Cylinder Hones

[Paulsv]

I'm apparently not as sharp as granny on these matters. What grit of silicon carbide powder would you guys recommend, to lap a bored 12L14 or Cast Iron cylinder? I am planning on using an o-ring rather than an iron piston ring. (This is for a Webster.) Any suggestions on where to buy small quantities?

Oh, and one other question: What do you use as a binder for the silicon carbide powder? I assume you don't just use it dry?

 

[enfieldbullet]

for lapping not a binder, rather a dispersant. engine oil, kerosene, etc. it varies. you want to form a slurry.

dry lapping is still a possibility, but maybe not in this setup.

silicon carbide powder can be found on Ebay or local abrasives store.

there are also other available abrasives, such as emery.

 

[Ramon]

Re the honing - I can understand 'aonemarine's' reluctance in using brake type hones as he is used to a far more professional set up but I did use a brake type hone to successfully size the nine CI liners on the Bentley engine to a plug gauge - I set the hone in the drill so that it would only just expose about 5mm at each end and experienced no bell mouthing despite having to do some for considerably longer periods than others to get them all matching. That is not to imply disagreement with anyone as it is very easy to bellmouth both in honing and lapping if not taking care.

Hi
Re my post above whilst I did succcessfully 'hone' these cylinder liners to size using a cylinder hone I did nearly spoil them by making the half a thou or so interference fit in their barrels shorter in length than the barrels themselves. When the plug gauge was tried after pressing them in it would not pass through the tight part of the bore It quickly became aapprent that the hone would not readily solve this problem so a lap was made which did - and in quite short order - and then the bores were honed again to provide a good surface finish.

If it's of interest I'm currently I'm decribing the above and other attempts at lapping small diesel engine liners and pistons and smaller bores over here http://www.modelenginemaker.com/index.php/topic,1908.0.htmlon

I see someone has already answered your question Paulsv - I use light oil to form a runny paste as suggested. The powders can also be obtained from Lapidary suppliers but be aware that they also offer grits lower down the grade which are much too coarse to use for this application. I have found F320 to be the coarsest required in 12L14 or cast iron providing the surface finish as turned is good and smooth.

Flex hones have their use but purely for putting on a surface finish after the bore has been trued and smoothed by lapping - assuming no access to a honing machine is available - which it usually isn't for most of us.

Hope no one minds the reference to the other site but time precludes me repeating it all again

Regards - Ramon

PS the underlined not was missed out on first posting

 

[Jasonb]

A good woodworking suppliers should also have lapping powders

http://www.leevalley.com/US/wood/page.aspx?p=33017&cat=1,43072

 

[Paulsv]

for lapping not a binder, rather a dispersant.

Doh! Granny would have known that!

 

[Paulsv]

Thanks, all!

So what do you think: maybe start with 320 grit, and finish with, say 400 then 600 grit?

 

[enfieldbullet]

seems good.

you're going to lap it? making one shouldn't be too hard.

 

[Paulsv]

Actually, I have an acrolap in the right size, so I was planning to use that. My dad was a tool and die maker, and it's amazing what he had in his tool boxes. Unfortunately, he passed before I got into this hobby, tho I did work in his shop for a few summers when I was young.

 

[aarggh]

I use this crowd in OZ for silicone carbide powder, pretty cheap and it's imported, probably the same stuff is available in the US even cheaper:

http://www.aussiesapphire.com.au/index.php?main_page=index&cPath=156_170

cheers, Ian