22 replies to this topic

[JonnyBMX]

While this can be done on a lathe it is not the ideal method.

A common assumption is that it is only necessary to indicate the bushing so it is running true/concentric to the lathe chuck. The issue is that the needle bearing may not be concentric with the installed bushing and the bushing actually needs to be offset bored. That is why the stepped, piloted reamer is ideal. The pilot on the reamer is supported by the needle bearing which insures that when the bushing is reamed it is concentric to the needle bearing.

Again, while this can be done on a lather (or a mill for that matter) it is necessary to insure that the arm is properly fixtured so that boring the bushing is done concentric with the existing bore for the needle bearing.

very true, luckly my dad has been a precision enginner for well over 40 years and was able to get it all bang on, he brought the correct reamer home from his tool box at work now and this was much easier to do,

[Yoda]

I have a long reamer and I just make up the diameter with duct-tape in order to line up the reamer with the bush and supporting to achieve parallelism with the needle roller bearing.

he did a 'bodge job' using a small flap wheel in an electric drill. It actually worked,

Great minds think alike! i have used both these methods. But as you say, not ideal. I now use a home made reamer and used a "cheap" new radius arm pin and cut off the thread from the grease nipple end, used the grease drilling as a centre and bored the pin out to an interference fit with the reamer tail, warmed up the pin in the oven and fit the pin in the bored hole, once cooled, the reamer was well and truly fixed in. I used a "cheap" pin so that the metal was soft enough to machine. Then i cut the thread off the other end and welded a nut smaller than the diameter of the pin on the end so i could use a spanner or socket to turn my new tool !

Works perfectly.

[Cooperman]

I have a long reamer and I just make up the diameter with duct-tape in order to line up the reamer with the bush and supporting to achieve parallelism with the needle roller bearing.

he did a 'bodge job' using a small flap wheel in an electric drill. It actually worked,

Great minds think alike! i have used both these methods. But as you say, not ideal. I now use a home made reamer and used a "cheap" new radius arm pin and cut off the thread from the grease nipple end, used the grease drilling as a centre and bored the pin out to an interference fit with the reamer tail, warmed up the pin in the oven and fit the pin in the bored hole, once cooled, the reamer was well and truly fixed in. I used a "cheap" pin so that the metal was soft enough to machine. Then i cut the thread off the other end and welded a nut smaller than the diameter of the pin on the end so i could use a spanner or socket to turn my new tool !

Works perfectly.

Good solution Colin. Now the 'jobsagoodun' every time.

[Yoda]

'jobsagoodun'

What did i say about great minds? I used that phrase just today

[1984mini25]

while looking around for sutable reamers the other day just to get an idea of whta one should look like, I also came across this...

http://ado20mini.web...artsrepairs.htm

[mike.]

Well that makes it look easy! Good link that!

My radius arms need doing, but is it really that easy to do at home...

[1984mini25]

As long as you have a suitable reamer it is. I did also come across the proper reamer for the job, but at over £400 I think I'll give that a miss lol.

[Ethel]

I got a reamer like the one in the link from http://www.tracytools.com/ you might have to ring them if it's not on the site.