Author Topic: Needle Eye Laps  (Read 433 times)

Offline Hugh Currin

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Needle Eye Laps
« on: January 10, 2019, 04:53:42 PM »
Searching for small laps I ran across "Needle Eye Laps". Available from several sources, this is just one. Does anyone have experience with these? Seems a lot easier than building a small lap and not too expensive.

This is to lap a cylinder for a small LTD Stirling engine. The cylinder ID is 1/4".

Thanks for any insight and help.

Hugh
Hugh

Offline Roger B

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Re: Needle Eye Laps
« Reply #1 on: January 10, 2019, 05:29:11 PM »
I use small Acro needle eye laps for my fuel injection systems (1.5 to 2mm diameter) and Acro barrel laps for my cylinders (15-25mm diameter).

http://acrolaps.com/index.htm

They have done what I have expected with various grades of diamond lapping pastes resulting in several running engines.
Best regards

Roger

Offline Hugh Currin

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Re: Needle Eye Laps
« Reply #2 on: January 10, 2019, 07:21:31 PM »
Roger:

Thanks for the note. Yours was the only post that popped up on a search for Needle Eye Laps. It mentioned the source but not how well they worked. Good to hear they do work. Thanks.

How hard are they to adjust? I see there's a tool included and there is likely some spring in the laps.

Hugh
Hugh

Offline Roger B

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Re: Needle Eye Laps
« Reply #3 on: January 10, 2019, 07:39:13 PM »
You get a simple sort of expander tool with each set or you can buy a 'plier like' tool. I have the plier tool and use it to gently expand the 'eye' until I get some contact with the bore. I then add some abrasive and start lapping using a little light machine oil. If there is obviously no more contact I use the pliers to expand the eye a little more until I reach my target diameter (in the case of my injector components measured with a precision pin gage).
As with all new techniques there is a learning curve, I put quite a lot of effort in learning how to ream properly  ::). Give it a try first on a hole in a piece of spare material.
Best regards

Roger