Metric Size Nuts

Dave Sherburne NY · Feb 11, 2011

I need a nut for the output shaft on an 8 Horse Honda engine. I've got one stamped 18 but its to small. It looks like fine threads too. What's the next size up from the 18?

BCnT · Feb 11, 2011

are you positive its metric???
some shafts use sae threads for specific attachments.

Janicholson · Feb 11, 2011

There are two or more common thread pitches in metric threads. the last row of sizes is the drill size for tapping Jim

M 18x1.0 1.00 17.00
M 18x1.5 1.50 16.50
M 18x2.0 2.00 16.00
M 20x1.0 1.00 19.00
M 20x1.5 1.50 18.50

Dave Sherburne NY · Feb 11, 2011

Yes, I have lots of SAE nuts around here and they only go on about2 threads

cadet trooper · Feb 11, 2011

Janicholson is on it metric threads are measured by the amount of thread in mm per mm so the smaller the number the finer the thread. A millimeter is roughly .0394" I reccommend getting a metric thread gauge from maybe NAPA or a good machine shop. Usually metric fasteners offer three options instead of SAE"s fine and coarse. I"m sure our Canadian and European friends can quote the normal thread pitches because they work with them all the time. I probably missed something here so forgive me. I"ve been working in Industrial maintenance for close to forty years and metric versus SAE for over 25 so I probably have something wrong here but I deal with it everyday.

Anonymous-0 · Feb 11, 2011

do yu have access to fastenal,or better yet they have all that info in there book,but anyway from the bookit should be 20

NCWayne · Feb 11, 2011

You should be able to look at the Honda website and go to the specs for the specific model you have. It should tell you the thread and the pitch options available on each model....unless it"s some OEM special deal. Looking at several of them it appears they use both metric and standard threads so it could be either one, depending on the model number. Goodluck.
Honda

36 Coupe · Feb 11, 2011

I have a metric pitch gauge in my tool box, cost 4 bucks ,you need one.

Bob Bancroft · Feb 11, 2011

I find I use my thread file for a pitch gauge more often than I do for a file!

Anonymous-0 · Feb 11, 2011

Are you sure it's metric? Honda makes direct replacement engines for B&S powered machines and others. I'm not saying the nut you need isn't metric but it could be standard thread. Dave

Fred Martin · Feb 12, 2011

Take a flat piece of lead and lay it on the threads and tap it with a hammer and it will imprint the threads per inch or millimeter. Take a piece of number 9 wire and bend in a loop/u shape and bend till it just touches the outside diameter of the male threads with no clearance or gap and head for an automotive machine shop or such. They can tell you what thread it is. I have made nuts in this way that fit like a charm...without seeing the threaded shaft. And the good part of this is the machinist that fits you up will look over at his coworkers when you leave and say "There is a smart man!" ohfred

greygoat · Feb 12, 2011

That would be no problem for me, since I have
Inch/fractional, and metric thread gauges, or
I have inch and metric thread cleaning files
that I could lay on it to check the threads.
Those and an inch/metric calipers are all under $20, and very useful.

RodinNS · Feb 12, 2011

19 would be the next size I think... or mabey 20. You do know that there's three different thread pitches as well?

Rod

barn E · Feb 12, 2011

If they are cheap, buy a handful of your best guesses. Works for me. They call me "nuts" Dave

Dave Sherburne NY · Feb 13, 2011

Thats what I had planned but Fastenal was closed yesterday.

Metric Size Nuts

Dave Sherburne NY

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BCnT

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Janicholson

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Dave Sherburne NY

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cadet trooper

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Anonymous-0

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NCWayne

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36 Coupe

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Bob Bancroft

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Anonymous-0

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Fred Martin

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greygoat

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RodinNS

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barn E

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Dave Sherburne NY

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