I just ordered a small plow plane from lee valley and I noticed that they have blades for it in millimeter sizes. I was wondering exactly what size in millimeters is 1/4 inch undersized plywood because it would be easier to use the plywood for drawer bottoms than to make 1/4 inch panels for them.
We get to soon oldt und to late schmart
Replies
6mm is the closest at 0.234 inch ( full 1/4 = 0.250 in)
Imported hardwood-veneer plywood which is sold as quarter inch is manufactured to be 5.2 mm (.204"). (I don't know why the industry has picked that odd-ball number.) I generally find that a dado which is .20" will accept the plywood -- that is, the plywood is a tad thinner than 5.2 mm. A true 6 mm dado (.236") would be a little sloppy, but the best you can do if you're restricted to whole-millimeter sizes.
the reason I was asking they offer the blades in sizes 4mm through 10mm in 1 mm sizes. I was just wondering what would give the best fit for plywoods.
We get to soon oldt und to late schmart
If you are using ply around 1/4 inch thick for drawer bottoms then I would advise you to get three cutters to cater: 5mm, 6mm and 7mm.
There seems to be big tolerance limits with USA plys so if you buy 1/4 inch stuff (6.35mm) the 7mm cutter is the one. Remember that no ply is perfectly straight so even though you may think that there is too much difference between say 6.35mm and 7mm in practice it will be a good fit.Buy high quality furniture grade multi ply then manyh of these discrepancies disappear....
If you buy nominal 6mm ply then you have the choice of either the 5mm (for under size plys) or the 6mm.
At any rate, I would get all the cutters, and you can always grind some "specials" . Surely they are not that expensive?Philip Marcou
25.4 mm = 1 Inch
I know- it has been so for some time (;)Philip Marcou
I know- it has been so for some time
No, I think they just changed it :-)
Lee
I recently purchased several sheets of 1/4" birch plywood from my local lumber co. (not a big box store) for drawer bottoms. The client that I occasionally make drawer boxes for likes the bottoms to be a good fit in the dados so using micrometers I check all the sheets for thickness. This lot of plywood ranged from a low of 0.205 for one sheet to a max of 0.237 for the thickest sheet. This is becoming a problem as I now make the dados using a 1/8" wide blade and making multiple passes to get the exact size groove for each sheet of plywood. Wish there was a good standard for the industry. Also plywood from China is all over the lot and the face veneer is so thin that in some places the glue discoloration can be seen. Local lumber co also offers China birch at a reduced cost.
Bird,
There you go. You noted thicknesses ranging from 5.2mm to 6.02 mm in that batch-which is in my view not acceptable, but one pays for one gets....I am fairly certain that there are standards relating to ply thickness tolerances in the States, but only those in industry would be familiar. Meanwhile all the funnies get sold to Joe Public....
But are you making those drawer bottom grooves by hand with a plough?
If I had this problem I would machine the grooves to 5.5 mm and just hand plane or even sand the fat ones to fit...Philip Marcou
.. and don't forget the Veritas Side Rabbet Plane if you want to tune the gap ..
http://www.inthewoodshop.com/ToolReviews/TheVeritasSideRabbetPlane.html
Regards from Perth
Derek
Derek,You are a plane-pusher, in more ways than one!Still, it's a relatively harmless addiction.Lataxe, trying hisself not to go right down to the bottom o' that slippery, slippery slope.
I make about 50 drawer boxes a month so when I used to get a constant plywood thickness I used a router that gave me the perfect fit, now I use the table saw and do it in two passes with a 1/8" wide blade. Some of these drawer boxes are large 32" wide x 22" deep so there would be a lot of hand work if sanding or hand planing was involved.
1/4"=6.35mm
1mm=.03937"
Life is what happens to you when you're making other plans .
"Life is not a success only journey." Dr. Phil
You can always type "1/4 inches in millimeters" in a google search and google will give you an answer. Handy little tool.
I'm not the fastest guy on the planet but... why not get the 1/4" blade? The metric sizes are available but are not the standard. In fact I think the default blade size is... you guessed 1/4"!
(ack, I see now... the plywood is undersized 1/4"!)
Edited 10/7/2008 6:51 am ET by TPI
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