Thread: Dado Blades

I don't have a drama, I usually size all my stock to metric and then set the stack to the appropriate width. Most of the time, the shims are adequate for the job.

Robert

Quite so. No problem with MDF. Even if the dado head was metric, you wouldn't want to chop a size-for-size trench. Just shim as necessary - follw the table/chart that came with the unit.

Originally Posted by MurrayD99

Quite so. No problem with MDF. Even if the dado head was metric, you wouldn't want to chop a size-for-size trench. Just shim as necessary - follw the table/chart that came with the unit.

Why wouldn't I cut a 19mm trench for a 19mm board? back to the point I was trying to make, can metric sizes be assembled using imperial shims?

I always do my dado setups by trial and error and get great fit for metric - the shims are enough to do metric or imperial trenches (aka dados)

Mini, the ply and MDF boards you buy are never exactly the nominal thickness. For example, if you buy some 16mm ply sheets, you will find the thickness varies between sheets, and you could end up having a 15.5mm sheet. Having a 16mm dado setup would result is a bit of a loose dado trench.

That is why you will find most dado blade setups are a bit thinner than nominal - easier to add shims to get the exact thickness to match your timber. The chart you get with the blade tells you exactly what blades and shims to use for any thickness of timber.

Have a look here. He found that with the nominal setup of his Freud dado blades, all the cuts were actually thinner than they should have been

can metric sizes be assembled using imperial shims?

I think I was getting off the the point Mini wanted addressed. The dado blades sets are usually 1/8" outside blades, 1/8" chipper blades, and 1/16" chipper blades.

The shim sets that come with the Freud SD208 setup are all metric 0.5, 0.3, 0.2, 0.1mm thick, so yes, you can make any thickness up to 7/8" or 22.2mm.

Have a look at the chart here . You will see the imperial sizes and the combination required, and the metric measurement has been added in. You can work out the blades and shims to meet any metric thickness

Size for size tends to be too tight or loose - which could be because the stock is slightly oversize or undersize as Jill notes above. I have the Freud SD208 set and adjust for the stock I am using. There are also dial-adjust heads - I don't know how they would deal with metric dimensions. Possibly not.