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 :thumbsup:

[Shiraz]

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

[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]

:thumbsup:

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]

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]

:thumbsup::thumbsup::thumbsup: photos ,, please .

Brian.

[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 :thumbsup:

[GeoffW1]

Second that :thumbsup:

Cheers

[sn1987a]

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