Imperial tools on Metric fastener

[Rosso]

Hi,

Bit of a strange one this, i need a 38mm spanner/wrench for work, along with a 50mm crowsfoot.

I am a professional tech so i tend to only purchase Snap On stuff. I tried a couple of Stahwille crowsfoots/wrenchs but was disappointed that they rusted pretty badly. The finish on them isn't chrome and must have lots of imperfections as they are covered in pin ***** rust spots.

Anyway, a 38mm spanner is over £200, the crowsfoot is £107 !

I can however get a 1.5" wrench which converts to 38.1mm and a 2" crowsfoot which is 50.8mm at a great price.

Has anyone used imperial tools on metric fasteners ? Just wondering if they would work or slip. The crowsfoot is needed for BMW Diff lock nuts which are extremely tight.

 

[rust in the eye]

Fasteners in larger sizes are way less fussy about fit.
You're a pro and wondering if a tenth of a millimeter on a 38mm fastener will make a difference? 8 tenths at 50mm?
These differences are probably within tolerance for the correct mm size wrenches.
Go ahead and buy the imperial size tools

 

[BrandonV]

A 1-1/2" spanner per the ANSI standards could be anywhere between 38.0 mm and 38.1 mm.

In other words... just fine.

 

[Wrench97]

I have a 1" impact labeled 1 1/2" on one side and 38mm on the other, used for semi truck lug nuts.

The larger the size the more forgiving.

 

[SwissMetric]

Once again: Have a look at the table at the end of the Stahlwille catalog. It lists alll common metric and imperial sizes with tolerances and associated thread diameters.

I'd only use mismatched tools where:
1) The difference is so close that it doesn't matter;
Or
2) In cases where the "wrong" socket is tighter due the random tolerance pair.

In all other cases there's a risk to damage the tool and/or bolt/nut.

Typically it's good to have both metric and imperial tools for the most common sizes, at least some sockets and combination wrenches.

 

[garfunkle24]

I bought a Snap-on 1 7/16" 4-way angle wrench many years ago as they didn't make a 36mm at the time.

After many years of about 50/50 metric and sae, I've pretty much memorised which sizes cross over perfectly (or virtually anway) and which ones are slightly bigger and smaller etc. I will swap out as and when needed.

 

[AdAstra]

This chart might help you decide: https://www.garagejournal.com/forum...nch-sae-tool-interchangeability-chart.510030/

 

[cherrybomb]

This chart might help you decide: https://www.garagejournal.com/forum...nch-sae-tool-interchangeability-chart.510030/

And take your digital caliper and do some of your own exams with bolt heads,nuts and open ends,tolerances between manufacturers. Sometimes the tool that fits the best,no matter the family will work.Above and inch or so it gets a bit interesting what can be substituted.

 

[RoninB4]

-Do I use metric/imperial on each other? Selectively all the time after doing the math for fitment. You're already aware of the 38mm being very close to 1-1/2" but the 2" is, to me, a bit too large for use on a stubborn nut/bolt. With almost 1/32" slop and the amount of force needed I'd be concerned with the corners of the lock nuts deforming and no longer being a true hex. Can you get a machine shop to mill a smaller crow-foot wrench larger for fitment?

 

[Semi-hole mechanic]

I’ve used 15/16” on a 24 mm.

 

[mikey03]

Here’s what my uncle shared with me he’s no Engineer but it makes sense to me at least

your asking if .1 mm matters at 38 mm size

thats close to 40 which is 4x a 10 mm

divide 0.1 mm by 4

you get 0.025

would 0.025 mm make a difference on a 10 mm fastener? Because as fastener scales so does tolerance since it’s a percent of the size

now your talking 50.8 which is 5x bigger than 10

0.8 divided by 5 is 0.16

would 0.16 matter on a 10 mm fastener? It might so I wouldn’t mess with this esp on a crow foot where your not getting much engagement anyway

but 0.025 on a 10 mm is nothing so I think the 38 mm one is fine honestly

 

[bwringer]

Yup, I've done this many times. Everything I work on is metric, but sometimes a "close-enough" inch tool is more easily available and/or a helluva lot cheaper. (It's 2025, yet metric fasteners are still considered "newfangled" in the US. But that's another rant for another day.)

US-made heavy equipment and farm equipment still uses a lot of inch too, so larger tools tend to be more easily available in inch. Although plenty of Asian and Yurpian equipment is in use over here as well.

As noted above, at large sizes tolerances are such that it usually makes little or no difference.

I think the smallest match I use almost daily is a 5/16" nut driver I stole from my Dad when I was a teenager that I use on 8mm stuff. (5/32" works fine on 4mm, too.) The conversion is so close to exact that it works perfectly well.

 

[Bert_]

I do it as much as possible. I carry the absolute minimum of metric tools. If a standard wrench fits I see no reason to have it in metric.

 

[Wrench97]

I’ve used 15/16” on a 24 mm.

Next you'll tell us you used a 5/8 " on a 16mm...............

 

[dcg9381]

I do it as much as possible. I carry the absolute minimum of metric tools. If a standard wrench fits I see no reason to have it in metric.

I'm the opposite. I have "odd" sizes of metric, like 16mm.
For tough things, you need both.

 

[bwringer]

5/8" = 15.88mm (16mm)
3/4" = 19.05mm (19mm)
13/16" = 20.64mm (close, but doesn't always work on 21mm)
7/8" = 22.23mm (22mm)
15/16" - 23.81mm (24mm)
1-3/16" = 30.16mm (30mm
1-1/4" = 31.75mm (32mm)
1-3/8" = 34.93mm (35mm)
1-7/16" = 36.51mm (36mm-ish; although most tool sets don't include 1-7/16")

 

[Zimbo]

I’ve got a few sockets which have both sizes on, as mentioned before, all in the larger sizes.