I must be OLD! I HATE the Metric System!!

[Julie Moriarty]

Well, it's either I am getting OLD !! , or being stuck in the House because of the Coronavirus shutdown !! Went through the latest woodworking catalogs , and took a look at some nice Wood Chisels. I am used to the standard 1/4. 1/2, 1/8, 3/4 and 1 INCH !! Wood chisels.. WELL...... The set I looked at was in METRIC !!! Oh, it was nice looking alright. But, when I compared the Metric sizes to STANDARD INCH sizes, some were under sized, some were over sized. WHY !!! can't they make Metric sized Chisels that are equal in size to STANDARD size Wood Chisels ????

Off my Soap Box now !!

I'm slowly (VERY slowly) starting to make the mental comparisons from metric to imperial. But it's not just that. For instance, when buying plywood we find 1/4", 1/2" & 3/4", though they are all "undersized", none of which match common metric dimensions. I used a caliper to check and I'm getting 5.5mm, 11mm and 18mm.

So if I want to buy router bits for creating dados, I can only use "undersized" imperial bits. Even if we make the transition, we still have to contend with things like that.

In other words - it's good to be old.

[Jim Koepke]

I'm slowly (VERY slowly) starting to make the mental comparisons from metric to imperial. But it's not just that. For instance, when buying plywood we find 1/4", 1/2" & 3/4", though they are all "undersized", none of which match common metric dimensions. I used a caliper to check and I'm getting 5.5mm, 11mm and 18mm.

So if I want to buy router bits for creating dados, I can only use "undersized" imperial bits. Even if we make the transition, we still have to contend with things like that.

In other words - it's good to be old.

Another problem is my metric blades made for a Record #405 are different than another manufacturer's choice for size. Some makers use 18mm for 3/4" others use 20mm. Some make 25mm equivalent to 1" some use 24mm.

Could it be a conspiracy to sell more side rabbet planes?

jtk

[mike stenson]

I'm curious as to why the cutter size really matters that closely. I could probably mic most of mine and find them to vary (despite being nominally xx dimension). In the hand tool case, everything tends to be relative anyway and in the case of router bits, there are better ways to ensure that those dados are perfectly sized that do not involve buying special bits and would likely cost some scrap and a couple carriage bolts (making that relative too)

[Jim Koepke]

I'm curious as to why the cutter size really matters that closely. I could probably mic most of mine and find them to vary (despite being nominally xx dimension).

It is helpful to have various tools match in size. A mortise in a style is one example. Running a slot with an undersized plow blade can be a mess if the mortise chisel is slightly larger. Going the other way isn't a whole lot better for creating neat work.

Making a dado for shelves when using Borg pine/fir at its standard cut of 3/4" it is less fussing if the blade cutting the dado is 3/4"/19mm rather than having to trim an 18mm dado or repair a 20mm dado.

My electric router hasn't been used in years. It is too noisy for my woodworking enjoyment.

Since tools designated in dimensions to my liking exist, why should my choice to purchase those matter?

If the Borgs and everywhere else start selling a skinny 3/4", there are already some 18mm blades in my kit.

My tools have also been checked with a mic. Sometimes it is useful to know which one is slightly undersized for use when needed.

jtk

[Halgeir Wold]

Just a point... 3/4" is actually 19.05mm.... if your ply is US made as 3/4" it really should measure 19mm, but if it's import from Europe ( Baltics?), 18mm is the european standard size, - maybe sold in the US as 3/4" or "close enough"...??

[Jim Koepke]

Just a point... 3/4" is actually 19.05mm.... if your ply is US made as 3/4" it really should measure 19mm, but if it's import from Europe ( Baltics?), 18mm is the european standard size, - maybe sold in the US as 3/4" or "close enough"...??

Yes, the relationship of 3/4" and 19mm is pretty standard for automobile lug nuts. 0.05mm is less than 0.002". Most all of my 3/4" auger bits are off by more than that.

In the land of "close enough" a person is lucky if their 2X4s are 1-5/8" by 3-1/4".

When pavement thickness or concrete pour is specified as 4" a contractor's measuring standard is often an off cut of 2x4.

jtk

[Curt Harms]

When pavement thickness or concrete pour is specified as 4" a contractor's measuring standard is often an off cut of 2x4.

jtk

I've never thought about that. 4" concrete could be really 3 1/4" to 3 1/2".