Accurate reaming aluminium

[LewisM]

Got some guidescope rings in (solid type - I detest the rings with 6 adjustment screws). The finder-guider I use is a 53mm tube OD, whereas these rings have an ID of 52mm, so I need to lose 1/2mm each side (or 1mm inner diameter).

I want to do this accurately, without it looking like a hacksaw and hammer bodge job. I do NOT have access to a lathe or mill, and a 53mm reamer is gonna cost a small fortune, so...

Reckon it would take long sanding out 1mm of aluminium by sticking a sheet of 60 grit paper on a 53mm can? (I have several spray paint cans who's diameter is 53mm - the added 1/2mm of the paper should give me enough space for some thin felt). Or is there a better way? I am NOT going to resort to the inaccuracy of using a drum sander on a Dremel

My OCD perfection requires I do it right

[Shiraz (Ray)]

Simple. sand down the outside of the OTA - the tube rings will remain perfect.

[LewisM]

I need that strumming my fingers on the desk emoticon...

[JA]

Hi Lewis,
at that size, if you demand accuracy, you need a lathe. Maybe you should try to arrange a beer-machining barter with a local machinist or maybe even forum member here?

Best
JA

[raymo]

Hi Lewis, Are you intending to put some felt or similar material onto the inside of the rings? if so, then you will obviously need to remove more
than a mm.
raymo

[brian nordstrom (As avatar)]

Any good engineering supplier will sell those round
Flap Discs ' kinda like a bore honer , get a few say 60 grit ones put them in your drill chuck and these will remove 1/2mm each side fast and cleanly.

We use them a lot for cleaning the inside of pipe fittings before welding. They remove internal material neatly and reasnebly fast .

Brian.

[LewisM]

Brian,

I beat ya to it - went and got exactly that at Bunnings earlier. One done, one to go.

[LewisM]

Forgot to mention - these are SPLIT rings, so each half is not a complete semi-circle - made it a little trickier, but got there.

[The Mekon (John Briggs)]

Lewis,

The best way to do this job would be with a cylinder boring bar as used by workshops that can bore motorcycle cylinders.

Other than that, if the rings can be held in a lathe chuck, then the lathe.

Thirdly a router can be used if you make an accurate wooden jig and are able to hold the rings very firmly.

Finally a cylinder honing tool could be used, but it would take a long while and possibly wear out the honing stones.

Good luck!

[Kunama]

You should have called me ......
I have been on the lathe for a few hours today !!!!

[brian nordstrom (As avatar)]

photos ,, please .

Brian.

Originally Posted by LewisM

Forgot to mention - these are SPLIT rings, so each half is not a complete semi-circle - made it a little trickier, but got there.

[Kunama]

Originally Posted by LewisM

Forgot to mention - these are SPLIT rings, so each half is not a complete semi-circle - made it a little trickier, but got there.

You just need to put the appropriate thickness washer between the two halves and bolt them up tight before putting it on the lathe

[GeoffW1 (Geoff)]

Originally Posted by Kunama

You just need to put the appropriate thickness washer between the two halves and bolt them up tight before putting it on the lathe

Second that

Cheers

[sn1987a (Barry)]

A 52mm hole saw with sandpaper laid over and stuck on the outside ?