogie wheels that have lost flanges due to derailments. The biggest I've done were 6" diameter for a Stirling Single, made from blanks burnt out of a bit of steel plate. the first cuts were a bit rough on the tool!
Put a small chamfer on the leading edge of the wheel centre to make sure it fits snugly to the tyre face.
Make sure the tyre is packed up sufficiently for the wheel centre to pass clear of the support surface. A bit obvious but its easy to forget the wheel hub is proud of the rim.
Make a test bar the same length as the diameter of the wheel centre to try in the tyre when you are heating it. When it just goes in you need a bit more heat.
I'm guessing you've still got the wheel centres on the axle. I would not recommend shrinking a tyre on a wheel off the axle. If the wheel is an easy fit on the axle it won't be after the tyre cools!
When you lower the wheel into the tyre use the hammer if the wheel sticks before it reaches the bottom - TO KNOCK THE TYRE OFF!! Trying to drive it on will end in disaster. Cool the wheel centre and try again. The wheel centre should drop in easily. If it shows any sign of snagging the tyre isn't hot enough and it won't go all the way as the wheel warms up rapidly.
Now just do it. Best of luck.
Eddie
Thanks you for your reply Eddy
Particularily the chamfer. I increased mine just in case ! I did the first axle the other evening and it work a treat. Dead simple. Mind-you i did use a kiln which un-be-known to me had a broken stat so the temp was quite high in there. The wheel was about 450/500. It was black but not glowing. The tyre went so easily and then you see the old paint on the wheel starting to be affected by the heat transfer and slowly that happened all around as the tyre contracted and made full contact.
The only thing that was a bit worrying with all this heat transfer was whether it would affect the loctite wheel/axle joint or not. Left to cool, it seemed to have survived. I used loctite retaining compound think its the 609 type. We'll soon see when i put the profiles on.
Particularily the chamfer. I increased mine just in case ! I did the first axle the other evening and it work a treat. Dead simple. Mind-you i did use a kiln which un-be-known to me had a broken stat so the temp was quite high in there. The wheel was about 450/500. It was black but not glowing. The tyre went so easily and then you see the old paint on the wheel starting to be affected by the heat transfer and slowly that happened all around as the tyre contracted and made full contact.
The only thing that was a bit worrying with all this heat transfer was whether it would affect the loctite wheel/axle joint or not. Left to cool, it seemed to have survived. I used loctite retaining compound think its the 609 type. We'll soon see when i put the profiles on.
Steel tyres
Keith,
Pleased you have had success. I suspect your loctite will be redundant now if you have 5 -6 thou interference on your tyres since this or at least some if it will have transfered to the wheel centre.
I take it you machine the profiles with the wheel set between centres. Are you able to bring the lathe tool up to the headstock end with the wheel set in situ? You can machine the profile of the wheel nearest the headstock with a right hand tool if you can. This way you will not need to put the torque through the axle. No wind-up and no chatter. I can do this with a 5" wheel set in my Myford ML7, but you may not be able to with a bigger machine with a wider saddle. I can't do driving wheels for 3 1/2" gauge this way.
Looking forward to seeing your 1500 at Gilling in May.
Regards
Eddie
Pleased you have had success. I suspect your loctite will be redundant now if you have 5 -6 thou interference on your tyres since this or at least some if it will have transfered to the wheel centre.
I take it you machine the profiles with the wheel set between centres. Are you able to bring the lathe tool up to the headstock end with the wheel set in situ? You can machine the profile of the wheel nearest the headstock with a right hand tool if you can. This way you will not need to put the torque through the axle. No wind-up and no chatter. I can do this with a 5" wheel set in my Myford ML7, but you may not be able to with a bigger machine with a wider saddle. I can't do driving wheels for 3 1/2" gauge this way.
Looking forward to seeing your 1500 at Gilling in May.
Regards
Eddie
Yes, I will be machining the wheel profiles on the ML7 between centres.
Thats how how I turned down the wheels ready for the tyres. I took it easy and it worked out ok so i was going to do the same when applying the profile. Plus working at the tail stock end i can set the top slide over and machine the 3 degrees.
You have touch on another subject there - machining profiles.
I picked up this method from Harrow and Wembly's web-site
http://www.hwsme.org.uk/open_weekends.htm
I am going to use it in lieu of any another other method.
I shall make a gauge with a 3/32 step in it so as i can judge when the flange thickness is right and another gauge with a 1/16th step to judge when i have the very tip of the flange to the final thickness. The 1/16th comes from the dimension table for 4&11/16 back to back in the above web link.
From there assuming the set of the tool at 20 degrees is correct and having worked in towards the flange, creating the finished diameter of the wheel, I can wind out the top slide and complete the profile. then finally put the chamfer on.
any other methods or tip are welcome too.
Thanks
Keith
Thats how how I turned down the wheels ready for the tyres. I took it easy and it worked out ok so i was going to do the same when applying the profile. Plus working at the tail stock end i can set the top slide over and machine the 3 degrees.
You have touch on another subject there - machining profiles.
I picked up this method from Harrow and Wembly's web-site
http://www.hwsme.org.uk/open_weekends.htm
I am going to use it in lieu of any another other method.
I shall make a gauge with a 3/32 step in it so as i can judge when the flange thickness is right and another gauge with a 1/16th step to judge when i have the very tip of the flange to the final thickness. The 1/16th comes from the dimension table for 4&11/16 back to back in the above web link.
From there assuming the set of the tool at 20 degrees is correct and having worked in towards the flange, creating the finished diameter of the wheel, I can wind out the top slide and complete the profile. then finally put the chamfer on.
any other methods or tip are welcome too.
Thanks
Keith