Lapping (and honing) - some techniques for discussion

[gbritnell]

Ramon,
Thanks ever so much for the detailed explanation and photos. It now is perfectly clear. I just had trouble getting my head around the 'D' bit part of the explanation. Did you find that a certain thickness of copper worked better than another? I will be making some of these up shortly.
gbritnell

[gbritnell]

Ramon,
I have an idea that might work to prevent the excess solder from wicking back around the copper shell. How about cleaning up the copper and the lap, fluxing it up and using a piece of silver solder sheet material. Just cut a strip and lay it between the lap and the mandrel. Once everything is brought to heat there should only be enough silver solder to fuse the edge. It's a thought.
gbritnell

[gary hart]

Gbritnell,s idea sounds like a good one.   
 In my limited experiecne the best method of stopping solder going some place not wanted is a well oxidized surface.

Thinking if lap surface is oxidzed with a oxygen rich flame to badly discolored surface and then only the inner area of lap that want bonding is mechanically cleaned by sanding, filing or scrapping should keep silver solder going past the cleaned area.  Use a little more then minimum of flux and silver solder sheet as sugested by George.                     gary

[Bezalel]

Great detail Ramon.
Thank you
 
I was thinking of the method of adhesion between the shaft and the copper, but Aussie beat me to it.
 
As I understand it the cylinder is hand held, so the forces involved must be relatively low and the temperatures produced during lapping must be well below the liquidus of eutectic Sn/Pb solder.  Or for that matter  any cyanoacrylate, adheasive. 
 
Are you aware of any reasons either method could not or should not be used? (other than that wasn't the way  the orignal was.)
 
Bez
 
 

[Jo]

Looks like I might need to make one of these for the Crosskill 

Ramon you mentioned these work down to about 3/8",, the Crosskill is 7/16", what sort of problems do you get with these small laps? or is it more a case of making the lap?

Jo

[Jasonb]

George even using silver solder foil the solder will want to flow where the metal is clean so a resist is the best method, I tend to use Tipex (typewriter correction fluid) but must be the solvent based one.

Jo, I'd hang on until Ramon covers his more recent laps which would be easier to make in the small sizes.

J

[modeng2000]

My thanks as well Raymon.

I would like to keep a paper copy of your writing and photos and wonder if there is a preferred way to do this. It would be just the relevant sections without the general comments, important as they are. Have tried copying and pasting to OpenOffice but not much success.

Perhaps you might be able to arrange your writings and photos as a pdf file or something like and then do an attachment.

Keep up the good work,
John

[Jo]

I'd hang on until Ramon covers his more recent laps which would be easier to make in the small sizes.

J

Will do, there is no rush for the Crosskill 

I wonder if lapping the cylinder is something I could use as part of the demonstration at the show 

Jo

[Ramon Wilson]

Wow - I didn't expect quite the response

George - at some stage in making these laps I used a piece of copper tube rather than making it from sheet. It soon transpired that the wall thickness was not really adequate from a 'lasting' point of view so since then I have used 10swg copper sheet and formed it by tapping around a form. This is about ideal - not so thick as to give too much resistance to the screw but plenty of meat left to use several times - even re-turning it to suit a smaller bore if required.

Re the solder question guys Georges idea is a good one - must admit I'd never given the thought to slipping  foil or even a piece of rod beaten to a flat section between the faces. It takes quite a bit of heat to get the steel up to temp with it surrounded by the copper so laying a piece of solder directly on the join line would not be so feasible as it would melt long before the work reached temperature.
I don't see why soft solder should not work either - just never tried it because as Bez remarks that was the original method. As a long time user of various cyanos in model aircraft I dont think the quality of join between the wrap and the steel would give a good enough joint for cyano to be an efficient substitute though - but you're right there is no heat in the process but there is at times considerable drag.

Jo - I don't know if you missed my previous answer in post 22 - just below the first pic -  but I think the work involved in making a lap like this might be a tad uneccessary - that said you may want to try but lapping brass would be another ball game using a copper lap, aluminium might be better and such a lap will get decribed later - tonight with luck  Personally though, as said before, providing that your surface finish is good I'd just give it a quick smoothing with some 1200 wrapped round a smooth mandrel.

John ('modeng2002') - All the typing and images are done directly into the post box. Apart from the images none of it is kept on file so unfortunately what you see is all there is. I don't think I have time to help you here unfortunately - hope you understand.

I think that's covered everybody but if you've been 'missed' give me a dig

Regards for now - Ramon

[b.lindsey]

Just wanted to add my thanks for the excellent write-up and pictures Ramon,,,very interesting thread to follow and am looking forward to more!

Bill

[tel]

Same here - can't wait to give it a try!

[peatoluser]

A superb tutorial. Picked up some really useful tips from your other posts Ramon, but for me, this is the icing on the cake! looking forward to the next instalment

peter

[Tennessee Whiskey]

Ramon, if you ever want a couple of days " off" from here again we'll be glad to let you have them as long as you come back with this kinda stuff. Great tool, good design, easy to make, and maintain. :ThumbsU:ThumbsUp:     All request for time off should be directed to Zee, by the way

Yo Redneck,
Eric

[Don1966]

Ramon I do have a question in regards to the length of the lap verses the length of the bore. I had read that the lap had to be 1/2 to 3/4 the length of the bore. Can you elaborate on this?

Don

[zeeprogrammer]

I was glad to see the post on how you made the lap Ramon. Very interesting. I learned a lot.

Good question Don.

Hush Eric.