Lapping in a lathe

[Danny M2ZParticipant @dannym2z]

G'day all.

I have used my minilathe successfully to manufacture a few pistons and cylinders for my model engines over the years.

Now just setting things up to restore an ancient ME.Snipe by boring and lapping the liner to round and them machining a new piston from cast iron and lapping it to size I began to wonder about the effect of the stray lapping compound on my lathe.

The bedways I always cover with cardboard, so I was wondering about what happens to any lapping paste that strays into the chuck?

Current lapping compound ranges from 1000 – 4000 grit, carborundum though to jewellers rouge. I am contemplating using diamond lapping compound to save time but it is a PITA to remove from the components and I am only contemplating using this substance as I have an ultrasonic cleaner.

A lathe chuck is a bit big for my ultrasonic cleaner.

Maybe I am overthinking this (always dangerous for me)

So, over to the experts.

* Danny *

[Danny M2ZParticipant @dannym2z]

[Thor 🇳🇴Participant @thor]

Hi Danny,

I do much the same as you, cover the bedways and clean up afterwards. I wrap the inside of the chuck with clingfilm and of course clean up afterwards, so far the chucks seems not to have suffered.

Thor

[Ramon WilsonParticipant @ramonwilson3]

Hi Danny,

Never had an issue with the chuck side of things a card or thin plywood disc that fits over the lap mandrel could help I suppose – I have done that to limit the movement of the liner over the lap but never given thought to it keeping the compound out of the lap. The bedways I just cover with three or four layers of paper hand towel.

Though I have it I very rarely use diamond and use silicon carbide or carborundum instead. Having said that recently I did a friends PAW 29. Getting the bore true proved very difficult so it's coming back for the diamond treatment .

I always use plenty of paraffin and oil so it always wipes off easily enough

Good luck with the Snipe

Tug

[JasonBModerator @jasonb]

Same here I've not really found it gets onto the chuck, lap or piston holder positioned a short way from the chuck helps keep it away. I use a sheet of ply over the bed.

[Ramon WilsonParticipant @ramonwilson3]

Posted by Ramon Wilson on 27/01/2022 07:21:43:

Hi Danny,

Never had an issue with the chuck side of things a card or thin plywood disc that fits over the lap mandrel could help I suppose – I have done that to limit the movement of the liner over the lap but never given thought to it keeping the compound out of the lap. The bedways I just cover with three or four layers of paper hand towel.

Though I have it I very rarely use diamond and use silicon carbide or carborundum instead. Having said that recently I did a friends PAW 29. Getting the bore true proved very difficult so it's coming back for the diamond treatment .

I always use plenty of paraffin and oil so it always wipes off easily enough

Good luck with the Snipe

Tug

That should have read chuck!

[Author]

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