Lap has to be softer than the material to be cut and allow the abrasive to embed, so I'd suggest an aluminium alloy or even wood.

Neil

Hi Clive, If you need the lap adjustable make a lead lap, I have made many of these to lap barrels. I knurl a BMS rod then drill and taper ream for a taper pin, split this section of the BMS rod and deburr the inside for the taper pin then cast an oversize section of lead over the knurled section. I made a split alluminium mould for this.

lastly turn to the diameter requiered and "load" with lapping paste by rolling the lap on a glass plate. It can of course be expanded by tapping in the taper pin. Oh and don't forget to put some oil in the bore and wash well when fininshed. For an extra fine finish use pumis mixed with oil but I have not used this on bronze.

Good luck John.

I use wooden laps, turned to a sliding fit, and split down the middle, a wood screw is fitted in the slot to expand the lap as required. Ian S C

Hi Nigel ,

Honing is done with solid fine stone – like piece of a slipstone . It is usually done in a controlled manner using a manufactured 'hone' with one or more stones and a means of adjustment .

Lapping is done using grinding paste on a soft metal (or wood/Tufnol etc ) tool which is just rubbed against the job . Tools are often improvised but usually have simple means of adjustment .

There is a backwards version of lapping where grinding paste is applied to a flat surface and the work rubbed against it .

Both honing an lapping are capable of producing high accuracy work .

As usual there is much more to it .

Michael Williams