Educate me on brass barrel laps, please.

[Brian Rupnow]

I am thinking of buying a "brass barrel lap" from Travers Tool to use for lapping the 1" bore on the cast iron cylinder of the engine I am building. I have never used one, and I don't know anyone who has. I have always made my own "one time use" laps by turning a piece of round aluminum to .002" to .003" less than the diameter of the cylinder bore, and using successive grades of carborundum paste to lap the bore. I would like to hear from anybody who has used these adjustable brass barrel laps. Does lapping wear them out?---are they a valuable item to purchase in terms of usage?---I am ready to move up a notch from my home made laps, but I would like to hear a bit about these brass barrel laps from knowledgeable users.----Brian
http://traverscanada.com/skulist.asp?RequestData=CA_Search&navPath=All+Products%2F%2F%2F%2FUserSearch1%3Dlap&q=block+id+112470+and+class+level3+id+29980&minPrice=$3.23

 

[BobsModels]

Brian
I do not get on this site very often, but I have used these on my model engines for years. I get them from McMaster :

http://www.mcmaster.com/#barrel-laps/=tw6lab

They are from this company:

http://www.acrolaps.com/

They are great to use. They have a taper sleeve and yes they wear down but not very fast, I have done several sleeves with no noticeable wear. I always buy the arbor set and two spare sleeves. Then I use each sleeve with different grade of paste to be sure of no contamination.

Another thing of note is that once you have an arbor, depending on size you may just need to buy sleeves. For example my arbor for 5/8 has a range of sleeves 5/8 to 1". I have 5/8,3/4,7/8 sleeves for it. The smaller arbors seem to be single use.

I also have the needle laps (11.95) for 18 piece set .032 to .25

I was going to make this type of lap based on an article in Model Engine Builder but for the price these laps are a bargain.

I have used these on my 1/8 Galloway, 1/4 Gade, and on numerous small holes on parts and pumps when I was into building 7 1/2 gauge steam locomotives.

Bob

 

[Brian Rupnow]

Thank you Bob. I cheaped out and used my own tried and true method of a 1" diameter chunk of round aluminum used with 600 grit carborundum paste as a lap.---Brian